Organometallic chemistry, Volume 27

Orga nometalI ic Chemistry Volume 27

A Specialist Periodical Report

Organometallic Chemistry Volume 27 A Review of the Literature Published during 1997 Senior Reporter M. Green, University of Bath, UK Reporters M.J. Almond, University of Reading, UK 3.6. Brennan, State University of New Jersey, Rutgers, Piscataway, New Jersey, USA M.I. Bruce, University of Adelaide, Australia I.R. Butler, University College o f North Wales, Bangor, UK N. Caw, University o f Bristol, UK K.R. Flower, UlMlST, Manchester, UK C.E. Housecroft, Universitat Basel, Switzerland C. Jones, University o f Wales, Swansea, UK RC. McGowan, University of Leeds, UK E.M. Page, University o f Reading, UK A. Sella, University College, London, UK R. Snaith, University of Cambridge, UK J.A. Timney, Central Newcastle High School, Newcastle upon Tyne, UK L. Tonks, University of Bath, UK S.A. Wass, University o f Reading, UK J.M.J. Williams, University o f Bath, UK D.S. Wright, University of Cambridge, UK

RSK ROYAL E)ocIETv O f CHEMISTRY

ISBN 0-85404-31 8-7 (;

The Royal Society of Chemistry 1999

All rights reserved Apurt from unyfuir dwling for the purposes of research or private study, or criticism or review us permit fed under the terms of the UK Copyright, Designs cmd Putents Act, 1988, this publicution muy not he reproduced, stored or trunsmitted, in uny form or by uny means, without the prior permission in writing of The Royul Society of Chemistry, or in the cuse of reprogruphic reproduction only in uccorrlunce with the terms of the licences issued by the Copyright Licencing Agency in the UK, or in uccordunce with the terms of the licences issued by the uppropriute Reproduction Rights Orgunizution outside the UK. Enquiries concerning reproduction outside the terms stutecl here should be sent to The Royul Society of Chemistry ut the uckiress printed on this p u p .

Published by The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 OWF, UK For further information see our web site at www.rsc.org Typeset by Computape (Pickering) Ltd. Pickering, North Yorkshire, UK Printed by Athenaeum Press Ltd, Gateshead, Tyne and Wear, UK

In the preparation of this volume there was an unavoidable delay in the delivery of one of the contributions and in order to help with the production of the volume the sequence in which the various chapters are arranged was changed. For Volume 28 we will revert to the original order and this volume will also contain the chapter on Group 4 chemistry which has not been included this year. To reflect the increasing interest in the organic aspects of organometallic chemistry more space is being devoted to this important area, and to mark this change of focus the structure of Grubb’s ruthenium carbene catalyst is displayed on the front cover of this volume. I would like to thank all the contributors for their dedication and commitment. Michael Green

V

Contents

Chapter I

Complexes Containing Metal-Carbon o-Bonds of the Groups Titanium to Manganese, Including Carbenes and Carbynes By Patrick C. McGowan, Elizabeth M. Page, Nicholas Curr and Sherilyn A . Wuss Part I: Group 4,by Patrick C. McGorvm

1

1

33

References Part 11: Group 5 , by Elizabeth M . Page

36

I Reviews

36

2 Alkyl Complexes

37

3 Alkylidene Complexes

38

4 Alkylidyne Complexes

41

5 Alkyne Complexes

42

6 Ally1 Complexes

43

7 N-Bridged Dinuclear Complexes

44

8 Aryl Oxide Complexes

44

9 Other Complexes

44

46

References Part 111: Group 6, by Nicholas Carr

47 64

References Part IV: Group 7, by Sherilyn A. Wass

68 78

References vii

...

ContenIS

Vlll

Chapter 2

Chapter 3

Chapter 4

Complexes Containing Metal-Carbon o-Bonds of the Groups Iron, Cobalt and Nickel, Including Carbenes and Carbynes BJ)Nicholus Carr

81

1 Reviews and Articles of General interest

81

2 Metal-Carbon o-Bonds Involving Group 8 , 9 or 10 Metals 2.1 The iron Triad 2.2 The Cobalt Triad 2.3 The Nickel Triad

82 82 95 105

3 Carbene and Carbyne Compounds of Groups 8 , 9 and 10

I 16

References

1 I9

Metal Carbonyls By John A. Timney

132

1 Introduction

132

2 Reviews

133

3 Theoretical, Spectroscopic and General Studies 3.1 Theoretical Studies 3.2 Spectroscopic Studies 3.3 General

133 133 134 135

4 Chemistry of the Metal Carbonyls 4. I Titanium, Zirconium and Hafnium 4.2 Vanadium, Niobium and Tantalum 4.3 Chromium, Molybdenum and Tungsten 4.4 Manganese, Technetium and Rhenium 4.5 Iron, Ruthenium and Osmium 4.6 Cobalt, Rhodium and Iridium 4.7 Nickel, Pdhdiurn and Platinum 4.8 Copper, Silver and Gold 4.9 Mixed Metal Carbonyls

136 136 136 137 138 139 141 142 142 142

References

144

Organo-Transition Metal Cluster Compounds By Michael I. Bruce

151

1 Introduction

151

ix

Contents

2 General Reviews

151

3 Spectroscopic Studies 3.1 iR 3.2 NMR

152 152 152

4 Structural Studies

152

5 Large Clusters

153

6 Group 4

157

7 Group 5

157

8 Group 6

157

9 Group 7 9.1 Manganese 9.2 Rhenium

158 158 158

10 Group 8 10.1 M3(CO),*Clusters 10.2 Iron 10.3 Ruthenium 10.4 Osmium

1 60

11 Group9 11.1 Cobalt 11.2 Rhodium 11.3 Iridium

185 185 187 188

12 Group 10 12.1 Nickel 12.2 Paliadium 12.3 Platinum

188 188 189 190

13 Group 11 13.1 Copper 13.2 Silver 13.3 Gold

191 191 191 191

14 Mixed-metal Clusters 14.1 Group 6 14.2 Group7 14.3 Group8 14.4 Group 9 14.5 Group 11

192 192 198 199 202 203

160 160 163 179

Contents

X

14.6 Clusters Containing Three Different Metals 14.7 Clusters in Catalysis

Chapter 5

References

207

Hydrocarbon Transition Metal n-Complexes Other Than q-CsH5 and q-Arene Complexes By K . R. Flower

22 1

1 Introduction

22 1

2 Reviews

22 I

3 Complexes Containing Allyls or Monodlkenes 3.1 Cr, Mo, W 3.2 Fe, Ru, 0 s 3.3 Co, Rh, Ir 3.4 Ni, Pd, Pt 3.5 Other Metals

222 222 224 227 229 232

4 Complexes Containing Unconjugdted Alkenes

234

5 complexes Containing Cyclic Conjugated Alkenes 5.1 Cr, Mo, W 5.2 Fe, Ru, 0 s 5.3 Other Metals

236 236 237 238

6 Complexes Containing Acyclic Alkenes

239

7 Complexes Containing Alkynes

242

8 Polymetallic Complexes

244 244 250 255

8.1 Bimetallic Complexes 8.2 Multimetallic Complexes 8.3 Ferrocenyl Containing Complexes

Chapter 6

206 207

References

255

q-CsH5 and q-Arene Substituted Transition Metal Complexes By I. R. Butler

271

1 Introduction and Main Group Cyclopentadienyl Ligands

27 1

2 Monocyclopentadienyls

272

xi

Conlents

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8

Lanthanides and Actinides Titanium, Zirconium and Hafnium Vanadium, Niobium and Tantalum Chromium, Molybdenum and Tungsten Manganese, Rhenium and Technetium Iron, Ruthenium and Osmium Cobalt, Rhodium and Iridium Nickel, Palladium and Platinum

272 273 273 274 275 276 278 280

3 Bis-cyclopentadienyl Compounds 3.1 Main Group, Lanthanides and Actinides 3.2 Titanium, Zirconium and Hafnium 3.3 Vanadium, Niobium and Tantalum 3.4 Chromium, Molybdenum and Tungsten 3.5 Iron, Ruthenium and Osmium 3.6 Cobalt, Rhodium, Iridium and Platinum

28 1 28 1 28 1 284 284 285 293

4 Arenes 4.1 Main Group 4.2 General 4.3 Chromium Arenes 4.4 Manganese Arenes 4.5 Iron Arenes

294 294 294 294 294 295

References

295

Chapter 7 Organic Aspects of Organmetallic Chemistry By Louise Tonks and Jonathan M .J. Williams

309

1 Introduction

309

2 Coupling Reactions: C-C Bond Formation

309

3 Coupling Reactions: C-X Bond Formation

3 10

4 Reactions Involving Carbon Monoxide

3 12

5 Allylic Substitution Reactions

313

6 Alkene Metathesis Reactions

315

7 Reactions Involving Carbenes

316

8 Hydrogenation and Related Reactions

3 19

9 Oxidation Reactions

320

xii

Chapter 8

Chapter 9

Contents

I0 Miscellaneous Reactions 10.1 Conjugate Addition Reactions 10.2 Ring-opening Reactions of Epoxides 10.3 Planar Chiral n-Complexes as Asymmetric Catalysts 10.4 Higher-order Cycloaddition Reactions 10.5 Catalytic Protonation 10.6 Electrochemically Driven Metal Catalysed Reactions

320 32 1 323 323 323 324 324

1 I Fluorous Phase Organometallic Chemistry

324

References

326

Scandium, Yttrium and the Lanthanides By John G. Brennan and Andrea Sella

329

1 Introduction

329

2 New Compounds and Complexes 2.1 Cp Compounds 2.2 Substituted Cp Ligands 2.3 Disubstituted Cp Ligands 2.4 Cp* Complexes 2.5 Linked Cp Ligands 2.6 Lanthanide Carbaboranes 2.7 Neutral Hydrocarbon Donors 2.8 Extended Aromatic Anions 2.9 Cyclooctatetraene 2.10 Nitrogen-based Supporting Ligands 2.1 1 Organolanthanideswithout Ancillary Ligands 2.12 Halide Compounds

329 329 329 33 1 332 333 334 334 335 336 336 337 338

3 Polymerization Catalysis 3.1 Ethylene and Other Simple Olefins

339 339

4 Lanthanide Organometallics in Organic Synthesis

339

5 Theoretical and Spectroscopic Studies 5.1 Hypothetical and Labile Species 5.2 Molecular Complexes

340 340 341

References

342

Organometallic Chemistry of Group 15 Elements By Cameron Jones

347

1 Phosphorus

347

...

Conten i s

xi11

2 Arsenic, Antimony and Bismuth

351

References

354

Chapter 10 Carbaboranes, Including Their Metal Complexes By Catherine E. Housecroft

359

1 Introduction

359

2 Theoretical and Spectroscopic Studies

359

3 Rings and Ring Stacking

360

4 Composition CJ3, and C3B,

36 1

5 Composition C2B3

362

6 Composition CB4 and C2B4

362

7 Composition C2B8

364

8 Composition CBg, CBloand CBII

364

9 Composition C2B9

365

10 Composition C2BIO

37 1

11 Studies Relating Specifically to BNCT

375

References

376

Chapter 11 Group 13: Boron, Aluminium, Gallium, Indium and Thallium By M.J . Almond 1 Boron

1.1 General 1.2 Compounds Containing Nitrogen, Oxygen or Phosphorus 1.3 Compounds Containing a Metal Atom 2 Aluminium 2.1 Compounds Containing Nitrogen 2.2 Compounds Containing Oxygen or Sulfur 2.3 Compounds Containing Another Metal Atom

380 380 380 38 1 383 390 390 394 400

Contents

xiv

3 Gallium 3.1 General 3.2 Compounds Containing a Group I5 Element 3.3 Compounds Containing a Group 16 Element 3.4 Compounds Containing Another Metal Atom

402 402 403 406 407

4 Indium

408

5 Thallium

4 I4

References

415

Chapter 12 Group I: The Alkali and Coinage Metals By R. Snuith

419

1 Alkali Metals 1.1 Introduction: Organisation and Major Advances I .2 Alkyl Derivatives 1.3 Alkenyl, Allyl, Vinyl, Alkynyl and Related Derivatives I .4 Aryl Derivatives 1.5 Cyclopentadienyl and Related Derivatives

419 419 419 423

2 Copper, Silver and Gold 2.1 Introduction: Organisation and Major Advances 2.2 Copper Compounds 2.3 Silver Compounds 2.4 Gold Compounds

427 427 427 428 429

References

43 1

Chapter 13 Group 2 (Be-Ba) and Group 12 (Zn-Hg) By Dominic S. Wright

424 426

435

1 Scope of the Review

435

2 Group2

435

3 Group 12

439

References

444

Author Index

449

Abbreviations

Ac acdC acacen Ad AIBN amPY Ar Ar* arphos ATP Azb 9-BBN BHT BINAP biPY Bis bma BNCT BP bpcd bPk t-bupy Bz Bzac cbd 1,5,9-~dt chd chpt CIDNP [COI (CO) cod coe cot CPIMAS CP CPR CP*

acetate acetylacetonate NN‘-ethylenebis(acety1acetone iminate) adamantyl azoisobutyronitrile 2-amino-6-methylpyridine Aryl 2,4,6-tri(t-buty1)phenyl 1-(diphenylphosphinio)-2-(diphenylarsino)ethane adenosine triphosphate azobenzene 9-borabicyclo[3.3.1Inonane 2,6-dibu t yl-4-met hylphenyl 2,2’-bis(dipheny1phosphino)-1,l’- binaphthy1 2,2’-bipyridyl bis(trimethylsi1yl)methyl 2,3-bis(diphenylphosphino)-maleic anhydride boron neutron capture therapy biphenyl 4,5-bis(diphenylphosphino)-cyclopent-4-en-1,3-dione benzophenone ketyl (diphenylketyl) t-butylpyridine benzyl benzoy lacetonate cyclobutadiene cyclododeca-1,5,9-triene cyclohexadiene cycloheptatriene Chemically Induced Asymmetric Nuclear Polarisation cobalamin cobalozime [Co(dmg)2derivative] cyclo-octa-1,5-diene cyclo-octene cyclo-octatriene Cross Polarization/Magnetic Angle Spinning q5-cyclopentadienyl q5-alkylcyclopentadienyl q5-pentamethylcyclopen tadieny l xv

A bbreviutions

xvi

CP' Cp" CV CY Cyclam CYm CYttP dab dabco dba dbpe DBU DCA depe depm DFT diars diarsop dien diop DIPAMP diphos DiPP dipyam DMAD DMAP DME DMF dmg dmgH dmgH2 DMP dmpe dmpm dmpz DMSO dpae dpam dPPa dPPb dPPbZ dPpe dPPf dPPm

trimeth ylsilylcyclopentadienyl tetrameth ylethylcyclopentadienyl cyclic voltammetry( ogram) cyclohexyl 1,48,11-tetraazacyclotetradecane p-cymene PhP(CH2CH2CH2PCyz)z 1,4-diazabu tadiene 1,4-diazabicycl0[2.2.2]octane dibenzylideneacetone 1,2-bis(dibutylphosphino)ethane 1,8-diazabicyclo[5.4.O]undec-7-ene 9,l O-dicyanoanthracene 1,2-bis(diethyIphosphino)ethane 1,2-bis(diethyIphosphino)methane density functional theory o-phenylenebis( dimethy1)arsine { [(2,2-dimethyl- 1,3-dioxolan-4,5-diyi)bis(meth ylene)]bis[diphenylarsine]} diethylenetriamine { [(2,2-dimethyl- 1,3-dioxolan-4,5-diyl)bis(meth ylene)]bis- 1-[diphenylphosphine] ) 1,2-bis(phenyl-o-anisoylphosphino)ethane 1,2-bis(diphenyIphosphino)ethane 2,6-di-isopropylphenyl di-(2-pyridy1)amine dimethyl acetylenedicarboxylate 2-dimethylaminopyridine 1,2-dimet hoxyethane NN-dimeth y1formamide dimethylglyoximate monoanion of dimethylglyoxime dimeth ylglyoxime dimethylpiperazine 1,2-bis(dimethyIphosphino)ethane bis(dimet hy1phosphino)methane 1,3-dimet h y lpyrazol yl dimethy1 sulfoxide 1,2-bis(diphenyIarsino)ethane bis(dipheny1arsino)methane 1,2-bis(diphenyIphosphino)ethyne 1,4-bis(diphenylphosphino)butane 1,2-bis(diphenylphosphino)benzene 1,2-bis(diphenylphosphino)ethane 1,l '-bis(dipheny1phosphino)ferrocene bis(dipheny1phosphino)methane

xvii

Abbreviutions

dPPP DSD edt EDTA ee EELS EH MO ELF en ES MS EXAFS F6aCdC Fc Fe* FP FP' FTIR FVP glyme GVB HBpz3 HBpz*3 H4cyclen HEDTA hfa hfacac hfb HMPA HNCC HOMO IGLO im Is* ISEELS KTP LDA LiDBB LNCC MA0 Med 14ldieneN4

4,7-Me2phen 3,4,7,8-Me4phen Mes

1,3-bis(diphenyIphosphino)propane diamond-square-diamond ethane-1,Zdithiolate ethylenediaminetetraacetate enantiomeric excess electron energy loss spectroscopy extended Huckel molecular orbital electron localisation function ethylene-1,2-diamine electrospray mass spectrometry extended X-ray absorption fine structure hexafluoroacety lacetonate ferroceny I Fe(CO)2Cp* Fe(COkCp Fe(C0)2(q5-C5H4Me) Fourier Transform Infra-red flash vacuum pyrolysis ethyleneglycol dimethyl ether generalized valence bond tris(pyrazoly1)borate tris(3,5-dimethylpyrazoly1)borate tetrdazd-1,4,7,1O-cyclododecane N -hydroxyethylethylenediaminetetraacetate hexafluoroacetone hexafluoroacetylacetonato hexafluorobutyne hexamethyl phosphoric triamide high nuclearity carbonyl cluster highest occupied molecular orbital individual Gauge for localized Orbitals imidazole 2,4,6-tri-isopropylphenyl inner shell electron energy loss spectroscopy potassium hydrotris( 1-pyrazolyl)borate lithium diisopropylamide lithium di-t-butylbiphenyl low nuclearity carbonyl cluster methyl alumoxane 5,7,7,12,14,14-hexamethyl1,4,8,I 1-tetra-azacyclotetra4,11-diene 5,5,7,12,12,14-hexamethyl-l,4,8,1 l-tetraaZaCyClOtetrddeCdne 4,7-dimethyl-1,I 0-phenanthroline 3,4,7,8,-tetramethyl-1,lO-phenanthroline mesityl

xviii

Abbreviations

2,4,6-tri-butylphenyl Mes* methyltetrahydrofuran MeTHF metachloroperbenzoicacid mcpba Metal-Ligand Charge Transfer MLCT 1-naphthyl nap norbornene nb norbornadiene nbd N-bromosuccinimide NBS N-chlorosuccinimide NCS neutron capture theory NCT neopenty1 Neo 1-naphthyl NP N(CH2CH2PPh& np3 nitrilotriacetate nta octaethylporphyrin OEP trifluoromethanesulfonate (triflate) OTf phthalocyanin Pc photoelectron spectroscopy PES pentamethylenediethylenetetramine PMDT pentane-2,4-dionate Pd 1,lo-phenanthroline phen pentamethyldieth ylenetriamine pmedta P(CH2CH2PPh2)3 PP3 [PPN]+ [(Ph3P)*NI+ pyridine PY pyridazine PYdZ py razoly 1 PZ (R)-(+)-1,2-bis(diphenylphosphino)propane R-PROPHOS R,R-SKEWPHOS (2R,4R)-bis(diphenylphosphino)pentane radial distribution function RDF ring opening metathesis polymerisation ROMP salicylaldehyde sal NN’-bis(salicyla1dehydo)ethylenediamine salen NN-bisalicylidene-o-phenylenediamine saloph self consistent field SCF tet racyanoethy lene TCNE 7,7,8,8-tetracyanoquinodimethane TCNQ 2,2’,2”-terpyridyl terpy 1,1,4,7,10,10-hexaphenyl1,4,7,1O-tetraphosphadecane tetraphos trifluoroacetic acid TFA tetrafluorobenzobarrelene tfbb trifluoroacetylacetonato tfacac triflate, trifluoromethylsulfonate tfo tetrahydrofuran THF thiosalicylate (2-thiobenzoate) thsa tetra hydrot hiophen tht

xix

Abbreviutions

TMBD TMEDA (tmena) tmP TMS tot TP TP* TPP Trip Triph triphos TRIR Tsi TTF vi WGSR XPS XYl

NN N’N”-tetramethyl-2-butene1,4-diarnine tetramethylethylenediamine 2,2,6-6-tetramethylpiperidino tetramethylsilane tolyl hydrotris( 1 -pyrazolyl)borate hydrotris(2,5-dimethylpyrazolyl)borate meso-tetraphenylporphyrin 2,4,6-triisopropylphenyl 2,4,6-(tripheny1)phenyi 1,1,1 -tris(diphenylphosphinomethyl)ethane Time resolved infrared (spectroscopy) tris(trimethylsi1yl)methyl (Me3Si)3C tetrathiafulvalene vinyl water gas shift reaction X-Ray Photoelectron spectroscopy XYlYl

1 Complexes Containing Metal-Carbon o-Bonds of the Groups Titanium to Manganese, Including Carbenes and Carbynes BY PATRICK C. MCGOWAN, ELIZABETH M. PAGE, NICHOLAS CARR and SHERILYN A. WASS

Part I:Group 4 by Patrick C. McGo~van This article will solely concentrate on the formation and reactivity of o-carbon bonds of Group 4 compounds. There is still a great effort in the quest for catalytically active species for this group and there has been much published in the last year concerning the evaluation and activity of catalysts for Group 4. This article will not discuss the catalytic activity of Group 4 complexes and focus on the making and breaking of the MC o-bond. MNp,C14-x (x = 1,2,3) can be synthesised by the comproportionation reaction between the titanium and zirconium homoleptic neopentyl complexes, TiNp4 and ZrNp4 (Np = 2,2'dimethylpropyl; CH2CMe3)and the metal tetrachlorides, TiC14 and ZrC14. All the complexes described are moisture-sensitive, and light-sensitive in the case of the titanium complexes. The neopentyl chloro complexes, and the isotopically labelled species (where (Np-d) = CH(D)CMe3), have been spectroscopically characterised, the 'H NMR resonance of the CH2 protons displays an increasing shift to high frequency in the series MNp4, MNp3C1, MNp2C12, MN pC13. Treatment of the titanacyclopentadiene compound [Ti(OC,H3Ph2-2,6)&Eh)] 1 (OCbH3Ph2-2,6 = 2,6-diphenylphenoxide) with olefins leads to the formation of a variety of stable titanacyclopentane derivatives along with one equivalent of substituted 1,3-cyclohexadiene.The structural and spectroscopicproperties of the ethylene product [Ti(OC6H3Ph2-2,6)2(CH2)4] 2 show a ground state titanacyclopentane structure, but facile fragmentation on the NMR time scale to form a bis(ethy1ene) complex has been detected. The substituted products [Ti(OC6H3Ph2-2,6)2(C4H6R2)1 (R = Met Et, Ph) formed from a-olefins RCH=CH2 exist as a mixture of regio- and stereoisomers in hydrocarbon solution. Alternative routes to the titanacyclopentane compounds involve treatment of the dichlorides [Ti(OC6H3Ph2-2,6)2C12] or [Ti(OC6HPh4-2,3,5,6)2C12] with either sodium amalgam (2 Na per Ti) or 2 equivalents of ("BuLi) in the presence of the substrate olefin. Using these conditions the titanabicyclic com-

'

Organometallic Chemistry, Volume 27 0The Royal Society of Chemistry, 1999 1

2

Orgunometuiiic Chemistry

pounds [(A~O)~T~{CH~CH(C~HS)CHCH~)](A~O = OCbH3Ph2-2,6, OC6HPb2,3,5,6) can be obtained by intramolecular coupling of 1,7-0ctadiene. Addition of phosphine donor ligands (L) leads to a series of titanacyclopropane compounds [Ti(OC6H3Ph2-2,6)2(q2-CHR=CH2)(L)] (R = H, Me, Et, Ph) along with 1 equivalent of olefin. Addition of Ph2C=O or PhCH=NR (R = Ph, CH2Ph) to the titanacyclopentane and titanacyclopropane compounds leads to different products depending upon the reagent and reaction conditions. These can be classified as 2-oxa(aza)titanacycloheptanes, 2-oxa(aza)titanacyclopent~nes,2,5diioxa(diaza)titanacyclopentanes, and examples of 2-oxatitanacyclopropane (q2-ketone) and 2,7-dioxatitanacycloheptanecompounds. The 2-azatitanacyclopentane compounds [Ti(OC6H3Ph2-2,6)2((PhCH2)NCH(Ph)CH2CH2)] and trans[Ti(OC6H3Ph,-2,6)2((Ph)NCH(Ph)CH2CH(Ph)}] react with alkynes to produce the corresponding 2-azatitanacyclopent-4-ene which hydrolyse to produce a stoichiometric equivalent of allylamine.2

Tetravalent titanium complexes 3 containing the ethylene-linked bis(pheno1ato) ligand ebmp (R = Me, Ph, CH2Ph, CH2SiMe3) exhibit a C2-symmetry. in solution, a fluxional process equivalent to an enantiomerisation is d e t e ~ t e d . ~ Reaction of two equivalents of N-trimethylsilylaniline with two equivalents of n-butyllithium, followed by subsequent treatment with Si2Ci6 leads to the formation of the tetrachlorodisilane RSiC12SiC12R (R = PhNSiMe3). This is

4

3

I : Complexes Contuining Metal-Curbon o-Bonds of the Groups Titunium to Mangunese

3

converted to RSi(NH2)2Si(NH2)2R by reaction with liquid ammonia and RSi(NH2)2Si(NH&R reacts with TiCp*(Me)3 to yield the diazadisilatitanacyclopentane RSi(NH2)N HTi Me(Cp*)NHSi(NH2)R 4.4 The bis(benzy1) [(cb)2Ti(CH~Phh]5 and alkylidene bridged dimer [(cb)2Ti(pCHSiMe&Ti(cb)2] are formed by adding carbazole [Hcb = N(C6H11)2] to the tetraalkyls piR4] (R = CH2Ph, CHzSiMe3); the reaction with 2,6dimethylphenyl isocyanide leads to organometallic products containing new carbon-carbon bonds Me

WH*' S

6

The chemistry of electrophilic zirconium complexes stabilised by a sterically open diamide ligand has been studied. [{ Me2Si(NCMe3)2}ZrCI2]2(THF) was converted to diafkyi complexes { Me2Si(NCMe3)2)ZrRz 7 (R = CH2Ph, CH2CMe3) using M g B ~ ~ ( d i o x a n eand ) ~ .LiCH2CMe3, ~ respectively, but dimethylation was unsuccessful. Alkyl abstraction from 7 using B(C6F5)3 cleanly afforded { Me2Si(NCMe&)Zr(CH2Ph)( q6-PhCH2B(C6F5)3} 8, in which the anion strongly coordinates to the benzylzirconium cation via the aromatic ring. Protoafforded the Lewis-base adduct [{Me& nolysis of 8 using [PhMe2NH3fB(C6F5)41 (NCMe3k)Zr(CH#hXNMe2P?i)]+, whereas [Ph3C][B(C6F5)4I gave 1 equivalent of Ph3CCH2Ph and a mixture of two cationic species, proposed to be monomeric and dimeric benzylzirccmium cations. Reaction of 8 with 0.5 equivalent of the trityl reagent afforded the dizirconium complex [ { MezSi(NCMe3)2)2Zr2(CH2Ph)3]+. The cationic species 8 cleanly and rapidty reacted with 2butyne to afford the single insertion product, [ { Me2Si(NCMe3)2}Zr{q ',q6C(Me)=C(Me)CHzPh 1If, stabilised by a chelating n-coordination of the benzene ring of the hydrocarbyi ligand. 8 also underwent single alkene insertion giving {Me2-Si(NCMe,),)Zr{qt-CH&H(R)CH2Ph) { q6-PhCH2B(C6F,),) (R = H, Me), stabilised by anion coordination to zirconium. The dramatic effects of anion, Lewis base, wtvent, and substrate variation on the rate of insertion have been rationalised in terms of the facility of anion or base dissociation from the twnzylzirconium cation!

Orgunomrtullic Chemistry

4

L2ZrCI2 [L = PhC(NSiMe3)2], reacted cleanly with 1 equivalent of MezMg in Et2O to give LzZrMe2 which was isolated as colourless crystals from CH2C12 or Et20. Attempting to prepare the methyl chloride derivative using 0.5 equivalent of Me2Mg yielded mixtures of dichloride, dimethyl and methyl chloride derivatives. L2ZrC12 reacted cleanly with 1 equivalent of the bulkier alkyl LiCH2SiMe3 giving L2Zr(CH2SiMe3)C1. Reactivity of methyl derivatives with a variety of small molecules (CO, C02 or acetone) is reported. The dimethyl compound, L2ZrMe2, reacted cleanly with B(C6F5)3 to form the methyltriarylborate complex L2Zr[MeB(C6F5)3]Me.Additionally, several other derivatives are conveniently prepared by salt-metathesis reactions with the dichloride including; L2Zr(CH2Ph)2, L2Zr(OS02CF3)2, L2Zr[NH(C6H3Pri2-2,6)]Cl, L2Zr(BH4)2, L2Zr[ESi(SiMe3)3]C1(E = Se or Te). The 1% Na-Hg amalgam reduction of L2ZrC12 in the presence of diphenylacetylene or trimethysilyl-acetylene yielded

9

orange zirconacyclopentadienes L2Zr(C4Ph4) 9 and LzZ~[C~H2(SiMe~)~-2,41 in moderate yields. The compound L2Zr(C4Ph4)reacted readily with CO to give the dark red q2-cyclopentadienone L2Zr[q2-C(0)C4Ph4]. Analogously, reduction in the presence of ethylene gave the zirconacyclopentane, L2Zr(C4H8), in good yield. When the reduction is carried out in the absence of any trapping ligands, however, a benzamidinate ligand is oxidatively cleaved and the dimeric imidoiminoacyl compound, [LZr(q2-PhCNSiMe3)(p-NSiMe3)]2, is isolated as orange crystals in moderate yield.7 The titanium diamide complex [ArN(CH2)3NAr]TiMe2 (Ar = 2,6-iPr2C6H3) reacts with B(C&5)3 in pentane to give an insoluble yellow-orange solid, of which pentane suspensions slowly evolve methane over the course of several hours to give the new pentane-soluble derivative [ A ~ N ( C H ~ ) ~ N A ~ ] T ~ [ C H ~ B ( C ~ F ~ ) Z ] ( C 10, which was structurally chardcterised. Addition of a BC6F5 group across an intermediate Ti=CH2 unit is proposed. The reaction of 2 equivalents of LiNHAr (Ar = 2,6-iPr2C6H3) with 1,3dibromopropane yields the diamine ArHN(CH&NHAr ((BAIP)H2). Several zirconium starting materials are prepared from this and alkylation of (BAIP)ZrCl2pyz or (BAIP)ZrC12 with 2 equivalents of MeMgBr, 2 equivalents of

10

11

I : Complexes Containing Meiui-Curbon a-Bonds of the Groups Tiiunium to Mungunese

5

PhCH2MgC1, and 1 equivalent of NaCp(DME) which yield the alkyl derivatives (BAIP)ZrR2 (R = Me, CH2Ph) 11 and (BAIP)Zr(q5-CSHS)C1,respectively. The reaction of 2 equivalents of PhMe2CCH2MgCI with complex (BAIP)ZrC12py2 yields the q2-pyridyl complex (BAIP)Zr(q5-N,CNC5H4)(CH2CMe2Ph). An Xray study of the latter revealed a capped tetrahedron geometry with the pyridyl nitrogen occupying the capping position.' A (CNN)titanium(IV) (CNN = monoanionic C ~ H ~ ( C H ~ N ( M ~ ) C H ~ C H T N Me2)-2) dimethyl complex 12 is accessible via reaction of [TiC12(CNN)(01Pr)] with two equivalents of MeLi and contains likewise an q3-fac-C,N,N'-bonded CNN ligand.''. ' I

12

Titanium complexes bearing the pyridine diamide ligands [2,6(RNCH2)2NCSH&- (R = 2,6-diisopropylphenyI (BDPP); R = 2,6-dimethylphenyl (BDMP)) have been synthesised. Reduction of the dichloride precursors (BDPP)TiC12 and (BDMP)TiCI2 with excess 1% Na/Hg amalgam in the presence of >2 equivalents of internal (PhC =CPh, EtC =CEt, PrC = CPr) or terminal (HC E CSiMe3, PhC 5 CH) alkynes yields metallacyclopentadiene derivatives in good yield. The a,&substituted titanacycle (BDPP)Ti[C4H2(SiMe3)2] 13 was characterised by X-ray crystallography and is best described as a distorted square pyramid with the metallacycle carbon C(4) occupying the apical position. The a,a-substituted titanacycle (BDMP)Ti[C4H2(SiMe3)2] reacts with excess 3-hexyne and 4-octyne to give the asymmetric metallacycles (BDMP)Ti[C4Et2H(SiMe3)] and (BDMP)Ti[C4Pr2H(SiMe3)], respectively. l 2 The synthesis, structures, bonding and reactivity of neutral (0x)zMR~and cationic (Ox)2MR+ zirconium and hafnium alkyl complexes which contain substituted 8-quinolinolato ligands (Ox- = 2-Me-8-quinolinolato, MeOx-, 2; 2Me-5,7-Br2-8-quinoIinolato, MeBrZOx-) are described. Alkane elimination and halide displacement reactions provide routes to (MeOx)2ZrR2 (R = CHzPh, CH2CMe3, CH2SiMe3), ( M e o ~ ) ~ H f ( C H ~ p (MeBr20~)~ZrR2 h)~, (R = CHZPh, CH2CMe3), ( M e B r 2 0 ~ ) ~ H f ( c H ~ P h(MeOx)2ZrClz, )~, (MeBr20x)2ZrCI2, and (MeBr2Ox)zZr(NMe&. An X-ray crystallographic analysis shows that in the solid state ( M ~ O X ) ~ Z ~ ( C adopts H ~ P ~a) distorted ~ octahedral structure with a trans-0, cis-N, cis-R ligand arrangement and that one of the benzyl hgands is bonded in an q2-fashion. Solution NMR data are consistent with this structure and establish that exchange of the distorted and normal benzyl hgands is rapid on the NMR time scale. Thennolysis of (MeBr*Ox)2Zr(CH2Ph)2 results in

Organomerallic Chemistry

6

Br

Br

14

migration of a benzyl ligdnd from Zr to C2 of a MeBrzOx- ligand, yielding (MeBr20x)(2-Me-2-CH2Ph-5,7-Br2-Ox)ZrCH2Ph 14 as a single diastereomer. Reaction of (MeOx)*ZrR with [HNMe2Ph][B(C6F5)4] yields the base-free cationic ) ~ ] ( R CH2CMe3).l 3 complexes [ ( M ~ O X ) ~ Z ~ ( R ) ] [ B ( C ~ F=~CH2Ph, The reaction of Zr(CH2Ph)4with the pyridine alcohols 6-pyCR' R20H (R' = R2 = CF3; R' = R2 = Me; R' = H, R2 = CF3) yields dibenzyl complexes (pyCR' R20)2Zr(CH2Ph)2. These species adopt distorted octahedral structures with a trans-0, cis-N, cis-C ligand arrangement but undergo rapid inversion of configuration at Zr on the NMR time scale, with racemisation barriers in the range from 8.6 to 10.1 kcal/mol. (pyCR' R20)2Zr(CH2Ph)2 reacts with B(C6F5)3 to yield [(pyCR'R20)2Zr(CH2Ph)][PhCH2B(C6F5)3] and with [HNMetPhj[B(C6F5)4]to yield [(pyCR'R20)2Zr(CH2Ph)][B(C6F~)4](R'= R2 = CF3; R' = R2 = Me; R' = H, R2 = CF3). NMR spectra indicate that the latter complexes are not strongly ion-paired in CD2C12.l4 Alkylation of [NON]Zr12with MeMgI in diethyl ether gives [NON]ZrMe2 15 in 70% yield. NMR spectra even at -7O"C, suggest that it has C2v symmetry on the N M R time scale. Addition of B(C6F5)3to 15 afforded 16 is stable in the solid state at -35°C and an X-ray study of 16 showed it to be the 'zwitterion' analogous to structurally characterised compounds obtained by adding B(C6F5)3

I : Complexes Contuining Metal-Curbon a-Bonds of the Groups Titunium to Mungunese

7

to Group 4 methyl metallocenes. In the same paper, alkylation of Ti[NON]C12 with 2 equivalents of MeMgCl affords [NON]TiMe2.'5 The reaction of C6Hlo(NLiSiMe3)2-l,2(Li2L') with [ZrC14(thf),] (thf = tetrahydrofuran) afforded the tetra-amide [ZrL12]. Similarly treatment of (RHNSiMe2)20 (H2L2,R = Bu; H2L3,R = cyclohexyl) with LiBu" followed by [ZrC14(thf)2]led to [ZrL22Jand [ZI-L~~], respectively. Reaction of Zr(CH2Ph)4 with H2L3gave the pale yellow zirconium dibenzyl compound [Zr(CH2Ph)2L3], while the analogous reaction with H2L4 (R = quinolin-8-yl) led to ruby-red [Zr(CH2Ph)2L4]17. In addition the bis(pyrro1e) [(2-C4H3NH)CH=NCH& (H2L5) reacted with Zr(CH2Ph)4giving the complex [Zr(CH2Ph)2LS].In 17 all available donor atoms co-ordinate to zirconium, including the silyl ether moiety, leading to a distorted trigonaI bipyramidal structure for [Zr(CH2Ph)2L3] and an approximately pentagonal bipyramidal geometry for 17. Although L3 and L4 have flexible frameworks, the heteroatom donors and the metal form an essentially coplanar arrangement. The zirconium-amido nitrogen distances proved to be highly variable, depending on the degree of electron deficiency and the co-ordination of the metal centres,l 6

17

Progressing from the 'open amide and alkoxy systems', there has been much work carried out on macrocyclic systems. The synthesis, characterisation, and reactivity of a series of neutral and cationic Zr alkyls supported by DAC (deprotonated 4,13-diaza-l8-crown-6) ligation are reported. Reaction of H2DAC with Z ~ ( C H Z Paffords ~ ) ~ a 1:4 mixture of cis- and rrans-Zr(DAC)(CH2Ph)2.The pure isomers undergo slow cis-trans isomerisation in solution to regenerate the 1:4 cis:truns equilibrium mixture. Reaction of Zr(CH*Ph)2C12 with H*DAC, followed by treatment with LiR (2 equivalents), gives cis-Zr(DAC)R2 (R = CH2SiMe3, CH2CMe3) exclusively. Alkyl abstraction from cis- or transZr(DAC)(CH2Ph)2using B(C6F5)3 ( 1 equivalent) produces the stable cation [Zr(DAC)(CH2Ph)]' [B(CH2Ph)(C6F5)3]- as a yellow oil. NMR studies in CD2C12 show no evidence for q2-benzyl formation or anion coordination. Protonation with [n-Bu3NH]+ [BPh4]- similarly yields [Zr(DAC)(CH2Ph)J'

8

Organometullic Chemistry

[BPh4]-. [Zr(DAC)(CH2Ph)]' [B(CH2Ph)(C6F5)3]- reacts with t-BuNC to form the vinyl amide complex [Zr(DAC)(N(t-Bu)CH=CHPh}]+ [B(CH2Ph)(C6F5)31 - Floriani et al. have examined the formation and the main properties of Zr-C functionalities supported by the O4 matrix of either the monoalkylated (trianionic) or dialkylated (dianionic) forms of [p-Bu'-calix[4]arene]. The alkylation of [p-But-calix[4]-(OMe)2(0)2ZrC12]led to the corresponding dialkyl/aryl derivatives [p-Bu'-cali~[4]-(OMe)~(O)2ZrR2] (R = Me, CH2Ph, CH2SiMe3, pMeC6H4). They undergo a base-induced demethylation and de-alkylation illustrated by the obtention of [p-BuL-calix[4]-(OMe)(0)3Zr(CH2Ph)(Py)],while the thermal decomposition gives a particularly interesting result, with the formation of the corresponding q2-benzyne, [p-Bu'-calix[4]-(OMe)2(0)2Zr(q2MeC6H3)]. Cationic alkyl derivatives of zirconium have been obtained, using the monoelectronic oxidising agent [Cp2Fe]+ or a strong Lewis acid such as B(C&5)3, to give [p-Bu'-cali~[4]-(OMe)~(0)2Zr(CH2Ph)]+BPh4-, [p-But-calix[4]-(OMe)2(0)2Zr(CH2Ph)(thf)]+BPh~and [p-BuL-calix[4](OMe)2(0)2Zr(CH2Ph)]' [B(C6F5)3(CH2Ph)]-. The cationic alkyl derivatives undergo easy demethylation by pyridine to give [p-BuL-calix[4](OMe)(O),Zr(CH2Ph)(Py)]. The alkylation of [CI-P-B~'-~~~~X[~]-(OM~) with LiPh led to a dimeric dimetallic aryl compound, [(pL-p-Bu'-calix[4](OMe)(0)3}2Zr2Ph2] 18, where the calix[4]arene unit bridges two metal atoms and the methoxy groups are only weakly bound to the metal. The spectator methoxy group binds strongly to the metal in the monomeric q2-iminoacyl [pBu'-calix[4]-(OMe)(0)3Zr(BuN'=CPh)] , formed from the migratory insertion of BuNC' into the Zr-Ph bond. Six of the proposed structures in the paper have been supported by X-ray crystallography. l 8 Chemistry of this system was exploited further by way of migratory insertion of carbon monoxide and isocyanides into the metal-carbon bonds of the ZrR2 fragment anchored to the tetroxo matrix. The relevant differences between the two fragments [p-Bu'-cdli~[4]-(OMe)2(0)2Zr]~+and [Cp2ZrI2+are experimentally proven and theoretically interpreted. Unlike those for [CpZZrI2+derivatives, the reaction of CO with [p-BuL-calix[4]-(OMe)2(0)2ZrR2][R = Me, CH2Ph, pMeC6H4] proceeds via a two-step migration directly to the corresponding q2metal-bonded-ketones [p-Bu'-calix[4]-(OMe)2(0)~Zr{q2-C(R2)0}] (R = Me, CHZPh, p-MeC6H4) 19. The Zr-C functionality in 19 maintains its inserting capability in the reaction with ketones, i.e., Ph2C0, leading to the diolate (R = p-MeC6H4), or derivative [p-Bu'-calix[4]-(OMe)2(0)2Zr{OC(R~)C(Ph~)O}] with Bu'NC, forming [p-But-calix[4]-(OMe)2(0)2Zr(OC(Me2)C(CN Bu')N(Bu')}]. The reaction of [p-Bu'-calix[4]-(0Me)2(0)2ZrR2] with Bu'NC proceeds through two different pathways, depending on the temperature and the R substituent at the metal. The first one leads to the q2-metal-bonded imine [p-BuL-calix[4](OMe)2(0)2Zr{q2-N(Bu')C(R2)}] [R = Me, CHzPh], which inserts two additional molecules of Bu'NC to give a metalladiazacyclopentane, [p-BuL-calix[4](OMe)2(0)2Zr(N(Bu')C(Me2)C(CNBu')N(Bu')}]. The second pathway led, at low temperature, to the bis-q2-iminoacyls [p-Bu'-calix[4]-(0Me)2(0)2Zr{q2N(Bu')=C(R)}2] [R = Me, p-MeCsH41, which at 60°C couple to the corre-

I : Complexes Containing Metal-Curbon a-Bondsof the Groups Titanium to Mangunese

18

9

19

sponding enediamido ligand in [p-BuL-calix[4]-(OMe)2(0)2Zr(N(Bu')C(R)= C(R)N(Bu')}] [R = Me, p-MeC6H4]. The most significant differences between [p-B~'-calix[4]-(OMe)~(O)~Zr]~+ and [Cp2ZrI2 have been interpreted on the basis of the frontier orbital sets of the two fragments.'' Butadiene derivatives were prepared using the same starting material [{ p-Bu'c d l i ~ [ 4 ] - ( 0 M e ) ~ ( O ) ~ } Z ~by l ~ ] reaction with Mg(C4Hs)(thf)2 and Mg(Ph&H4)(thf)3 which led to [ { p-BuL-calix[4]-(OMe)2(0)2) -Zr(q4-C4H~)]20 and [(p-Bu'-cali~[4]-(0Me)~(0)2)Zr(q~-Ph~C~H~)]. The butadiene fragment exhibits a n2, q4 bonding mode, as shown by an X-ray analysis on both compounds. Extended Huckel calculations confirmed the energetically preferred s-cis conformation and the 7~ 2, q4 bonding mode vs. the 02,n, q4 one. The parent compound 20 of this series behaves, however, both as a source of zirconium(I1) in displacement reactions or as a dialkyl derivative of zirconium(1V) in insertion reactions. In the former class of transformations, the reaction of 20 with Ph2CO and PhCOCOPh led to the dioxo metallacycles [ { p-But-calix[4]-(OMe)2(0)2) -2r { -0C(Ph)2-C(Ph)20-}], and [{ p-BuL-calix[4](OMe)2(0)2)Zr{-OC(Ph)=C(Ph)O-))I respectively. Butadiene was also displaced by diphenylacetylene leading to [{ p-BuL-calix-[4]-(OMe)~(0)~} Zr(q2Ph2C2)], and by a phenylnitrene source [PhNJ forming the binuclear phenylimido-bridged complex [{ p-But-calix[4]-(OMe)~(0)~} 2Zr2(pNPh)2]. Ph2CO reacted with 20 at low temperature to form [{ p-But-calix[4](OMe)2(0)2)Zr(CH2CH=CHCH2C(Ph)20}] and [(p-BuL-calix[4](OMe)~(0)~}Zr(OC(Ph)2-CH2CHdCHCH2C(Ph)20-}].Using 2 mol of acetone, [(p-But-calix[4](OMe)2(0)2)Zr{-OC(Me)2CH2CH=CHCH2C(Me)20-}] was obtained. MeCN and EtCN inserted in single Zr-C bond (of a formal 02, A, q4 structure) yielding [ {p-BuL-calix[4]-(OMe)2(0)2} - Zr{-CH2CH=CHCH2C(Me)=N-)] and [{ p-Bu'cali~[4]-(OMe)~(O)~}Zr{ -CH2CH=CHCH2-C(Et)=N-)]. Bu'NC engaged 20 in a multi-step insertion reaction leading to [(p-Butcalix[4]-(OMe)202)Zr((Bu')NC(C,H,)C(C=NBut)NBut)-}], via a pathway which has been observed in the reaction of Bu'NC with dialkylzirconium calix[4]arene derivatives. The o2 behaviour of butadiene in 20 was further verified in the reaction with H20 to give [{ p-But-calix[4]-(oMe)2(0)2}2Zr2(p-O)2] and butenes." Zirconium(IV) and hafnium(1V) complexes of the tropocoronands, [MY2(TC-n,m)](M = ZtfIV), Hf(1V); Y = CI,CH2Ph 21,CH2SiMe3) have been -+

10

Orgunometullic Chemistry

prepared and structurally characterised. By using this ligand system the authors were also able to isolate the first Group 4 macrocyclic q2-ketone complex [Hf(TC-3,5)(q2-OC(CH,Ph)2) 22 by insertion of CO into [Hf(TC-3,5)(CHzPh)2] 21.2' The compounds exhibit variable stereochemistry depending on the number of methylene units, n and m, in the polymethylene linker chains connecting the two aminotroponiminate rings, although in all cases the cis stereoisomer is formed. With the smallest ligand (TC-3,3), the dialkyl and dichloro complexes display slightly distorted trigonal prismatic structures; increasing the size of the macrocyclic ring substantially shifts the geometry at the metal centre toward octahedral stereochemist ry . Concomitant with the reorientation toward octahedral symmetry, the stabiIity of the complexes decreases and the metal centre can attack the C-H bonds in the alkyl linker arms of the ligand. Substitution of the latter with xylyl groups eliminates this undesired decomposition pathway while still affording strained complexes. Finally, when the binding cavity of the ligand

21

becomes too large, binuclear species such as { [Hf(CH,siMe3)3]2(TC-5,5)) are obtained.22Reaction of the tropocoronand complexes [M(TC-3,n)Rz](M = Zr(IV), Hf(1V); n = 3, 5; R = CH2Ph, Ph) with aryl and alkyl isocyanides is examined where alkyl isocyanides induce migration of both benzyl groups to afford the = 5, R = Cy , "Bu; n bis(iminoacy1) species [Hf(TC-3,n){q2-(R)N=C(CH2Ph))2](n = 3, R = Cy3) 23. Different products were isolated with aryl isocyanides, depending on the rate of substrate addition. Treatment of [M(TC-3,n)(CH2Ph)2] with excess 2,6-dirnethylphenyl isocyanide (ArNC) generated the enediamido compounds [(TC-3,3)MN(Ar)C(CH*Ph)=C(CH,Ph)N(Ar)] (M = Zr, Hf) via coupling of two bis(iminoacy1) groups, whereas slow step-wise addition produced

I : Complexes Contuining Mrtul-Curbon o-Bonds of the Groups Titunium to Mungunese

11

[(TC-3,n)-MN(Ar)C(CH,Ph)2C(=Ar)](M = Zr, n = 3; M = Hf, n = 3, 5). The q2imine complex [(TC-3,5)HfN(Ar)C(CH2Ph)2],was isolated and characterised, but the corresponding zirconium species was unstable in solution, decomposing to form the imido-bridged compound {[Zr(TC-3,3)]2(p-NAr)2}. Altering the nature of the carbon donor ligands also influenced the reactivity. Addition of both aryl and alkyl isocyanides to solutions of [Zr(TC-3,3)Ph2] afforded the q2-imine complexes [(TC-3,3) ZrN(R)C(Ph)2] (R = Cy , Ar), the stability of which may be due in part to interactions between the metal centre and a phenyl ring. Electronwithdrawing R substituents enhance this effect.23 Titanium complexes of the general type Ti(q5:q'-C5H4SiMe2NCH2C6H3X22,5)c12 (X = H, F), containing a linked benzylamido-cyclopentadienyl ligand, were prepared by reaction of Ti(q5-C5H4SiMe2CI)C13with lithium amide Li(N HCH2C6H3X2-2,5). Ti(q 5:q'-CSH4SiMe2N CH2C6H5)C12 can be alkylated with a variety of reagents to form extremely sensitive complexes of the type Ti(q5:q'-C5H4SiMe2NCH2C6H5)R2 (R = Me, CH2C6H5, CH2SiMe3, of Li2[C5Me4SiMe2NCH2C6H5]with TiC13(THF)3 C H ~ C M ~ ~ C 24. ~ HReaction S) gave Ti(q5:q1-C5Me4SiMezNCH2C6H5)C12, which can also be alkylated to form dialkyl complexes of the type Ti(q5:q'-C5Me4SiMe2NCH2C6H5)R2(R = Me, CH2C6H5, CH2SiMe3, C6H5) 25. A single-crystal X-ray structural analysis of q5:q'-C5Me4SiMe2NCH2C6H5)(CH2C6HS)2suggests the presence of alphaagostic bonding of one of the titanium-bound CH2C6H5groups to the titanium centre. 24

U U

26

Thermal decomposition of the carbyl compounds { C5H4(CH2)2NR}TiR12 26 proceeds through R- and -H elimination to give stable aryne, alkylidene, and olefin complexes in the presence of PMe3. Reaction of the dibenzyl compound { C5H4(CH2)2NtBu}Ti(CH2Ph)2 with B(C6F5)3 gives the cationic [ {CSH~(CH~)~N'BU}T~CH~P~]+.~~

This report highlights an efficient synthesis of the 'constrained geometry' Group 4 dibenzyl complexes Me2Si(q5-Me4C5)('BuN)MR2(CGCMR2, where R = CH2Ph; M = Ti 27, Zr 28), as well as the substantially different reaction patterns in the co-catalytic activation of the R = CH2Ph and Me complexes with B(C6F&, PBB (tris(2,2',2"-perfluorobiphenyl)borane), and Ph3C+B(C6F5)4-. The reaction of the neutral free hgand CGCH2 with Ti(CH2Ph)4 in aromatic or saturated hydrocarbon solvents at 60 "C cleanly affords 27 in 90%yield, while the corresponding reaction with Zr(CH2Ph)4 produces 28 in lower yield. When activated with Ph3C+ B(C6F5)4- at low temperatures, 28 generates cationic

12

Orgunometallic Chemistry

CGCZrCH2Ph' B(C6F5)4-. However, unlike the corresponding metallocene dibenzyl, the cationic derivative of which (Cp2ZrCH2Phf B(C6F5)4-) can be isolated in quantitative yield, the reaction of 27 with B(C6F5)3and Ph3C' B(C6F5)4- affords intramolecular C-H metalation products Me2Si(q5-,q'C5Me3CH2)('BuN)Ti+[q"-PhCH2B(C,F,),I- and Me2Si(q5,q'-C5Me3CH2)('BuN)Ti+ B(C6F5)4-, respectively. In contrast, the reaction of CGCTiMe2with B(C6F5)3cleanly generates CGCTiCH3+ CH3B(C6F5)3- without C-H bond activation as well as binuclear [CGCTiMe(p-Me)MeTiCGC]+ MeB(C6F5)3-, which is in equilibrium with CGCTiCH3' CH3B(C6F5)3- and CGCTiMe2 (AG298K = 1.3(2) kcaVmol) in favour of (CGCTiCH3' CH$(C6F5)3-). The reaction of CGCTiMe2 with sterically encumbered PBB and Ph3Cf B(C6F5)4yields predominantly cationic binuclear species, and analytically pure [CGCTiMe(p-Me)MeTiCGC]+[MePBBI- can be isolated in quantitative yield.26

MqSi N-M-w,,,,

/ 'Bu

/

'Bu

29 ' R

M = T i 2 7 , Zr28

'

\N N\/F-Me 'c, Me

The reactions of 2 equivalents of CNR (R = tert-butyl, 2,6-xylyl, Me) with [(C5Me4)SiMe2(N'Bu)]ZrMe2,proceed sequentially with isocyanide insertion into both Zr-C(methy1) bonds of this 14-electron complex to give the corresponding q2-iminoacyl Zr complexes [(C5Me$3Me2(NLBu)]ZrMe[q2-C(Me)NR], and [(C5Me4)SiMe2(N'Bu)]Zr[q2-C(Me)NR]2. Subsequent thermolysis of the latter leads to C,C-coupling of the two q2-iminoacyl units and proceeds solely with formation of the enediamidate derivative [(CsMe&Mez( N'Bu)]Zr[N(R)C(Me)=C(Me)N(R)] 29. Alkyl- and aryllithium reagents add cleanly to the electrophilic carbon centre C6 of 6-(N,N-dimethylamino) fulvenes to yield the corresponding substituted cyclopentadienyllithium systems Li[C5H4CR R2NMe2J. Subsequent treatment with ZrC14.2THFgives the corresponding Cp-functionalised zirconocene dichlorides. These were reacted with methyllithium to give the (C5H4CR'R2NMe2)2Zr(CH3)2 complexes (R' = R' = CH3) (R' = CH3, R2 = Ph), respectively. Treatment with tris(pentafluoropheny1)borane was carried out to generate the corresponding alkylmetallocene cations, which turned out to be unstable under the reaction conditions applied (-20°C) with regard to liberation of 1 equivalent of methane by CH activation at a methyl group adjacent to nitrogen and formation of the spiro-metallocenecomplex systems 30.28 The dialkyl compound [(q ' - N B U ' ) S ~ M ~ ~ C H ~ ( ~ ~ - C I ~ H ~ ) ] Z 31~ ( C H ~ was prepared from Me3SiCH2MgCI and [(q '-NBu')SiMe2CHz(q5-C13Hg)]ZrC12. The N M R spectroscopic and X-ray data point to a fairly congested environment

*'

'

1: Complexes Contuining Metal-Curhon cr-Bonds of the Groups Titunium to Mungunese

13

31

30

around the zirconium atom. In contrast to the -SiMez- bridged analogues, the -SiMe2CH2- linked amido-fluorenyl complex features a relatively unstrained ligand backbone with a close to ideal trigonal planar geometry at the amido nitrogen The reaction of [CpTiC12IN and Cp*TiC12(thf) with C P * ~Li ( C P * ~ , C5Me4CH2CH2NMe2;Cp*, C5Me5)leads to Cp*" CpTiCl and C P * Cp*TiCl, ~ respectively. The monochlorides are oxidised by PbC12 to give c ~ * ~ C p T i C and l2 C~*~cp*TiC12. The fulvene complex Cp*N(C5Me4CH2)TiCH=CH2and the titanacyclobutane Cp*NCp*TiCH2CH2C=CH2,32, respectively, are formed under mild conditions viu the titanocenevinylidene intermediate [Cp*NCp*Ti=C=CH2],generated by R-H transformation from the vinyl complexes CP*~CP*T~(CH=CH~)(CH~) and C P * ~ C P * T ~ ( C H = C HThe ~ ) ~formation . of Cp*NCp*TiCH2CH2C=CH2is suggested to be influenced by the nitrogencontaining side chain in the C P * ~ ligand. A stabilisation of [Cp*NCp*Ti=C=CH2]by intramolecular Ti-N coordination is not observed under the reaction conditions. Intermolecular trapping of the latter with transition metal carbonyls M(C0)6 leads to the heterobinuclear titanaoxetanes Cp*NCp*TiOC(=M(CO)5)C=CH2 (M=Cr, W).30 A convenient 'one-pot' synthesis of a bifunctional Me4Cpkphenolate2- ligand and the efficient 'one-step' synthesis of the corresponding Ti (IV) and Zr (IV) complexes has been reported. The reaction of 2-bromo-4-methylphenol with 2 equivalents of "BuLi followed by addition of 2,3,4,5-tetramethyl-2-cyclopentenone produces the bifunctional mono-Cp phenol ligand precursor 2-(tetramethylcyclopentadienyl)-4-methylphenol (TCP)H2. Reaction of (TCP)H2 with

32

/

34

Orgunometullic Chemistry

14

Ti(CH2Ph)d at 60 OC in toluene cleanly generates (TCP)Ti(CH2Ph)2 33, while the corresponding reaction with Zr(CH2Ph)4 at higher temperatures affords the chelated C2-symmetric zirconocene (TCP)2Zr 34. In solution at room temperature, the two benzyl groups of 33 are magnetically equivalent, however, in the solid state, X-ray diffraction reveals that one benzyl group is coordinated in a normal q'-fashion and the other in an q2-mode. The small Cp-(centroid)-Ti-0 angle of 107.7(2)" in 33 indicates sterically open features in comvon with amidobased 'constrained geometry' polymerisation catalysts. Low-temperature N MRscale reactions of 33 with B(C6F5)3and Ph3C+ B(C6F5)4- indicate the formation of the corresponding cationic complexes (TCP)TiCH2Ph'PhCH2B(C6F5)3- and (TCP)TiCH*Ph' B(C6F5)4- .3' The reaction of the new ligdnd [2,6-(CH2CsH4)2C5H3N]2-Naf2 (LNa2) with ZrC14 in T H F affords in good yield the trigonal-bipyramidal complex LZrCI2, where the two chlorine atoms are not equivalent. When LZrCI2 and RMgCl (R = CH3, n-butyl, CH2Si(CH3)3) are reacted in 1:l and 1:2 molar ratios, the corresponding complexes LZr(CI)R and LZrR2 can be isolated in good yields. Differently from the C ~ ~ z r ( n - B uwhich ) ~ , has never been isolated due to P-H elimination, the analogous L z r ( n - B ~ is ) ~thermally stable 35 and its X-ray crystal structure has been solved, confirming its trigonal-bipyramidal geometry with the alkyl groups occupying an equatorial and an axial position.32 The dimethylzirconocene complex [ ( c ~ - c M e ~ - P A r ~ ) ~ Z r (Ar M e ~=] ,p-tolyl), was treated with 1 molar equiv. of B(C6Fs)3 to yield the salt [(Cp-CMe2PAr2)2ZrMe+ MeB(C6F5)3-] 36. The X-ray crystal structure analysis of 36 shows that both -PAr2 units are intramolecularly coordinated to zirconium in a close to C2-symmetric arrangement with the [Zrl-CH3group placed in the central position in the bent metallocene 0-ligand plane. 2 equivalents of B(C6Fs)3 react with [(CpCMe2-PAr2)2ZrMe2], to generate the highly reactive dication system [(Cp-CMe2PAr2)2Zr 2+](with two MeB(C6F5)3 - anions). This abstracts chloride from, e g . , dichloromethane solvent to yield [(Cp-CMe2-PAr2)2Zr-C1+- ] (with MeB(C6F5)3anion). The C2-symmetric1internally -PArz-stabilized dication adds acetonitrile or 2,6-dimethylphenyl isocyanide to give the respective C2-symmetric donorligand adducts in which the -PAr2 coordination to zirconium is retained.33 The functionality of the arm can be extended by reaction of LiR with M(q5:q ':q1-C5Me4SiMe2NCH2CH20Me)CI2 (M = Zr, Hf) giving the isolable, thermally stable complexes M(q5:q ':q 'C5-Me4SiMe2NCH2CH20Me)R237 (R = Et, "Pr, "Bu), which contain two alkyl ligands with P-hydrogen atoms.34

37

35

36

I : Complexes Contuining Metul-Curbon o-Bonds ofthe Groups Titanium to Mungunese

15

The Lewis acid tris(pentafluoropheny1)boraneadds to the (butadiene)group 4 metallocenes (metallocene = Cp2Zr, Cp2Hf, ( M e c ~ ) ~ Z(Me3CCp)zZr) r, to give the metallocene-(p-C4H6)-borate-betaine complexes 38. (1soprene)zirconocene and (2-pheny1butadiene)zirconocene also add the B(C6F& reagent regioselectively at the carbon atom C-4. The complexes 38 all show a pronounced M...F-C interaction with one of the six ortho-B(C6F5)3 fluorine atoms. The resulting metallacyclic structures were characterised by X-ray diffraction (Zr..-F approximate to 2.40 Angstrom, angle Zr-F-C approximate to 140"). The I9F NMR spectra of the complexes 38 are dynamic even in the non coordinating solvent toluene-ds. The Zr...F-C bond of the complexes 38 is cleaved by the addition of the donor solvent THF with formation of acyclic 1,2-q2-ally1 metalfocene complexes.35 The betaine complex 38 inserts one equivalent of methylenecyclopropane at -40 "C, giving the regioisomeric insertion products 39 and 40 in a 60:40 ratio. These products exhibit the cyclopropylidene moiety in the a- and f3-positions, respectively, relative to zirconium. The corresponding hafnocene complexes are obtained in a 70:30 ratio. The reaction of (CH2CHCHCH2B(C6F5)3)ML2with allene gives a single insertion product 41 in each case where the exo-methylene group is in the alpha-position to the metal centre ([2, I]-insertion). These complexes are c h i d and exhibit a pronounced re-interaction of the internal -CH=CH- double bond of the o-ligand chain with the metal centre in addition to a metalloceneb CH2[B]- ion pair interaction.36 Addition of B(C6F5)3 to (q4-butadiene)ZrCp2* derivative yields the open-chain metallocene-hydrocarbylborate-betaine complex where the presence of the bulky Cp* prohibits the formation of the M..-F-C interaction 42.37

F

42

16

Orgunometullic Chemistry

Reacting the dilithium salts of T M M (trimethylenemethane), tribenzylidenemethane (TBM ), tert-bu ty I t ri benzy lidenemet hane (‘Bu-TB M), and dibenzylidenemethylenemethane (DBM) with either Cp*ZrCI3 or CpZrC13(DME) gives a variety of products: in the case of the small T M M fragment, the product is the zwitterionic Cp*(TMM)Zr(p-Cl)2Li(TMEDA). Larger TMM derivatives give discrete salts such as [Cp*(TBM)ZrCI2][Li(TMEDA)2], [Cp(TBM)ZrC12][Li(TM EDAh], [Cp(‘Bu-TB M)ZrC12][Li(TM E DA)2], [Cp*(‘ Bu-TBM)ZrC12][Li(TThe reaction of MEDA)2], and [C~*(~~O-~~~O-DBM)Z~C~~][L~(TMEDA)~]. TBM( LiTMEDA)* with Cp*ZrCI2CH2Ph affords [Cp*(TBM)ZrCI(CH2Ph)][Li(TMEDA)2] 43; thus the retention of LiCl(TMEDA)2 by zirconium is strong. Structural characterisation of these complexes reveals crowded environments around the zirconium, especially when both TBM and Cp* are coordinated. It is

1 0

also possible to take advantage of intramolecular o-bond metathesis reactions to convert coordinated allyl ligands to TMM-related fragments. For example, [Cp*(TMM)Zr]2(p-CH2) is derived from Cp*(q3-CH2C(Me)CHz)ZrMe2, and Cp*(TBM)ZrMe(TH F) is from Cp*(PhCH2C(CHPh)2)ZrMe2. Formation of the methylpropargyl complex Cp*(TBM)Zr(q3-CH2CCMe) from Cp*(TBM)ZrMe(THF) and 2-butyne instead of a butenyl derivative is a consequence of steric constraints.38 The reduction of [MC13Cp”] [M = Zr or Hf; Cp” = q-C5H3(SiMe3)2-1,3] with sodium amalgam in the presence of dienes gave the compounds [MCl(diene)Cp”] which are alkylated with MeMgBr or RMgCl (R = allyl) to give [MX(diene)Cp”] (X = CH3 or q3- C3H5; diene = 2,3-dimethylbuta-l,3-dieneor isoprene) 44. Reduction of [ZrCl(CHCMeCH)Cp”] with an excess of Na-Hg leads t o the binuclear q4 (5e)-butadienyl complex [Zr(p-rj :q4-C4H3Me2-2,3)Cp”]2 45, also formed from [ZrMe(C4H4Me2)Cp”] by methane e l i m i n a t i ~ n .The ~ ~ butadiene complex [Zr(q3-CH2CMeCHCH2)(q4-C4H6)Cptr]is obtained directly from [ZrC13Cp”] and MeCHCHCH2MgCI. The complexes [M(allyl)(diene)Cp”] react with B(C6F5)3 to give the zwitterionic complexes [Cp”M+(q3-C3Hs)-( q3(C4H4R’R2)B-(C6F5)3}] 46 which contain a 14 electron [CpM(allyl)2]+ core stabilised by agostic bonding of the B-CH2 methylene hydrogens. The thermal stability of the zwitterionic active species depends strongly on the steric requirements of the dienyl ligands and decreases sharply in the order R’ = R2 = Me > R’

’

1: Complexes Containing Metal-Curbon o-Bonds of he Groups Titanium to Mungunese

17

= Me, R2 = H much greater than R' = H, R2 = H; i.e. the dimethylbutadiene derivatives are stable at room temperature, while in the latter case decomposition is significant even at - 60 "C. The complexes [Zr(q3-CH2CHCHR'){q3(CH2CR2MeCHCH2B)(C6F5)3}Cp"](R' = H, R2 = Me, R' = Me, R2 = H) 45 decompose via an unusual C-H activation pathway, with alkene elimination and concomitant migration of a C6F5 substituent from boron to zirconium, to give the catalytically inactive borylidene complexes [Zr(C6F5){ q4-

(CH~CR'CHCHB)(C~F~)~)CP''].~' Addition of 2 equivalents of the stannylated compound 47 to ZrC14 affords the bis-ally1 complex 48 in good yield. The dialkyl complex [(trop)2Zr2] (R = Me, CH2Ph) complexes can be obtained by the reaction of 48 with two equivalents of MeLi o r PhCH2MgCL4' The titanium( I I) alkyl trans-TiMe2(dmpe)2, where dmpe is 1,2-bis(dimethyIphosphino)-ethane, reacts with 1,3-butadiene and trans,truns-l,4-diphenyl-l,3butadiene at - 20°C to produce the titanium(I1) butadiene complexes TiMe2(q4C4H4R2)(dmpe), where R is H or Ph. NMR spectra are consistent with structures in which the methyl groups are mutually cis, and this has been verified crystallographically for the 1,4-diphenyIbutadiene complex. These molecules are flux-

47

48

Orgunometullic Chemistry

18

ional on the NMR time scale, and the activation parameters for exchange are AH: = 9.1 If: 0.2 kcal mol - I and AS: = 3 k 1 eu for the 1,4-diphenylbutadiene complex. The process that exchanges the two Ti-Me groups, the two ends of the dmpe ligand, and the two ends of the butadiene ligand is proposed to be a trigonal twist, also exists that the exchange involves five-coordinate intermediates generated by dissociation of one 'arm' of a chelating ligand. If the reaction of TiMez(dmpe)~and I ,3-butadiene is allowed to proceed at - 20 "C for prolonged periods (> 12 h), a second titanium 'butadiene' complex is formed, which has been identified as the titanium( IV) q3, q '-octa- 1,6-diene- 1,8-diyl complex TiMe2(q3;q '-CsH 12)(dmpe) 49. Treatment of TiMe2(dmpe)2 with 1,3-butadiene in the presence of AIEt3 results in reduction to the titanium(0) complex Ti(q4C4H6)2(dmpe),which has also been crystallographically characterised. Unlike the behaviour seen for certain other early transition metal butadiene complexes, in both Ti-(q4-C4H6)2(dmpe)and TiMe2(q4-C4H4Ph2)(dmpe)the butadiene ligands are bound like true

49

Hafnium-ally1 chemistry has been exploited by way of cationic mono(pentamethylcyclopentadienyl) organohafnium complexes with q3-2-methallyl ligands, [(C5Me5)Hf(q3-2-C4H7)Me][MeB(C6F5)3] and [(C5Me5)Hf(q3-2-C4H7)2][B(C6F5)4] have been prepared.43 Complex { Me2Si(q5-1-indenyl)(q3-2-inden~l))Hf(NMe2)~ has been prepared in 21% isolated yield by thermolysis of (q5-CgH6SiMe2CgH7)-Hf(NMe2)3 160 "C and can be converted to {Me$i(q'-lindenyl)(q3-2-indenyl)JHfMe2 (1 00%)NMR) by reaction with A1Me3.44 The first acetylene complex of hafnium, Cp2HqMe3SiC=CHf(H)Cp2], was synthesised by the reaction of hafnocene dihydride CpzHfH2 with bis(trimethy1si1yl)acetylene in benzene. The reaction is accompanied by elimination of the Me3Si group from the molecule of the initial acetylene, as a result of which the acetylenide derivative of hafnium Cp2Hf(C=CSiMe3)(H) acts as an acetylene ligand in the complex. Under analogous conditions, the reaction of zirconocene dihydride Cp2ZrH2 with bis(trimethylsilyl)acetylene affords an analogous acetylene complex of zirconium Cp2Zr[M3SiC=CZr(H)Cp2].45 The ti tanocene vinylidene intermediate [Ti(=C=CH2)( q-C5Me5)2],formed by ethane or methane elimination from [Ti(CH2CH2C=CH2)(q-C5Me&] or ri(CH=CH2)Me(q-C5Me5)2]respectively, reacted with isothiocyanates RNCS (R = C ~ H1,I Ph or But) by a [2 + 21 cycloaddition, to give the titanthietane 50. In all cases the regioisomer in complexes [Ti(SC(=NR)C=CH2}(q-C5Me5)2] which the sulfur atom is bonded to titanium is observed as the primary product. Upon heating in the presence of pyridine a rearrangement to the regioisomeric

1: Complexes Conruining Metal-Curbon o- Bonds of the Groirps Titanium to Mungunese

I9

50

titanacyclobutane derivative [Ti{C(=NR)SC=CH2)(q-C5Me5)2] 51 was observed.46[Cp*2Ti=C=CH2] can easily be generated in two ways, from methylenetitanacyclobutane C P * ~ T ~=CH2)CH2CH2, C( obtained viu a C P * ~ T ~ ( C H = C H * ) ~ intermediate in quantitative yield, or by a-H-elimination of methane from the vinyl-methyl derivative, C P * ~ T ~ ( C H = C H ~ ) C [ CHP~*. ~ T ~ = C = Ccan H ~ ]be used in a great number of different organometallic reactions. Of considerable interest are syntheses of cycloaddition products, by trapping with cumulenes, transition metal carbonyls, nitriles, phosphaalkynes and alkynes. With oxygen containing cumulenes and heterocumulenes, monomeric metallaoxetanes exhibiting a planar ring geometry are obtained for the first time. Due to its reactivity in solution the metallaoxetanes can be divided in classical (forming Ti=O) and nonclassical oxetanes (forming Ti=C).47*48 The thermal decomposition of dibutylzirconocene at room temperature affords paramagnetic butylzirconocene( I I I), zirconocene( I I I) hydride, the diamagnetic butenylzirconocenehydride dimer, 52 and the 1,l -bis(cyclopentadienyI)-2-methyl3-(zirconocenyl hydride)- 1-zirconacyclobutane(IV) dimer 53. Initially, decomposition furnishes crotylzirconocene(IV) hydride, followed by I , 1-bis(cyclopentadienyl)-2-ethyl- 1-zircons-cyclopropane(IV) and 1, I -bis(cyclopentadienyl)-3,4diethyl- 1-zirconacyclopentane(IV), listed in the order of appearance. Crotylzirconocene( I V) hydride has also been synthesised independently from zirconocene chloride hydride and crotylmagnesium bromide.49 Reaction of alkenylzirconocenes Cp2ZrX(MeC=CHz) (X = CI, Br) with dialkylzirconocenes Cp2ZrR2 (R = Me, Et, Bu) yielded the unexpected bimetallic zirconocene complexes Cp2Zr(pL-X)(p-C=CCH3)ZrCpz (X = C1, Br). The monitoring of the reaction of CpzZrBuz with CpzZrBr(MeC=CH2)

53

20

Orgunometullic Chemistry

revealed that the first step of this reaction was an exchange reaction of the Bu and Br groups.50 Allenyl carbenoids (3-chloro- 1-1ithioalk-1-ynes) insert into zirconacyclopentanes and zirconacyclopentenes 54 to afford cyclic q3-allenyl/prop-2-ynyl zirconocene complexes 55 which give allenyl, alkynyl or cyclised-alcohol products on addition of aldehydes activated with boron trifluoride-diethyl ether.5’

54

Diacetylenic phosphanes are cleanly transformed when reacted with zirconocene into zircona-cyclopentadiene phosphiranes 56, These new cyclic systems are the source of a variety of unsaturated phosphorus compounds like phospharadialene or alkenyl alkynyl phosphanes. Other examples are reported where the dialkynyl phosphane (‘BuP(C 3 C-Ph)2 and zirconocene benzene provide unusual dihydrophosphete--zirconium c o m p l e ~ e s . ~ ~ 2-Phosphinophospholes and stiboles are prepared from the reaction of benzynezirconocene 57 with alkynylphosphines followed by addition either of dichlorophosphines or a dichlorostibene. Treatment of alkynylphosphine with [ZrPhzCpz] leads to the formation of phosphinozirconaindenes 58 (Cp = C5H5, C5H4BuL;R = H, Ph). Addition of MC12R (M = P, Sb; R = Ph, But) leads to the substitution of the ZrCp2 moiety giving 59.54These systems can be extended by reacting the zirconaindane phospholane 60 with PhSbCl2 or Me2SnCl2 to give tricyclic systems incorporating phosphorus, antimony or tin 61; the same reaction involving R2PCI (R = Ph, Et) leads to acyclic-cyclic d i p h ~ s p h a n e s . ~ ~ The employment of phosphazirconacycles in metallacycle transfer reactions is a facile method for the synthesis of main-group phosphacycles. Triphosphanato complex C P ~ Z ~ ( P reacts P ~ ) ~with PhPCI2 or ‘Bu2SnCI2to yield (PPh)4 and (tBu)z-Sn(PPh)J, respectively. Reaction of phosphametallacyclobutene Cp2Zr(P(R*)C(Ph)=CPh)with PhPCI2 results in the formation of the unsymmetrically substituted 1,2-diphosphetene P(Ph)P(R*)C-(Ph)=CPh, while reaction , the with PhBCI2 yields PH(C~H~-(~-CH~C(CH~)~)-~,~LBU~)B(P~)-C product of ring expansion via C-H activation. Phosphametallacyclo-pentene (Cp2Zr(P( Mes)P(Mes)C(Ph)=CPh)62 reacts with PhPCI2 to furnish the unsymmetrically substituted 1,2,3-triphospholene P( Ph)P(Mes)P( Mes)C(Ph)=CPh 63.56

I : Complexes Containing Metul-Curbon o-Bonds of the Groups Titunium to Mungunese

6 o f i

62

21

ph

61

63

Ph

64

65

It has been shown that carbon dioxide reacts with acetylene complexes of titanocene Cp2Ti(RC2R) (R = Ph 64,SiMe3) at room temperature and atmospheric pressure to form binuclear o-alkenylcarboxylate complexes of trivalent titanium Cp2TiC(R)=C(R)-COOTiCp2 65 containing two fused chelate cycles and a tricoordinated oxygen atom. The interaction of these binuclear carboxylate complexes with air oxygen at 20°C results in rapid formation of titanafuranone metallacycles Cp,TiC( R)=C( R)-C(0)-0. X-ray diffraction studies of complexes Cp2TiC(SiMe+C(SiMe3)-COOTiCp2 and Cp2TiC(Ph)=C(Ph)-C(0)-0 have been carried Bis(q5-cyclopentadienyl)-2,4-bis(trimethylsilylethynyl)-3,5-bis(trimethylsilyl)titanacyclopenta-2,4-dieneand the seven-membered zirconacyclocumulene bis(q cyclopentadieny1)-2,4,7- tris(trimethylsily1)- 3 -(trimethylsilylethynyl)zirconacyclohepta-2,4,5,6-tetraene react with sulfur monochloride to yield an identical product, 2,4-bis(trimethylsilylethynyl)-3,5-bis(trimethylsilyl)thiophene.A one-toone mixture of the homo- and heterobimetallic bis-o,n-acetylide bridged complexes Cp2Ti(p-ql:q2-C=CSiMe3)M(p-q’:q2-C=CSiMe3)Cp2 (M = Zr, Ti) is formed in the reaction of zirconacyclocumulene with three equivalents of Cp2Ti(q2-Me3SiC=CSiMe3).The reaction proceeds most likely via alkyne elim-

’-

22

Orgunome~ullic.Chemistry

ination, a C-C-single bond activation, and the cleavage of the starting diyne takes p~ace.~' insertion of PhC=C-C=CPh into Cp2Ti(q2-Me3SiC2SiMe3)gives the unstable five-membered titanacyclocumulene 66, which is stabilised by dimerisation to yield the binuclear complex 68. In this reaction complex 66 shows an equilibrium and also behaves as a metallacyclocumulene and a metal alkyne complex 67.By the coupling of the internal double bond of the cyclocumulene with a complexed

CpzTi

b f-

" IFJh

triple bond of the diyne, a complex with fused titanacyclopentadiene and titanacyclopentene is formed. With acetone and water complex 66 reacts like an . ~ ~ reaction alkyne complex to give the titanadihydrofuran and a t i t a n ~ x a n e The of Cp2Ti(q2-Me3SiC2SiMe3)(THF)69 with bis(trimethylsily1)octatetrayne gives 70 by complexation of the middle two triple bonds.6a SiMq

II II It II

+

SiMe,

The synthesis and reactivity of monomeric, 16-electron hafnocene silyl hydride complexes are described. The complex CpCp*HflSi(SiMe3)3] 71 prepared by the reaction of CpCp*Hf(H)CI with (THF)3LiSi(SiMe&, reacts rapidly with both

I : Complexes Contuining Merul-Curhon 6 -Bonds of the Groups Titanium to Mungunese

23

71

ethylene and diphenylacetylene with elimination of HSi(SiMe3)3 to afford the corresponding hafnacyclopentane and tetraphenylhafnacyclopentadiene complexes 72.6' Bis(propyny1)zirconocene reacts with tris(pentafluoropheny1)borane to yield the carbon-carbon coupled C P ~ M ( ~ - R C ~ R ) B ( C betaine ~ F ~ )product ~ (M = Zr, R = CH3) 73.A variety of differently substituted analogues were prepared (M = Zr, R = n-butyl, phenyl, cyclohexyl; M = Ti, R = CH3; M = Hf, R = CH3, phenyl, SiMe3). These complexes are chiral due to the presence of a rather stable propeller-like R-B(aryl)3 conformation. The activation barrier of the intramolecular enantiomerisation process of many examples of this series of complexes was determined by dynamic 'H NMR spectroscopy, with (AGS z 13 -- 16 kcal mol- I ) , depending on the substitution pattern. Cp2Zr(p-MeC4Me)B(C6F5)3 reacts with 2,6-dimethylphenylisocyanideto yield the methylenecyclopropene derivative 74 that was characterised by X-ray diffraction.62

FNR

Me

&@

2,6dimethylphenyIisocyanide _____t

CP*~M@

B(C6FSh

73

Me Bis(propyny1)zirconocene also reacts with 0.5 molar equiv. of trityl tetraphenylborate by a propynyl group transfer to form Ph3CC = CCH3 and Cp2ZrC= CCH3+. The in-situ-generated (propyny1)zirconocene cation is not stable under the reaction conditions but instantaneously reacts with the neutral starting material CpzZrC = CCH3' to form the [ ( p C = CCH3)(p-CH3C = CC = CCH3)(ZrCp2)2'][BPh4-] salt 75. By X-ray crystallography, it contains an unsymmetrically bridging hexadiyne ligand and exhibits a phnar-tetracoordinate carbon centre that is stabilised by a three-centre two-electron interaction with the two adjacent zirconocene moieties. In solution, it exhibits dynamic NMR spectra that indicate a

Orgunometullic Chemistry

24

R

I

symmetrising exchange of the bonding situations between the two ends of the p-hexadiyne I i g a ~ ~ d . ~ ~ Bis(propyny1)zirconocene was treated with H(C6F5)3and then with two equivalents of rut-butyl isocyanide to yield the organometallic three-membered ring product 76. Subsequent hydrolysis gives the substituted (2-iminioethy1idene)cyclopropeneborate betaine system that exhibits a pronounced cyclopropenylioborate betaine character. This follows from its characteristic structural features (Xray crystal-structure analysis of the cis-isomer) and its chemical features. A very facile cisltrans isomerisation by formal rotation around the exocyclic partial CCdouble bond is observed (AG',,,,, z 17 kcal mol- I).@ The organometallic cation [Cp2ZrCH3(thf)]+,employed as the tetraphenylborate salt, reacts cleanly in 1:1 stoichiometry with the isocyanates derived from valine methyl ester or valylvaline methyl ester, respectively. In each case addition of the Zr-CH3 group to the isocyanate sp-carbon centre is observed with formation of a functionalised zirconocene cation derivative containing a chelating N-metallated N-acetylvaline methyl ester or N-acetylvalylvaline methyl ester moiety 77, respectively, coordinated in the bent metallocene o-ligand plane. The spectroscopic data of 77, supported by an X-ray crystal structure analysis of the zirconated dipeptide derivative, have revealed the presence of chelating (q ' - 0 :I - ~ N)-coordination of the terminal N-acetyl groups in addition to a Zr-O=C interaction with the adjacent valyl amido The benzonitrile hydrozirconation product Cp2ZrCI(N=CHPh) was treated with propynyl lithium to yield the (propynyl)(benzaldimido)ZrCp2'. Subsequent

I : Complexes Conruining Metui-Curbon cr-Boncisofthe Groups Titunium to Mungunese

25

treatment with trityl tetraphenylborate generated [CpzZr(C= C-CH3)+BPh4-] that instantaneously added to (propynyl)(benzaldimido)ZrCp2+ to eventually form the (p-aldimido)(p-q':q2-hexadiyne)ZrCp278. The X-ray crystal structure analysis shows a planar-tetracoordinate carbon atom that is stabilised by forming a three-centre-two-electron bond with the two adjacent metal atoms. Similarly, complex (propynyl)(benzaldimido)ZrCp2+ reacted with [Cp2Zr(CH3)+CH3B(CsF5)3-]to yield the planar-tetracoordinate carbon (for a review on planar tetracoordinate carbon see ref. 66) containing (p-aldimido)(pq':q2-2-butyne)ZrCp2+ cation 79. Both complexes exhibit dynamic N MR spectra due to their rapid reorganization of the dimetallabicyclic frameworks (AGf = 10 kcal mol-') in addition to an anchimerically assisted C=N bond rotation (AGf = 15 kcal m ~ l - ' ) . ~Treatment ' of { Cp2Zr}2(p-CI)(p-CHCH2) 80 with B(CsF5)3 gives the stable CZv methane derivative 81 in 60% yield.@

-c

I

I

78

im

79

ph

The reaction of the bis(alkyny1) titanocenes [Ti](C=CR')(C=CR2)([Ti] = (q5C5H4SiMe3)2Ti;R1 = R2 = SiMe3; R' = R2 = But; R ' = SiMe3, R2 = But) with (CSH5N)AuCI3, LAuCl (L = PPh3, SMe2) as well as (Me2S)AuR' (R3 = C=CSiMe3, R3 = C=(CBu)-Bu'; R3 = ChH2(CF3)3-2,4,6; R3 = Me) is described. Treatment of [Ti](C=CSiMe3)2 with (C5H5N)AuC13 produces [Ti]C12 and Me3SiC=C-C=CSiMe3together with Au(0). However, the linear two-coordinated gold( I) chlorides LAuCl react with [Ti](C=CSiMe3)2 to afford different products, depending on the Lewis bases applied. While in the reaction of the Ph3P donorstabilised gold([) chloride, the titanocene dichloride along with (Ph3P)AuC=CSiMe3 is obtained, with the appropriate Me2S donor stabilised molecule, the titanocene dichloride along with the heterobimetak tweezer molecule { [Ti](C=CSiMe3)2> AuC=CSiMe3 is formed. A possible mechanism for the different chemical behaviour is discussed. Other tweezer compounds have also been reported. An ESR investigation has revealed that permethyltitanocene tweezer complexes with an embedded Mg ion

26

Orgunometullic Chemistry

between the acetylide arms [(C5Me5)2Ti(q'-C=CR)2]-[Mg(OEt2)X]' (X = CI or C=CR) (R = Me, Et, nPr, 'Bu, cyclohexyl, Ph, and SiMe3). Their ESR spectra are characterised by g-values in the range' 1.990-1.993, coupling constant to the proton at an a-carbon atom of the acetylene substituent 2.0-2.5 G and by coupling constants to Ti-47 and Ti-49 isotopes in the range 7.6-8.7 G. This paper also reports the synthesis of the tweezer complex [(CSMe5)2Ti(q '-C=CSiMe3)2]-[Mg(THF)CI]'.69 Crystal structures of the Ti(II1) tweezer complexes [(C5HMe4)2Ti(o-C=CSiMe3)2]-[Li(THF)2]', [(C5HMe4)2Ti(o-C=CSiMe3)2]Na' and [(C5HMe4)2Ti(~-C=CSiMe3)2]Csfhave also been determined. In all of them the alkali metal cation is placed away from the Ti-aC1-aC2-plane at the distance: Lif 0.51 1 A, Na' 1.023 A and Cs' 0.521 A. The reason for the deviation of Lif in [(C5HMe4)2Ti(o-C=CSiMe3)2]-[Li(THF)2]+ is the asymmetrical orientation of the T H F ligands in the [Li(THF)2]' cation with respect to the Ti-aC1-aC2-plane, which seems to release the steric congestion between the T H F ligands and the trimethylsilyl groups.70 Longer tweezer arms can be made by reaction of [Ti]C12 {[Ti] = (q5-CSH4SiMe3)2Ti} with two equivalents of LiC=C-C=CR (R = C2H5, R = %Me3) giving the bis[(o)- 1,3-butadiyne-l -yl] titanocenes [Ti](C=C-C=CR)2 (R = C2H5, SiMe3) in high yield; with LiC=CSiMe2-C=C-SiMe3 the bis[(o)-l,4-pentadiyne-l-yl]titanocene [Ti](C=C-SiMe2-C=CSiMe3)2 is formed. These react with equimolar amounts of Ni(CO)4 to give the heterobimetallic nickel-titanium complexes { [Ti](C=C-C=CR)2) the latter with two mole equivalents of C O ~ ( C O )compound ~ {[Ti](C=C-SiMe2-[(q2-C=CSiMe3)Co2 (CO)&)Ni(CO) is formed in which the inner C=C triple bonds of the 1,4-pentadiyne-1-yl groupings are n-bonded to a low-valent Ni(C0) building block, whereas the outer C=C triple bonds are each q2-coordinated to a C02(C0)6 transition metal fragment. Depending on the amount of C O ~ ( C O ) ~ used the reaction of C02(C0)8 with [Ti](C=C-SiMe2-C=CSiMe3)2yields different products: ([Ti](C=C-SiMe2-C=CSiMe3)2}Co(CO), [Ti](C=C-SiMe2-C=CSiMe3){ C=C-Me2Si-[(q2-C=CSiMe3)Co,(Co>,l), [Ti]{C=C-SiMe2-[(q2C = C S ~ M ~ ~ ) C O ~ (1C2 O as ) ~ ] well as [ ~ i{ [] ( q 2 - ~ = ~ ) ~ o 2 ( ~ 0 ) 6 l - ~ i ~ e 2 - [ ( q C=CS~M~~)CO~(C 2. OOn ) ~ ] )treatment of titanocenes with Pd(PPh3)4 or Pt(PPh&( H2C=CH2) the heterobimetallic complexes { [Ti](C=C-C=CC2H5)2} M(PPh3) (M = Pd, Pt) and {[Ti](C=C-SiMe2-C=CSiMe3)2}Pd(PPh3) are produced. In many of the compounds a low-valent Ni(C0) or M(PPh3) (M = Pd, Pt) moiety is complexed by the inner C=C triple bonds of the C=C-C=CR or C=C-SiMez-C=CSiMe3 l i g a n d ~ . ~ ' It has been shown that the reaction of the dinitrogen complex [ C P ~ T ~ C ~ H ~ I ~ N with a mixture of C6H5Li and Li in ether results in the formation of ammonia and aniline after hydrolysis. The interaction of [Cp2TiC6H5]2N2 with p - , rn- and o-tolyllithium reagents in the presence of lithium also gives aromatic amines and ammonia after hydrolysis. Similar results have been obtained for the dinitrogen complex [ C P ~ T ~ ( ~ - C H ~ C ~ H ~ ) I ~ N ~ . ~ ~ Reaction of [Zr{q5-C5H4(SiMe2C1))C13] with alkyl, amido and alkoxy transfer reagents (4 equiv.) to afford complexes [Zr{q5-C5H4(SiMe2X))X3](X = NMe2, OSiMe3, CHZCMezPh, C6H5, C6F5 and CH2SiMe3) in good yields. Reaction of

1: Complexes Contuining Metul-Curhon o-Bonds of the Groups Titunium to Mungunesc

27

[Zr{r15-C5H4(SiMe2CI)}C13]with Mg(CH2Ph)2.2THF (4 equiv.) yields the tetrabenzyl complex [Zr{q5-C~H4(SiMe2CH2Ph)}(CH2Ph)3]. Reactions of the appropriate complexes with 3 equiv. of HCI gave the corresponding trichloro [Zr{q5C5H4(SiMe2R))C13](R = C6H5,C6F5,CH2Ph). The monochloro [Zrfq5-C5H4(SiMe2CH2Ph)}(CH2Ph)2Cl] and the dichloro derivative [Zr{q5-C5H4(SiMe2CH2Ph)}(CH2Ph)CI2]are observed, at 60 "C and 90 T, respectively, by NMR experiments in deuterated chloroform. The reaction of [Zr{q5-C5H4(SiMe2CI)}C13]with the lithium benzamidinate salt Li[C(Ph){N(SiMe3))2] leads to the complex [Zr { q5-C5H4(SiMe2C1)}C(Ph)[N(SiMe3)]zC12], which decomposes slowly in solution with elimination of SiMe3C1.73 Reaction of the compound Cp*TiMe3 with the potent Lewis acid B(C6F5)3 results in methyl carbanion abstraction from the titanium and formation of the corresponding complex C ~ * T ~ M ~ ~ ( C L - M ~ ) in B (which C ~ F ~a) ~ methyl , group bridges the titanium and boron atoms. The isotopically labelled compounds C P * T ~ ( C H ~ D )Cp*Ti(CH2D)2(p-CH2D)B(C6F5)3, ~, Cp*Ti((CH3)-Ci3)3, and Cp*Ti((CH3)-C'3)2(~-(CH3)-C'3)B(C6F5)3 have also been prepared to provide NMR probes of the possibility of alpha-agostic bonding in these compounds. The compounds Cp*TiMe3 and C ~ * T ~ M ~ ~ ( P - M ~ ) B react ( C ~further F ~ ) ~ to form the novel but unstable methyl-bridged species [Cp*TiMe2(pMe) TiMe2Cp*][MeB(C6F5),], which has been characterised by H ' and C i 3(HI} N MR s p e c t r o ~ c o p y . ~ ~ The solution structures and dynamics of (q-CsMes)TiMe(C6F~) (P-Me)B(CSF5)3, and [(q-C5Me5) Ti(OC6F5)2][BMe(C5F5)3]are compared and contrasted with those of the known initiator (q-C5Me5)TiMe2(pMe)B(C6F5)3. (q-C5Me5)TiMe(C6F5)(p-Me) B(C5F5j3 undergoes neither spontaneous ion-pair dissociation to the solvent separated [(q-C5Me5)TiMe(C6F5)]+and [BMe(C6F5)3]- nor borane dissociation to its precursors (q-C5Me5)TiMe2(C6F5)and B(C6F5)3; in contrast, (q-C~Me5)TiMe(OC6F5)(~-Me)B(C6F5)3 82 is more labile and does undergo ion-pair dissociation, while 4 exists in solution as the separated ion species in equilibrium with its precursors, (q-C5Me5)TiM e(OC6F5)2and B( C6F5)3.757 76

Two-electron oxidation of TiCp2(COj2 or double protonation of TiCp4 in toluene under carbon monoxide affords an exceedingly moisture-sensitive solid which has been isolated and identified as the tetraphenylborato derivative of the titanocene dicarbonyl dication [TiCp2(CO)z]2+ on the basis of both spectroscopic

28

Orgunometullic Chemistry

data and r e a ~ t i v i t y MCp2(C0)2 .~~ (M = Zr, H f ) react with PQ to give MCp2PDA which has been characterised by single crystal X-ray diffractometry for M = Zr. The structure consists of binuclear [ZrCp2PDA]2 units, the two ZrCp2 groups being bridged by the PDA ligands to give a 10-membered tetra-oxazirc~nacycle.~~ The reaction of B(C6Fs)3 with the tetramethyl zirconium fulvalene derivative [Zr(CSHS)(CH3)2]2(p-qs:~s-CloH8) in CH2C12 a t - 60 "C gives the cationic compound [ {Zr(CSHS)>2(p-CH3)(pL-CH2)(p-$:q '-cI OH8)]+ [BMe(C6F5)3]- 83. A similar reaction using the 1,3-di(tert-butyI) cyclopentadienyl derivative [Zr( 1,3B U ' ~ - C S H ~ ) ( C H ~ ) ~ ] ~ ( ~ -affords ~ ' : ~ ~a- C mixture ~ ~ H ~of) compounds, none of them being isolable as pure substances. However, monitoring the reaction by variable temperature NMR spectroscopy, between - 80 "C and 25 "C, permits the observation, at low temperature, of the intermediate dimethyl p-methyl cationic species [ {Zr(1 ,3-Bu'2-CSH3)(CH3)}2(~~-CH3)(p-rl'-rl'-C10H8)]+which decomposes with evolution of methane to give the p-methylene, p-methyl complex [{Zr(1,3BuL2-CSH3)} 2( pL-CH2)( p-C H 2)( 1-1-11': q '-C I 8)]+ [ B Me( C6Fs)3]- . In dichloromethane or chloroform complexes the latter and [ { Zr(CsHs)}2(p-CH3)(p-CH2)(pq':q'-CloH~)]' [BMe(C6F&]- undergo slow conversion to the p-chloro, pmethylene derivatives [ {ZrCp'} 2(p-CI)(p-CH2)(p-q':~'-cIOH8)]+[BMe(C,F&(Cp' = CSHS, l,3-But2-CSH3) by a halide abstraction process. The addition of an excess of donor ligands to a solution of [ {Zr(C5H5)}2(p-CH3)(p-CH2)(p-q5:q'CloH8)]+ [BMe(C6F5)3]- in dichloromethane-d2 at - 60 "C affords the cationic ~~s-C~~H~)]+ = adducts [ { Z r ( C ~ H ~ ) } ~ ( C H ~ ) L ( ~ - C H ~ ) ( p - ~ s : [BMe(C6F5)3]-[L PMe3, PMe2Ph, PPh3, THF] obtained as a mixture of syn- and ~ n t i - i s o r n e r s . ~ ~

Substitution of the chloride in Cp*FvTiCl with MR (Fv = C5Me&H2; R = Me, CH2SiMe3, CH2CMe3, CH=CH2, M = Li; R = CHZPh, M = K; R = C3H5, M = MgCI; R = Ph, M = Na) gives Cp*FvTiR. NMR spectroscopic evidence points towards a series of structurally related compounds with a bent-sandwich geometry. The substituent R is positioned in the wedge, midway below the exocyclic methylene group and a neighbouring methyl group of the fulvene. Thermolysis of Cp*FvTiR gives, dependent on the substituent R, reduction to Cp*FvTi (R = CH2Ph) or the double ring metallated Cp*[CSMe3(CH2)2]Ti(R = CH2XMe3, X = C, Si) or Cp*FvTiCH=CHMe (R = q3-C3H5).80B(C6F5)3 reacts with the fulvene complex (pentamethylcyclopentadienyl)(n-qs:c-q I - tetramethylfu1vene)phenylzirconium (Cp* FvZrPh) selectively under attack a t the fulveneCH2 group to form the highly sensitive zwitterionic complex (Cp*){C5Me4CH2B(C6F5)3}ZrPh84."

I : Complexes Contuining Metul-Curbon rr-Bondsof the Groups Titanium to Mungunese

29

The recently reported zwitterionic complex Cp*[r15-C5Me4CH2B(C6F5)3]ZrC6H5 reacts rapidly with 1 equivalent of acetone or acetophenone to form the adducts Cp*[r15-C5Me4CH2B(C6F5)3]zr(c6H5)[0=C(CH3)R] (R = CH3, C6H5 85) in 85% yield. Spectroscopic evidence in favour of this assignment is presented; the adduct nature of the complexes was also confirmed in each case via an X-ray structural analysis. The ketone ligands are bound in an q' end-on fashion (the Zr-O=C angles are near linear at 174.2"and 166.1 respectively), allowing for a 7ccomponent to the Zr-0 bonding. Unlike other fleetingly observed ketone adducts of non-zwitterionic cationic metallocenes, the ketone ligands in compounds do not undergo insertion into the Zr-C bond neither upon thermolysis nor in the presence of excess ketone.82 O

The reactions of so called 'tuck-in' permethyl zirconocene compounds Cp*(q 5q'-C5Me4CH2)ZrX (X = Cl, C6H5, CH3) with the highly electrophilic boranes HB(C6F5)2 and B(C6F5)3 are described. Cp*[q5-q 'C5Me4CH2B(C6FS)2(p-H)]ZrX (X = Cl, 74%, C6H5 62% 86), is formed by the reaction with HB(C6F5)2 where the metal is chelated by a pendant hydridoborate moiety. In the product of the reaction between Cp*(q5-q '-C5Me4CH2)ZrC6H5, and B(CbF5)3 to yield Cp*[q(5)-C5Me4CH2B(c6F5)3]zrC6H5, an ortho-fluorine interaction was found between the 'CH2B-(C6F5)3 and the metal centre. This yellow kinetic product converted upon heating gently to a thermodynamic orange polymorph in which the zirconium centre is compensated via an agostic interaction from an ortho C-H bond of the phenyl group and an interaction between the methylene group of the -CH$-(C6F5)3 counteranion. This reacts with H2 to form the zwitterionic hydride Cp*[q5-C5Me4CH2B(C6F5)3]ZrH87 characterised by N MR spectroscopy and X-ray ~rystallography.~~ The reduction of [C5Me4(SiMe3)]2TiC12 by excess Mg in T H F yields the paramagnetic compound { [q'-C Me4SiMe2(p-C H2 { Mg,Mg } )][q '-C5 Me4(SiMe3)]Ti1"(p-H)2Mg(THF))2. In the presence of Me3SiC 3 CSiMe3 the same system affords the paramagnetic compound [q5:q'-C5Me4SiMe2CH2][q5-C5Meq(SiMe3)lTi"' 88 in 75% yield. The crystal structures of both compounds reveal that one SiMe3 group in each of the compounds has been activated by hydrogen abstraction. For {[rlS-C5Me4SiMe2(p-CH2(Mg,Mg})][~5-C5Me4(SiMe3)]Ti1"(~H)2Mg(THF)}2 two titanocene-magnesium hydride-bridged units are held together by two methylene groups which link the two Mg atoms via a two-electronthree-centre Mg-C-Mg bond. In the mononuclear 88, a regular Ti-CH2 o-bond (2.204(5) binds the central Ti atom to the q5:q'-C5Me4SiMe2CH2l i g a ~ ~ d . ~ ~

A)

30

Orgunometullic Chemistry

The silyl derivative Si( I ,3-But2C5H3)(CH3)3 is an excellent precursor for monocyclopentadienyl trichlorotitanium and zirconium compounds M( 173-BU'2q5-C5H3)C13 [M = Ti, Zr]. The reaction of the titanium derivative with 2 equivalents of LiMe affords the chloro dimethyl derivative Ti( 1,3-Bu'2-q5C5H3)CI(CH3)2. The mixed dicyclopentadienyl compounds M( 1,3-Bu'2-q5C5H3)(C5H5)ClR [M = Ti, R = Me; M =: Zr, R = Me, Bz] o r the dialkyl [M = Ti, R = Me ; M = Zr, R = Me, complexes M(l,3-Bu'2-q5-C~H3)(C5H5)R2 with the Bz, Nf] were prepared by reaction of M( 1 ,3-But2-q5-C5H3)(CsH5)C12 appropriate alkylating reagent and molar ratio, in hexane at - 78 "C. When reacts with 2 equivalents of MgBz2(THF)2 or Ti( I ,3-But2-q5-C5H3)(C5H5)C12 LiCH2CMe2Ph the metallacyclic complexes Ti( 1-Bu'-3-CMe2CH2-q5CSH3)(C5HS)R[R = Bz, Nf] were isolated as red oils at room temperature, with the elimination of toluene or tert-butyl benzene respectively. The reaction of B(C6F5)3 with the monocyclopentadienyl trimethyl derivatives M( I ,3-Bu12-q5C5H3)(CH3)3[M = Ti, Zr], in the presence of PMe3, gives the cationic species [M( 1,3-Bu'2-qS-C5H3)(PMe3)2(CH3)2]+ [M = Ti, Zr], obtained as orange-yellow solids, stable at room temperature. The reaction of B(C6F5)3 with the metallocene dimethyl derivatives M( 1,3-Bu12-q5-CSH3)(q5-CsH5)(CH3)2[M = Zr, Hf], in a 1 :1 molar ratio and in hydrocarbon solvents gives the cationic derivatives [M( 1,3But2-q5-C5H3)(qS-C5H3)(CH3)]+ [(CH3)B(C6F5)3]- [M = Zr, Hf] as yellow oils which can be stored for weeks under an inert atmosphere. When the same reactions with B(C6F5)3 are carried out in 2:l molar ratio at room temperature, the complexes [[M( 1,3-But2-q5-C5H3)( q5-C5H5)Me]2(p-Me)][MeB(C6F5)3] [M = Zr, Hf] can be obtained as a mixture of syn- and anti-isomers as shown by NMR [M( 1 spectroscopic observations. [(CH3)B(C6F5)3]- [M = Zr, Hf] undergo heterolytic dissociation of the MetalMeB(C6F5)3 bonds, leading to the formation of the free [M(l,3-Bu12-q:C5H3)(q5-CsH5)(CH3)]+ 14-electron species. When compound [Zr( 1,3-Bu'z-q C5H3)(q5-C5H3)(CH3)]+[(CH3)B(C,F5)3]- was heated a t 50 "C the metallacyclic cation [Zr( 1-Bu'-3-CMe2CH2-q5-C5H3)(q5-C5H5)]+89 was formed.85

The reaction of zirconocene dichloride, Cp2ZrC12, and bis(indeny1) metal dichloride, Ind2MC12 (M = Zr, Hf), with one and two equivalents, respectively, of indenyl or fluorenyl lithium leads to sterically crowded complexes with three or four potential n-ligands (Cp2Zr(Ind)C17 Cp2Zr(Ind)z, Ind3ZrC1, Ind3HfC1, Ind2Zr( Flu)C186

I : Complexes Containing Metal-Carbon u-Bonds of the Groups Titanium to Manganese

31

Chiral C1-symmetric zirconocene complexes (R)- and (S)-Me2Si(q'-C13H16)(r15C5H3R*)ZrR2,90 where C13HI6= octahydrofluorenyl, R = NMe2, C1, or Me, and R* = (1R,2S,5R)-trans-5-methyl-cis-2-(2-propyl)cyclohexyl(( -)-menthyl), are described. The dialkyl zirconocene is prepared by reaction of MeLi with the dichloride compound (R)-and (S)-Me2Si(q5-C13H 16)(q5-C5H3R*)ZrC12.87 The reaction of rac-(ebthi)Zr(q2-Me3SiC2SiMe3) [ebthi = 1,2-ethylene-1,l'bis(q5-tetrahydroindenyl)] with an excess of ethylene at room temperature leads to the corresponding zirconacyclopentane 91, which was isolated as stable yellow crystals and characterised by an X-ray crystal structure analysis. At 203 K a zirconacyclopentene derivative is observed, possibly an intermediate in the reaction from rac-(ebthi)Zr(q2-Me3SiC2SiMe3)to 91. The reaction of 2 equivalents of styrene with the alkyne rac-(ebthi)Zr(q2-Me3SiC2SiMe3) leads to an unsymmetrically substituted zirconacyclopentane.88

R5

90

91

92

Stereoselective propene insertion reactions of chiral zirconocene species of the type rac-(EBI)Zr(q*-pyridyI)+ (EBI = ethylenebis(indeny1)) containing substituted q2-pyridyl ligands are described. The reaction of rac-(EBI)ZrMez with B(C6F5)3 followed by addition of 1 equivalent of the appropriate pyridine yields [ra~-(EBI)Zr(rl~-3-R~-5-R~-6-R~-pyrid-2-yl)][MeB(C~F~)~] pyridyl complexes (R3 = R5 = H, R6 = Me; R3 = R5 = H, R6 = Ph; R3 = R5 = R6 = H; R3 = Me, R5 = H, R6 = Me; R3 = H, R5 = R6 = Me; R3 = R5 = Me, R6 = H) 92. These compounds react with propene to yield the 1,2-insertion products [rac(EBI)Zr{q2-(C,N)-CH2CHMe(pyrid-2-yl)}][MeB(C6F5)3], for which two diastereomers that differ in the configuration of the metallacycle P-carbon are possible. Propene insertion under kinetic control at 23 "C is highly stereoselective when the pyridyl ring contains a 6-substituent. Molecular modeling calculations for model rac-(EBI)Zr(q*-pyridyI)(propene)+ species suggest that steric interactions between the pyridyl R6 substituent and the EBI c6 ring cause a tipping of the pyridyl ligand, which influences the pyridyl/propene steric contacts and the facial selectivity of propene binding. The modeling calculations also suggest that the more stable propene adduct diastereomer leads to the kinetic insertion prod~ct.'~ The reaction of ZrC4 with 2 equivalents of MeLi to form Me2ZrCia followed,

32

Orgunometullic Chemistry

by in situ metalation of Me2ZrC12 with the corresponding ansa-ligands produces the respective ansa-dimethylzirconocene complexes, 0-Xyl( 111d)~ZrMe2 [Ind = q5-1-indenyl; 0-Xyl = C6H4(CH3)2-1,2], 2-Bn(It1d)~ZrMe~[2-Bu = (-CH2CH=CHCH2-)], Et(Ind)2ZrMe2, and Me2Si(Znd)2ZrMe2 in high yields. Treatment of these compounds with HCI affords their ansa-dichlorozirconocene analogues in quantitative yields. Synthesis of ansa- dimethylzirconocene via MezZrClz is more efficient than that via Cp2ZrC12 (Cp2 = ansa-ligand) in the conventional met hods .90 Alkylation of [Zr(CpSi2Cp)C12] (CpSi2Cp = (q5-CSH3)2[Si(CH3)2]2)With 1 equivalent of RMgCl in T H F at 10°C gave the monoalkylated complexes [Zr(CpSi2Cp)CIR] (R = Et, “Pr, ‘Pr) in 80% yield, the isopropyl complex isomerising to the n-propyl derivative above 10°C. Addition of a second equivalent or an excess amount of the akylating agent resulted in the formation of the dialkyl compounds [Zr(CpSi2Cp)Rz] (R = Et, n-Pr). Hydrolysis of [Zr(CpSi2Cp)C1R] led to the p-0x0 binuclear complex [{ Zr(CpSi2Cp)Cl) 2(p-O)]. Thermal decomposition of T H F solutions of [Zr(CpSi2Cp)CIR] takes place with the evolution of an equimolar amount of alkane and alkene and the formation of [Zr(CpSi2Cp)C12]and an unidentified residue. Formation of [Zr(CpSi2Cp)Et2] is always accompanied by decomposition with the evolution of ethane to give [ { Zr(CpSi2Cp)Et) 2(p-CH2=CH2)] in 70‘7” yield. A similar behaviour was observed for [Zr(CpSi2Cp)(”Pr)2]. Other reactions concerning this complex involve the reaction of [Zr(CpSizCp)Mez] with CNR (R = 2,6-Me2C6H3, ‘Bu) yields [Zr(CpSi2Cp)Me(q2-CMeNR)](R = 2,6-Me2C6H3, ‘Bu), which reacts with a stoichiometric amount of water to give the v-0x0 dimers [Zr(CpSi2Cp)(q2CMeNR)]2(p-O) (R = 2,6-Me&H3, ‘Bu). The chloro neophyl complex [Zr(CpSi2Cp)2C1(CH2CMe2Ph)]and other P-hydrogen containing zirconium chloro alkyls [Zr(CpSi2Cp)CIR] (R = Et, n-Pr, i-Pr) react with CN(2,6-Me2C6H3) to yield the related chloro iminoacyl complexes [Zr(CpSi2Cp)CI{ q2-CRN(2,6Me2C6H3)}](R = Et, n-Pr, i-Pr), whereas no reaction was observed when CN(tBu) was used.92 Reaction of Cp2M(PMe3)2 complexes (M = Ti, Zr; C p = qs-C5H5) with the N(p-tolyl)-diphenylketeniminePh’N=C=CPh2 (Ph’ = p-MeC&) in a I :1 molar ratio affords the ketenimine-containing metallocene derivatives Cp2M(q2-(C,N)Ph‘N=C=CPhz)(PMe3) (M = Ti, Zr). The ketenimine ligand reacts in the same way with the ‘Cp*2M’ species generated from the reduction of the corresponding C P * ~ M C complexes I~ with Li‘Bu (1 :2 molar ratio) to give the related complexes Cp*2M(q2-(C,N)-Ph’N=C=CPh2) (M = Ti, Zr) 93. The molecular structure shows a titanium atom bonded to two q’-cyclopentadienyl rings and a q2-(C,N)bonded ketenimine ligand. Reaction of ‘ C P * ~ Twith ~ ’ the ketenimine ligand in a 1 :2 molar ratio gives 1,1,5,5-tetraphenyl-3-(p-tolyl)-2-(p-toluidino)-3-az~-l,4-pentadiene, which probably results from the coupling, followed by hydrolysis, of two ketenimine molecules coordinated to one titanocene moiety. Protonation of c~*~Ti(q~-(c,N)-Ph’N=C=cPh~) with Et3NHCI or H20 (1: 1 molar ratio) affords the intermediate species Cp*2Ti(X)(q2-(C,N)-Ph’N ..C(H).-CPh2) (X = CI, OH), which on hydrolysis evolves to give the enamine Ph’N(H)-CH=CPh2 as the final product. Finally, Cp*2Ti(q2-(C,N)-Ph’N=C=CPh2) reacts reversibly

I : Complexes Containing Metul-Curbon o-Bonds of the Groups Titunium to Mungunese

33

with H2 to give the hydride enamidate complex Cp*zTi(H)(q ‘-Ph’N-CH = CPh2) 94.93 Treatment of Cp*Zr(CI)CH3 with sodium cyclopentadienide gives Cp3ZrCH3. Its reaction with dimethylanilinium tetraphenylborate yields the CpJZr(THF)+ cation. [Cp3Zr+ CH3B(C6F5)3-] is generated by treatment of Cp2Zr(CI)CH3with B ( C ~ F S )Nitriles ~. add to form the ligand-stabilised tris(q5-cyclopentadieny1)zirconium cation systems Cp3Zr(N=CR)+. Carbon monoxide adds to [Cp3Zr+ CH3B(C6FS)3-] to give the cationic metal carbonyl complex [Cp3Zr(CO)+ CH3B(C6F5)3- 1. With tert-butyl isocyanide, the donor-ligand-stabilised - ] formed. X-ray crystal structure analysis [Cp3zr(C 3 NCMe)CH3+ B ( C ~ F S ) ~is shows that its cation consists of three uniformly coordinated q’-cyclopentadienyl ligands about the zirconium atom. The acetonitrile ligand is end-on coordintted. In the linear [Zr]-N-C-CH3 unit the C r N triple bond [N-C2 1.126(5) A] is the slightly shorter than in the free acetonitrile molecule [dc=N =1.141(2) structure of which was determined as a reference by X-ray diffraction of a crystal obtained by IR-laser- induced zone melting on the d i f f r a c t ~ m e t e r9s .~~~ Simple transition-metal complexes of the formula Cp*M(CO)(n)BR2 containing an electrophilic, covalently bound main-group ligand react with alkanes and release products resulting from selective functionalisation of an alkane at the terminal position. These reactions produce alkylboronate esters, which are common reagents in organic synthesis. Mechanistic analysis shows that ligand dissociation is induced photochemically and that thermal reaction of the resulting intermediate occurs with alkanes.

A],

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34

Organometallic Chemistry

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J. D. Scollard, D. H. McConville, and S. J. Rettig, Organometallics, 1997, 16, 1810. J. D. Scollard, D. H. McConville, and J. J. Vittal, Organometallics, 1997, 16,4415. J. G. Donkervoort, J. Jastrzebski, B. J. Deelman, H. Kooijman, N. Veldman, and A. L. Spek, Organometallics, 1997, 16,4174. J. G. Donkervoort, C. M. P. Kronenburg, B. J. Deelman, J. T. B. H. Jastrzebski, N. Veldman, A. L. Spek, and G. vanKOten, J. Organomet. Chem., 1997,547,349. F. Guerin, D. H. McConville, and J. J. Vittal, Organometallics, 1997, 16, 1491. X. H. Bei, D. C. Swenson, and R. F. Jordan, Organometullics, 1997,16,3282. T. Tsukahara, D. C. Swenson, and R. F. Jordan, Organometallics, 1997,16, 3303. R. Baumann, W. M. Davis, and R. R. Schrock, J. Am. Chem. Soc., 1997,119,3830. N. A. H. Male, M. Thornton-Pett, and M. Bochmann, J. Chem. Soc., Dalton Trans., 1997,2487. L. Lee, D. J. Berg, and G. W. Bushnell, Organometallics, 1997, 16, 2556. L. Giannini, A. Caselli, E. Solari, C. Floriani, A. ChiesiVilla, and Rizzoli, J. Am. Chem. Soc., 1997,119,9 198. L. Giannini, A. Caselli, E. Solari, C. Floriani, A. ChiesiVilla, and Rizzoli, J. Am. Chem. Suc., 1997,119,9709. A. Caselli, L. Giannini, E. Solari, C. Floriani, and N. Re, Organometullics, 1997, 16, 5457. M. J. Scott and S. J. Lippard, J. Am. Chem. Soc., 1997,119,341 I . M. J. Scott and S. J. Lippard, Inorg. Chim. Acta, 1997,263,287. M. J. Scott and S. J. Lippard, Organometullics, 1997, 16, 5857. J. Okuda, T. Eberle, and T. P. Spaniol, Chem. Ber.-Recueil, 1997, 130,209. P. J. Sinnema, L. vanderveen, A. L. Spek, N. Veldman, and J. H. Teuben, Organometallics, 1997,16,4245. Y. X . Chen and T. J. Marks, Organometallics, 1997,16, 3649. L. Kloppenburg and J. L. Petersen, Organometallics, 1997,16, 3548. A. Bertuleit, C. Fritze, G. Erker, and R. Frohlich, Organometallics, 1997,16,2891. H. V. R. Dias and Z. Y. Wang, J. Organornet. Chem., 1997,539,77. R . Beckhaus, J. Oster, B. Ganter, and U. Englert, Organometallics, 1997,16, 3902. Y. X.Chen, P. F. Fu, C. L. Stern, and T. J. Marks, Organometallics, 1997,16,5958. G. Paolucci, G. Pojana, J. Zanon, V. Lucchini, and E. Avtomonov, Organometallics, 1997,16,5312. B. E. Bosch, G. Erker, R. Frohlich, and 0. Meyer, Organometallics, 1997,16, 5449. F. Amor, T. P. Spaniol, and J. Okuda, Organometallics, 1997,16,4765. J. Karl, G. Erker, and R. Frohlich, J. Am. Chem. Soc., 1997, 119, I 1165. J. Karl and G. Erker, Chem. Ber.-Recueil, 1997,130, 1261. J. Karl, G. Erker, and R. Frohlich, J. Organornet. Chem., 1997,535, 59. G. Rodriguez and G. C. Bazan, J. Am. Chem. SOC.,1997,119,343. G. J. Pindado, M. ThorntonPett, and M. Bochmann, Chem. Comm., 1997,609. G. J. Pindado, M. ThorntonPett, and M. Bochmann, J. Chem. Soc., Dalton Trans., 1997,3115. G. G. Lavoie and R. G. Bergman, Angew. Chem., Int. Ed. Engl., 1997,36,2450. M. D. Spencer, S. R.Wilson, and G. S. Girolami, Organometallics, 1997,16, 3055. B. Hessen and H. vanderHeijden, J. Organornet. Chem., 1997,534,237. J. N. Christopher, R. F. Jordan, J. L. Petersen, and V. G. Young, Organometallics, 1997,16, 3044. L. I. Strunkina, M. K. Minacheva, P. V. Petrovskii, Z. S. Klemenkova, B. V. Lokshin, V. V. Burlakov, and V. B. Shur, Russ. Chem.Bull., 1997,46,820.

9. 10.

I I. 12. 13. 14. 15. 16.

17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45.

I : Complexes Contuining Metul-Curhon o-Bonds of the Groups Titanium to Mungunese 46. 47. 48. 49. 50. 51. 52.

53. 54. 55.

56. 57. 58.

59. 60.

61. 62. 63. 64. 65. 66. 67. 68. 69. 70.

71. 72. 73.

35

R. Beckhaus, J. Sang, T. Wagner, and U. Bohme, J. Chem. Soc., Dulton Truns., 1997,2249. R. Beckhaus, J. Oster, J. Sang, I. Strauss, and M. Wagner, Synlett, 1997, 241. R. Beckhaus, Angew. Chem., Int. Ed. Engl., 1997,36,687. V . K. Dioumaev and J. F. Harrod, Orgunometullics, 1997, 16, 1452. T. Takahashi, Y. Nishihara, W. H. Sun, R. Fischer, and K. Nakajima, OrgunometCrI1ic.s 1997, 16, 22 16. G. J. Gordon and R. J. Whitby, Chem. Comm., 1997, 1321. A. Mahieu, Y. Miquel, A. Igau, B. Donnadieu, and J. P. Majoral, Orgunumetul/ics, 1997,16,3086. L. Dupuis, N. Pirio, P. Meunier, A. Igau, B. Donnadieu, and J. P. Majoral, Angew. Chem., Int. Ed Engl., 1997,36,987. Y. Miquel, A. Igau, B. Donnadieu, J. P. Majoral, L. Dupuis, and N. Pirio, Chern. Comm., 1997,279. M. Zablocka, A. Igau, B. Donnadieu, J. P. Majoral, A. Skowronska, and P. Meunier, Chem. Comm., 1997, 1239. T. L. Breen and D. W. Stephan, Orgunometullics, 1997, 16,365. V. V. Burlakov, A. I. Yanovsky, Y. T. Struchkov, U. Rosenthal, A. Spannenberg, R. Kempe, 0. G. Ellert, and V. B. Shur, J. Orgunomet. Chem., 1997,542, 105. V. V. Burlakov, N . Peulecke, W. Baumann, A. Spannenberg, R. Kempe, and U. Rosenthal, Cull. Czech. Chem. Comm., 1997,62,331. V. V. Burlakov, N. Peulecke, W. Baumann, A. Spannenberg, R. Kempe, and U. Rosenthal, J. Orgunomet. Chem., 1997,536,293. P. M. Pellny, N. Peulecke, V. V. Burlakov, A. Tillack, W. Baumann, A. Spannenberg, R. Kempe, and U. Rosenthal, Angew. Cliem., Int. Ed. Engl., 1997, 36, 2615. G. L. Casty, C. G. Lugmair, N. S. Radu, T. D. Tilley, J. F. Walzer, and D. Zargarian, Orgunometullics, 1997, 16, 8. W. Ahlers, B. Temme, G. Erker, R. Frohlich, and T. Fox, J. Orgunornet. Cliem., 1997,527, 191. W. Ahlers, B. Temme, G. Erker, R. Frohlich, and F. Zippel, Orgunometullics, 1997, 16, 1440: W. Ahlers, G. Erker, R. Frohlich, and F. Zippel, Chem. Bet-.-Recueil, 1997, 130, 1079. M. Oberhoff, G. Erker, and R. Frohlich, Chem. Eur. J., 1997,3, 1521. D. Rottger and G. Erker, Angew. Cltem., Int. Ed. Engl., 1997,36, 81 3 . W. Ahlers, G. Erker, R. Frohlich, and U. Peuchert, Chrm. Ber.-Recueil, 1997, 130, 1069. J. Schottek, G. Erker, and R. Frohlich, Angew. Chem., Int. Ed. Engl., 1997,36,2475. V. Varga, L. Petrusova, J. Cejka, and K. Mach, J. Orgunomet. Chem., 1997, 532, 251. J. Hiller, V. Varga, U. Thewalt, and K. Mach, Coll. Czech. Chem. Comm., 1997, 62, 1446. H. Lang, I. Y. Wu, S. Weinmann, C. Weber, and B. Nuber, J. Orgunomet. Chem., 1997,541, 157. E. G. Berkovich, V. S. Lenenko, L. I. Vyshinskaya, G. A. Vasileva, and V. B. Shur, J. Orgunumet. Chem., 1997,535, 169. G . Ciruelo, T. Cuenca, R. Gomez, P. GomezSal, A. Martin, G. Rodriguez, and P. Royo, J. Orgunomet. Chem., 1997,547,287.

36

Orgunometullic Chemistry

74.

Q . Y. Wang, D. J. Gillis, R. Quyoum, D. Jeremic, M. J. Tudoret, and M. C. Baird, J. Orgunomet. Chern., 1997,527,7. T. L. Tremblay, S. W. Ewart, M. J. Sarsfield, and M. C. Baird, Chem. Comm., 1997, 831. M. J. Sarsfield, S. W. Ewart, T. L. Tremblay, A. W. Roszak, and M. C. Baird, J. Chem. Soc., Dulton Trans., 1997,3097. F. Calderazzo, G. Pampaloni, and G. Tripepi, Orgunornetullics, 1997,16,4943. F. Calderazzo, U. Englert, G. Pampaloni, U. Kolle, and G. Tripepi, J. Orgunomer. Chem., 1997,543,20 1 . T. Cuenca, M. Galakhov, G. Jimenez, E. Royo, P. Royo, and M. Bochmann, J. Orgunomet. Chem., 1997,543,209. G. A. Luinstra, P. H. P. Brinkmann, and J. H. Teuben, J. Orgunornet. Chem., 1997, 532, 125. X. J. Song and M. Bochmann, J. Orgunornet. Chem., 1997,546,597. Y. M. Sun, W. E. Piers, and G. P. A. Yap, Orgunomeiullics, 1997,16,2509. Y. M. Sun, R. Spence, W. E. Piers, M. Parvez, and G. P. A. Yap, J. Am. Chem. Soc., 1997,119,5132. M. Horacek, J. Hiller, U. Thewalt, M. Yolasek, and K. Mach, Orgunometullics, 1997,16,4185. J. 1. Amor, T. Cuenca, M. Galakhov, P. GomezSal, A. Manzanero, and P. Royo, J. Orgunomet. Chem., 1997,535,155. C. Schniid, H. G. Ah, and W. Milius, J. Organomet. Chem., 1997,544, 139. Y. Obora, C. L. Stern, T. J. Marks, and P. N. Nickias, Orgunometullics, 1997, 16, 2503. S. Mansel, D. Thomas, C. Lefeber, D. Heller, R. Kempe, W. Baumann, and U. Rosenthal, Orgunometullics, 1997, 16,2886. S. Dagorne, S. Rodewald, and R . F. Jordan, Orgunornetullics, 1997, 16, 5541. J. T. Park, B. W. Woo, S. C. Yoon, and S. C . Shim, J. Orgunomet. Chern., 1997,535, 29. F. J. Fernandez, P. GomezSal, A. Manzanero, P. Royo, H. Jacobsen, and H. Berke, Orgunometullics, 1997, 16, 1 5 5 3. A. M. Barriola, A. M. Cano, T. Cuenca, F. J. Fernandez, P. GomezSal, and Manzanero, J. Orgunomet. Chem., 1997,542,247. R. Fandos, M. Lanfranchi, A. Otero, M. A. Pellinghelli, M. J. Ruiz, and J. H. Teuben, Orgunometullics, 1997, 16, 5283. T. Brackemeyer, G. Erker, and R. Frohlich, Orgunometullics, 1997,16, 531. T. Brackemeyer, G. Erker, R. Frohlich, J. Prigge, and U. Peuchert, Chem. Ber.Recueil, 1997, 130,899. K. M. Waltz and J. F. Hartwig, Science, 1997,277, 21 1.

75. 76. 77. 78. 79. 80. 81. 82. 83. 84.

85. 86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96.

Part 11: Group 5 by Elizabeth M . Page 1

Reviews

A review article describes recent progress in the field of homogeneous organometallic catalysts for olefin polymerisation focusing on the metal-carbon bond character of the transition metal complexes used as catalysts. Although the majority of such complexes are derivatives of Group 4 metals, results are included

1: Complexes Containing Metal-Carbon o-Bonds of the Groups Titanium to Mangunese

31

from a study on mono(cyclopentadienyl)mono(diene) complexes of Group 5 metals. I A review has been published of the inorganic and organometallic chemistry of hydridotris(pyrazoly1)borato complexes of Group 5 metals. Although many of the examples are of 0x0-vanadium species the second part of the review concentrates on advances in the field of four-electron alkyne niobium and tantalum complexes.2

2

Alkyt Complexes

A series of alkyl niobocene complexes having general formula [Nb(qs-

CsH4SiMe3)2R(q2-(C,Z)-ZCCR’Ph)] (2 = NPh, 0; R = Me, R’ = H, Me, Et, Ph) has been obtained by treatment of [Nb(q5-C5H4SiMe3)2Cl(q2-(C,Z)-ZCCR’Ph)] with Li(BEt3H) and the Grignard (RMgI) or dialkyl magnesium. The X-ray crystal was detem~ined.~ structure of [Nb(q5-C5H4SiMe3)2Me(q2-(C,O)-0CCPh2)] The olefin-hydride complexes, Cp’2Nb(H)(q2-CHR=CHR’)(CH=CHR’) (Cp‘ = qs-CsH4SiMe3, R = CH2CH3,CH2CH2C6HS;R’ = H, C6HS),formed from the Grignard reaction of [CpP2NbC1]2 with RMgX, undergo reaction with CO to give the alkylniobocene complexes Cpt2Nb(CO)R.The same products can be obtained from C 0 2 insertion in Cp’,Nb(H)(q2-RHC=CH2) ( R = C6H4CH3, C6H40CH3).4 Treatment of [TaClfMe3] with LiZ(cot”) (cot” = 1,4-bis(trimethylsilyl)cyclooctatetraene) was found to yield r]ra(q-cot”)Me3] which on reaction with [NHPri2Et]CI in CH2CI2 yielded the complex p a {q8-C&14(SiMe3)2-1,4}C13]. The X-ray crystal structure of F a { q8-C8H4(SiMe&I ,4}C13] showed it to contain a single pantalene ligand bound through all eight carbons to the Ta atom.5 The V(II1) methyl complexes [(Me3Si)2N]2VMe(THF) and [(Me3Si)2N]2V-

Equation i Me(pyr) have been obtained from reactions involving [(Me3Si)2N]2VCI(THF) and MgMe2 or LiMe. The chelated aryl amine [(Me3Si)2N]2V(u-Me2NCH2C6H4) has been synthesized from [(Me3Si), N]zVCI(TH F) and Li(o-Me2 NCH& H4) according to equation i.6 One electron oxidation of [(Me3Si),NI2VX(THF)(X = C1, Me, Ph) with CuCl resulted in the V(1V) species [(Me3Si)2N]2VCl(X). Reaction of [(Me3Si)2N]2VCI(THF) with dilithioacetylide in the presence of TMEDA led to rearrangement of the C1 ligands and the formation of the anionic compound [Li(TMEDA)2][(Me3Si)2N]2VC12. The analogous dimethyl compound was

38

Orgunornetullic Chemistry

synthesized from the reaction of [(Me3Si)2N]2VCl(THF) with LiMe in the presence of TMEDA.7 Treatment of (Nb[q:o-C5H4(CH2)3N]C12} with MeMgBr gave the dimer ~ M ~ N ~ [ ~ ~ - C S H ~ ( C H ~ ) , ( ~ - N ) ( ~ - ~ ( N ) : ~ ~ ~ - ( N , C ) - N C bMez} H(CH~)~-~~-C which was shown by crystallography to be an ansa-bridged q-cyclopentadienylimido complex.8 The complex [C5H4(CH2)2N-'Pr]V(N-'Bu)Me has been obtained as an intermediate in the formation of adducts of simple olefins to a cationic V (V) metal

fi" i-Pr

1

2

Equation ii centre and its X-ray crystal structure was determined.' The reaction of (q5-C5MeS)TaMe4 with the silanetriol, 1, was found to lead to stepwise formation of the tantalum siloxane cage complex, 2, according to equation ii." Insertion reactions of the tantalum(V) carborane alkyl and aryl complexes (Et2C2B4H4)CpTaR2 (R = Me, Ph) by nitriles leads to azaalkenylidine complexes (Et2C2B4H4)CpTaR(N=CR'2)upon irradiation. With isonitriles insertion is rapid at room temperature into the Ta-C bond of ( E ~ ~ C ~ B ~ H ~ ) C P T ~ R ~ .

'

3

Alkylidene Complexes

The lithium salt of the potentially C,N , N'-chelating anionic aryldiamine ligand

2TaCI ~(=CH-~-BU)(THF)~]

+

.

-2LiCI. 4THF EQ0. -78OC

[Li { CbH4(CH2N(Me)CH2CH2NMe2)-2} 12

CMe3

Equation iii

3

1: Cvmplexes Contuining Metul-Curbon

6-Bonds of

the Groups Titunium to Mungunese

39

[C6H4(CH2N(Me)CH2CH2NMe2)-2]- (CNN) has been used to obtain the alkylidene complex [TaC12(=CH1Bu)(CNN)]by reaction with [TaC&(=CH'Bu)(THF)2] (equation iii). The complex was obtained as a mixture of three diastereoisomers. The structure of the major isomer, 3, has been determined and was shown to be a tetragonal bipyramidal complex. The dialkoxide complexes [Ta(=CHR)(CNN)(O'Bu),1 (R = 'Bu, CMe2Ph) have been obtained with [Li(CNN)]2. Reaction by transmetallation of [T~CI(=CHR)(O'BU)~(PM~~)] of the CMe2Ph complex with ethene yielded the tantalum alkene [Ta(CNN)(O'BU)~(H~C=CH~)].'~ with LiO'Bu gave the Reaction of [TaC12(=CH'Bu)(C6H3(CH2NMe2)2-2,6}] rearranged product [Ta(=CH'Bu)(C6H3(CH2NMe2)2-2,4}(OtBu)2],4 according

Equation iv to equation iv. The reaction proceeds via an isomerization reaction involving the intermediate, [TaCI(=CH'Bu)(C6H3(CH2NMe2)2-2,6}(OtBu)]to the rearranged (O'Bu)]. Both these comintermediate [TaCI(=CH'Bu){ C6H3(CH2NMe2)2-2,4} plexes have been prepared independently and ~hardctet-ked.'~ The trichloride complexes, [Ta(OC,jHPh2-2,6-R2-3,5)C13] (R = H, Ph, Me, 'Pr, 'Bu), obtained by treatment of TazCllo with the corresponding 3,5-disubstituted2,6-diphenylphenols, 5, have been employed as starting materials for the Me3)3]. Reaction of [Ta(OCbHPh2tris(a1ky 1s) [Ta(OC6HPh2-2,6-R2-3,5)2(CH2Si

RqK:h

Ph

'9

c ' p .P *

R R = H,Ph,Me,i-Pr, f-Bu 5

6

Orgunometullic Chemistry

40

2,6-R2-3,5)C13]with LiCHzSiMe3 yielded the tris(alky1s) which were shown to have trigonal bipyramidal geometry with axial aryl oxide groups. Photolysis of the tris(alky1s) yielded the alkylidene complexes [Ta(OC6HPh2-2,6-R23,5)2(=CHSiMe3)(CH2SiMe3)].l 4 A new bonding mode of the C5H4 ligand has been observed in the alkylidene complex [(q5-C5H5)Ta(NEt2)2(=C5H4)]. Reaction of [(q5-C5H5)Ta(NEt2)2C12] with MeLi at - 35 "C in a toluene ether mixture resulted in evolution of CH4 and a very low yield of [(q5-C5H5)Ta(NEt2)2(=C5H4)]. The molecular structure of the complex, 6, was shown to possess the three-legged piano-stool geometry with a terminal alkylidene ligand. l 5 Diphenylacetylene undergoes reaction with [(Me3Si)*N]2V(THF)(BHq) to yield a V(V) bicyclic alkylidene-amide complex, 7, via insertion of the alkyne into a V-C bond according to equation v. The complex, 7 features a distorted

Me Me

\I

I'

5l -S?

/"\ /"\ N -S? CH2 \ ISi S? b

sf

-7

+ PhCrCph -trmcs-stilbene

Si' = MesSi R=Ph

7

Equation v tetrahedral geometry around the V atom which is combined in two fused five-membered metallocycles.'6 The same complex can be prepared via reaction of ([Me3Si)2N]V[p-CH2SiMe2N(SiMe3)])2 with four equivalents of diphenylacetylene. An experimental analysis has been conducted into the energetics of the formation of multiple M=C bonds in Ta-alkylidene complexes. Thermochemical data is presented for reactions, including that depicted in equation vi, which were used to obtain estimates of D(Ta-C) and D(Ta=C). The figures derived showed

I : Complexes Contuining Metal-Curbon o-Bonds ofthe Groups Titunium to Munganwe

41

Equation vi

an unexpectedly high Ta=C bond enthalpy which could account for the driving force in Ta-alkylidene formation.l7 Thermolysis of the (silox),Nb(q2-NC-py) complex for 1 h in benzene at 70°C

+=\ -

(sil0~)3Nb

H

N*Nb(sil0~)~ 8

yielded the ring opened product (silox),Nb=CH(CH=CH)(CH=CH)N=Nb(silox)3, 8. ' H and I3C{' H ) NMR were used to investigate the equilibria between the four stereoisomers of 8 and activation energies for the transformations were calculated. The X-ray crystal structure of the trans, cis isomer was determined.I8 4

Alkylidyne Complexes

Reaction of neophylzinc chloride, [ZnCl(CHzCMezPh)] with the alkylidene complex [TaC13(=CHCMe2Ph)(THF)2] gave the Ta neophylidyne complex proposed to be [ { (TaC12(p-CCMe2Ph)(p-CI)(THF)2){Zn(m-Cl)))2],9. Dissolution of 9 in THF followed by removal of the solvent led to a new complex, 10, suggesting

THF 9

R = CMCZF%

10

Equation vii the solution equilibrium shown in equation vii. From 9 the Ta-Zn neophylidyne complexes paC12(p-C6H4CH2NMe2-2)(p-CCMe2Ph)ZnCI(THF)]and [TaC12 (pC6H3(CH2NMe2)2-2,6)(p-CCMe;?Ph)ZnCl]were obtained by reaction with [Zn(C6H4CH2NMe2-2)2] and [ { Li { C6H3(CH2NMe2)22,6)121 respectively.''

42

5

Orgunometallic Chemistry

AIkyne Complexes

The Nb(1V) alkyne complexes Nb(q5-C5H4SiMe3)2(q2(C,C)-RC= CR'), 11, have been prepared by reduction of the corresponding Nb(V) species Nb(q5C5H4SiMe3)2(q2(C,Q - R C = CR')(Cl) with Na/Hg. Reaction of 11 with [FeCp2J[BPh4J in the presence of the appropriate Lewis base gave the cationic niobocene alkyne complexes 12 as shown in equation viii. A 1+

R' 12

R , R' = Ph, COOMe, Me L = MeCN, fBuCN, THF, Py Equationviii

binuclear

divinylidene

d2

niobocene

complex,

(q5-C5H4SiMe3)2-

(CO)Nb=C=C(CH,(CH3)C=C=Nb(CO)(q5-CgH4SiMe3)2[BPh4J2 was obtained from the oxidation of Nb(q5-C5H4SiMe3)2(q2(C,C)-MeC 3 CC02Me) when the reaction was carried out at a slightly higher temperature.20 The reaction of vanadocene VCp2 with Me3SiC= C-C s CSiMe3 or Ph2PC = CC r C P P h 2 resulted in an oxidative addition with the formation of the homobimetallic vanadium d'-d' complexes (Cp2V)2( 1-2q:3-4q-Me3SiC=C-C=CSiMe3),

13

1: Complexes Contuining Metal-Curbon o-Bonds of the Groups Tituniurn to Munganese

43

14

13, and (Cp2V)2(1-2q:3-4q-Ph2PC=C-C=CPPh2), 14. The bond distances and angles associated with the V-acetylene interaction indicate that the acetylene molecule is symmetrically attached to the V atom through two s-type V-C bonds.

'

6

Ally1 Complexes

The imido-based half-sandwich complex Cp*Ta(=N(2,6-diisopropylphenyl)( q I -

15

C3H5)(q3-C3H5) , 15, was found to polymerise ethylene in the presence of [(C6H5)3C]+,[(CbF5)4B]- or B(CbF&. In an attempt to understand the chemistry of the Ta centre template other similar half-sandwich imido systems were constructed including the complex C ~ * T ~ ( = N S ~ ( ' B U ) ~ ( ~ ' - C ~ H ~ ) ( ~ ~ - C Despite the similarity to 15 this complex was not found to be active in ethylene polymerization.22 Low valent vanadium(I1) species have been used to mediate the allylation of carbonyl compounds with ally1 halides in mixed solvent THF/HMPA systems. It is thought that the addition of HMPA s t a b i k s a V-C bond of an allyl-vanadium species generated in sit^.^^

Organometullic Chemistry

44

7

N-Bridged Dinuclear Complexes

The binuclear unsu-bridged q-cyclopentadienylimide complex [MeNb { pC5H4(CH2)3N){ P - N C H ( C H ~ ) ~ C ~NbMe21 H ~ ) was obtained by treatment of [Nb{q5,~N-C5H4(CH2)3N}C12] with MgMeBr and the crystal structure determined.24 Three binuclear tantalum complexes containing NAr, CNAr or HCNAr groups have been synthesized from (Me2S)C12Ta(p-Me2S)(p-C1)2TaC12(SMe2) and N,N'-diphenylformamidinate, DPhF- . In the presence of Zn and DPhFthe compound (q2-DPhF)2Ta(p-NPh)(p-q2-CNPh)Ta(q2-DPhF)2.C7Hg was isolated. With Na/Hg as the reducing agent and N,N'-di(p-toly1)formamidinate (DTolF-) (q2-DT~lF)Ta(p-NTol)(p-~~2-CNTol)(p-DTolF)~Ta(q2-DTo 1.5C6HJ4was obtained. In both compounds there is a formal single bond between the Ta atoms which are bonded to intact formamidinate ions as well as the two fragments which result from the cleavage of a formamidinate ligand. In the absence of a reducing agent the reaction of LiDTolF and (Me2S)CI2Ta(p-Me2S)(p-C1)2TaC12(SMe2)leads to C12(q2-DTolF)Ta(p-NTol)(pq2, q2-HCNTol)Ta(q2-DTolF)2.In this complex a tolylformimidoyl fragment (HCNTol) binds to the Ta atom through the C and N atoms in a q2,q2 mode.25

8

Aryl Oxide Complexes

Methylation of the aryloxide complex (q6-C6Me6)Ta(oAr)2C1 (Ar = 2,6C6H3iPr2) by MeMgBr resulted in (q6-C6Me6)Ta(OAr)2Me.Alkylation of (q6C6Me6)Ta(OAr)C12 with RMgBr (R = Me, Et) yielded (q6-C6Me6)Ta(oAr)R2. Monoalkylation reactions of (q6-C6Me&I'a('OAr)C12 were also investigated.26 Addition of 1,3-~yclohexadieneto the trihydride compounds [Ta(OC6H3Cy22,6)2(H)3(PMe2Ph)2] and [Ta(OC6HPh2-3,5-Cy2-2,6)2(H)3(PMe2Ph)2] gave the products [Ta(OC6H3Cy2-2,6)2(q'-c6H~*-q4-c6H~)] and [Ta(OC6HPh2-3,5-Cy22,6)2(q'-C6Hl~-q4-C6H7)] which were found to contain a partially hydrogenated non-Diels-Alder dimer of 1,3-~yclohexadiene.~~

9

Other Complexes

Reactions of the unsubstituted tantalacyclobutane complex [Ta{(CH2)31,3)(CNN)(OtBu)2], 16, with propene and styrene led to the complexes pa{CH2CH(Me)CH2- 1,3)(CNN)(O-'Bu)2], 17, and [Ta{CH2CH(Ph)CH21,3}(CNN)(OrBu)2], 18, (CNN = [C6H4(CH2N(Me)3)Ta(CH2CH2NMe2)-2]-) which have been isolated according to equation ix. The complexes 17 and 18 were found by X-ray crystallography to be seven coordinate pentagonal bipyramidal species. Reaction of 18 with CO yielded the oxytantalacyclopropane complex 19. Complexes 17, 18 and 19 were found [Ta{C(0)((CH2)3-l ,~))(CNN)(O'BU)~],

I : Complexes Containing Metul--Curbonu-Bonds of the Groups Titunium to Mungunese

17

16

18

45

R=Me R=Ph

Equation ix

19

Me 20

21

Equation x

to undergo insertion reactions with 'BuNC to afford [Ta{C(=N'Bu)CH2CH(R)CH2-l .~}(CNN)(O'BU)~] (R = H, Me, Ph).28 A series of vinyl-ketene complexes of niobium has been prepared by treatment of the E-enacyl niobium complex, 20, with excess KO'BU in THF according to equation x. The NMR spectra of the products, 21, confirmed the coordination of the vinyl substituent. A comparison was made of the reactivity patterns of the conjugate acid-base pair, 20 and 21.29 Interest in the stereospecific polymerisation of olefins has resulted in the isolation of certain Group 5 complexes having metal-carbon o-bonds. The ansametallocenes of formula [CgH4-C(CH3)2-C5H4]M[=N(2,6-iPr&6H3)][N(CH3)2] (M = Nb, Ta) have been isolated and structural investigations showed the hydrocarbon ligand to adopt an q':q5-coordination mode to the metal atoms in the solid state. The complexes reacted with (CH3)3SiCl to afford the ansa-

46

Orgunometullic Chemistry

metallocenes [CSH4-C(CH3)2-CSH4]M[=N(2,6-'Pr2C6H3)]C1 which were found to have a conventional q5:q'-coordination for the bis(cyclopentadieny1) ligand.30 A stable metallapyridine complex of tantalum, Tk(=NC'Bu=CHC'Bu=&H)(OAr)2(THF) has been prepared by the thermolysis of the q 2 ( N ,C)-pyridine complex [q2(N , C)-2,4,6-NC5'Bu3H2JTa(OAr)2Me in THF. When the reaction was carried out in benzene the metallapyridine dimer [~a(~-NC'Bu=CHC'Bu=dH)(OAr)2]2 was ~ b t a i n e d . ~ ' A study has been made of the electronic structure of a series of metallocarbohedrenes which includes N bsC I 2, using anion photoelectron spectroscopy. The spectra were quantitatively interpreted by molecular orbital schemes derived from a capped tetrahedral MSCl2 cluster.32 Approximate density functional theory has been used to investigate the mechanistic details of C-H bond activation in methane brought about by a Ta' ion in the gas phase.33

References 1. 2. 3.

4. 5.

6. 7. 8.

9. 10. 11. 12.

13.

14. 15. 16. 17. 18.

K. Mashima, Y. Nakayama and A. Nakamura, Aclv. Polymer Sci., 1997, 133, 1. M. Etienne, Cuord. Chem. Rev., 1996, 156, 201. A. Antinolo, A. Otero, M. Fajardo, R. Gil-Sanz, M.J. Herranz, C. Lopez-Mardomingo, A. Martn and P. Gomez-Sal, J. Orgunomet. Chem., 1997,533,87. A. Antinolo, F. Carrillo-Hermosilla, I. del Hierro, A. Otero, M. Fajardo and Y. Mugnier, Orgunumetullics., 1997, 16, 4161. Q.A. Abbasali, F.G.N. Cloke, P.B. Hitchcock and S.C.P. Joseph, Chem. Commun., 1997, 1541. C.P. Gerlach and J. Arnold, J. Chem. Soc., Dalton Truns., 1997,4795. C.P. Gerlach and J. Arnold, Orgunumetullics, 1997, 16, 5148. P.T. Gomes, M.L.H. Green, A.M. Martins and P. Mountford, J. Orgunomet. Chem., 1997,541, 121. P.T. Witte, A. Meetsma, 9. Hessen and P.H.M. Budzelaar, J. Am. Chem. Soc., 1997, 119, 10561. A.I. Gouzyr, H. Wessel, C.E. Barnes, H.W. Roesky, M. Teichert and I. Uson, Inorg. Chem., 1997,36, 3392. E. Boring, M. Sabat, M.G. Finn and R.N. Grimes, Orgunumetullics, 1997,16,3993. M.H.P. Rietveld, W. Teunissen, H. Hagen, L. van de Water, D.M. Grove, P.A. van der Schaaf, A. Muhlebach, H. Kooijman, W.J.J. Smeets, N. Veldman, A.L. Spek and G. van Koten, Orgunometullics, 1997, 16, 1674. M.H.P. Rietveld, E.G. Klumpers, J.T.B.H. Jastrzebski, D.M. Grove, N. Veldman, A.L. Spek and G. van Koten, Orgunumetullics, 1997,16,4260. N.S. Vilardo, M.A. Lockwood, L.G. Hanson, J.R. Clark, B.C. Parkin, P.E. Fanwick and I.P. Rothwell, J. Ciiem. Sue., Dalton Truns., 1997, 3353. P.M. Briggs, V.G. Young Jr. and D.E. Wigley, Chern. Cornmun., 1997,791. M. Moore, S. Gambarotta, G. Yap, L.M. Liable-Sands and A.L. Rheingold, J. Chrm. Soc., Chem. Cummun., 1997,643. L. Loo, L. Li and T.J. Marks, J. Am. Chem. Sue., 1997,119,8574. T.S. Kleckley, J.L. Bennett, P.T. Wolczanski and E.B. Lobkovsky, J. Am. Chem. Suc.. 1997, 119, 247.

I : Complexes Containing Metul-Curbon 6-Bonds of the Groups Titunium to Mungunese 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.

31. 32. 33.

47

M.H.P. Rietveld, P. Lohner, M.G. Nijkamp, D.M. Grove, N. Veldman, A.L. Spek, M. Pfeffer and G. van Koten, Chem. Eur. J . , 1997,3, 817. A. Antinolo, A. Otero, M. Fajardo, C. Garcia-Yebra, C. Lopez-Mardomingo, A. Martn and P. Gomez-Sal, Orgunometallics, 1997, 16, 2601. R.Choukroun, B. Donnadieu, 1. Malfant, S. Haubrich, R. Frantz, C. Guerin and B. Henner, Chem. Comrnun., 1997,23 15. D.M. Antonelli, A. Leins and J.M. Stryker, Orgunometallics, 1997, 16,2500. Y. Kataoka, I. Makihira, T. Yamagata and K. Tani, Organometallics, 1997, 16, 4789. D.M. Antonelli, P.T. Gomes, M.L.H. Green, A.M. Martins and P. Mountford, J. Chem. Soc., Dulton Trans., 1997,2435. F.A. Cotton, L.M. Daniels, C.A. Murillo and X. Wang, Inorg. Chem., 1997,36,896. D.S.J. Arney, P.A. Fox, M.A. Bruck and D.E. Wigley, Organometallics, 1997, 16, 3421. V.M. Visciglio, J.R. Clark, M.T. Nguyen, D.R. Mulford, P.E. Fanwick and I.P. Rothwell, J. Am. Chem. Soc., 1997,119,3490. M.H.P. Rietvald, H.Hagen, L. van de Water, D.M. Grove, H. Kooijman, N. Veldman, A.L. Spek and G. van Koten, Orgunometullics, 1997,16, 168. M.E. Kerr and J.W. Bruno, J. Am. Chem. Soc., 1997,119,3183. W.A. Herrmann, W. Baratta and E. Herdtweck, J. Organomet. Chem., 1997, 541, 445. K.J. Weller, I. Filippov, P.M. Briggs and D.E. Wigley, J. Orgunomet. Chem., 1997, 528,225. S. Li, H. Wu and L.S. Wang, J. Am. Chem. Soc., 1997,119,7417. N. Sandig and W. Koch, Orgunometullics, 1997,16, 5244.

Part 111: Group 6 by Nicholas Carr

Several review articles concerned with aspects of the organometallic chemistry of chromium, molybdenum and tungsten have appeared in the literature. Topics covered include photochemical reactions of Group 6 metal carbonyls in catalytic transformations of alkenes and alkynes;' the activation of C-H bonds by transition metal complexes;* organometallic fluorides, which are described as species having fluorine-metal and carbon-metal bonds with the same metal;3 the synthesis, reaction chemistry and electrochemistry of mono-, bi- and poly-nuclear metal complexes containing Cz, C4 and C8 ligands as well as substituted derivatives of allenylidene and butatrienylidene l i g a n d ~ ;the ~ chemistry of organo-molybdenum and -tungsten complexes with respect to additive-reductive carbonyl dimerisation, the spontaneous transformation of methyl ligands into pmethylene ligands and selective carbonylmethylenation.6 The physical organic chemistry of Fischer carbene complexes has been reviewed with particular emphasis on kinetic and thermodynamic acidities, and on the mechanisms of hydrolysis reactions and reactions with n~cleophiles.~ The use of transition metals in organic synthesis has been reviewed,* as has the use of (1-alkenyl)cdrbene complexes for the regio- and stereo-selective formation of C-C and C-X bonds.' The synthesis, structure, bonding, metal coordination chemistry and catalysis reactions of N-heterocyclic carbenes have been discussed.l o

48

Organometullic Chemistry

Charge decomposition analysis has been used to distinguish between donative and covalent bonding to transition metals, and the study includes case studies of low valent (Fischer type) and high valent (Schrock type) carbene complexes. I The 0-donor and n-acceptor coordinative properties of the CNCN ligand have been compared to those of the CO ligand by comparison of the density functional calculated bond energies of the two ligands to the Cr(CO)5 fragment in [Cr(CO)5(CNCN)] and [Cr(CO),]. The isocyanogen ligand is found to be an only slightly stronger n-acid.I2 A quantum chemical study has shown that ethene insertion into the Cr-CH3 bond of [CrCI(H20)(CH3)]+ is a feasible reaction, suggesting that ethene polymerisation with Cr(II1)-based catalysts proceeds via this m e c h a n i ~ m . 'Density ~ functional calculations have been carried out on a metathesis-like reaction between complexes of the type [W2(OR),] and alkynes affording alkylidyne complexes, in order to better understand how the reaction proceeds.14 The reaction between carbene complexes [Mo(=CH(R))(NH)(OR')2] (R = H, Me; R' = CH3, CF3) and ethene has been investigated by a combination of ub initio molecular orbital and density functional theory methods. l 5 The gas phase reactivity of the naked W' cation towards hydrocarbons containing up to six carbon atoms has been studied by Fourier transform ion cyclotron resonance mass spectrometry." The tungsten ion was found to be one of the most reactive bare metal cations so far studied, with all the hydrocarbons except acetylene being activated at thermal energies. Reactivity is dominated by dehydrogenation. The primary products of the reactions between laser-ablated Group 6 metal atoms and C02-Ar mixtures are the insertion compounds OMCO and 02M(C0)2 (M = Cr, Mo, W), as identified by isotopic substitution experiments. l 7 The structures of [Li{(CH3)3N)[W(CH&]] and [WF(CH3)4(CH3CN)2]*WF have been determined by X-ray diffraction.'* Both the anion present in the former and the [WF(CH3)4(CH3CN)2]part of the latter adopt a capped octahedral geometry. Tetraalkylated Cr( IV) complexes [CrR4] (R = CH2CMe3, CH2SiMe3) react with the surface of partially dehydroxylated silicas giving discreet mononuclear organometallic fragments, the stoichiometry of which is dependent upon the density of surface hydroxyl groups. With silica containing deuterated hydroxyl groups unlabelled and monodeuteroalkanes are liberated, suggesting that chromium alkylidene intermediates are involved. l9 A series of q2-nitrile and q2-alkyne complexes (e.g. l), in which the side-bound nitrile or alkyne act as four-electron donors, have been prepared from a tungsten metallacycle through reaction with fluorinated aromatic nitriles or excess alkyne. Structures were confirmed by X-ray diffraction studies.20 Treatment of

'

(3)R', R2 = Me, Ph

I : Complexes Contuining Metul-Curbon

0-

Bonds of the Groups Titanium to Mungunese

49

[~(C6H4CH2N(Me)CH2CH2~Me2) F(CO),] with P E CBu‘ results in coupling of CO and phosphaalkyne with subsequent C-H activation of an N-Me group Electron affording 2, having an q4-ligated 3,4-diphospha~yclopentadienone.~’ deficient internal alkynes, R C r C R ’ (R, R’ = Me, Ph), react with the metallacycle [dlo{ C&4CH=NCH2CH2k Me2}CI(C0)3] through migratory insertion to give the q2-vinyl complexes 3.22 Reaction of B(C6F5)3 with the methyl complexes [MMe(C0)3(q-CSHS)] (M = Mo, W) affords [ M m ) M e - 2 } ( C O ) 2 ( q - C 5 H 5 ) which ] can be converted to [kl{C6F3H-5-C(b)Me-2} (C0)2( q-C5H5)] viu unusual C- F activation reactions. 23 The X-ray crystal structure of the ortho-metallated complex [ ~ s H 4 ) ( N o ) ( H ) ( q - C g H 5 ) has ] been determined and the complex has been shown to undergo facile ligand-induced reductive elimination of arene, giving [W(NO)(H)(L)(q-C5H5)] { L = CNCMe3, Me2C0, Me(OEt)CO, CN(c-C6H*I),

$

5

’

5

Mo

(4) M = Cr,Mo, W x = Ct, I

(CH2)4CO) .24 The dinuclear ortho-metallated complexes 4 were prepared by reaction of Li[M(CO)S(PPh2)] (M = Cr, Mo, W) with the corresponding metallocene dichloride. Methylated compounds were similarly prepared from [ M o C ~ ~ ( ~ \ - C ~ Hand ~ M ~alkylated )~] diastereoisomers [(q-CSHs)(R)Mo { (qC ~ H ~ ) P P ~ ( O - CMO(CO)~] ~ H ~ ) ) (R = Me, Et) were obtained by reactions with Grignard reagents.25 The chromacyclopentane complexes [&{CH2(CH2)&H2}(PR&q-C5Me5)] (R = Me, Et) and [dr{CH2(CH2)2kH2}(PR3){N(Me)2(CH2)2C5Me4}] and the corresponding chromacycloheptane complexes have been prepared from either 1,4-dilithiobutane or 1,6-dichIoromagnesiohexaneand the appropriate chromium dichloride. The structures were confirmed by X-ray crystallography.26 The purple oxametallacyclopentene complex [lb(C(Ph)=CHC(Me)(OEt)b}(NO)(q-C5Me5)] was obtained by thermolysis of the vinyl complex [W{q1-C(Ph)=CH2}(CH2SiMe3)(NO)(r\-C5Me5)]in ethyl acetate via reductive coupling of phenyl acetylene and ethyl acetate. In the presence of CH3CN a deep red coloured diazametallabicyclic complex is obtained whereas in wet acetonitrile one molecule of CH3CN is { incorporated to give red [ ~C(Ph)=CHC(Me)=&H}(OH)(NO)(q-C5Me5)], which in the solid-state has a nearly planar azacyclopentadiene ring.27 Alkylation of the anions [M(CNR)(C0)2(q-C5Me5)]- (M = Mo, W; R = alkyl) with methyl iodide affords the corresponding methyl complexes which decompose to q2-iminoacyls [M { q2-C(=NR)Me}(CO)2(q-C5Me5)] or q3-l-azaallyls

50

Organometullic Clwmistry

[M { q3-CH2C(H)N R))(CO)Z(q-CSMeS)], with efficient donor solvents favouring the former and poor donors such as benzene f'dvouring q3-azaallyl formation. For reactions involving tungsten complexes, the use of acetone leads to zwitterionic metallacyclic compounds [W- { C( Me)=N+(R)C(Me2)6}(CO)2(q-C~Me5)].~* Similarly, thermolysis of the indenyl complexes [MMe(C0)2(CNBu')(q5-CgH7)] (M = Mo, W) cleanly affords mixtures of isomeric iminoacyls and azaallyls

Ph

co

p" Ph

(5)

(7)

[M(q2-C(=NBu')Me}(CO)2(q5-CgH7)] and [M{q3-H2CC(H)NBu')(C0)2(q5C9H7)], respectively. The dynamic behaviour of these species was studied by NMR spectros~opy.~~ Treatment of the nitrosyl compound [ M O H ( N O ) ( C O ) ( P M ~ P ~ with , ) ~ J ethylene at 50 "C and 50 psi gave [ ~ O ( C H ~ C H ~ ~ C H & H ~ ) ( C ~ H ~ ) ( N O )while (PM~P~~) with propylene a slower reaction occurs giving isomeric [Mo{q2C(O)CH2CH$H3} (NO)(PMePh2),] and [Mo { T ~ - C ( O ) C H ( C H3~(NO)(P)~ MePh2)3]. With styrene the emerald green complex 5 is obtained in high yield.3o Reaction of [W(CO)(PhC = CPh)3] with excess diphenylacetylene affords mainly the metallacyclic complex [W(PhC = CPh)(q8-C8Ph8)] which itself reacts with carbon monoxide t o give both 6 and 7.3' Treatment of the metallophosphenium complex [W { P(Ph)[N(SiMe3)2])(CO)2(q-CsHs)] with diazomethane affords the crystallographically characterised species [-(Ph)N(SiMe&} (CO),(q-C5H5)].32 The anions [M(C0)3(q-C5H5)]- (M = Mo, W) react with dichloromaleic anhydride and dichloromaleimides to give metallated cyclopentenediones NCHzPh, [M { bC(0)XC(b)CCl}(C0)3(q-CsH5)] (X = 0, NC6HdMe-4, NCH,CO,Et, NCH(Me)C02Me).33 A series of stable coordinatively unsaturated dialkyl complexes having phydrogen atoms [W(R)2(NPh){C6H4(NSiMe3)2-1,2}] (R = Me, Et, Pr", Bu',

(8) R = Me, CH2CMe3

I : Complexes Contuining Metut--Curbon a-Bonds of

die Groups

Titanium to Mungunese

5I

CH2CH2Ph, CHZPh, CH2CMe3, CH2CMe2Ph) have been prepared from the dichloride precursor and the X-ray crystal structures of the complexes with R = Me and CH2CH2Ph were determined.34 With PMe3 these complexes afford the corresponding q2-alkene derivatives [W( q-H2C=CH R)(PMe3)2(N Ph) { C6H4(NSiMe3)2-l,2}] through a pathway involving p-H a b ~ t r a c t i o nTreatment .~~ of the dialkyl adducts with CNBU' gave the black trigonal bipyramidal complexes 8 via the monoadducts [W(R)(NPh)(CNBut){C6H4(NSiMe3)2-I ,2}], which for R = CH2CMe3was isolated and ~ h a r a c t e r i s e d . ~ ~ Photoreaction of [MMe(C0)3(q-C5H5)](M = Mo, W) with substituted aminophosphites gave the complexes [MMe(C0)2{PN(M~)CH~CH~X(OR))(~-CSHS)] (X = NMe, 0), which in turn react with BF3*OEt2 followed by 1 PPh3 affording tran~-[M(C0)~(PPh~) { PN( Me)CH2CH2X(Me))(q-C5H5)][BF4] through methyl group migration from the metal to the pho~phorus.~' Diphenylphosphine and the complexes [Mo(R')(C0)3(q-C5H5)] (R' = Me, Et) gave the acyls [Mo{C(0)R1}(C0)2(PPh2H)(q-C5H5)] in high yield. Low temperature deprotonation (dbu) and alkylation with R21 (R2 = Me, Et, R2COCI) of these yielded complexes [Mo {C(O)R ) (C0)2(PPh2R2)(q-C5H5)] and [Mo {C(O)R } (CO)2{PPh2C(0)R2}(q-C,H,)], respectively. In contrast, room temperature deprotonation leads to migration of the metal acyl group giving the anions [Mo(C0)2{PPh2C(0)R'}(q-C5H5)]- which are readily alkylated to the acylphosphine alkyl complexes [Mo(R2)(CO)2{PPh2C(0)R'}(q-C5Hs)].38 Alkylation of [CrCI(NC5H5)(Tp')] {Tp' = hydrotris(3-BuL-5-methylpyrazolyl)borate} with Grignard reagents gave the alkyl complexes [CrR(Tp')] (R = Et, Ph, CH2SiMe3) which reversibly add pyridine to give five-coordinate adducts [CrR(NC5H5)(Tp')]. X-ray diffraction studies showed that the four-coordinate complexes adopt an unusual geometry derived from octahedral by removal of two mutually c i s - l i g a n d ~ . ~ ~ Mild oxygen sources such as dimethyl sulfoxide and propylene oxide convert [WH(q-CH2=CH2)(q-C5H5)2][PF6] into the terminal oxo(ethy1) compound [W(o)(Cq2CH3)(q-C5H5)2][PF6]. Reaction of the latter with PMe2Ph gave a strongly coloured compound which was shown by X-ray diffraction to be a mixed valence dimer of W(IV) and W(V1) in which a [W(O)2(Cr\2CH3)(q-C,Hs)l fragment is coordinated through an 0x0 ligand to [W(Cq2CH3)(q-C5H5)2]+.40 Fluoroalkyl complexes [MI { C H ~ C H ~ C ( C F ~ ) ~ ) ( ~ - (M C S= H ~Mo, ) ~ ] W) are formed by reaction of IC(CF3)3 with the alkene complexes [M(q-CH2=CH2)(qC5H5)2] through selective fluorination of the ethene ligand. In contrast, ICF(CF3)2 reacts exclusively at the cyclopentadienyl ligand affording [MI(H)(qC5H5){q-C5H-CF(CF3)2}].4' Treatment of [CrC12(thf)] with two equivalents of Li[C6H2(CF3)3-2,4,6] in the presence of PMe3 gave [Cr(PMe& { C#2(CF3)32,4,6}2], whereas [Cr(N Buf)2C12] and [Mo(NBut)2C12(dme)]with Li[CbHz(CF3)32,4,6] yielded hexavalent complexes [M(NBuL)2{ CbH2(CF3)3-2,4,6}2] in which fluorines on two orzho-CF3 groups lie in close contact with the metal centre!2 Reaction of Na[W(C0)3(q-C5HS)] with bromopropargyl amine at 0 "C gave the q -propargy 1 species [W(CO)3{ q -CH2C EE CCH(Ph)( N HTs) ) (q-C5H5)], which upon warming (40 "C) underwent intramolecular cyclisation affording I

'

'

'

52

Orgonometallic Chemistry

q'-2,5-dihydropyrrole. This in turn was isomerised by CF3C02H to its q '-2,5-dihydropyrrolyI isomer, the structure of which was established by X-ray diffraction. Treatment of the former complex with [Ph&][BF4] and H 2 0 converted it into an q1-2,3-dihydropyrrolium cation which gave the latter complex through loss of H'. LiA1H4 reduction of the q '-2,5-dihydropyrrole complex gave the q '-tetrahydropyrrolyl complex [W { ~ H C H ~ N ( T S ) C H ( P ~ ) ~ H ~ } ( C O j)].43 ) ~ ( ~ - CMixtures ~H of the q1-2,5-dihydrofuran complex [W { dH=CHCH(R)OCH2}(CO)3(q-C5H5)] and q3-.~p-y-lactonecomplexes were obtained by treatment of q I-4-(triethylsiloxy)propargyl complexes and q 1-4-(tripropylsiloxy)propargyl complexes [W { CH2C= CC(OSiR3)R) (C0)3(q-CSHS)] with CF3C02H, the product ratio depending upon the alkyl and d o x y substituents. Chiral dihydrofurans, and yand &lactones have been obtained by the same method.44 The reaction between Na[W(C0)3(q-C5H5)]and 3-butyn-2-one at 0 "C gave a mixture of the vinyl complexes cis- and trans-[W { q '-CH=CHC(OMe)}(C0)3(q-C5H5)], the cis-isomer of which converts into the allylic y-lactone complex [W { q3-tHCHC(Me)OCO}(CO)z(rl-CSHS)1.4sThe Mo-C bonds of the bis(ally1)complex [Mo(q ':q2-C3H5)2(PMe3)3],obtained by reaction of allylmagnesium bromide with [MoCI2(PMe3)4], are attacked by only slightly polar molecules. Thus, CH2C12 generates propene, [ M o C I ~ ( P M ~ and ~ ) ~ ]PMe&I, while carbon monoxide brings about C-C bond coupling affording 1,5-hexadiene and cis[Mo(C0)2(PMe3)41.46 Treatment of the cationic species [Mo(acetone)(dppe)(q-C7H7)lf with HC r CF, (F, = (q-C5H5)Fe(q-C5H4)>followed by deprotonation with KOBu' afforded the alkynyl complex [Mo(C = CF,)(dppe)(q-C,H,)], which can be oxidised to the cationic species [Mo(C z CF',)(dp~e)(q-C7H~)]+.~~ Oxidation of the complexes [W(C = CR)(C0)3(q-C5Me5)] (R = Ph, C02Me, Pr", C(Me)CH2) with acidic solutions of H202 affords 0x0-peroxo acetylide complexes [W(O)(O,)(C = CR)(q-C5Me5)], which upon treatment with PPh3 give the dioxo compounds [W(0)2(C = CR)( q-C5MeS)]. The crystal structure of [W(0)2(C = CPh)(q-C5Me5)] was determined by X-ray diffraction!8 q '-Alkenylq3-allyl complexes, e.g. [W(C 3 CR)(q3-CH2CHCH2)(NO)(q-C5H5)],have been prepared from the anionic acetylide complex [W(C = CR)(CO)(NO)(q-C5H5)](R = Ph, CMe3, SiMe3) by reactions with allylic iodides, methallyl iodide and 3iodocyclohexane. These compounds were observed to isomerise to the corresponding q2-allene complexes on silica gel and neutral alumina.49 The first examples of selenoketenyl complexes, [ML(q2-SeCCC6H4Me4)(CO)(Tp)] ( T p = hydrotris(pyrazoly1)borate; M = Mo, W; L = PMezPh, PPh3, P(OMe)3} have been synthesised by reaction of the ketenyl complexes [ML(q2OCCC6H4Me-4)(CO)(Tp)] with 'Woollins reagent' (4PPh5/5Se8). These compounds readily alkylate at the chalcogen yielding complexes of selenato alkyne~.~' PhSSPh afforded Oxidation of [CrMe { N(SiMe2CH2PPh2)2}] with [CrMe(SPh) { N(SiMe2CH2PPh2)2}], a rare example of a five-coordinate organochromium( I I) complex with a terminal phenylthiolate ligand. An X-ray diffrac-

I : Complexes Containing Metul-Curbon a-Bonds of the Groups Titanium to Mungcmese

53

tion study revealed a distorted square pyramidal geometry with the methyl group in the apical p ~ s i t i o n . ~ ' A series of binuclear metal complexes containing 0-thienyl and a-fury1 ligands [M2(mTh)2(NMe2)4] and [ W ~ ( O - F U ) ~ ( N M(M ~ ~=) ~Mo, ] W; Th = 2-C4H3S, 3C4H3S, 2-methylthienyl, 2-benzothienyl) were prepared by reaction of [M2X2(NMe2)4](X = Cl, I) with the appropriate lithium salt. Reactions of these species with alcohols proceed with ring-opening (except for 3-thienyl derivatives) to give complexes of the type [W2(0R)5(p-CCH2CHCHS)(a-2-Th)].52 In hydrocarbon solvents the compounds [M2(OBu')6](M = Mo, W) react with C2H4 to give a mixture of cis- and trans-polyacetylene along with ethyne and pC4H4 metal complexes. The labile derivative [Mo2(p-c2H2)(oBu')6] was trapped by addition of pyridine or 4-methylpyridine to such reactions and an X-ray diffraction study undertaken. Addition of CO to solutions resulting from reaction of [M02(oBu')~]with an excess of C2H2gave [Mo2(~-C4H4)(CO)(oBu1),19, the ~~ of structure of which was confirmed by X-ray d i f f r a ~ t i o n . Reactions

[w2(0BUt)6]with NCC6H4X-4 (X = NMe2, SMe) afford the alkylidyne complexes [W( = CC6H4X-4)(OBut)3]. X-ray diffraction studies on these species revealed that in the solid-state they form infinite-chain structures through weak intermolecular dative bonds between the tungsten and donor atoms.54The reactivity of the related species [ W ~ ( O C H ~ B U towards ')~] a variety of reagents has been investigated: with allene, orange crystalline [W2(0CH2But)8(p-q',q3-C3H4)] was obtained and the structure established by X-ray diffraction. Benzophenone and [W2(0CH2But)8] gave [W2(0CH2Bu')8(q2-OCPh2)]while with thiobenzophenone the C=S bond is cleaved to give a mixture of the alkylidene [(W(=CPh2)(0CHZBu')~(~-OCH~BU and ~ ) [~{ W ) ~(]= S ) ( O C H ~ B U ' ) ~ ) ~ ] . ~ ~ The chemically useful reagents [W( =CR)X3(dme)] (R = But, Pr", Ph; X = C1, Br; dme = 1, 2-dimethoxyethane) were prepared in high yield by reaction of the corresponding complex [W( 3 CR)(OBu')3] with BX3 in dme.56 Methyl, phenyl and cyclopentyl complexes of the type [WR(N3N)] (N3N3' = (Me3SiNCH2CH2)3N3-) were obtained by alkylation of [WCl(N3N)], but attempted syntheses of linear alkyl complexes were unsuccessful affording molecular hydrogen and the alkylidyne complexes [W( = CR)(N3N)]. Thermally unstable [W { = C(c-propyl))(N3N)] liberates ethylene to give [W( 3 CH)(N3N)] while [W(c-butyl)(N3N)] initially decomposes to the tungstacyclopentene h(CHCH2CH,dH,)(N3N)] but this in turn decomposes to [W( = CCH2CH2CH3)(N3N)]. Attempts to prepare [W(c-pentyl)(N3N)] gave the alkylidene [W(=dCH2CH2CH2CH2)(H)(N3N)], as shown by X-ray

Orgunometallic~Chemistry

54

c r y s t a l l ~ g r a p h yThe . ~ ~corresponding molybdenum alkyl complexes [MoR(N3N)] were similarly prepared, and characterised by NMR spectroscopy and X-ray diffraction. The cyclopentyl and cyclohexyl derivatives undergo rapid reversible a-elimination at room temperature, while P-hydrogen elimination t o give [MoH( N3N)] occurs at higher temperatures. Thermolysis of [Mo(CH2CMe3)(N3N)] gave H2 and the alkylidyne [Mo( = CCMe3)(N3N)] through a,a'dehydrogenation, while [Mo(c-propyl)(NRN)] liberates C2H4 to give [Mo( = CH)(N,N)].s8 With ethylene and propylene, [WH(N3N)] gave [W( -CMe)(N3N)] and a mixture of [W( =CCH2CH3)(N3N)] and [W(H)3(N3N)]. Reaction with diphenylacetylene affords the metallacyclopropene [W(C(Ph)CH(Ph)}(N3N)], the structure of which was confirmed by an X-ray

-

diffraction study. A rare example of an oxycarbyne complex, [W(COSiMe3)(N3N)],was obtained from [WH(CO)(N3N)Jand Me3SiI/NMe3.s9 Depending on the conditions, reactions of [W { ZE CCH= CCH 2(C H2),CH 2CH 2) (NCMe)( C0)2(dppe)][ B Fj] with [Bu4N][S2P(OEt)2] and r I S2CPCy3 gives the alkylidyne complexes [W { = CCH=CCH2(CH2),,CH2CH2} (S~CPCY~)(CO)~{ S,P(OEt2}( CO)2(dppe)], [W { E CCH=CCH2(CH2)nCH*CH2} I (dppe)][BF4] and the 16-electron species [W { = CCH=CCH2(CH2)nCH2CH2}(S2CPCy3)(dppe)][BF4] (n = 1,4). An X-ray diffraction study of the latter type of complex (10, n = 1) was carried out.60 A variety of neutral and cationic chromium aminocarbyne and phenylcarbyne complexes having phosphine or alkyl isocyanide ligands, e.g. [Cr( = NPri)X(CO),(L)2] andfac-[Cr( = CPh)(CN But)3(CO)2][PF6], have been prepared by ligand substitution reactions of existing carbyne complexes.61 Related phenylcarbyne complexes [Cr( = CPh)(C0)2(-q-CSRS)] (R = H, Me) were obtained from reactions of cis-[Cr( = CPh)Br(C0)2(NCsH4Me-4)2] with Na[CSHS] and K[CSMeS], and the electrochemistry and reactions with PMe3 giving [Cr { =C(PMe3)Ph}(C0)2( T ~ C S H S ) and ] [Cr {C(Ph)CO}(CO)(PMe3)(q-C5Me5)] are reported.62 Sodium amalgam reduction of [Mo(CO){N[C(CD3)2CH3]C6H3Me2-3,5}3] and subsequent reaction with Bu'C(0)CI affords the carbidopivalate complex [Mo( = COC(O)Bu'} { N[C(CD3)2CH3]C6H3Me2-3,5}3], from which the methylidyne complex [Mo( = CH) { N[C(CD3)2CH3]C6H3Me2-3,5}31 was obtained by reaction with sodium in thf. Deprotonation of the latter with benzylpotassium gave the I

1

i

-

1: Complexes Contuining Metal--Curbon o-Bonds of the Groups Titanium to Mangunese

55

terminal carbido complex [Mo( = CK){N[C(CD3)2CH3]C6H3Me2-3,5}3]2 which was characterised by an X-ray diffraction study of the [potassium (benzo-15crown-5)2]+ salt.63 The cationic methylene complexes [W(=CHz)(PhC z CMe)(CO)(Tp')]+ and [W(=CHz)(PhC =CPh)(CO)(Tp)]+ were prepared by treatment of [W(CH3)(PhC z CMe)(CO)(Tp')]+ and [W(CH3)(PhC = CPh)(CO)(Tp')]+, respectively, with [Ph3C][PF6].With the aim of achieving metal-mediated enantioselective cyclopropane and aziridine synthesis, the reactivity of these racemic carbene complexes towards olefins and imines was studied. With N-arylamines both gave iminium complexes, e.g. [W { CH2N(Ph)=CH(Ph)}(PhC= CPh)(CO)(Tp)]+, which can be converted to the aziridine by treatment with ethyl d i a z ~ a c e t a t e . ~ ~ , ~ ~ [M { = CP=C(NR&}(C0)2(Tp')J Phosphaalkenyl carbyne complexes (M = Mo, W; R = Me, Et; Tp' = tris(dimethylpyrazo1yI)hydroborate) have been synthesised by reaction of the chlorocarbyne complexes [M( =CCI)(C0)2(Tp')] with phophaalkenes Me3SiP=C(N R2)2. Structures were confirmed by an X-ray diffraction study of [W { 3 CP=C(NEt2)2}(CO),(Tp')1.66 In the presence of TIPF6, H ~=) ]Me, Ph, reaction of suitable carbyne complexes [W( 5 C R ) ( C O ) ~ ( T ~ - C ~(R c ~ H ~ M e - 4 with ) PhzArCl afforded novel q2-arsinocarbene complexes The structure of the tolyl derivative [W { =C(R)ASP~~}(CO)~(~-C~H~)][PF~]. shows that the W=C(carbene) bond [1.923(5) A] is significantly shorter than in the corresponding phosphinocarbene complex.67 The reactions of various alkylidyne complexes of molybdenum and tungsten with 2-methylthiirane, C&S, have been studied and led to the first thioacyl complexes of these metals, e.g. [ M o ( ~ ' - M ~ S C H C ~ H ~ O M ~ - ~ )HB(pz)3}].@ (CO)~{ Boryl metal complexes of the type [M{B(Et)CH2(R))(CO)2(Tp')] {M = Mo, W; R = Me, C6H4Me-4; Tp' = tris(3,5-dimethylpyrazolyl)hydroborate} are readily obtained from reactions of the corresponding complex [M( E CR)(C0)2(Tp')] with ' E ~ z B H ' . ~ ~ Alkylidyne complexes containing the tridentate, linear phosphine PhP(CH2CH2PPh2)2 (triphos) have been prepared from [W( = CC6H4Me-4)Br(C0)2(NC5H4Me-4)2]by ligand substi tu tion. 70 Protonat ion (H BF *OEt2) and methylation reactions afforded mer-[W(=C(H)C6H4Me-4)Br(triphos)(CO)][BF4] and mer-[W( = CCbH4Me-4)(Me)(triphos)(CO)], respectively. The chiral-at-metal carbene complex [Mo{=C(OMe)Me}(NO)(CO)(Tp')]was synthesised by stepwise reaction of [Mo(NO)(C0)2(Tp')] with MeLi and MeOTf. Elaboration of the carbene fragment through deprotonation and alkylation gives

-

,OMe (OC),Cr,= C

RC.+ (11) R = Ph, Pr", SiMe,, CMe3

56

Orgunometullic Chemistry

two isomers with only moderate diastereoselectivity due to the presence of syn and unti alkyl isomers in the carbene reagent." The first stable alkynecarbene complexes containing a neutral Group 6 metal carbonyl unit 11 have been synthesised by low temperature photodecarbonylation of the complexes [Cr{=C(OMe)R}(CO)5]. These compounds, which are stabilised by a rigid C2-unit bridging the alkyne and carbene ligands, can be regarded as intermediates in the chromium-mediated benzannulation reaction. The structures were confirmed by X-ray ~rystallography.~~ Novel carbonyl-free carbene I complexes [W{=CN(R)CH2CH2NH}(PhCG C P ~ ) (R ~ ] = H, Et) were obtained by reaction of the cationic species [W(CO)(PhC = CPh)3]' with the appropriate amino-substituted iminophosphorane and the structures were established by an X-ray diffraction The in situ generated aminocarbene anions [M {=C(NH)R}(CO)s]- (M = Cr, Mo, W; R = Me, Ph) react with (Pr'2N)2PCl affording the first examples of N phosphanyl substituted carbene complexes [M { =C(R)N(H)PNPri2}(CO),1.74 Photolysis of the cyclohexenyl carbyne complex [W { = C(c-C6H9)>(CO){P(OMe)3}2(q-C5H5)] in the presence of CHCI3 gave the carbene complex 12, providing the first direct evidence for the formation of carbene complexes in photooxidation reactions of carbyne complexes.75 In the presence of CuI catalyst, [WCI(CO),(q-C5H5)] and alkynols gave qlalkynyl complexes [W {C=CCH~CH(OH)R}(CO)~(T)-C~H~)] (R = Me, Ph) which in turn react with R'CHO/BF,*OEt, yielding ql-furylidene and q'pyrilidene salts (e.g. 13). With nucleophiles these oxacarbeniums gave furan and pyran derivatives viu a,a-double addition reactions and with diazomethane undergo diastereoselective c y c l ~ p r o p a n a t i o n . ~ ~ Treatment of the carbamoyl metallates [M { =C(OL~)NPI-'~)(CO)~] (M = Mo, W) with iodine in the presence of PPh3 gave the complexes [M(q2-OCNPr'2)I(C0)3(PPh3)], which serve as convenient precursors to a variety of carbamoyl complexes viu ligand exchange reactions. Reaction of [W(CO),] with LiNPr12 followed by I2/PPh3 gave the aminoethylidyne complex [W( 5CNPrI2)ICon(C0)3(PPh3)] in addition to the expected [W(q2-OCNPri2)I(CO)3(PPh3)].77 venient routes to aminomethylene complexes [M(=CHNPr'2)(CO)2(S2CA)2](M = Mo, W; A = NMe2, NEt2, N(CH2)4, OEt) have been developed through the reaction of alkylidyne complexes [M( = CNPri2)Cl(CO)3(PPh3)] with [EtNH,][S2CNEt2], [N H4][S2CN(CH2)4]and Na[S2CNMe2].78 Unstable phosphite carbene complexes 14 were generated by treatment of [W (=C(OLi)R}(CO)5](R = Ph, Et, Bu, C6H4CI-4, C6H4(CF3)-4)with 2-chloro1

K

o.,.o

(0c)5w P

Ph

I: Complexes Contuining Metul-Curbon

6 -Bonds of

the Groicps Titunium to Mungunese

57

5,Sdimethyl 1,3,2-dioxaphosphorinane.Above - 30 “C these compounds decompose to 1,2-diphosphite(a1kene)tetracarbonyl complexes.79 The reactions of [W {=C(fjCH2CH2CH2CH2)(CE CPh)}(CO),] and [W{=C(OMe)(C= CC6H4Me-4)}(C0)5] with the 1-phosphaallyl anion r [PhPCH(Ph)C(Ph)(?(Ph),1- and subsequent protonation gave, stereoselectively, the dihydrophosphate 15 and bis(viny1phosphine) (16) complexes, respectively, Structures were confirmed by X-ray diffraction.80 Carbene complexes of the type [W{=C(OMe)Ph}(CO)5](M = Cr, W) are demethylated by metal carbonyl anions M’- { [Fe(CO)z(q-C5Hs)]-, [Re(C0)5]-, [Mn(C0)4(PPhd]- , [Co(C0)3(PPh3)1-, [ C ~ ( C ~ ) ~ ~ ~ - C S M ~and S)I[Mo(C0)3(q-C5H5)]-} to give acyl anions [M (C(O)Ph}(CO),]- and methyl complexes M’-Me. The complex [W { =C(OEt)Ph}(C0)5] reacts more slowly implying that these reactions proceed viu nucleophilic attack on the methyl of the methoxy group of the carbene complex.8’ Thermolysis of the bis(alky1) complex [W(CH2CMe&(NO)(q-C5Me5)] in SiMe4 gave [W (CH2SiMe3)(CH2CMe3)( NO)(q-C5Me5)]via C- H bond activation. Labelling experiments established that this reaction proceeds through the alkylidene complex[W(=CHCMe3)(NO)(q-C5Me5)] by intermolecular C-H bond activation. This is the first observation of such a process. In the presence of PMe3, [W(=CHCMe3)(NO)(PMe3)(q-C5Me5)] and [W(c-C6HIO)(NO)(PMe3)(qC5Me5)]were isolated and the structures determined by X-ray crystallography.82 The q2-dimethylamino(thio)carbene complexes 17 were obtained from reactions of the metallate anions [M(C0)3(L)]- { L = q-CgH5, q5-C5(CH3)4CH2CH3, HB(pz)3, HB(pzMe2)3j with dimethylthiocarbamoylchloride. The structures of the compounds with R = q-C5H5and HB(pz)3 were determined.83 Sequential reaction of [W{ =C(NMe2)C= CH}(CO)5] with Bu”Li, CuI and BrC = CSiMe3 yielded [W {=C(NMe2)C= C-C = CSiMe3}(C0)5]which is readily desilyated to [W { =C(N Me2)Cz C-C = CH } (CO),]. The iron derivative [(OC),W { =C(NMe2)C=C-C = CFe(C0)2(q-C,H,)}] was similarly obtained by employing [FeI(C0)2(q-C5H5)].Also, using 0.5 equivalents of HgC12 gave the novel C4HgC4-bridged complex [(OC)5W{ =C(NMe2)C= C-C = CHgC = Cchromium carbene complexes C = CC(NMe2)=W(CO)5].84 The [Cr{=C=C(R)R’}(C0)5]{C(R)R’ = CPh2, C(CH&, CMe2, CH(Me)} react with MeC- CNEt, to give the cyclobutenylidenes[Cr{dC(Me)C(NEt2)&R)R’}(C0)5] by regiospecific addition of the C r C bond of the alkyne to the vinylidene C=C bond. The analogous reaction of [Cr{=C=CH(Ph)}(C0)5] proceeds via cycloaddition and a formal 1,3-hydrogen shift to give

58

Orgunometullic Chemistry

[Cr{kC(Ph)C(NEt2)kH(Me)f(CO)J1. X-ray structural studies of these compounds revealed a strongly delocalised n-system and Kurtz powder measurements show harmonic generation efficiencies 4 to 35 times that of urea.*, OMe

(19) M=Cr,W

*W(C0)5 Me0 (18) X = pC6H4,SC(Me)=CHCH=k(Me)

The differing mechanistic pathways followed in the conversion of the dialkyl complexes [M(CH2SiMe3)2(NO)(q-C5Me5)] ( M = Mo, W) to the anionic alkylidenes [M(=CHSiMe3)(CH,SiMe,)(NO)(q-C5Me5)]with different lithium reagents have been studied and various intermediate complexes have been isolated and structurally characterised.86 Reactions of [W(CO),(thf)] with H C = CH(OH)XCH(OH)C = C H ( X = pC6H4, SC( Me)=CHCHC( Me)) gave monometallic alkenylcarbene complexes [W (=C(OMe)CH=CH-X-CH(0H)C= CH >(CO),] and bimetallic bis(alkeny1) complexes 18. Both types of complex undergo aminolysis reactions to give aminocarbene derivative^.'^ Similar bis(carbene) complexes 19 containing a tetrahydrofuran-2-one ring were prepared by the reactions of [M { =C(OMe)CH2Li)(CO),] ( M = Cr, W) with fumaroyl dichloride. An X-ray diffraction p e 3 (Oc)5W=c =c -R~(co),

ptolyl

.

1

“

(21a) X = CO (21b) X = 0

analysis was carried out (M = Cr).@ Treatment of the methylene complex [W(=CH2)( PhC E CMe)(CO)(Tp’)] with excess base gave the deep green coloured C3H5-bridged dimer [(Tp’)(CO)(PhC = CMe)W-CH2CHCH2-W(PhC= CMe)(CO)(Tp’)][PF6], which was structurally characterised by X-ray crystaIl~graphy.*~ Thermolabile vinylidene-bridged compounds of the type [(OC),W=C=C(CMe3)(pX)ML,] (e.g. 20) {(p-X)ML, = CH2CH*Re(CO),, (q2C3Hs)Mo(CO)(NO)(~-C,H,), (q4-C6H4R)Fe(C0)3, (q4-C7H9)Fe(C0)3, (q5C6H6)Mn(C0),, ( T ~ ~ - C ~ H ~ ) M(M= ( C OCr, ) ~ W)) have been synthesised from the alkynyl complex [Bu4N][W(CCCMe3)(CO),1 by reaction with appropriate cationic complexes in hydrocarbon solvents. These can decompose by elimination of the W(CO)5 fragment and 1,2-shift of the vinylidene group from the middle to the terminal carbon atom of the C - CCMe3 group.” Oxidation of the bridging alkylidyne of [(q-C5H5)(C0)2W{ C(C6H4Me-

1: Complexes Contuining Metul-Curhon

6-Bonds

of the Groups Tituniuni to Mungunese

59

4)C6H4CH2NMe2}PdCI] with an excess of Me3N0 gave the corresponding ketone, while with 2-4 molar equivalents the mono- and dioxo-tungsten derivatives 21a and 21b, which are likely intermediates in the formation of the ketone, were obtained.” The dinuclear 0-, rn- and p-xylyl-bridged complexes [(qCSM~~)(CO)~M(~-CH~C~H~CH~)M(CO)~(~-C~M~~)] (M = Mo, W) have been prepared from thermal reactions of Na[M(C0)3(q-CSMe5)]with dichloroxy~enes.~~ Deprotonation of the carbene complexes [M {=C(X)Me}(C0)5] (M = Cr, W; X = OMe, OEt, NHBu‘, NMe2, NMePh) and subsequent reactions with [Mn(CO)3(q-C,&)][ PF6] yielded neutral complexes [(q5-C&&H2C(X)=M(CO)5], the structures of which were confirmed by an X-ray diffraction study {M = W; X = NMe(Ph)}. Similarly, anions of [Cr{=cOH(R)CH2CH2)(CO)5] (R = H, Me) and (q5-cyclohexadiene)iron tricarbonyl cations yielded q4-diene derivative^.^^ The related 0,x-bimetallic carbene derivatives [(OC)5M{ =C(OEt)}q5-SC4H3Cr(C0)3] were prepared by reaction of lithiated [Cr(C0)3(SCdH4)] with [M(C0)6] and subsequent alkylation with [Et30][BF4]. The benzothienyl complex [(OC)5Cr{=C(OEt)[q6C8H5SCr(C0)3])]was similarly obtained. The Cr(C0)3 fragment in these species is readily displaced, affording new mononuclear carbene derivatives [M { =C(CaH3S)O(CH2)4OEt}( C O ) S ] . ~ ~ A series of dinuclear bis(carbyne) complexes of molybdenum and tungsten containing CH2CH2, CH=CH and C = C linkages have been reported. Thus, addition of Bu”Li to [(TP’)(CO)~M= CCH(R)CH(R)C = M(COh(Tp’)] (M = Mo, W; R = H, Me, CH2Ph) and oxidation of the intermediate dianionic species gave =CC(R)C(R)C = M(C0)2(Tp’)], which in turn react with K[OBu‘] [(TP’)(CO)~M to give intermediate C4-cumulene-bridged dianions ’M=C=C=C=C=M’ { d( I3C)

280 and 258 ppm} which are readily oxidised to the neutral species [(Tp’)(C0)2MrC-CrC-C= M(C0)2(Tp’)]. The structure of [(Tp’)(CO)zM= CC(Me)=C(Me)C = M(CO)*(Tp’)] was confirmed by an X-ray diffraction The alkyne complexes [Mo2(p-RC= CR)(C0)4(q-CSH5)2] (R = Ph, C02Me) react with 1,3-dithiole-2-thiones by cleavage of the C=S bond, ring opening of the resulting carbene and coupling with the alkyne ligand affording complexes 22?6 Reactions of dimethyl acetylenedicarboxylate and di-p-tolylacetylene with the oxoacetylide complex [WRe(0)(CO)4(p-H)(p-CCPh)(q-C5Me5)] afforded four

60

Orgunomet a l k Cli emist ry

complexes by linking hydride, acetylide and alkyne fragments. All were characterised by X-ray crystallography and two of them show the presence of a folded metallacyclopentadienyl fragment (e.g. 23).97 The remainder of this section will cover the use of Fischer carbene complexes of the type [M (=C(OR)R’}(CO)s]in organic synthesis. A high yield synthesis of the chemically useful reagent [Cr{=C(OEt)Obenzyl}(CO)5] has been developed through the low temperature reaction of [Cr(CO),]*- with acid chloride.98 The methoxy and amino carbene complexes 24 were synthesised by the standard method from 4-bromo[2.2]metacyclophane and subsequent aminolysis to give the a m i n ~ c a r b e n e Carbohydrate.~~ modified Fischer-type carbene complexes have been prepared through combination of a sugar electrophile with a nucleophilic metallate, or vice versa, and are reported to show much promise in the areas of preparation and modification of multifunctional sugar skeletons, due to the regio- and stereo-selective ligand- and metal-centred reactivity (e.g. benzannulation and C2-homologisation),100,101 The scope of the cobalt-mediated carbonylative cycloaddition reactions of alkynylcarbene complexes of the type [M{=C(L)CrCPh}(CO),] (M = Cr, W; L = allylamino) has been investigated and various new carbene complexes thus prepared and characterised. The reaction was found to proceed under milder conditions than the more conventional Pauson-Khand protocol. Io2 Variable temperature NMR studies on the reaction of anionic propargyl compounds [M {=C(OMe)RCCR’f(CO)s]- with methanol showed that protonation occurs, with 1,2-tungsten migration affording vinylmetal species which decompose above 0 ° C giving [W(CO)s(thf)] and allenyl ethers. Iodine oxidation of the intermediate vinylmetal species gave a variety of products. Io3 A comparison of the photoinduced reactivity of chromium and tungsten carbene complexes of the type [M{ =C(OMe)R}(CO)5] (R = Me, biphenyl) with organic substrates suggests that the mechanism does not involve CO loss.’@’ Efficient routes to funtionalised p-lactones have been developed through thermal reactions between chromium carbene complexes and propargylic alcohols in the presence of acetic anhydride and NEt3.1°5.106 Optically pure spiro-lactones have been prepared by application of the stereospecific exoselective [4+2] reaction between sl,p unsaturated exocyclic chromium carbene complexes and 2-amino- 1,3-butadienes. Treatment of alkenyl N-H imidates RCH=CR’C(OEt)=NH (R = H, Me, Ph) with the carbene complexes [M(=C(OEt)C=CPhR)(CO)5] (M = Cr, W) gave novel 5-aza- I -metalla- 1,3,5,7-0ctatetraenes [M (=C(OEt)CH=C(Ph)N=C(OEt)CR’=CHR)(C0)5] along with 2,5-diethoxy-2H-pyrrole and 2,4-diethoxy-2H-dihydroazete complexes, the ratio of products being strongly influenced by the metal.I0* The same complexes with the alkenyl imine PhCH=CHCH=NPr’ gave the dihydropyridinyl complexes [M { =C[b=C(Ph)N(Pri)CH=CHI‘H(Ph)](OEt)}(CO)5] (vicr [4+3] cycloaddition) and zwitterionic metallates [M - { q’-b=C(Ph)CH(Ph)CH=CHN+(Pr’)=C(OEt)}(CO),] (via [4+2] cycloaddition). With sterically demanding imines such

I : Complexes Containing Metul-Curbon o-Bonds of the Groups Titunium to Mungunese

61

(25) M = Cr, W

as phenanthrene-9-carboximine, the [4+2] cycloaddition product 25 was obtained. The metallates generated upon addition of phenylethynyl lithium to complexes [W (=C(OMe)R)(CO)S] have been used for the regioselective preparation of furans, pyrroles and butenolides with a variety of

(28) M = Cr,W

substituents.’l o Similarly, PhC = CPh and [Cr {=C(OLi)NEt2>(CO),] gave [Cr{ q6-C6H~-C=C(Ph)CH(NEt2)0CO](CO)sJ from which y-functionalised butenolides are obtained after demetallation. In contrast, PhC =CH and the same carbene complex gave 26 through combination of five alkyne molecules and one co molecule.I The reactions between the complex [W { =C(OEt)C3 CPh)(C0)5] and open chain enamines (R’)HC=C(NR2)Me (NRZ = pyrrolidine, NBu’2; R’ = Ph, C02Me, C02Et, C02Bz, C02BuL) afforded novel metallates [W {C(OEt)=C[C(=NR2)Me]C(Ph)=CHR’}(CO)5] 27 which slowly isomerise in solution (E+ Z).’ l 2 Base induced condensation of alkenykarbene complexes [M {=C(OEt)C= CPh)(CO)5J (M = Cr, W) with trans-6-phenyl-5-hexene-2,4-

’

Ph

h

(OC)&r

=c’

N

.\

L R

O

62

Orgunometullic Chemistry

dione gave regioisomeric 6-( 1-ethynyl)pyran-2-ylidene complexes 28 and 29. Animation of 28 (M = W) afforded the metalla-l,3,5,7-octatetraene30 and its regioisomer. I 3 A highly efficient method for the construction of the 4-alkoxy-2-butene-4lactam skeleton, which forms the basic structure of several pharmacologically promising natural products, has been developed from carbene complexes [M{=C(OMe)R}(CO)S](M = Mo, W; R = Pr', Ph), alkenyl lithium reagents and tosyl isocyanate. l 4 Thermal decomposition of ( 1-acyloxy)carbene complexes generated in situ by reaction of [M{=C(ONMe4)R}(C0)=J (R = Me, CH2Ph, (CH2)3CH3, CH(CH3)CH2CH3, c-C6H c-C3H5, CH2SiMe3) with carboxylic acid halides yields enol esters exclusively or predominantly as the Z-isomer. The ZIE ratio can be improved by adding pyridine. I l 5 Alkylation of optically active aminocarbene complexes gave the corresponding alkylated complexes 31, which upon photolysis in the presence of 2,4,5-trichloropheno1 afford optically active a-amino esters. I l 6 The cyclohexadienone annulation of p,P-disubstituted vinyl carbene complexes [M { =C(OMe)C(R1)=CR2(R3)}(CO)5]with chiral 2-ynyl ethers in the formation of cyclohexadienones has been shown to occur with significant 1 ,4-asymmetric induction and the sense of induction provides the first experimental determination of the stereoselectivity associated with electrocyclic ring closure of a metal complexed vinyl ketene intermediate. I l 7 Reactions of the anions derived from the carbene complexes [M{=C(OMe)Me}(CO)S] (M = Cr, W) and the anion from [Fe{C(O)Me}(CO)(PPh3)(q-C5HS)] with a-bromoglycine esters R'(0)CNHCH(Br)C02R2 (R' = Ph, OCMe3; R2= Me, But) have been used to introduce organometallic fragments into side chains of a-amino acids in peptides.' l 8 Unusual cycloaddition and condensation reactions of 2-methyl-l,3-dimorpholino-l,3-butadiene with the complexes [M { =C(OMe)CR1=CR2(R3)}(C0)5] and [M {=C(OR1)R2}(CO)5] giving metal-free carbocycles of different sizes and highly functionalised carbene complexes have been reported. l 9 Highly functionalised siloxycyclopentene derivatives were obtained from reactions of dienes H+C(TBSO)CH=CH(R) (R = Ph, C02Me) with the complexes [Cr{=C(OMe)R'}(C0)5] (R' = Me, Ph), via carbene metathesis and subsequent formal [3+2] cycloaddition of the newly formed carbene ligands to the dienes. 2o 4-Substituted 2-(t-butyldimethylsiloxy)1,3-butadienes and chromium carbene complexes afforded bicyclo[4.1.O] heptene derivatives through an intramolecular C-H insertion reaction of the initially formed DieIs-Alder adduct. The role of both the metal and the heteroatom ligand in the carbene complex was examined.12'

'

'

I : Complexes Containing Metal-Carbon a-Bonds of the Groups Titunium to Mungunese

-

63

Reactions of ethyl trans-2-phenylethynylcyclopropanecarboxylateand the complex [Cr { =C(NHz)CHCH2CHC = CPh}(CO)S] with norbornene gave esters and good yields of metal carbene funtionalised em-tricyclodecenones via an intramolecular Pauson-Khand reaction. Incorporation of the alkyne is moderately regioselective but less diasterioselective. 122 Alkynes and the 2-inolyl chromium carbene complexes 32, containing a chiral imidazolidinone, afford 4Hcarbazol-4-ones in high diastereoselectivity. This represents the first asymmetric cyclohexadienone annulation of a Fischer carbene complex. 123 Thermal reaction between the alkyne HC =CCH2CH2CH(C02Me)2, possessing an active methyne proton, and [Cr { =C(OEt)Me}(C0)5] gave a 5-membered cyclic ketone through insertion of a CO ligand between the active methyne carbon and the alkyne carbon. 124 Insertion reactions of alkynes and CO with alkynylaminocarbene complexes of the type [Cr{=C(NRR’)R2}(CO)s] have been used to prepare pyrroloindole, pyrrolochinoline and azaacenaphthylenone frameworks. 125 The selective preparation of 5-, 6- and 7-membered N-heterocycles has been achieved through reactions of 2-aza- 1,3-butadienes with the carbene complexes [M{=C(OMe)R}(CO)S] {M = Mo, W; R = Ph, 2-fury1, C-CSiMe3, C-CPh, CH=CHPh, CH=CH(2-furyl)} Ferrocene carboxaldehyde and [Cr{=C(OMe)Me} (CO),] gave the violet coloured complex [(OC),Cr { =C(OMe)CH=CH[C5H4Fe(q-C5H5)]}]which was used for the diastereoselective cyclopropanation of alkenes ( 1-hexene, cyclohexene, norbornene). 127 Anions of [M {=C(OMe)Me}(CO)S]react with pyrylium salts to give benzophenones, via dienones after ring-closure and aromatisation by double &hydrogen elimination. 128 Iodine oxidation of cyclic diamino-substituted carbene complexes [M{=CN(R)CH2(CH2),N(R)}(CO)s](M = Cr, Mo, W; n = 1,2) at 120°C gave imidazolidin-2-ylidinium iodides and related 6-membered derivatives. ‘29 The cyclopropylcarbene complexes [M { = C ( O R ) m H ( R ’ ) )(CO),] and [M { =C(OR)CHCH(Br)CH(Ph)}(C0)51 were prepared with high diastereoselectivity by reactions of the chiral vinyl complex [M { =C(OR)CH=CH(R’)}(C0)5] (M = Cr, W; R = (-)-8-phenylmenthyl; R’ = 2-fury1, Ph, p-C6H5CI) with iodomethyllithium and dibromomethyllithium, respectively. Enantiopure 1,Zdisubstituted and 1,2,3-trisubstituted cyclopropanes were obtained from these cyclopropyl carbene complexes using similar methodology. I3O Tin and germanium substituted enol ethers and 2-alkoxy- 1,3-butadienes have been obtained from reactions of trialkylvinyl-tin and -germanium compounds with carbene complexes [M {=C(OR)R’)(C0)5].1 3 ’ Treatment of the molybdates [MO{=C(OL~)R}(CO)~] with BF30Et2 afforded thermally unstable difluoroboroxy carbene complexes [MO(=C(OBF~)R}(CO)~J (R = Bu, Ph, 2-Nph, PhC= C, PhCH=CH), characterised by NMR spectroscopy. Above - 60°C these complexes decompose to 1,2-diketones, I ,2-hydroxyketones or dimers R-R. In the presence of 3-buten-2-one, the Michael addition products RC(O)CH$H*C(0)Me were obtained. 32

-

Orgunometullic Chemistry

64

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73. 74.

75. 76. 77. 78. 79.

81. 82. 83. 84. 85. 86. 87.

88. 89. 90. 91. 92. 93.

I : Complexes Contuining Metul-Curbon a-Bonds of die Groups Titunium to Mungunese

94. 95. 96. 97. 98. 99. 100. 101. 102. 103. 104. 105. 106.

107. 108. 109. 110.

111.

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116. 117. 118. 119. 120. 121. 122. 123. 124. 125. 126.

67

Licandro, A. Papagni, S. Maiorana, W.-D. Meng and G. R. Stephenson, J. Orgummet. Chem., 1997,545,9. Y. M. Terblans and S. Lotz, J. Chem. Sue., Dulton Truns., 1997,2177. B. E. Woodworth, P. S. White and J. L. Templeton, J. Am. Chem. Soc., 1997, 119, 828. H. Adams, M. N. Bancroft and M. J. Morris, Chem. Commun., 1997, 1445. Y. Chi, H.-L. Wu, S.-M. Peng and G.-H. Lee, J. Chem. Soc., Dalton Truns., 1997, 1931. A. D. Reed and L. S. Hegedus, Orgunometullics, 1997, 16, 2313. A. Longen, M. Nieger, F. Vogtle and K. € I . Dotz, Cizem. Ber., 1997, 130, 1105. K . H. Dotz and R. Ehlenz, Cizem. Eur. J . , 1997,3, 1751. K. H. Dotz, R. Ehlenz, W. Straub, J. C. Weber, K. Airola and M. Nieger, J. Orgummet. Chem., 1997,548,91. L. Jordi, S. Ricart, J. M. Viafis and J. M. Moreto, Orgunometullics, 1997, 16, 2808. N. Iwasawa, T. Ochiai and K. Maeyama, Orgunometullics, 1997,16, 5137. M. L. Gallacher, J. B. Greene and A. D. Rooney, Orgunometullics, 1997,16,5260. J. P. A. Harrity, N. M. Heron, W. J. Kerr, S. McKendry, D. Middlemiss and J. S. Scott, Synlett., 1997, I 184. J. P. Harrity, W. J. Kerr, D. Middlemiss and J. S. Scott, J. Orgunumet. Chem., 1997, 532,2 19. J. Barluenga, F. Azner, S. Barluenga, S. Garca-Granda and C. Alverez-Rua, Synlett., 1997, 1040. R. Aumann, R. Frohlich and F. Zippel, Orgunometullics, 1997, 16,2571. R. Aumann, Z. Yu and R. Frohlich, J. Orgummet. Chem., I997,549,3 1 1. N. Iwasawa, K. Maeyama and M. Saitou, J. Am. Chem. Soc., 1997,119, 1486. C. Alverez-Toledano, 0. Baldovino, G. Espinoza, R. A. Toscana, R. GuitierrezPkrez and 0.Garca-Mellado, J. Orgunomet. Chem., 1997,540,41. R. Aumann, K. Roths and R. Frohlich, Orgunometullics, 1997,16,5893. Z. Yu, R. Aumann, R. Frohlich, K. Roths and J. Hecht, J. Orgunumet. Chem., 1997, 541, 187. N. Iwashwa and K. Maeyama, J. Urg Chem., 1997,62, 1918. B. C. Soderberg, J. Liu, T. W. Ball and M. J. Turbeville, J. Org. Chem., 1997, 62, 5945. J. Zhu, C. Deur and L. S. Hegedus, J. Org. Chem., 1997,62,7704. R. P . Hsung, J. F. Quinn, B. A. Weisenberg, W. D. Wulff, G. P. A. Yap and A. L. Rheingold, Chem. Commun., 1997, 61 5. B. Kayser, K. Polborn, W. Steglich and W. Beck, Chem. Ber., 1997, 130, 171. J. Barluenga, F. Azner and M. Fernandez, Chem. Eur. J., 1997,3, 1629. M. Hoffmann, M. Buchert and H. Reissig, Angew. Chem. Int. Ed. Engl., 1997, 36, 283. K. Takeda, Y. Okamoto, A. Nakajima, E. Yoshii and T. Koizumi, Synlett., 1997, 1181. 0 .Kretschik, M. Nieger and K. H. Dotz, Chem. Ber., 1997,130, 507. J. F. Quinn, T. S. Powers, W. D. Wulff, G. P. A. Yap and A. L. Rheingold, Orgunometullics, 1997, 16,4945. T . Ishibashi and M. Mori, J. Org. Chem., 1997,62,7058. C. Bouaucheau, A. Parlier and H. Rudler, J. Org. Cizem., 1997,62,7247. J. Barluenga, M. Tomas, A. Ballesteros, J. Santamana and A. Suarez-Sobrino, J. Org. Chem., I997,62, 9229.

68 127. 128. 129. 130.

13 1 . 132.

Orgunometullic Chemistry

J. Barluenga, A. Fernandez-Acebas, A. A. Trabanco and J. Florez, J. Am. Clietn. Soc., 1997,119,759 1. P. Le Poul, F. R.-Le Guen, M.-C. Senkchal-Tocquen and B. Caro, J. Orgunornet. Cliem., 1997,545446,447. S.-T. Liu, R.-Z. Ku, C.-Y. Liu and F.-M. Kiang, J. Orgunornet. Chem., 1997, 543, 249. J. Barluenga, P. L. Bernard Jr., J. M. Concellon, A. Piiiera-Nicolas and S. GarcaGranda, J. Org. Chem., 1997,62,6870. J. Barluenga, R. Gonzalez and F. J. Faiianas, Orgunometullics, 1997, 16,4525. J. Barluenga, F. Rodriguez and F. J. Faiianas, Orgunomefallics, 1997, 16, 5384.

Part IV: Group 7 by Sherilyn A . Wass Useful information may be found in reviews covering the co-ordination chemistry of manganese,' technetium2 and rhenium' for 1994. The use of rhenium and technetium 0x0 complexes, especially MTO, in the study of organic oxidation mechanisms has been r e ~ i e w e dThe . ~ importance of photochemistry as a tool for investigating the mechanisms of the carbonylations of metal-alkyl bonds has been reviewed. Reference is made to studies on the model system Mn(CO)5(COCH3). The similarity of structural units in solid state ternary metal carbides to those in metal carbonyl, alkyl and carbene complexes has been discussed. The materials considered contain carbon, a transition metal (Cr to Ni and their heavier congeners) and a highly electropositive multivalent metal such as a lanthanide, Sc, Y or Th.6 X-ray crystallography has shown that the structure of the [Re(CH&I2- anion of [Li(Et20)]2[Re(CH&] is square antiprismatic as predicted by its ESR spectrum. Allyldimethylmanganates such as 2 have been prepared by transmetallation reactions of allylic stannanes with trimethylmanganates according to eq. 1. The resulting allyldimethylmanganates reacted with epoxides to give allylated products exclusively in good yields.' Reaction of allylic and prop-2-ynylic bromides with the tetrdbutylmanganese ate complex 'Bu4MnLi2' afforded the corresponding ally1 and prop-2-ynyl-manganese species. Addition of electrophiles such as aldehydes, ketones, epoxides and chlorosilanes gave high yields of the corresponding allylated products, prop-2-ynylated or allenylated products, or mixtures of the two. The composition of the products obtained in the reactions of the prop-2-ynyl-manganese species depended on the bulkiness of the electrophile and the nature of R.9 Functionalised aryl and alkenylmanganese halides such as p-chlorophenylmanganese iodide and 5-chloropentenylmanganese iodide have been obtained from the corresponding functionalised aryl and alkenylhalides by a

I : Complexes Containing Metal-Carbon a-Bonds of the Groups Titanium to Munganese

69

one-pot procedure involving halogen-lithium exchange followed by lithiummanganese transmetallation. lo Kinetic studies using stopped-flow spectrophotometry have been carried out on the formation of trans-[Rex( 3 CCH,R)(dppe)2]+ (X = C1; R = Ph, C6H4Me-4, But, C02Me, C02Et; X = F; R = C02Et) by protonation of the corresponding vinylidene complexes tr~ns-[ReX(=C=CHR)(dppe)~]with [NHEt3][BPh4]. The reactions have been shown to proceed by three pathways: direct protonation at the remote carbon atom, protonation of the metal followed by intramolecular migration, or protonation of the metal followed by acid-catalysed rearrangement. The relative contributions of these three pathways have been shown to depend on the nature of R and X." The emissive d' complex ReV'( =CAr')(PPh3)(H20)C13 (Ar' = 2,4,6-C6H2Me3) has been prepared by refluxing a CHC13 solution of [ReV(= CAr')(PPh3)2(CO)(H20)Cl]ClO4(2) containing aqueous HC1. 2 has been characterised by X-ray crystallography. I 2 The magnetic properties of the bimetallic assembly [Ni1'(en)2]3[Mn"'(CN)&.2H20, obtained in the form of microcrystals by the reaction of [Ni(en)3]X2 (X = C1- or C104-) and K3[Mn(CN),], have been in~estigated.'~ Addition of a MeCN solution of [Fe(q-C5H5)2][BF4]to a CH2Cl2 solution of [N(PPh3)2]3[Mn11'(CN)6] gave the magnetic cyanometallate [N(PPh3)2]2'[Mn'V(CN)6]2-, which was precipitated from solution with Et2O. The salt is stable in both MeCN and CH2C12. It has been characterised by X-ray crystallography and spectroscopic measurements. l 4 [Re1"(S2CC6H5)(S3CC6H5)21(3), prepared by the reaction of [Et4NI2ReS4and (C6H5CS2)2, undergoes a sulphur abstraction reaction with [Et,N]CN affording [Et4N][Re"'(S2CC6H5)3(CN)] (#), which reforms on refluxing with excess sulphur. X-ray diffraction analysis shows that the anion of # has a distorted pentagonal bipyramidal geometry. l 5 Treatment of a solution of [Mn(CNCsH3Me2-2,6)5]- (9, formed by the naphthalenide reduction of [Mn(CNC6H3Me2-2,6)5C1], with SnClPh3 gave [Mn(CNC6H3Mez-2,6)=,(SnPh3)]. The [K( 18-C-6)(dme)]+ salt of 5 has been crystallised, and the anion shown by X-ray crystallography to have trigonal bipyramidal geometry.16 (1) has been obtained in good yield by the methylation

Ph' N C

N Ph'

C

Ph' N

Ph'

'N

Orgunometullic Chemistry

I0

of [Mn-'(CNPh*)5]- (Ph* = 2,6-(CH3)2C6H4) with CH31, and characterised by X-ray crystallography. Treatment of [Tc(NO)C12(PPh3)2(NCCH3)] (6) with excess tert-butylisonitrile in CH2C12 afforded [Tc(NO)Cl2(PPh3)2(CNBuL)].[Tc(NO)C12(PPh3)(CNBut)2] was formed by refluxing 6 with excess ligand in CH2C12 and [Tc(NO)CI2(CNBu')3] by refluxing 6 with excess ligand in benzene. All three substitution products have been characterised using IR and FAB (+) mass spectroscopy. l 8 Structurally characterised mer-[ReCl3(CNC6H4-2-OH)(PPh3)2] (2) has been obtained by the reaction of 2-(trimethylsiloxy)phenyl isocyanide (7)with mer[ReC13(NCCH3)(PPh3)2]. The reaction of 7 with fuc-[Re(0)C13(SMe2)(0PPh3)] afforded a Re(V) diisocyanide complex which underwent Si-0 bond cleavage to give fac- { Re(o)C13[~N(H)C,H4-2-~]~) (3). X-ray crystallography has shown that (3) is a cis-dicarbene complex with one molecule of OPPh3 hydrogen-bonded to one carbene N-H proton. l9 Thermochemical studies have been carried out on the irreversible isomerisation reaction [Mn(C0)5(q'-C3H~)]-, [Mn(C0)4(q3-C3H5)]. Values of AfHmo(g)have been used to determine enthalpy contributions for the (propenyl-Mn) bonds in these molecules.20 The reaction between (q5-SCHCHCHCLi)Cr(C0)3 (8) and Mn(CO)5X (X = CI-, Br-) afforded (q ':q5-SCHCHCHCMn(CO)5)Cr(C0)3, which was irreversibly converted into (q ':q5-SCHCHCHCCr(CO)5)Mn(C0)3 at 0 "C in acetone. (q ':T~~-SCHCHCHCC(O)M~(CO)~)C~(CO)~ (4) was also obtained as a product of the reaction. Treatment of 8 with excess BuLi at - 70 OC afforded (5).21 (q6-C8Hl&ho-q4:q '-CgH I I)Re(C0)5 ( 9 ) has been prepared by reaction of Na[Re(CO)5J and [(q6-C8H,o)Ru(q5-C8H l)]BF4. Crystallisation of 9 from pentane gave (q4-C8Hlo)(OC)Ru(p-q4:q '-C& 1 l)Re(CO)s, which has been characterised by X-ray crystallography.22 0

I : Complexes Containing Metul-Curhon a-Boncis of the Groups Titunium to Mungunese

71

Theoretical studies have been carried out on the interaction mode of p-'C2' units in dinuclear L,MC2ML, complexes of late transition metals in low oxidation states. The results of density functional calculations on the model complexes [(MCln(C0),-,}2(p-C2)] (M = Cr, Mn, Fe or Co; m = 4 or 5; n = 0 or 1) have been used to explain why only the acetylenic structure is found, and why most of the experimentally known compounds have a d7 ML, fragment config-

ration.^^ The heterobimetallic ethynylcarbene complexes [(CO)5W= C(NMe2)C-CM(CO)5] (M = Mn, Re) have been obtained by Pd-catalysed coupling of [(CO)SW=C-(NMe2)C= CSnBu31 with [BrM(CO)5].24 The reaction of tosylethyne with Na[Re(CO)S] afforded structurally characterised (OC)5Re-C(H)=C(H)(tosyl) (6) and (OC)5Re-C= CH (20). 20 has also been obtained by cleavage of the Me3Si group from (0C)SRe-CEE C-SiMe3.25

Investigations into the preparation of dinuclear metal complexes with saturated and unsaturated hydrocarbon bridges have resulted in the preparation of truns[Re]-(CH2)2-CH=CH-(CH2)2-[Re],structurally characterised cis-[Re]-(CH2)3CH=CH-(CH2)3-[Re], and [Re]-(CH2),-CH2-CrC-CH2-(CH2),-[Re] {[Re]=Re(CO)s,p=l , 3) from the reactions of the bis(triflates) truns-Y-(CH2)2CH=CH-(CH&-Y, cis-Y-(CH2)3-CH=CH-(CH2)3-Y and Y-(CH2)p-CH2-C=CCH2-(CH2),-Y [Y = FJCSOR, p = 1, 31 with Na[Re(CO)S].26 Bismetallated olefins have been obtained by the nucleophilic substitution of C1 in dichlorocyclopentenedione, dichloromaleic anhydride and dichloromaleimide by Re(CO)S-. The structure of the 2,3-bis(pentacarbonylrhenium)-maleimide (7) has been determined by X-ray crystallography. The cyclometallation reaction between MeMn(CO)Sand the Schiff's base (8) afforded structurally characterised Mn { 24 Bun-N=CH)5-(N02)C6H3}(C0)4 (9). Kinetics studies on the effect of varying ligand substituents on the rate of reaction show that the rate increases with more electron-rich ligands. Addition of PhLi to (lo), followed by methylation with MeOTf, gave (ll), which has been characterised by X-ray cry~tallography.~~ Co-ordination of Mn(C0)3+ to the carbocyclic ring of benzothiophene activates the C(ary1)-S bond, resulting in the formation of a x-bonded complex, which on chemical reduction afforded 12 (R = H). In analogous reactions, 12 (R = Me, Et), underwent C(viny1)-S bond scission to give 13, which formed 14 via a metallathiacycle ring contraction.30 [Re(C0)3(C5H5)],[Re2(C0)6(p,qs:qs-CloHS)]and structurally characterised [Re2(CO)8(p,q':qs-C5H4)],have been obtained by the reaction of a 1:l molar ratio of [Re2(C0)8(MeCN)2] with diazocyclopentadiene. [Re2(C0)8(p-

72

Organometallic Chemistry

N2(C5H&}], which has also been characterised by X-ray crystallography, was obtained using a 1:2 molar ratio of reagent^.^' The reaction of ethyldiazoacetate with [Re2(p-H)2(CO)8] afforded [Re2(pH)(Co)8(~-r12-CHC02Et)](15) with loss of N2. (15) was characterised by

R

R

analytical data and NMR spectroscopy. [Re2(C0)8(p!$CPR3)] (R = cyclohexyl, Pr') have been prepared by addition of S2CPR3 to [Re*(C0)8(p-H)(pCH=CHBu")], formed by irradiation of Re2(CO)lo with l - h e ~ e n e . ~ ~ [Mn(CO)3(Pri-DAB)]- ( I I ) has been obtained by electrochemical reduction of OEt

I

0/

C

H

\cJ"

I : Complexes Containing Metui-Curbon o-Bonds of the Groups Titunium 10 Mungunese

73

[Mn(X)(CO),(Pr'-DAB)] (X = Me, Bz). 11 is formed by dissociation of X' from the one-electron-reduced intermediate [Mn(X)(CO)3(Pri-DAB)]'- (12). 12 (R = Me) has been detected using cyclic ~ o l t a m m e t r y . ~ ~ Isolable [Mn(q2-H2)(CO)P4]BPh4(P = P(OEt3), PPh(OEt)2) and solutions of [Mn(q2-H2)(C0),P3]' (P = P(OEt3), PPh(OEt),, PPh20Et) have been prepared by the protonation of MnH(CO)P4 and MnH(C0)2P3 with HBF4.Et20. The complexes lose H2 forming [Mn(CO)P4]BPh4(13) and [Mn(C0)2P3]BPh4 (14), which are probably stabilised by agostic interactions between the metal centres and the C-H protons of the phosphites. Treatment of 13, 14, and also of the triflate compounds [Mn(q'-OS02CF3)(CO)3P2] (P = P(OEt3), PPh(OEt),, PPhZOEt) with Li'RC=C- (R = Ph, p-tolyl) produced the acetylide derivatives [Mn(C= CR)(CO)P4], [Mn(CE CR)(C0)2P3] and [Mn(C=CR)(C0)3P2], respectively. [Mn(CO)(p-tolylNC)P4]BPh4 and [Mn(C0)2@-tolylNC)P3]BPh4 have been obtained by the reaction of 13 and 14 with the appropriate ligand~.~~ Extended Huckel molecular orbital calculations have been carried out to estimate the barriers towards haptotropic shifts of the Mn(CO)3 moiety over the surface of the tetracyclic cyclopentanophenanthrenyl system. The results suggested the involvement of an intermediate exocyclic (q3-cpp) species, stabilised by the presence of a naphthalene-type 1011aromatic system. The preparation of q3-cpp (cppH = 4H-~yclopenta[deflphenanthrene)complexes by loss of a ligand from an ql-cpp precursor or by addition of a ligand to an $-system have also been studied. The reaction of ( ~ ~ - c p p ) M n ( C Owith ) ~ PPh3 afforded (q'cpp)Mn(CO),(PEt,), (16), shown by X-ray crystallography to have a transmeridional arrangement of phosphine ligands at manganese. (16) has hindered rotation about the cpp-Mn o-bond. The barrier to the fluxional process, 16.5 kcal mol-', was determined by means of selective inversion NMR spectroscopy.36 The bridging carbonato complex (dppe)(C0)3MnOC(O)OMn(CO)3(dppe)has been obtained by stirring a solution of (dppe)(CO)3MnC(0)OCH3 in CH2C12 saturated with water.37 Reduction of the yellow isomeric forms of salts of the type [Re2CI3(p dppm)z(CO)(CNXyl)2]Y (Y = C1, 03SCF3,PF6, Re04) gave the neutral congener [(XylNC)CIRe(j~-Cl)(p-CNXyl)(p-dppm)2ReCl(CO)]CI, which was shown by Xray crystallography to be an edge-sharing bioctahedron with a p-CNX~l-bridge.~~

Mn .

Orgunometullic Chemistry

74

R NC

I'

CI

c'I\c,

pop

Treatment of the open bioctahedrai complex Re2C14(p-dppm)2(CO)(CNXyl)2 with equimolar amounts of T103SCF3 and XylNC afforded one isomeric form of [Re2C12(p-dppm)2(CO)(CNXyl)3]2+ (17). A second isomeric form (18) was obtained from a similar reaction using the triflate salt of [Re2C13(pdppm)2(CO)(CN XYl)21+. 39 The cisoid-q 4( 5e)-butadien y1-substi tuted complexes [Re{ =C( Ph)-q 3C(R)CHCHC6H4PPh2-o}(q-CSHs)3[BF4](19) (R = Me or Ph) have been prepared by the reaction of [ReBrz(q2(4e)-PhC2R}(q-C5H5)J with AgBF4 (2 equivalents) and o-diphenylphosphinostyrene. (19) (R = Me) has been characterised by X-ray crystallography. Treatment of (19) (R = Ph) with K[BHBuS3] afforded [Re{q4-CH(Ph)=C(Ph)CH=CHC6H4PPh2-o)(q-C5H5)], which reacted with [Ph&][BF,] to regenerate (19) (R = Ph). This established the relationship between the q4(5e)-butadienyl and q4-I,3-diene ligand~.~' Reaction of (q5-C5Me~)Re(NO)(PPh3)(C=CH) and one equivalent of CU(OAC)~ gave (q5-CsMeS)Re(NO)(PPh3)(C=CC E C)(Ph3P)(ON)Re(q5C5Me5) ( 1 9 , shown by NMR spectroscopy to be a 5050 diastereomer mixture. Crystallisation from CH2Cl2kexane produced (SS,RR)-Z5.2CH2C12 and solutions enriched in (SR,RS)-15 (meso). Treatment of (SS,RR)-15 and (SR,RS)-15 with Ag+PF6- yielded (SS,RR)-152+.2PF6- and (SR,RS)-1S2'.2PF6-, two geometrical isomers about the +Re=C=C=C=C+Re+ linkages. X-ray CryStdllOgrdphy has shown that (SS,RR)-15.2CH2C12has C = C and C-C bond lengths similar to those in butadiyne, and that (SS,RR)-152+.2PF6- has Re=C bond lengths similar to those in a related complex containing 'Re=C=C=C=Mn.4' The reaction = C)H >3 and [Os3between chiral racemic [(q5-C5Me5)Re(NO)(PPh3)((C

I : Complexes Contuining Metul-Curbon a-Bonds of the Groups Titanium to Mungunese

15

(CO)I o(NCMe)z] afforded [(q 5-C5Me5)Re(NO)(PPh3)C(C)Os3(CO)OH]. X-ray crystallography and spectroscopic data suggest that it is a hybrid of Re-(C=C)(Os3) and Re+=(C=C),=(Os3)- resonance forms?2 Sequential reaction of Re2(CO),o and Me30+BF4- to (q5-C5Me5)Re(NO)(PPh3)(CSCLi) produced cis-(q'-C5Me5)Re(NO)(PPh3)(C = CC(OMe)=)Re(CO)4Re(CO)s ( 16).Treatment of with excess BF3 gas in toluene precipitated structurally characterised [(q5C~Mes)Re(No)(PPh,)(p-q':q3:q '-CCC)(Re(CO)4)Re(CO)S]+B F4-, which may be regarded as a fully-metallated R propargyl or PRe=CC=C-Re(CO)Sadduct of Re(C0)4.43 [(q5-C5R5)Re(NO)(PPh3)CN(Ph3P)(ON)Re(q5-CSR'5)]+OTf (17) (R, R'=H, Me) have been prepared as mixtures of SR, RSISS, R R diastereomers (pseudo mesold) by the reactions of (q5-C5R'5)Re(NO)(PPh3)(OTf)(R' = H/Me) and (q5C5R5)Re(N0)(PPh3)(CN)(R = H/Me). The reaction between (S)-(q5-C5H~)Re(NO)(PPh3)(OTf) and (R)-(qS-CSH5)Re(NO)(PPh3)(CN)gave (RR)-17 (R, R' = H) (retention), a diastereomer not formed from the racemates. (SR,RS)-17 (R, R' = H) has been characterised by X-ray crystallography.44 Cp*(CO)(NO)ReC(O)OSiEt3 and Cp*(CO)(NO)ReC(0)OSiMe2Phhave been prepared in moderate yields by the reactions of Cp*(CO)(NO)ReC02H and the appropriate chloroalkylsilane and diisopropylethylamine, or by the reaction of Cp*(CO)(NO)ReC02- Na+ and the appropriate chloroalkylsilane. Good yields were obtained by the reaction of NaOSiEt, and NaOSiMe2Ph and Cp*(CO)2(NO)Re+BFi in CH2C12. The complexes were characterised by IR and NMR spectroscopy, which indicated non-chelating p(q '-C:q '-0)metalloester structure~?~ has been preStructurally characterised [Cp*(CO)(NO)Re(C02)Rh(q4-COD)]~ pared by the reaction of [(CF3S03)Rh(q4-COD)]with Cp*(CO)(NO)ReC02H and EtPr'zN. It has a Re2Rh2(p3-C02)2 core with two p3-(q1-C(Re):q'-0(Rh):q'O(Rh')] carboxylate ligands, and is structurally similar to the catalytically active [(RCO2)Rh'(diene)I2complexes.46The p2-q3C02-bridged complex Cp*Re(CO)(NO)(C02)Sn(Cl)Me2 (18) has been prepared by the reaction of Cp*Re(CO)(NO)(C02)SnMe3 with Me2SnC12. In the presence of water, 18 formed [Cp*Re(CO)(NO)(C02)]2SnMe2 (19). 18 and 19 have been characterised by X-ray crystal10graphy.~' Addition of 3-chloroperoxybenzoic acid to a CH2C12 solution of [q5:q'-C5H4CN2CH2N(CH3)2]Re(CO)2 afforded structurally characterised

[q5:q'-C5H4CH2CH2N(CH3)2]Re(CO)(q2-C02)(20).48 The reactions of [(C0)2ReN(CH3)CH2CH2(q5-C5H4)]-(20) with electrophiles

+

16

Orgunometullic Chemistry

RX (RX = CH31, CH2=CHCH2Br, C6H5CH2Br, HC =CCH2Br) occurred at the nitrogen centre forming (C0)2ReNR(CH3)CH2CH2(q5-C5H4).However, the reactions of 20 with electrophiles R'X (R'X = CH2C02CH3Br,CH2C02C2H5Br, CH2CNBr) took place at the rhenium centre giving [(C0)2(R')ReN H(CH3)CH2CH2(q5-C5H4)]+Brafter protonation. (C0)2ReNH(CH3)CH2CH2(q5-C5H4) reacted with RX and R'X, leading to alkylation at the Re centre in both cases. [(C0)2(C6H5CH2)ReNH(CH3)CH2CH2(q5C5H4)]+BPh4-(21) has been characterised by X-ray cry~tallography.~~ The carbene carbon atom of Cp(C0)2Re=CHCH2CH2CMe3is amphiphilic, reacting with the PPh3 to give Cp(C0)2ReCH(PMe3)CH2CH2CMe3and with HCI to give ~ ~ s - C ~ ( C O ) ~ C I R ~ C H ~ C H(21). ~ C To H ~determine C M ~ ~ the absolute stereochemistry of 22, the rotationally restricted analogue (C0)2Re=C(CH3)C(CH3)CH2(q5C5H4) (22), having a tether between the cyclopentadienyl ring and the carbene carbon, was synthesised. X-ray crystallography confirmed that addition of HCl across the Re=C bond gives cis ~tereochemistry.~~ Treatment of [Cp*Re(q3-C3H5)(C0)2][BF4]with NH2- or C6H5Li resulted in nucleophilic addition either at the q3-allyl or the CO ligand. At low temperature the CO was attacked, forming Cp*Re(q3-C3H5)(CO)(COR)(23) (R = NH2, C6H5). Unlike (R = C6H5), 23 (R = NH2) was unstable in solution, completely Cp*Re(q3decomposing to give the substituted propene at room temperat~re.~' C3H,)(CO)Cl, prepared by the photolysis of Cp*Re(C0)3 and ally1 chloride, or by the reaction of [Cp*Re(q3-C3H5)(C0)2]2fwith PhIO and Me4NCI, has been converted to Cp*Re(q3-C3H5)(CO)H by treatment with LiBEt3H, and to the phenyl or alkyl derivatives Cp*Re(q3-C3H5)(CO)Ph or Cp*Re(q3-C3Hs)(CO)R by treatment with LiPh or RMgX (X=CI, R=C4H9; X=Br, R=CH3, C2H5, C3H5).52 Only hydrosilane/manganese carbonyl precatalyst systems that most readily effected hydrosilation of the acetyl ligand in Cp(L)(CO)MC(O)CH3 ( M = Fe, Ru; L = CO, PPh3) reacted with the methoxycarbonyl complexes Cp(C0)zMC02CH3 (24) (M = Fe, Ru). PhSiH3/2-3% (PPh3)(C0)4MnC(0)CH3and 24 (M = Fe, Ru) or PhMe2SiH/2-3% (CO)5MnCH3 and 24 (M = Fe) both afforded (q4C5H6)M(C0)3and m e t h o ~ y s i l a n e s . ~ ~ The redox chemistry and mixed-valence properties of 2 1 cyanide-bridged complexes M-CN-M' (M, M' = (C0)5Cr, ( C O ) 5 M ~ ,(CO)5W, Cp(CO);?Mn, Cp(COhFe, Cp(CO)(CN)Fe, Cp(dppeFe, Cp(PPh3)2RU, Cp(PPh3)Ni,

I : Complexes Contuining Metul-Cwbon

0-Bonds

of'the Groups Titanium to Mangunese

77

(PPh3)zAg) prepared by the reaction of M-CN and M-X (X = leaving group) have been reported.54Diisocyanomethane, obtained by the fractional condensation of CH2CII solution of bis(formy1amino)methane under high vacuum, reacted with [CpMn(CO),thf] to give (22) and (23).55 Tr~ns-(q~-C~Me~)Re(C0)~(Ar)I (Ar = phenyl and tolyl) have been isolated from the reactions of ~ i s - ( q ~ - C ~ M e ~ ) R e (with C0)~ ArCu. 1 ~ On treatment with MeLi, they formed truns-(q5-C5Me5)Re(C0)2(Ar)Me.Trans-(q5-CSMe5)Re(C0)2(Ph)I has been characterised by X-ray cry~tallography.~~ At low temperatures, the reactions between [Cp'(CO)2Mn=C(OEt)CHR]-(R = H, Me) and the a,&unsaturated ketones R'(H)C=C(H)C(O)-Me (R' = H, Me, Ph) formcd the Michael adducts Cp'(CO)2Mn=C(OEt)CH(R)CH(R')CH2C{O)Me on acid hydrolysis. Allowing the reaction mixture to attain room temperature before acid hydrolysis afforded the cyclohexenone complexes Cp'(CO)2Mn(q2-CH=CHCH(R)CH(R')CH2C{ 0)),which reacted with PPh3 or CO to give the corresponding substituted 2-cy~lohexenones.~~ The reactions between Cp*(C0)2Re=Re(C0)2Cp* (25) and HC(CR (R = H, CH3, C6H5, C(CH3)=CH2, OCH2CH3) afforded the dimetallacyclopentenones Cp*(C0)2Re(p-q ,q3-CH=CRCO)Re(CO)Cp*. HC=CC02Me and CH3C=CC02Me also reacted with 25 forming Cp*(C0)2Re[p-q',q3CH=C(C02CH3)CO]Re(CO)Cp* and Cp*(CO)2Re[p-rl ,q3(CO2CH3)C=C(CH3)CO]Re(CO)Cp*, respectively. 'H NMR spectroscopy showed that Cp*(CO),Re(p-CO)Re(CO)(HC=CCH3)Cp* and Cp*(C0)2Re[pq ',q3-C(CH3)=CHCO]Re(CO)Cp*were formed as intermediates in the reaction between propyne and 25. Protonation of the dimetallacyclopentenonesgave vinyl dirhenium cations.58 The reactions of [Mn(C0)3{q5-c5H4[(q5-C6H,)Mn(co)3]}] and [WMe(C0)3(q5-C5H4[(q5-C6H,)Mn(co)3])] with LiR (R = 0-,m-,p-MeC6H4, Ph, p-MeOC6H4, p-CF3C6H4) produced acylmetallate intermediates. These reacted with Et30BF4 to give [Mn(C0)3{q5-C5H4[(q5-C6H6)(oc)2Mn= C(OEt)R])] (26) and [WMe(C0)3{ q5-CSH4[(q5-C,H,)(oC)2Mn=c(oEt)R]}]. (R= o-MeC6H4)has been shown by X-ray crystallography to have the carbene ligand attached to the Mn atom co-ordinated to the q5-cyclohexadienylmoiety.S9 A comparative density functional investigation has been carried out on CH3M03 (M = Re , Tc) and their NH3 adducts. The influence of the relativistic effects on the reactivity of the two metal centres is discussed.60 [RR'(0)-ReV'(p-O)l2 (R = R'= (cyclo)-C3H5,Pr'; R = CH3, R' = C2H5 ; R = CH3, R' = Pr') have been synthesised from Re207 and dialkylzinc precursors. They can be handled in air at room temperature. [(CH3)R(O)Re(p-O)]?(R = C2H5, CH(CH3)2) have been obtained as mixtures of cisltruns isomers by the reactions of MTO with dialkylzinc compounds. The compounds were characterised by NMR, IR and Raman spectroscopy.6' Treatment of MTO with the nitrogen ylide PhC(0)CH-N+(CH2)5(CH3) afforded Me4Re204(27) and structurally characterised Re04- PhC(0)CH2N'(CH3)(CH2)5. The reaction between PhC(O)CH-N+(Et)3 and MTO also gave 27, together with Re04-PhC(0)CH2N'(Et)3, showing that the methyl groups in 27 did not come from the NMe group of the ylide.62

'

78

Orgunometullic Chemistry

A ligand-accelerated catalytic system, involving the use of aqueous H202 as oxidant with catalytic amounts of pyridine and MTO, has been proposed as a cheap and efficient way of synthesising epoxides from olefins.6’ Alkylrhenium oxides such as MTO have been prepared from perrhenates by a new one-pot method that does not require the rigorous exclusion of air and water.64 It has been proposed that, together, the new catalytic system and method of synthesis are well suited to large scale applications in the synthesis of epoxides from o~efins.~~ MTO has been found to catalyse the cycloaddition reactions of epoxides with aldehydes or ketones to form 1,3-dioxoIanes in which the geometric configuration of the epoxide substituents remain unchanged as a result of two consecutive configuration inversions.66 1% MTO has been found to be a good catalyst for the Diels-Alder reaction between a,&unsaturated ketones or aldehydes, and dienes such as isoprene, 2-methyl- I ,3-pentadiene, 2,3-dimethyl- 1,3-butadiene, cyclopent adiene, 1,2,3,4,5-pen tame t hylcyclopentadiene, and 1,3-cyclohexadiene, especially in aqueous solution. Kinetic studies of some of these reactions have been reported. 67 The reactions of MTO with C6H5CH2NMe2 and C6H4(CH2NMe2)2-1 ,3 afforded [MeRe03.C6H5CH2NMe2] and [(MeRe03)2.C6H4(CH2NMe2)2-l ,3] (28), respectively. [Re03{C6H4CH2NMe2-2}] has been prepared by the transmetallation reaction of ClRe0’ with [Zn{C6H4CH2NMe2-2}(2)] (2: 1 molar ratio). Similarly, addition of a mixture of [Liz {C6H3(CH2NMe2)2-2,6}2] and ZnCl2 to C1ReO3yielded [Re03{C6H3(CH2NMe2)2-2,6}] (29). The structures of 28 and 29 have been determined by X-ray-crystallography.68 The adduct of Troger’s base ((5R,1 1 R)-(+)-2,8-dimethyl-6H, 12H-5,I 1-methanodibenzo[b,f]-[ 1,5]diazocine) with MTO has been characterised by X-ray crystallography and found to have an exceptionally long Re(VI1)-N bond distance (2.589(5) A). The structural and spectroscopic properties of this and other N-base adducts of MTO have been examined in connection with their use as epoxidation and sulfoxidation cataI y st s.69

References 1.

2. 3. 4. 5. 6. 7.

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M.M. Lynam and J.C. Vites, Coorri. Chem. Rev., 1997, 162,275. C.E. Housecroft, Coord. Chem. Rev., 1997, 162, 305. M.M. Lynam and J.C. Vites, Coorci. Chem. Rev., 1997, 162, 319. K.P. Gable, Advunces in Orgunornet. Chem., 1997.41, 127. W. Boese, K. McFarlane, B. Lee, J. Rabor and P.C. Ford, Coord Chem. Rev., 1997, 159, 135. R.B. King, J. Organomet. Chem., 1997,536,7. V. Pfennig, N. Robertson and K . Seppelt, Angew. Chem. Int. E d Engl., 1997, 36, 1350. J. Tang, H. Yorimitsu. H . Kakiya, R. Inoue, H. Shinokubo and K. Oshima, Tor. Lett., I997,38, 90 19. M. Hojo, H. Harada, H. Ito and A. Hosomi, Chem. Commun., 1997,2077. I. Klement, H. Stadtrniiller, P. Knochel and G. Cahiez, Tet. Left., 1997,38, 1927.

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12. 13. 14.

15. 16. 17. 18.

19. 20. 21. 22. 23. 24. 25. 26. 27, 28. 29. 30. 31. 32. 33. 34. 35.

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Orgunometullic Chetnistry

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M. Brady, W. Weng, Y. Zhou, J.W. Seyler, A.J. Amoroso, A.M. Arif, M. Bohme, G. Frenking and J.A. Gladysz, J. Am. Clzem. Soc., 1997, 119, 775. S.B. Falloon. A.M. Arif and J.A. Gladysz, Chem. Comm., 1997,629. S.B. Falloon, W. Weng, A.M. Arif and J.A. Gladysz, Orgunumetullics, 1997, 16, 2008. G.A. Stark, A.M. Arif and J.A. Gladysz, Orgunometullics, 1997, 16,2909. M.D. Cavanaugh, S.M. Tetrik, C.J. Masi and A.R. Cutler, J. Orgunomet. Cliem., 1997,538,41. S.M. Tetrick, F.S. Tham and A.R. Cutler, J. Am. Chem. Sue., 1997, 119, 6193. D.H. Gibson, J.M. Mehta. M.S. Mashuta and J.F. Richardson, Orgunometullics, 1997 16,4828. T.-F. Wang, C.-C. Hwu, C.-W. Tsai and K.-J. Lin, Orgunornetullics, 1997, 16, 3089. T.-F. Wang, C.-Y. Lai, C.-C. Hwu and Y.S. Wen, Orgunometullics, 1997, 16, 1218. C.P. Casey, C.J. Czerwinski, D.R. Powell and R.K. Hayashi, J. Am. Chem. Soc., 1997,119,5750. Y.-X. He, R.J. Batchelor, F.W.B. Einstein, L.K. Peterson and D. Sutton, J. Orgunomet. Chem., 1997,531,27. Y.-X. He and D. Sutton, J. Orgunomet. ChcJm.,1997,538,49. M.D. C'avanaugh, B.T. Gregg, R.J. Chiulli and A.R. Cutler, J. Orunomet. Chem.. 1997,547, 173. N.Y. Zhu and H. Vahrenkamp, Chern. Ber.IRecl., 1997,130, 1241. J. Buschmann, T. Bartolmb, D. Lentz, P. Luger, I. Neubert and M. Rottger, Angew, Chem. lnt. Ed. Engl.. 1997,36,2372. A.H. Klahn, A. Toro. M. Arenas, V. Manriquez and 0. Wittke, J. Orgunomet. Chem., 1997,532, 39. C. Mongin, N. Lugan and R. Mathieu, Orgunomrtullics, 1997, 16,3873. C.P. Casey. R.S. Cariiio and H. Sakaba, Orgunometullics, 1997, 16,419. R . Li, J. Chen, Y. Yu and J. Sun, J. Chern. Sot... Dalton Trans., 1997,205. S. Kostlmeier, V.A. Nasluzov, W.A. Herrmann and N. Rosch, Orgunometullics, 1997,16, 1786. F.E. Kiihn, J. Mink and W.A. Herrmann, Chem.Ber.lRecl., 1997,130,295. H . Rudler, J.R. Gregorio, B. Denise and J. Vaissermann, J. Orgunomet. Chem., 199, 548,295. J. Rudolph, K.L. Reddy, J.P. Chiang, K.B. Sharpless, J. Am. Chem. Sue., 1997, 119, 6189. W.A. Herrmann, R.M. Kratzer and R.W. Fischer, Angew. Chem., Int. Ed. Engl., 1997,36,2652. A. Gansauer, Angeiv. Clwm., Int. Ed Eng., 1997,36,2591. Z. Zhu and J.H. Espenson, Orgunometullics, 1997, 16, 3658. Z. Zhu and J.H. Espenson, J. Am. Chem. Sue., 1997,119,3507. M.H.P. Rietveld, L. Nagelholt, D.M. Grove, N. Veldman, A.L. Spek, M.U. Rauch, W.A. Herrmann and G. van Koten, J. Orgunomet. Chem., 1997,530, 159. W.A. Herrmann, F.E. Kuhn, M.R. Mattner, G.R.J. Artus, M.R.Geisberger and J.D.G. Correia, J. Orgunomet. Cltem., 1997,538, 203.

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2 Complexes Containing Metal-Carbon 0-Bonds of the Groups Iron, Cobalt and Nickel, Including Carbenes and Carbynes BY NICHOLAS CARR

1

Reviews and Articles of General Interest

Several review articles containing material relevant to this chapter have appeared. Topics covered include the activation of C-H bonds by transition metals,' metalassisted cycloaddition reactions in organotransition metal chemistry,2 organometallic fluorides, which are defined as complexes having metal-fluorine and metalcarbon bonds with the same metal,3 complexes of 'all carbon ligands', specifically the synthesis, reaction chemistry and electrochemistry of a variety of mono-, bi,~ metals in and poly-nuclear complexes having C2, C4 and cp l i g a n d ~transition organic ~ynthesis,~ the application of transition metals in hydroformylation and related systems5 and recent advances in organometallic homogeneous ~ a t a l y s i s . ~ The use of laser flash photolysis with time-resolved infrared spectroscopy to probe mechanisms of the carbonylation of metal-alkyl bonds has been reviewed,' as has the synthesis, characterisation and reactivity of acylcobalt carbonyl Recent advances in the chemcomplexes of the type [Co {C(0)R}(L)n(C0)4-n].9 istry of arene complexes of Ru(0) and Ru(I1) have been discussed" and an article covering the synthesis and reactions of polynuclear cobalt-alkyne complexes contains some material of relevance.' The relationship between the molecular and crystal structures of complexes containing p3-CH and p2-CH2 groups has been investigated. Oxidative-addition reactions of organoplatinum(I I) complexes with N-donor ligands have been r e ~ i e w e d , and ' ~ so has the subject of the resolution of tertiary phosphines and arsines with orthometallated palladium(1I) amine c ~ m p l e x e s . ' Recent ~ advances in the area of C-F bond activation, including reactions involving metals of groups 8, 9 and 10, have been discussed.'6 Some aspects of ruthenium catalysed organic syntheses have been r e ~ i e w e d . ' ~ The chemistry of zerovalent complexes of nickel and platinum containing benzyne and related small ring alkynes has been reviewed" and a discussion of the reactivity of palladacycles as key intermediates in preparative ring-forming reactions appeared. I9 General synthetic routes to heterobimetallic ethynylcarbene complexes have been developed: sequential reaction of carbene complexes [(OC)SM'=C(NMe2)C=CSiMe3] (M'=Cr, W) with KF/thf/MeOH, Bu"Li and metal halides

'*

Organometallic Chemistry, Volume 27 0The Royal Society of Chemistry, 1999 81

82

Orgimometullic Chemistry

[MXL,] afforded propynylidene complexes of the type [(OC)sM’=C(NMe2)C= CML,] (ML, = Ru(C0)2(q-CsH~), Ni(mes)(PMe2Ph)z, Rh(CO)(PPh,),, Fe(C0)2(q-CSHS)}. The novel N-metallated complex [(OC),W=C(N( Me)Fe(C0)2(q-CSHs)}Csz CSiMe31 was obtained by reaction of [(OC)SW=C(NMe2)C= CSiMe3] with MeLi *LiBr and [FeI(C0)2(q-CsH5)].Complexes of the type [(OC)SM’=C(NMe2)C CML,] { MLn = Ru(CO)~(~-CSHS), Ru(CO)(PPh3)(q-CsHs), Mn(CO)S, Re(CO)S} were accessed through Pd-catalysed coupling of the carbene complexes [(OC)sM’=C(NMe2)C = CSnBu31 with [MXL,]. Various structures were determined by X-ray diffraction analysis.20 A theoretical study of the insertion of the 16-electron species [M(CO)(q-CSHs)] (M = Ru-, 0 s - , Rh, Ir, Pd’, Pt’) into methane showed that oxidative-addition reactions with alkane C-H bonds are promoted by electron rich as well as heavy transition metals, while reductive-elimination reactions of C-H bond forming are likely to occur with electron deficient and lighter metak2’ The bonding in transition metal inserted thiophene complexes of Fe, Ir, Rh and Pt has been studied by Fenske-Hall molecular orbital calculations and the results suggest that the nucleophilicity of the sulfur centre is related to the s-character of the HOMO while the electrophilicity of the metal centre depends on both the character of the of only acetylenic LUMO and the geometry of the ~ o m p l e x .The ~ ~ observation .~~ structures in dinuclear complexes of the type [ {MCl,(CO),-,)2(p-C2)] (M = Cr, Mn, Fe, Co; m = 4,5; n = 0, I ) has been investigated by density functional calcu~ations.~~

2

Metal-Carbon 0-Bonds Involving Group 8,9 and 10 Metals

2.1 The iron Triad - Approximate density functional theory has been used to examine the electronic structures of a series of q ‘-acetylide complexes containing electron rich ruthenium centres, [Ru(C = CR)(PH3)(q-CsH5)] and [Ru(C = CR)CI(PH3)4]. Trends in ionization potentials were analysed in terms of oxidation-induced changes in the strength of the ruthenium-acetylide bond.2s A computational study of the cationic complex [Fe(C2Hs)]+ and its tautomer [FeH(C2H4)]’ using density functional and Hartree-Fock theory suggests that interconversion involving agostic interactions, and thus low barriers for phydrogen transfers, are characteristic for low spin complexes.26 Kinetic and thermodynamic data for the reaction of cis,trans-[OsI(Me)(CO)z(PMe3)2] with CO were presented and compared to those obtained from complexes of iron and ruthenium. The reaction with C ~ H I I N was C also studied and the stru zture of the product, trans-[Osl { C(O)Me}(C6HI I NC)(CO)(PMe3)2], was determined by X-ray d i f f r a ~ t i o nEquilibrium .~~ constants for the insertion of CO into the Ru-CH3 bond of cis,trans-[Rui(CH~)(CO)2(PMe3)2] have been measured in toluene at various temperatures and the results compared with those from isoelectronic complexes of iron.28The carbonylation reaction of cis,trans[FeI( Me)(CO)z(PMe3)2] giving cis,trans-[FeI ( C(0)Me)(CO)2(PMe&] and subsequent isomerisation to the truns,truns-isomer have been studied in polar and apolar solvents, and the structures of two compounds were determined by X-ray

2: Complexes Contuining Meid-Curbon 6-Bonds o f t h e Groups Iron, Cobah uncl Nickel

83

~rystallography.~~ Competing isomerisation reactions of the complexes [Ru(CH=CHR)(C&~X-~)(L)(L)(CO)~] (R = Ph, CMe3, H, Me, OEt; X = H, CI, OMe; L, L'= PMezPh, PMe3, P(OMe)2Ph, PPh3) involving intramolecular construction of a vinyl aryl ketone or a simple redistribution of the ligands have been studied and the product ratios shown to be determined by kinetic rather than thermodynamic factors.30 The first homoleptic carbonyl cation of a 3d metal, [Fe(CO)6]2', was generated by oxidative carbonylation of [Fe(CO)5] with either C12 or SbF5 and spectroscopically characterised (vco 22 16 cm-').' Short-lived 16-electron complexes [Ru(CO)2(dmpe)]*S (S = Ar, Xe, CH4) were obtained by low-temperature U V photolysis of [R~(CO),(dmpe)].~~ A synthetic route to new tris(pyrazoly1)borate-containingmethyl complexes of ruthenium, [RuMe(Tp or Tp')(cod)], was established through reaction of [RuMe(OS02CF3)(bpzm)] with KTp or KTp'{ T p = hydridotris(pyrazoly1)borate; Tp'= hydridotris(3, 5-dimethylpyrazoly1)borate). One of the new complexes displays an unusual three-centre B(p-H)Ru bond.33 Room temperature reaction of AIR3 (R = Me, Et) with [RuCl(cod)(Tp)] gave the corresponding alkyl complexes [ R u R ( ~ o d ) ( T p ) ] . ~ Alcohols ~ RCH20H are decarbonylated by [RuH(CH3CN)(PPh3)(Tp)] giving alkyl and aryl complexes of the type [RuR(CO)(PPh3)(Tp)] (R = H, CH3, C2H5, C3H7, C6H5, C6H4Me-4, C&&1-4), via q2-aldehyde and q2-dihydrogen intermediate^.^^ Carbon monoxide reversibly affording [RuCl(C6H4N02adds to [RuCI(C~H~N~~-~)(CO!(PP~~)~] 4)(C0)2(PPh3)2], from which the q2-acyl complex [RuCI { q2-C(0)C6H4N H24}(CO)(PPh3)2]was obtained by reduction and treatment with base. Protonation (HBF4) of the latter brought about a reverse migratory insertion reaction with formation of [RuCl(C6H4NH 3-4)(C0)2(PPh3)2][BF4].36 The thermolabile species [Ru(H)~(CO)(PBU'~M~)~] reacts with HC =CPh giving [RuH(C = CPh)(CO)(PBu12Me)2]and dihydrogen, and with Me1 affording a mixture of [RuI(Me)(CO)(PBu12Me)2]and [RuI(H)(CO)(PBU'~M~)~]. Reaction of [RuCI(H)(CO)(PBut2Me)2]with PhLi gave the aryl complex [RuH(Ph)(CO)(PBut2Me)2] which reacts with CO to give [ R u H ( P ~ ) ( C O ) ~ ( P B U ' ~ MOver ~ ) ~ ] .a period of two days these [R~H(aryl)(Co)(PBu'~Me)~] complexes rearrange to [Ru(CO)(PBu'2Me)(q6-arene)]. The structural and electronic properties of a number of these compounds were studied by core potential ab initio method^.^' With Me3SiOTf and Na[BAr4] { Ar = C6H3(CF3)2-3,5}, [RuF(Ph)(CO)(PB U ' ~ M ~yielded ) ~ ] the 14-electron species [Ru(Ph)(CO)(PBut2Me)2][BAr4]quantitatively. The presence of two agostic Ru-H-C interactions in this complex was The red, light-sensitive compounds confirmed by an X-ray diffraction [RuMe(EPh,)(CO),(Pr'-DAB)] (E = Sn, Pb) were obtained from the reactions of [RuCl( EPh3)(C0)2(Pr'-D AB)] with MeMgCI.39 Reactions between the new alkylisocyanobenzoates CNC6H4C02R-4 (R = Me, Et), [FeC1(CO)2(q-C5H5)] and [NH4][PF6] gave the complexes [Fe(CN C6HdC02R-4)3( q -C5HS)]. Metal iodides and the alkylisocyanobenzoates afforded [Fe12(CNC6H4C02R)4][PF6], [ C O I ~ ( C N C ~ H ~ C O ~ Mand ~-~)~] [Pd12(CNC6H4C02Me-4)2].Single crystal X-ray diffraction analyses were carried out on three of the iodo complexes.40

'

a4

Orgunometullic Chemistry

Hydrosilanes and the complexes [M(CO2Me)(L)(C0)(q-C5H5)] (M = Fe, Ru; L = CO, PPh3) afforded q4-cyclopentadiene compounds, e.g. [M(CO)3(q4CsH6)], and metho~ysilanes.~' Substitution of one or both of the chloride ligands of [FeC12{P(CH2CH2PMe2)3}]gave the complexes [FeCl(Me) { P(CH2CH2PMe2)3}] and [Fe(Me)2{P(CH2CH2PMe2)3)], which were characterised by NMR spectrocopy.^^ Formyl complexes of the type [Fe(C(R ')=C(R2)C(0)HJ(C0)2(q-C5H5)] were obtained from reactions between the metal ferrates M[Fe(C0)2(q-C5HS)] and P-bromo or P-chloro vinyl aldehydes, or with imminium salts. These complexes react with donor substituted primary amines yielding a,P-unsaturated y-~actarns.~' Cyclodextrin inclusion compounds of the complexes [FeMe(C0)2(q-C5R5)](R = H, Me) have been prepared and shown to undergo ligand substitution rather than CO-insertion/methyl migration reactions, under both thermal and photochemical condition^.^^ The complex [Fe(CO2)(depe)2] was synthesised by the reaction of [Fe(Nz)(depe)z] with C02 and the q2(C, @-bonding mode established by an Xray diffraction study. Reactions with Me3SiC1, Me1 and MeOTf resulted in removal of an 0 atom from the C02 ligand with formation of cationic carbonyl complexes.45Treatment of salts of the anions [M(C0)2(q-CsH5)]- (M = Fe, Ru) with carbon dioxide gave the spectroscopically characterised metallacarboxylates [M(C0)2{q'-C(0)0)(q-C5H5)]-, which were trapped as the complexes [M(q'C(0)OSiMe3}(CO)2(q-C5H5)]by reaction with Me3SiC1.46 Oxide transfer from C032- to the complex [R~(bpy)~(CO)2]~' in aprotic media has been observed: addition of [crown*K]2C03 to a CH3CN solution of [Ru(bpy)2(C0)2l2' gave [Ru(bpy)2(CO)(q '-CO2)] and carbon dioxide.47 Protonation (HBF4-OEt2) of [Ru(q5-CjMe5)(q6-3-C6Hg)] afforded yellow [Ru(q5-CSMe5)(q6-3-C6H lo)][BF4], containing an agostic Ru-H-C interaction as shown by both NMR spectroscopy and single crystal X-ray diffraction. Variable temperature N M R measurements demonstrated that the agostic hydrogen exchanges with other hydrogens on the dienyl termini.48 NMR has been used to show that the q '-indeny1 complex [Fe(CO)z(q '-C9H7)(q-C5H5)]undergoes 1,5metallotropic shifts. The intermediate isoindene was trapped by TCNE as its Diels-Alder adduct 1 and its structure was determined.49 Transmetallation of Qn2Hg (Qn = 8-quinolyl) with [OsX(H)(CO)(PPh3)3](X = CI, I) gave [OsX(q2-Qn)(C0)(PPh3),], the chelating nature of the quinolyl ligand of which was shown by an X-ray diffraction study. Derivatives were prepared by treating the chloride complex with AgPF6 and CO, NaI or N ~ S ~ C N M Q . ~ ' X-ray diffraction studies on crystals obtained from the mixture resulting from freezing the [PPN][RuC13(C0)3] catalysed hydroesterification of ethylene with methyl formate established that the mixture was composed of the species [PPN][Ru2(P-c1)3(q '-CH2CH3)2(C0)4], [PPN][Ru2(P-CIh(q '-CH2CH3)2(q I CH3)(CO)4] and [ P P N ] [ R U ~ ( P - C I'-CH3)2(CO)4]. )~(~ The former of these was used as catalyst precursor in the presence of chloride ions and led to the production of methyl propionate with 94%conversion and 84% ~electivity.~' Reaction of the bis(3,5-di-t-butylphenyl)phosphino MeO-Biphep (L) complex ,

2: Complexes Contuining Metul-Curbon a-Bonds ojtlze Groups Iron, Cobult und Nickel

85

[Ru(OAc)2(L)] with three equivalents of MeLi gave the novel complex 2, in which only one phosphorus atom is coordinated to the metal together with an arene q6C6H3 moiety derived from one of the biaryl rings.52 The phosphorus ylide CH2PPh3 and the complexes [Fe(C0)2(L)(r&H,)] (L = tertiary phosphite) afforded the compounds [Fe{C(O)CH=PPh,}(CO)(L)(qC5Hs)], via nucleophilic attack of the carbene carbon of the ylide on a carbonyl carbon.53 Deprotonation of the p-cymene ruthenium(1I) complexes [RuCl { q2(EPPh2)2CHR-E-E}(q6-MeC6H4Pri)] (R = H, Me; E = S, Se) occurs at the methylene carbon to give the cationic complexes 3, which were characterised by an X-ray diffraction study (R = Me; E = S).54

--

q+ O ,

Me

I

O\

Me

(2) R = Pf, C6H3(B~t)2-3,5

(3) E = S, Se; R = H, M e

Reaction between [Ru((R)-BINAP)H(MeCN)(S)2][BF4] (S = MeOH, thf; 1 ,If-binaphthyl)} and (a-methyl a-acetaBINAP = 2,2’-bis(dipheny1phosphinomidocinnamate (MAC) gave the crystallographically characterised complex 4, a possible intermediate in ‘Ru(B1NAP)’ catalysed hydrogenation reactions with a prochiral group bound to the metal. It was shown that 4 reacts with stoichiometric amounts of dihydrogen to give MACH2.55 Treatment of [Ru(cod)(cot)] with an excess of PMe3 at 50 OC results in selective displacement of the cod ligand and formation of [Ru(ql:1-3-q3-C8Hlo)(PMe3)~], ~ ~ neutral the structure of which was determined by X-ray d i f f r a ~ t i o n .The pentenediyl species 5a and 5b were obtained from reactions of malonate anions with cationic pentadienyl iron complexes.57

(4) PP = (F))-BJNAP

(5a)

R = Me, Ph, C02Me (5b) R’ = H, Me, OMe L = CO, PPh,

Alkynes cleave the binuclear species [ R u ~q(5-Ph4C4COHOCC4Ph4-q5)(pH)(C0)4] yielding [(OC)2(q5-Ph&4C6)RuC(Ph)=CPh] and [(q5-Ph&COH)-

86

Orgunometallic Chemistry

(CO)~RU{C(CO~M~)=CH(CO~M~)}], the latter of which catalyses the hydrogenation of alkynes.s8 Acetylene inserts into the Ru-B bond of [ R U ( B O ~ C ~ H ~ ) C I (CO)(PPh3)2] giving the borylalkenyl complex 6, an X-ray diffraction study of which established the Z geometry about the double bond of the vinylboronate ligand as well as a weak R u - 0 interaction. Transesterification of 6 with HOCH2CH20Hgave [~U(CH=CHB(OCH~CH~Q)}CI(CO)(PP~~)~].~~ Ruthenacyclobutane complexes [Ru(CH2EMe2CHz)(PMe3){ MeSi(CH2PMez)3}J have been prepared by reaction of [RuCI2(PMe3){MeSi(CH2PMe2)3)] with the Grignard reagents Me3ECH2MgCI (E = C, Si) and the structures were confirmed by crystallography (E = C).6* Photolysis of the acetylide complex [Fe(C ECPh)(CO)2(q-CSMeS)] in the presence of HC = CC02Me gave the red-brown metallabicyclic complex 7, incorporating two alkyne molecule^.^' The phosphinoenolate complex [ku{P(Pr')2CH2C(0)d)Cl(q6-C6H3Me3)] slowly rearranges in benzene to the phosphinomethanide isomer [ku{P(Pr')2CH(C02Me))CI(q6-C6H3Me3)],the structure of which was established.62

In hot toluene, [ R U ~ ( C O ) , ~and ] 2-(chloromethy1)pyridine gave the cycloruthenated pyridylacetyl complex 8 which reacts with PPh3 to give the crystallographically characterised species [ ~UCI(NC~H~-~-CH~C~)(CO)(PP~~)~].~~ Reaction of B(C6F5)3 with [FeMe(CO)z(q-C.jH5)] gave [fie { C6F&(b)Me-2} (CO)(q-C~H5)l which reacts with donor molecules L (PMe3, PPh3, NCBu') affording complexes of the tYpe [fie{ C6F4C(C))Me-2 1(L)(q-C5H 41.64 The hydrido complex [RuCI(H)(CO)(PP~~)~] and o-toluonitrilelH20 gave the metallacycle [ku { C6H3(Me)CH=kCH2C6H4Me}(Cl)(CO)(PPh3)2] 9, which was Compounds of this type have been characterised by an X-ray diffraction used to prepare ruthenium aryl complexes containing q2-bonded nitrite or nitrate ligands [Ru(q2-X)(R)(CO)(PPh3)2](R = aryl: X = NOz, N03) by reaction with Na[N02] and Na[N03], respectively.66 Related Os(I1) complexes 10 having a

2: Complexes Contuining Mcwl-Curhon 0 -Bonds ofthe Groups Iron, Cohult and Nickel

81

four-membered salicylideneiminium metallacycle and an q -bound NO2 ligand were obtained by reaction of the bromo-precursor with Na[N02].67 Novel osmacycloalkanes [bs{CH2(CH2)nCk2}(CO)4], diosmacycloalkanes [(OC),Os{ p-CH2(CH2),CH2} ~ O S ( C O ) ~and ] triosmacycloalkanes 11 were obtained from the reactions of Na2[Os(CO)4] with [F3CS03(CH2)n03SCF3] (n = 5-10, 12, 14, 16). The diosmacyclooctadeca-5,14-diene [(OC)40s{p-(CH2)3CH=CH(CH2)3)O~(C0)4] was obtained from N ~ ~ [ O S ( C O ) ~ ] With Na2[Fe(CO),] insertion of CO and [F3CS03(CH2)3CH=CH(CH2)303SCF3]. into the Fe-C bonds of the initially formed ferracycloalkanes leads to cyclic ketones and diketones.68 In 2-propano1, one of the alkenyl C = C bonds of [Os(C = CPh)2(CO)(PPri3)2]is cleaved by H20 affording [Os(CH2Ph)(C = CPh)(C0)2(PPr'3)2] viu a metalpromoted hydration/disproportionation of the transformed alkynyl ligand by the solvent. In the presence of C F ~ C O Z Hthe , mono(acety1ide) complex isomerises to the crystallographically characterised derivative [bs~C(CH2Ph)=CHC,H4}(CO)2(PPri3)2]. The mechanisms of these transformations were discussed on the basis of isotope labelling experiment^.^^

.. (11) n = 5-10,12,14,16

(12) M = RU; L = $-cymene M = Rh; L = q5-C5Me5

Ph,

(13) X = Ph, C(OH)Ph,

Under basic conditions [RuCI2(q6-cymene)]2 and [RhCI2(q5-C5Me5)l2react with enantiomerically pure N-phenyltriazolium perchlorate, viu abstraction of an ortho proton and elimination of HCI to yield the orthometallated complexes 12 with diastereomeric excesses of up to 95"/0.~' The coordinatively unsaturated complex [Ru{C6H3(CH2PPh2)2-2,6}CI(PPh3)] was prepared from [ R u C I ~ ( P P ~ and ~ ) ~ ]I ,3-(Ph2PCH2)2C6H4and used to synthesise a series of five- and six-coordinate complexes by reactions with neutral molecules (CO, PMe3) and with hydride source^.^' With the terminal alkynes HC = CPh and HC=CC(OH)Ph;? the same complex afforded the compounds 13, through unusual coupling reactions. With HC = CC(OH)(Me)(Ph) and HC = C-C-C~H lo(OH) dehydration occurs to give the coupling products [Ru{q4-C6H3(CH2PPh2)2-2,6-C=CHC(Ph)=CH2} (CI)(PPh3)] and respective~y.~~ [Ru { q4-C6H3(CH2PPh2)2-2,6-C=CH-c-CgHg)(CI)(PPh3)], Reaction of tran~-[RuCl~(dppe)~]with trimethylaluminium gave truns-[RuCI(Me)(dppe)2] and the orthometallated species [Ru{C~H~P(P~)CH~CH~PP~~}(C~)(~~~~)] 14. The latter is formed through the intermediacy of the cationic methyl complex [ R ~ M e ( d p p e ) 2 ] + . ~ ~ The novel C-bonded adenine ruthenium complex 15 was obtained from the

Orgunomet ullic Chemistry

88

CI (15)

s = dmso

reaction of [(dmso)2H][RuC14(dmso)2] with an adenine derivative and the structure was established by X-ray ~rystallography.~~ Condensation of 2,6-diformyl-4-methylphenol with aliphatic amines, NH2(CH2),,NH2 (n = 2,3,4), in the presence of PPh3 and [Ru(dmso)Cl2] gave the cyclometallated complexes 16, while aromatic monoamines afforded mononucIear metal c o m p ~ e x e s . ~ ~

(16) n = 2,3,4

The first CSHS-bridged complex, [(Ph,P),(CO)ClRuCH=CHCH=CHCH= RuCl(OH)(CO)(PPh,)2], was obtained from the reaction of [RuCI(H)(CO)(PPh3)3] with HC=CCH(OH)C-CH and reacted with PMe3 and dppe to give [(M~~P)~(CO)CIR~CH=CHCH(PM~~)CH=CHRUCI(CO)(PM~~)~][ and [(Ph3P)(dppe)(CO)ClRuCH=CHCH=CHCH=RuCI(OH)(CO)(PPh3)2], respecThe related deep purple coloured compounds [(T~-C~R~)(L)~R~=C=C=CHCH=C=R~(L)~(~-C~R~)][BF~]~ (R = H, Me; L = PPh3; (L)2 = dppe) were prepared by treatment of [ R ~ ( L ) ~ ( ~ - C S R ~ ) ]with [BF~] 0.45 equivalents of HC = CCH(0H)C = CH, and reacted with alumina to give the blue coloured C5H -bridged species [(q-CsR s)( L)2Ru=C=C=CHC=CRu(L)2(qC5R5)][BF4]. An X-ray diffraction study showed that the C5H ligand is symmetric with a delocalised n - s y ~ t e m . ~Protonation ~ (HBF,*OEt,) of [ { RuC1(CO)(PPh3)(dppe))2(p-CH=CHCH(OH)CH=CH)] afforded [(dppe)(PPh3)(CO)ClRuCH=CHCH=CHCH=KuCI(CO)(PPh3)(dppe)],having a delocalised structure in which the two metal centres are in identical

environment^.'^ Reaction of 1,4-diethynylbenzene with two equivalents of cis-[RuCl2(dppe)z] gave the yellow dinuclear compound [(dppe)2CIRuC = C-C6H4C z CRuCl(dppe)2]. The mononuclear complex [Ru(C CC6H4C= CSiPri3)Cl(dppe)2] was prepared from cis-[RuCl2(dppe)2] and HC =- CC6H4C= CSiPr'3 in the presence of Na[PF6].79 Dinuclear vinyl bridged ruthenium complexes [RuCl(CO)(PPh3)2]2(p-CH=CH(R)CH=CH) (R = p-C6H4, p-C6H4-C6H4)were obtained from the reaction of [RuCI(H)(CO)(PP~~)~] and the

2: Complexes Contuining Metul-Curbon a-Bonds of the Groups Iron, Cobalt and Nickel

89

appropriate diyne HC = C(R)C = CH. Treatment with 2,3,5,6-tetramethylphenyldiisocyanide and 4,4'-bipyridine affords oligomeric or polymeric species [RuCI(CO)(PPh3)2{ p-CH=CH(R)CH=CH ) RUCI(CO)(PP~~)~(~-L)]~.~~ Treatment of [Fe2(CO)4(p-q5,q5-C5H4CH2C5H4)] with alkynes RC = CR gave the vinylketone-bridged complexes [Fe2(CO)(p-C0){p-q ':q3-RC = C(R)CO}(pq5,q5-C5H4CH2C5H4)] (R = Ph, C02Me). Photolysis of [Ru2(C0)4(p-q5,q5CSH4CH2C5H4)] in the presence of PPh3 results in loss of two CO ligands and P-C insertion by ruthenium affording [Ru2(C0)(Ph)(p-CO)(p-PPh2)(p-q5,q5CSH4CH2C5H4)], while the presence of PhC = CPh leads to [ R u ~ ( C O ) ~ ( ~ - C O ) ( ~ q ':q '-C2Ph2)(p-q5,q5-C5H4CH2C5H4)] and the oxidised species [Ru2(CO)(pThe dimetallacyclopenCO) { p-q :q3-PhC=C(Ph)O}(p-q5,q5-C5H4CH2C5H4)].8 tenones 17 result from the reactions between [Fe(q-F3CC= CCF3)(CO)4] and [M(CO)Z(q-CSMeS)](M = Co, Rh, Ir).82 Phenylethyne reacts with ~is-[Fe~(CO)~(p-H)(p-CO)(p-PPh~)(p-dppm)] to give the isomeric complexes cis-[Fe2(C0)4(p-PhC=CH2)(p-PPh2)(p-dppm)]and trans[Fe2(CO)4(p-HC=CHPh)(p-PPh2)(p-dppm)]. Reaction with tmns-[Fe2(C0)4(pH)(p-CO)(p-PCy,)(p-dppm)] led to isolation of the a-substituted product trans[Fe2(C0),(p-PhC=CH2)(p-PCy2)(p-dppm)] only, but thermolysis of the crude reaction mixture gave the product expected from CO-insertion into the psubstituted isomer, [Fe2(C0)4{p-O=CC(Ph)=CH2}(p-PCy2)(p-dppm)].Propargyl alcohol reacts with the complexes cis-[Fe2(CO)&-H)(pCO)(p-PR2)(p-dppm)] (R = Ph, Cy) to yield mixtures of [Fe2(CO)4{p-C(CH20H)=CH2}(p-PR2)(p-dppm)] and [Fe2(CO)4{p-HC=CH(CH20H)}(p-PR2)(p-dppm)].83 Acids having coordip-dppm)] releasing nating anions react with [Fe2(CO)4(p-q2-HC=CH2)(pL-PCy2)( C2H4 with formation of halide- and carboxylate-bridged complexes and [Fe2(CO)4(p-q2-02CY)(p-PCy2)(p-dppm)] (Y = H, CF3, CC13, CBr3, C02H). In contrast, acids with poorly coordinating anions gave [Fe2(CO)&-PCy2)(pdppm)][Z] (Z = F, BF4, PF6, 0.5S04). The mechanisms of these reactions were studied by spectroscopic methods.84Photolysis of [Fe2(CO)7(p-dppm)]afforded [Fe2(C0)4(p-C= CPh)(p-PPh2)(p-dppm)] and [Fe2(C0)3(PhzPC= CPh)(pC E CPh)(p-PPh2)(p-dppm)],both of which were characterised by X-ray crystallography. In the presence of P(OEt),, thermolysis of the same complex gave [Fe2(C0)3{ P(OEt)3}(p-C 3 CPh)(p-PPh2)(p-dppm)].85

'

'

(17) M = Co, Rh, Ir

The phosphines HPXY (X = Y = Ph, Pr'; X = Ph, Y = H) and EtSH react with the perfluorovinyl compound [ { Fe(C0)3}2 { p-C(SMe)(CF3)CCF2}]affording the binuclear complexes [ { Fe(C0)3) 2 { p-C(SMe)(CF,)C(PXY)CF}J and [ { Fe(C0)3) { p-C(SMe)(CF,)C(SEt)CF}] 18, respectively, via cleavage of one C-F

90

Orgufiometullic Chemistry

bond.86 Reaction with P(OMe)3 gave [ f Fe(C0)3}2 { p-C(SMe)(CF3)C[P(OMe)20]CF}].87Diazomethane and [Fe2(COj6(p-EE’)] (E, E’= S, Se, Te) afforded two types of compound, [Fe2(C0)6EE’{p-CHCH3}Z] and [Fe2(C0)6{pECH(CH3)E’}]. In the former, two CH(CH3) moieties bridge opposite Fe-E vectors while the latter have a FezTeE tetrahedral butterfly core containing a CH(CH3) group bridging two wing tips of chalcogen atoms.88 Thermolysis of [Ru3(C0)12] with senecialdimine, Me2C=CHCH=NR (R = Pr’, Bu‘) at ca. 100°C gave the three dinuclear ruthenium complexes 19,20 and 21, as well as higher nuclearity species.89 Similarly, thermolysis with endiones trunsArCOCH=CHCOAr (Ar = Ph, CbH4Me-4) afforded three isomeric complexes having the same central bicyclic fragment, as well as two peripheral oxaruthenacycles concatenated with the central fragment viu spiro metal atoms as illustrated for 22. The difference between the isomers results from different orientations of the peripheral metallacycles relative to the central bicyclic moiety.” H

kH

Me Me

H

H

R

(211

(22) R = Ph, C6H4Me-4

The tris(methy1ene)-bridged diiron compound [Fe2(N0)4Se(p-CH2)3] was obtained from [Fe3(p-Se),(CO),], N-methyl-N-nitroso-p-toluenesulfonamideand KOH. The structure was established by X-ray crystallography. The Fe-Fe and Fe-Se edges of the triangle of two Fe and one Se atoms are bridged by methylene groups.” Reactions of the bridging methylene complex [ R u ~ ( ~ - C H ~ ) ( ~ - C O ) (CO)(M ~ C N ) ( Y - C ~ Hwith ~ ) ~diazoalkanes ] N2CR’(R2)gave the alkenic products [RU~(~-CH=CHR’)(~-H)(CO)~(~-C~H~~~] when R2 = H and alkenes CH2=CR’R2when R’ and R2 # H.92 Broad band U V photolysis of thf solutions of [M(C0)6] (M = Cr, Mo, W) and [Fe(q2-CS2)(CO)2(PR3)2] (R = Et, Ph) gave the bimetallic species [(R3P)2(OC)2Fe(p-q2:q’-CS2)M(C0)s]. The structures were established by X-ray diffraction studies.” Molecular structure determinations of the (4,0), (3,l) and (2,2) geometric trans-isomers of [Ru2(F~ap)4(C= CPh)2] { F ~ a p= 2-(2,3,4,5,6pentafluoroani1ino)pyridinate anion} were reported.94

2: Complexes Containing Metul-Carbon rr-Boncls of the Groups Iron, Cobalt und Nickel

91

A series of heterobimetallic bis(acety1ide)ferrocene complexes [(q-CSHS)Fe(qCSH4)C=CRu(dppm)s(C=CR)] were prepared by the reaction of [(qC5H5)Fe(q-C5H4)C= C R ~ ( d p p m ) ~ Cwith l ] acetylenes. The structure of trans[Ru(dppm)2{CC(C5H4-q)Fe(q-C5H5)) 2] shows a distorted octahedral geometry around the central ruthenium atom with the two ferrocenyl units bound in a linear fashion.95 Reaction of HC=CC02Me with [Os3(CO)lo(CNPr)(NCMe)] at 0 "C gave a mixture of [OS~(CO)~{~-~~:~~-C(OH)C(CO~M~)=CHCNHP and [Os2(C0)6{p-q2:q3-C(OH)CH=C(C02Me)CNHPr)], via C-C coupling reactions of alkyne and CO as well as alkyne and i ~ o c y a n i d e . ~ ~ The reactivity of 2-thienyllithium (Lith) towards a variety of dinuclear iron and ruthenium carbyne complexes has been studied: the cationic thiocarbyne complex cis-[Fe&-CSMe)( p-CS)(CO)2(q-C5H5)2]+ gave [Fez(p-CS Me)(p-CS)(CO),( q C5H5)(q4-C5H5th)]and [Fe2(p-CSMe)(pCS){ C(0)th)(CO)(q-C5H5)2], whereas the aminocarbynes [Fe2(p-CNRR')(p-CO)(CO)2(q-C5H&]+ (R, R'= Me, PhCH2) and [Ru~(~-CNM~~)(~-CO)(CO)~(~-C~H~)~]+ afforded the corresponding acyl derivatives [M2(p-CNRR')(p-CO)(CO){C(0)th)(q-C5H5)2].97 The reactivity of the diiron aminocarbyne complexes towards a variety of carbon nucleophiles was also studied and C-C bond forming reactions were found to occur at different sites depending on the nature of the carbanions. Thus, R'Li and R'MgCI reacted at the q-C5H5 ligand giving q4-cyclopentadiene complexes whereas acyl complexes were obtained from Li2Cu(CN)R'2 and LiC E CR reagents.98 The molecular quadratic and cubic hyperpolarisabilities of systematically varied o-arylacetylide ruthenium complexes [Ru(C= C R ) ( P R ' ~ ) ~ ( ~ - C S H(RS )=] Ph, 4-C6H4NO2, 4,4'-C6H4CbH4N@, (E)-4,4'-C6H4CH=CHC6H4NO2, 4,4'C6H4CE CC6H4N02,4,4'-C&4N =CHC6H4N02; R'= Me, Ph) were determined by hyper-Rayleigh scattering and Z-scan techniques. The results suggest an increase in non-linearity with increasing chain length in the C-CR group.99 A family of dinuclear iron merocyanines 23 and 24 were prepared from the ethylidyne complex [Fe2(p-CCH3)(p-CO)(C0)2(q-C5H5)2][BF4]. These compounds have large second-order non-linearities. loo

(24)n=1,2

Removal of the chloride from [Ru(Ph2PCH2CH2NMe2)Cl(q-C5Me5)] with [Ru{Ph2PCH2CH2N(CH2)Me)Cl(qNa[BPh4] in CH2C12 afforded C~Me5)][BPh41,having a tridentate ligand coordinated through P, N and C. This salt was used to prepare the cationic vinylidene complex

Organometullic Clzemislry

92

[Ru(=C=CHPh)(Ph2PCH2CH2NMe2)(q-C5Me5)] through reaction with phenylacetylene."' Treatment of [ R u ( H ) ~ ( C O ) ( P M ~ B U with ' ~ ) ~ ]an excess of Me3S i c = CSiMe3 afforded [Ru(SiMe3)(C= CSiMe3)(C0)(PMeBu12)2] and Me3SiCH=CHSiMe3. An X-ray diffraction study of the ruthenium complex showed it to have a square pyramidal geometry with an apical SiMe3 group and the C O and CCSiMe3 ligands in trans basal sites.'02 A series of ruthenium allenylidene complexes of the type [RU(=C=C=CR~)(PP~,)~(~-C~H~)J[PF~] were synthesised by the reaction of [ R u C I ( P P ~ ~q-C5H5)] )~( with alcohols, HC = CC(OH)R2, and alkynes, HC = CR', in MeOH in the presence of [NH4][PF6]. Within this series, the differing abilities of the R2C: fragment to stabilise a positive charge allowed tuning of the electronic and optical properties of the complexes by changing the relative contributions of the two canonical forms [Ru']=C=C=CR2 and [Rul-C = C-C+R2.Io3 The violet coloured allenylidene complex [Ru(=C=C=CHJ(q '-DPVP)2(qC5Me5)] (DPVP = diphenylvinylphosphine) reacts with further DPVP to give [Ru{C=C(CH2)2PPh2CH2} (q ]-DPVP)2(q-C5MeS)], containing a heterocyclic disubstituted vinylidene as confirmed by X-ray crystallography. Io4 Reaction of [Ru(Me,tacn)(PMe3)2(02CCF3)][PF6] with alkynes, RC = CH, in hot 1,2dichloroethane gave the vinylidene complexes [Ru(=C=CHR)( Me3tacn)(PMe3)(O2CCF3)][PF6] (R = Ph, C6H4Me-4). These react with R C E C H in methanolic KOH solution yielding the q3-butenynyl complexes [Ru(q3RC3=CHR)( Me3tacn)(PMe,)][PF6] 25. ' 0 5 The chiral-at-metal vinylidene complex [Ru(=C=CH(Ph)}CI(PPh3)(q-C5Me5)] was obtained from the reaction between [RuCI(PPh3)2(q-C5Me5)] and PhC = C H and the structure shows an antiperiplanar geometry between the P-vinylidene hydrogen and the chloride ligand suggesting elimination of HCI should readily occur. Thus, treatment with NEt3 in the presence of either C O or diphenylacetylene gave [Ru(C = CPh)(CO)(PPh,)(qC5Me5)] and [Ru(C EE CPh)(PhC = CPh)(PPh3)(q-C5Me5)], respectively. With terminal alkynes catalytic dimerisation occurred to give, predominantly, the head-to-head products trans-RCH=CHC = CR. The q3-butadienyl complex 26 was also isolated and characterised by an X-ray diffraction study. '06 Me

[PF~I

L

Molecular orbital calculations on the model complex [Ru(=C=C=CH2)(CO)(PH3)(q-C5H5)]' suggested that 23 and 31% of the LUMO are located on C, and C,, respectively, while 26% of the HOMO is based on Cp. In accord with this

2: Complexes Containing Metul-Curbon (z- Bonds of the Groups Iron, Cobult unti Nickel

93

the carbene complex [Ru{=C(C = CPh)CH=CPh2}(CO)(PPri3)(q-C5H5)][BF4] was obtained by treating [Ru(=C=C=CPh2)(C0)(PPri3)(q-C5H5)][BF4] with LiC = CPh and subsequent protonation with HBF4*OEt2. In the presence of KOH, the allenylidene complex and acetone gave [Ru{C = CC(Ph2)CH2C(Me)O}(CO)(PPri3)(q-C5H5)]which protonated to afford the unsaturated cyclic carbene complex [Ru{=(kH2C(Ph2)CH=C(Me)O}(b)(PPri3)][BF4]. lo7 A study of the reactivity of cationic allenylide ruthenium(I1) complexes towards nucleophiles (Nu) was undertaken and alkenyl and allenyl complexes [Ru{C =CCR(Ph)Nu}(L)2(q-CgH7)]and [Ru { C(Nu)=C=CR(Ph)}(L)2(q-CgH7)], respectively, were selectively obtained by consideration of the steric requirements of both the ancillary phosphine ligands and of the nucleophile.Io8 The P-keto-phosphine complexes [RuCl(q‘(P)-Ph2PCH2C(O)But}(PPh3)(q5L)] (L = C5H5 or C9H7) readily reacted with l,l-diphenyl-2-propyn-l-olto yield allenylidene complexes [Ru(=C=C=CPh2){q ‘(P)-Ph2PCH2C(0)Bu‘}(PPh3)(q5L)][PF6] which upon treatment with methanolic base afforded the alkynyl complexes [Ru{C 3 CC(OMe)Ph2 ) { q1(P)-Ph2PCH2C(0)Bu‘)(PPh3)(q5-L)] through nucleophilic addition of the methoxy group to the C, atom of the allenylidene chain. The allenylidene complexes can be diastereoselectively deprotonated to give the neutral phosphametallacyclobutane species [Ru{q2(C,P)C(=C=CPh2)CH[C(0)Bu‘]PPh2)(PPh3)( q5-L)]. An X-ray diffraction analysis (L = C9H7) revealed an almost linear ql-coordinated allenyl group.’w Aromatic imines react with the butatrienylidene cation [Ru(=C=C=C=CH~)(PP~~)~(~-C~H~)]+ to yield complexes containing either 4ethynylquinoline or 1 -azabuta- 1,3-diene ligdnds, electron withdrawing groups on the N-bonded aryl group favouring the latter. The structures of [Ru(C = CC9H4PPh3)2(qMeN)( PPh3)2(q-C5H5)] and [Ru { C -= CC(CHPh)=N (C~H4N02-3)}( C5H5)]were determined.’ lo A series of new vinylidene complexes of the type [Ru(=C=CHR)Cl(PPh3){H B ( ~ z ) ~(R ) ] = SiMe3, Bun, Bu‘, COzEt, C6H9) were synthesised in high yield from the reactions of [RuCI(PPh3)(dmf){HB(pz)3}] with terminal alkynes. The vinylidene groups in these complexes are readily displaced by nucleophiles (PMe3, PPh3, MeCN, py, CO) and vinylidene metathesis is extremely facile and reversible. The related compounds [Ru(=C=CHR)Cl{P(C6H 11)3) { HB(pz)3}] were similarly obtained from [RuCl{P(C6H I I )3 I(OCH2R’)iHB(pz)3I](R’= H, Me). I I Reactions between the carboxylato complexes [Ru(q2-o2CR)(PPh3)(q-C5R’5)] (R = Me, Bu’; R’= H, Me) and terminal alkynes H C r C R ” ( R ” = Ph, C02Me) gave the vinylester complexes [Rh{C(=CHR)OC(R)b}(PPh3)(q-C5R’5)]while [Ru(q2-02CMe)(PPh3)(q-C5H5)]and RR‘CN2 in the presence of A1203 and chloride ion gave the carbene complexes [Ru(=CRR’)CI(PPh3)(q-C5H5)].l 3 The photochemistry of the ql-ally1 complexes [Fe(q I CH2CR=CH,)(CO)( q5:q1-C5H4CH2CH2PPh2)],prepared by the reactions of allyl Grignard reagents with [FeC1(CO)(q5:q ‘-C5H4CH2CH2PPh2)], was studied.’14 The syntheses of paramagnetic allyl and vinyl iron porphyrin complexes of the type [Fe”’(R)(TTP)] (TTP = tetra-p-tolylporphyrin; R = allyl, 2methylallyl, vinyl, 2,2-dimethylvinyl) were reported. Low temperature NMR

’’

94

Orgunometullic Chemistry

studies established that the ally1 ligands are q1-bonded.Il5 In a separate study irradiation of iron porphyrin vinylidene and carbene complexes led to cleavage of the Fe-C double bond with formation of 4-coordinate iron(I1) porphyrin and free carbene.Il6 Mononuclear butadiynyl complexes of iron [Fe(C = CC = CH)(L)(L')(q-CSR5)] (R = Me, Ph; L = L'= CO; LL'= dppe) have been prepared from reaction of [FeBr(CO)2(q-C5Ph5)] or [FeI(CO)z(q-CSMe5)1 with LiC E CC = CSiMe3 and subsequent desilylation with K F or [Bu"N]F. I l 7 Treatment of the q2-vinylketone with two equivalents of complex [Fe{q2-PhCH=CHC(0)CH=CH(Ph)}(C0)4] lithium dimethylcuprate gave the novel complex 27, the structure of which was established by an X-ray diffraction study. I l 8

The allylic and vinyl sulfone Complexes [Fe { C(=CH2)CH2S02Ph}(C0)2(qC5H5)] and [Fe{C(Me)=CHS02Ph}(C0)2(q-C5H5)],respectively, were prepared by the reaction of CH2=C=CHS02Ph with the anionic species [Fe(C0)2(qC5H5)]-. Treatment with PPh3 gave monocarbonylphosphine derivatives which were alkylated regio- and stereo-selectively affording complexes [Fe { C(=CH2)CH( R)S02Ph}(C0)2(q-C5H5)] and [Fe { C(CH2R)=CHSO2Ph)(CO)2(q-C5H5)].I l 9 In the presence of thiophene or ethyl 2-thiophenecarboxylate, photolysis of [MH2{P(CH2CH2PPh2)3}] (M = Ru, 0 s ) gave the complexes [MH(C=CHCH=CHS){ P(CH2CH2PPh2)3}] and [RuH (C=CHCH=C(C02Et)S}{ P(CH2CH2PPh2)3}],respectively.I2O The hydridovinylidene osmium complex [Os(=C=CHPh)CI(H)(PPr'3)2] was synthesised by the reaction of sodium methoxide with the carbyne complex [Os( =CCH2Ph)C12(H)(PPri3)2] and exists as an equilibrium mixture of two conformers in solution. Activation of 0 2 by this complex gave the dioxo-styryl species [Os{( E)-CH=CHPh}(0)2(P P T ~ ~1 2)' ~ ] Treatment . of [Os12(PR3)2(pcymene)] (R = Me, Pr', Ph) with PhCrCH/AgPF6 gave the acetylide complexes [Os(C= CPh)I( PR3)(p-cymene)] and reaction between [OsI,(PPri,)2(p-cymene)] and AI2Me6 afforded the metallacycle [ds{CH2CH(Me)bPri2} I@-cymene)], via the methyl complex [OsI(Me)(PPr'3)(p-~ymene)]. The new compounds were and I7O NMR spectroscopy as well as by X-ray crystalstudied by 1870s, lography. 122 The related bis(acety1ide) species [Os(C = CPh)2(CO)(PPri3)2] was prepared from the reaction of [OsH2(q2-CH2=CHEt)(CO)(PPri3)2] with P h C r C H in a 2:5 molar ratio, but employing a 1 : l O ratio gave the diphenylbutenynyl complex [Os(C 5 CPh){q3-C(C= CPh)=CHPh}(CO)(PPr'&]. Protonation of the latter complex with HBF4'0Et2 yielded [OS(CH~P~)(FBF~)(CO)~(PP~~~)~] which reacted with NaCl to give [OS(CH~P~)CI(CO)~( P P T ' ~ )123 ~].

2: Complexes Contuining Metul-Curbon a-Bondsof the Groups Iron, Cobulf und Nickel

95

Treatment of [Os{(E)-CH=CHPh}CI(CO)(PPri3)2] with LiBu" gave the orthometallated species [OsH {C6H4(CH=CH2)>CI(Co)(PPr'3)2]which with C02 afforded the formato complex [Os{(E)-CH=CHPh)(q2-02CH)(CO)(PPri3)2]. The reactivity of this species was studied and, depending on the reaction conditions, protonation gave either the vinyl complex [Os{(E)-CH=CHPh)(MeCN)2(CO)(PP T ~ ~ ) ~ ] [or B the F ~ ]carbene complex [Os(=CHCH2Ph)(q2-02CH)(CO)(PPri3)2]. 124 A number of other publications in the general area of acetylide, vinylidene, polyynyl and related complexes of iron, ruthenium and osmium have appeared. '25 '41 2.2 The Cobalt Triad - A theoretical study of the relative stability of q2-ethene and hydridovinyl complexes of rhodium and iridium containing pyrazolylborate ligands showed that the ethene complexes are generally more stable but are more sensitive to the steric requirements of the pyrazolylborate ligands. 149 Molecular orbital calculations suggest that the observed bent geometry of the metallathiacycle in [kh{q2-(C,S)-2,5-Me2C4H2S}(PMe3)(q-C5H4Me)] and benzothiophene and dibenzothiophene analogues [Rh{C(Me)CHCHC(Me)S)(PMe3)(qC5H4Me)] is primarily due to steric factors. This was supported by X-ray crystallographic studies. I5O The dehydrogenation of ethane by [IRh(PH3)2] was the subject of a computational study.'" An ub initio molecular orbital study of the transformation of the q2-alkyne complex [RhCl(q-HC = CH)CI(PH&] into the vinylidene [Rh(=C=CH2)CI(PH3)2] established that the latter is 7.8 kcal mol- I more stable. The reaction was shown to proceed viu the oxidative addition product [RhH(C = CH)(CI)(PH3)2] followed by a bimolecular H-shift from the metal to the terminal carbon of the second molecule , rather than by intramolecular 1,3-H transfer.152Migratory insertion of N O into the Co-CH3 bond of [CO(CH~)(NO)(~-C~H was ~ ) ]studied using ub initio molecular orbital and density functional theory,'53 as was the mechanism of the activation of C-H bonds by the model complexes [M(CH3)(PH3)(q-C5H5)](M =Rh, Ir). 154 Relativistic density functional theory has been used to investigate the hydride and methyl P-migratory insertion processes in [M(CH,CH,)(R)(PH,)(q-CSHs)l (M = Co, Rh, Ir; R = H, Me), as well as the reverse p-elimination r e a ~ t i 0 n s . The l~~ intramolecular oxidative addition process rrans-[Rh(q2-CH4)CI(PH3)2] + [RhH(CH3)CI(PH3)2]'56 and the oxidative addition of F-CH3 to the complexes tran~-[M(X)(PH~)~l (M = Rh, Ir; X = CH3, H, CI) affording truns[MF(CH3)(X)(PH3)2I157 have been studied. Electrosprdy ionisation mass spectroscopy, isotopic labelling experiments and ub initio calculations have been employed to study the C-H activation reactions of [IR(CH3)(PMe3)(q-C5R5)] (R = H, Me).158 The chemistry of allenylidene complexes of rhodium has been of C02 adducts of [Co(HMD)I2' (HMD = 5,7,7,12,14,14d i s c ~ s s e d .A ' ~ study ~ -diene) by X-ray absorption near hexamethyl- 1,4,8,11-tetraazacyclotetradeca-4,11 edge spectroscopy suggested significant charge transfer from the metal to the C02 and provides the first evidence that metal catalysts can promote two-electron transfer, thereby facilitating the reduction of C02. Ih0 Treatment of [ C O ( C H ~ ) ( L ) ( ~ ~ ~( L B= F ~NC5H5, ) ~ ] PEt3; dmgBF2 = (difluoroboryl)dimethylgloximato) with two equivalents of [Ni(tmc)(OTf)] (tmc =

96

Orgunometullic Chemistry

1,4,8,1 l-tetramethyl- 1,4,8,1 l-tetraazacyclotetradecane) leads to methyl transfer from cobalt to nickel, thus providing the first model system for methyl transfer from methylcobalamin to the nickel containing enzyme carbon monoxide dehydrogenase. 1 6 ' The reactions of several organocobalt B12 model complexes with arene- and alkane-thiolates gave only thiolate-ligated products. The first crystallographically characterised organocobalt complex containing a unidentate thiolate ligand coordinated truns to the methyl group, [AsPh4][Co(SEt)(CH3)(DH)2] (DH = [dimethylglyoxime]-), was reported.162Model complexes of the imine/ oxime type containing alkyl groups (R), [Co{(DO)(DOH)pn}(R)(L)][Y] (L = H20, py, Me3Bzm, N-MeImd; Y = PF6, C104), have been prepared and characterised by X-ray diffraction studies. '63 Several 5-substituted heteroaromatic methyl cobaloximes were prepared by the reaction of arenesulfenyl chloride ArSCl (Ar = Ph, c6cl5, C6H3(N0&-2,4) with cobaloximes [ C O R ( ~ ~ ~ H ) ~ ( N(R C ~=H2-~ and ) ] 3-thienylmethyl, furfuryl). The success of this method is surprising in view of the susceptibility of Co-C bonds towards cleavage by electrophiles and r a d i ~ a 1 s . The I ~ ~ binding of N-methylimidazole to adenosylcobinamide has been studied as part of a series of investigations aimed at improving our knowledge of the role of the axial base coordinated adenosyl B12.165A variety of alkylcobaloximes with three different dioxime ligands have been synthesised and a rapid purification procedure using column chromatography developed. '66 Reactions of cobaloxime anions and hydrides Na[Co(NCSH5)(dmg)2] and [ C O H ( N C ~ H , ) ( ~ ~respectively, ~)~], with unsaturated acid chlorides, ynones and ynoates yielded a variety of p-cobaloxime-substituted a,P-unsaturated acyl complexes. 167 The bridged dicobaloxime complexes [(C~H~N)(L)~CO(CH~),C O ( L ) ~ ( N C ~ H(L ~ ) ] = dmgH-, dpgh-; n = 3-6, 10) were prepared from [Co(L)2(NC5HS)]and the appropriate alkyl dihalide. 168 Depending on the molar ratio, cobalt cobinamide and 1,l -dimethylpropyl hydroperoxide give a mixture of a- and p-ethylcobinamides, with an excess of hydroperoxide favouring the pdiastereoisomer. The kinetically controlled a- and P-alkylation reactions of cobinamide by propyl radical were discussed. 169 Photolysis of organocobaloximes [ C O { C H ~ ( C H ~ ) ~ C - C R ) ( N C ~ H ~( )R( = ~ ~H,~ H Ph,) ~SiMe3) ] with visible light in the presence of radical trapping agents yielded arranged or non-rearranged organic products (e.g. 2-phenylcyclopentyl sulfones) depending on R. I 70 The structures of the vitamin B12 model compounds 28 have been determined and Co-C and C o - 0 axial distances measured for compounds of this type with various R groups."' Two other model compounds having spacious lower coordination sites created by a novel Co-C-N ring have been subjected to X-ray

R

(28) R = CH2CF3,CH2C02Me

(29) L = H20, NCsH5, DMAP

2: Complexes Containing Metal-Curbon o-Bonds of the Groups Iron. Cobult uncl Nickel

91

diffraction analyses. These compounds allow differences in binding interactions of histidyl, irnidazole and benzimidazole to be compared.172 A series of ( 1,3-butadien-2-yl)cobaIt(salen)complexes 29 have been prepared and reacted with a range of dienophiles to yield Diels-Alder cycloaddition adducts. 173 The reactivity of 2-cobaloxime-substituted 1,3-dienes towards cyclohexenones has been studied and affords octalones with cis ring junctions, via e m transition states.174Several stable (0-a1kyl)cobalt porphyrins, e.g. 30, were synthesised through reaction of the corresponding halogeno complex with silyl enol ethers and ketene silyl acetals. The yields are dependent on solvent, halogen and the substituent on the porphyrin periphery. '71 Proton and 13C NMR spectroscopy and X-ray diffraction analysis have been used to examine whether agostic Co-C-H bonding is present in porphyrin complexes of this type; the results suggest it is not.176

Ph

(30)R' = Ph, OEt, OMe, vinyl R2 = H, Me

The reaction between coenzyme B 12 (adenosylcobalamin) and cyanide ion was studied using spectroscopic methods, showing that it proceeds in one kinetically observable step with the rate-determining step being attack of the first cyanide. 177 Like their alkyl analogues, benzyl cobaloximes were shown to decompose by a three step mechanism but the sequence of steps is different and involves compounds, e.g. monoxime and dimethylphenylisoxazole, which do not feature in the decomposition of alkyl complexes. 178 Proton chemically induced dynamic nuclear polarisation (CIDNP) has been observed during the photodecomposition of coenzyme B12 model compounds, suggesting that Co-C bond cleavage occurs from the singlet state.179 The alkyl complexes [CrR(C0)3(PBu3)] (R = Pr', Pr") were prepared by reaction of the appropriate alkyl halide with Na[Cr(C0)3(PBu3)] and their behaviour under hydroformylation reaction conditions was studied. 180 Monitoring of the stoichiometric reaction of allyldiphenylphosphine with [RhH(C0)2] by 'H and "P NMR spectroscopy led to the isolation of several compounds that are intermediates in the hydroformylation reaction. An electrochemical investigation of the oxidatively-induced reductive elimination of ethane from [RhMes(Cn)] (Cn = 1,4,7-trimethyI-1,4,7-triazacycIonane) was reported18* and the mechanism of the insertion of ethene into the Ir-OH bond of [IrPh(0H)(PMe3)(q-CsMe5)]affording the iridium-substituted aldehyde [IrPh (CH2-

98

Orgunometullic Chemistry

CH(0))(PMe3)(q-C5Mes)]was shown to be catalysed by trace amounts of species capable of generating the cationic complex [IrPh(PMe3)(r&Me5)]+. Mechanistic studies of the reactions of [IrMe(PMe3)(q-C,H,)]+ with pentane, cyclohexane and benzene using electrospray tandem mass spectroscopy established that the reactions involve an elimination-addition mechanism via Ir(II1) intermediates, rather than oxidative addition-elimination or concerted 0-bond metathesis. The iridium-methyl bond of trans-[IrMe-(CO)(PPh2(C,jH$03-2Na);!}] is rapidly hydrolysed upon dissolution of the complex in H20, giving methane and trans-[IrH(CO)( PPh2(C6H4S03-2-Na)2}]. A detailed study of the solution photochemistry of [Rh(C0)2(q-C~H5)],undergoing ligand substitution, and C-H and Si-H bond activation reactions, was in benzene to give reported.lp6 Photolysis of tr~ns-[RhCl(CO)(PMe~)~] [RhH(Ph)(CO)(PMq)z] was studied by time-resolved-infrared and optical spectroscopy and two pathways were detected: reaction of the excited state with benzene and a process involving CO photodissociation followed by oxidativeaddition of benzene.187 The cationic alkyl complexes [Co(CH2CH3){ P(OMe)3}(q-C5Me5)]+show a substantial inverse isotope effect for the catalysed polymerisation of C2H4 vs. C2D4 due to the presence of a Co-C-H (agostic) interaction in the catalysts resting state. 188 The yellow paramagnetic dianion [Rh(C6CIS),I2-, which is the first homoleptic organometallic complex of Rh(II), was isolated as its [Bu"4N] and [PBzPh3] salts from the reaction of [RhC13(tht)] with LiC6CI5. An X-ray diffraction study showed the metal to be in a perfect square-planar geometry. Oxidation of the dianion gave the Rh(II1) complex [PBZP~~][R~(C~CI~)~].'~~ A fluorous analogue of Vaska's compound trans-[IrCI(CO) { P[CH2CH2(CF2)5CF3]3}2] was synthesised and its oxidative-addition reactions in non-polar fluorous media that model key steps in catalytic reactions were studied. Treatment with CF3(CF2)7CH2CH21or CH31 gave the alkyl complexes [IrCI(I)(R)(CO){P[CH2CH2(CF2)5CF3]3}2],formation of the methyl complex occurring via a free radical pathway as opposed to the polar pathway for Vaskd's compound in organic media.19' Fluorination of the compounds [M(C0)2(qCsH5)] (M = Co, Rh) occurs exclusively a t the metal centre yielding neutral complexes of the type [M(CO)(Rf)(q-CsH,)] { Rf = CF2CF2CF3, CF(CF3)2} whereas [Co(PMe3)2(q-C5HS)] and CF3CF2CF2I give the ring-exo-fluoroalkylated complex [COI(PM~~)~(~~-C~H~-C:F~CF~CF~)].~~' Reactions of [RhH2(PMe3)(q-C5Me5)]with C6F6, C6F5H, C l 2 F I 0and CloFs gave the C-F cleavage products [RhH(arylf)(PMe3)(q-CSMeS)1, with C l ~ F l oand CloF8 giving The fluoroalkyl-aqua complexes the same product. 193 [Rh(OH2)(CF2R)(PMe3)(q-C5Me5)][BF4] (R = C6F5, CF2CF3) were prepared through addition of Ag[BF4] to wet CH2C12 solutions of [RhX(CF2R)(PMq)(qCSMe5)]. In the presence of H20, the triflate analogue [Rh(OTf)(CF2CF&F3)( PMe3)(q-CSMe5)] and Na[ B { CbF3(CF3)2-3, 5 } 41 gave the carbonyl complex [R h(CO)(CF2CF3)(PMe3)(q-CgMeS)][B{ CsF3(CF3)2-3,S}41 through hydrolysis of the CF2 group.194 The highly nucleophilic compounds [Rh {Ph2P(CH2),PPh2}][MgCl] (n = 2, 3) are methylated by Me1 and convert C02 to CO and C032-.195Grignard reagents

2: Complexes Containing Maul-Curbon o- Bonds ofthe Groups Iron, Cobalt und Nickel

99

and the isocyanide complexes [RhC12(CNCH2CMe3)(Tp’)] { Tp’= tris(3,Sdimethylpyrazuly1)borate) gave the corresponding alkyl (R = Me, Pr”, Pr’, cpropyl, vinyl) complexes.196 Treatment of [RhC13(tacn)]*H20(tacn = 1,4,7triazacyclononane) with a large excess of RLi and subsequent protonation gave good yields of the structurally characterised trialkyl complexes [RhR3(tacn)](R = Me, Et, Ph, viny1).I9’ Aldehydes (RCHO) rapidly react with the complex [IrX(Me)(PMe3)(ql-C5Me5)] (X = OTf, B{C6H3(CF3)2-3,5}4)affording methane and the salts [IrR(CO)(PMe3)(q-C5Me5)][X].Employing acrolein allowed isolation of the interA mediate n-complex [IrMe{q2-CH2=CHC(0)H}(PMe3)(q-C5Me511[0Tf].’98 mixture of the dinitrogen complex [Rh(N2)(CH3C(CH2CH2P(But)2)2}] and the low-valent hydrido(a1kene) complex [RhH {CH2=C(CH2CH2P(But)2)2}] was obtained by NaH reduction of [RhC1(H){CH3C(CH2CH2P(But)2)2}] under a nitrogen atmosphere. The two compounds inter convert via hydride migration-phydrogen elimination processes.199 In acetone, the reaction of [Ir(C0)2(q-C5Me5)]with [N2(C6H40Me-4)][BF4] gave the nitrogen extrusion product [Ir(CO)2(rl-C5Me5)(C6H40Me-4)][BF4], whereas in CH2C12 the binuclear product [(q-C5Me5)(C0)2Ir-IrC1(CO)(qC5Me5)][BF4]was formed and in EtOH [I~(CO)(OE~)(NHNA~)(~-CSM~~)][B having an aryldiazene ligand, was obtained. With [N2(C6H40Me-4)][BF4],the [( Ir(C0)2(q-CgMe5)}2(1-q ‘-1,2-q2binuclear compound afforded C6H40Me)][BF4]with a rare o,n-bridging aryl group. The structure was established by X-ray crystallography.200 The (phthalimidomethy1)- and (phenoxymethy1)-cobalt complexes [Co { CH2fiC(0)C6H4d(O)}(C0)4] and [Co(CH20C6H5)(CO)4], respectively, were prepared from N~[CO(CO)~] and the appropriate chloro complex. Both compounds are readily converted to the corresponding acyl complex by reaction with C0.201 Oxidative-addition of C-Cl bonds ( e g . CH2C12 and CHC13) to Rh(1) complexes containing terdentate N-donor ligands gave the alkyl complexes 31 which were characterised by X-ray diffraction studies.202Similar chiral bis(oxazoliny1)phenyl (Phebox) complexes 32 and related palladium complexes were prepared by reaction of Phebox-ip-SnMe3 with [RhC13(H20)3] and [PdC12(PhCN)2],

42

(31) R-CI = CH2C12, CHC13,

PhCH2C1, PhCHCIP, Clp

Orgunomet d i e CI?emistry

100

respectively.203The known P-C-P pincer complex 33a was obtained from the room temperature reaction of [RhCl(c-octene)2]2 with the aromatic ether C6H3(PB~L)2(OCH3)-1 ,2,3, thus providing the first example of insertion of a transition metal into an aryl-0 bond of an aryl ether.204The structure of the related iridium complex 33b was determined and its use as a dehydrogenation catalyst has been The synthesis and reaction chemistry of new chiral aminodiphosphines was reported: reaction of [Ir(cod)(OMe)] with (Cy2PCH2CH2)NCH(CH3)(C6H5) gave the 0th-metallated species 34.207 Whereas the compounds [Ir(CH3)(X)(PMe3)(q-C5Me5)](X = OTf, BAr4) are stable towards cyclometallation, the triphenylphosphine derivative [Ir(CH3)(OTf)(PPh3)(q-C5Me5)] is not and releases methane with formation of [mPhz)(OTf)(q-C5Mes)]. The related chloro complex [ m M e 2 ) ( C l ) ( q - C 5 M e 5 ) ] was prepared from reaction of (Me2PCHz)MgCI with [IrC12(dmso)(q-C5Me5)]and treatment with Ag[OTf] in C6H6 gave [I r( Ph)(OTf)( PM e3)( q-CSMeS)].208 Butp

But2

(33a) M = Rh, X = CI (33b) M = Ir, X = H

(34)

(35)

A series of methylcobalt(I1 I) complexes having solely classical ligands (NH3, H20, en, NOz-, CN- ) were prepared from the pentaaminecobalt(II1) cation, and characterised by 'H, 13C and 59C0 NMR spectroscopy and by X-ray diffraction studies.209 Reactions of [RhC12(Ph)(SbPh3)]with C5H4N4S and CSH3NS gave the complexes [RhCI2(Ph)(C,H4N4S)(SbPh3)], [RhCI2(Ph)(C4H,Ns)2(SbPh3)] and [RhC12(Ph)(C4H3NS)(SbPh3)2].The structure of the first of these was determined and represents the first structurally characterised rhodium complex with the antileukaemic drug p~rine-6-thione.~"Alkyl-substituted thiophenes react with [ir(H)2(C2H5)(triphos)] giving products such as 35, resulting from oxidative cleavage of C-H or C-S bonds.2' Heating [RhH(Ph)(PMe3)(q-C5Me5)]generates '[Rh(PMe3)(q-C5Me5)]', the reactivity of which towards insertion into C-S bonds of a variety of thiophenes has been studied. The structures of various thiophene, benzothiophene and dibenzothiophene derivatives were determined.2l 2 A rare example of a stable metallabenzene complex (36)was synthesised in high yield in three steps from [IrCI(PEt3)3]. First, treatment with potassium 2,4-dimethylpentadienidegave met--[I;{ CH2C(Me)=CHC(Me)=kH)(H)(PEt3)3], from which the hydride ligand can be removed with CF3S03Me. Deprotonation An X-ray with base then affords [Ik(=CHC(Me)=CHC(Me)=kH)(PEt3)3]. diffraction analysis revealed a square pyramidal geometry around the metal with

'

2: Complexes Contuining Metal-Carbon o-Bonds of the Groups Iron, Cobalt and Nickel

101

the metallabenzene ring nearly planar and the ring n-bonding delocalised. The ring protons are shifted downfield (d 10.91 and 7.18).2'3 A variety of cyclometallated products, including the rhodacyclopentadienyl species 37 and the bis(pvinyl) compound 38, were obtained by ultraviolet irradiation of [Rh(q-C2H&(qC5H5)]in the presence of alkynes RC-CR (R = Me, Et). In contrast, irradiation of [Ir(q-C2H4)2(q-C5H,)1 in hexane gave only the p-vinyl species 39.214 Two previously unseen coordination modes for creatinine were observed [IT(C~R~)(C~H~N~O)(PP~~)~] 40 and in the complexes [Ir(C4R4)(C4H7N30)(PPh3)2][BF4] 41, prepared by reaction of creatinine with [IrCl(C4R4)(PPh3)2] and [IT(C~R~)(NCCH~)~(PP~~)~][BF~], re~pectively.~'~ The rhodacyclopentane rner-[kh(CH2C(=CHPh)C(=CHPh)kH2)Cl(PMe3)] was isolated from the reaction between [RhCl(PPh3)3] and an excess of phenylalIene.2'6

(37)R = Me, Et

(38) R = Me, Et

Loss of dihydrogen from the acetylide complex [Ir(H)*(C=C P ~ ) ( P B U ' ~ P ~ ) ~ ] gives the ortho-metallated species [h-H(q2-C6H4PBu'2)(c= CPh)(PBut2Ph)2] which is unique in showing (sp2)-reductive eliminatiodoxidative addition that is thermally reversible at 25 0C.2'7 The alkyne-inserted products [IrH(C=CPh)(CH=CHN'Et3)(CO)(PPh3)2]+ and [ h {CH=CHCH=kH(CH=CHN'Et3)(C0)(PPh&] were obtained from the reactions of [IrH(C = CPh)(NCPh)(C0)(PPh3)2]+ and [h(CH=CHCH=kH)(NCPh)(CO)(PPh3)2]+, respectively, with HC = CH in the presence of NEt3. In contrast, HC=CPh afforded the alkynyl complexes [IrH(CrCPh)2(CO)(PPh3)2] and [I;(CH=CHCHdH)(C=CPh)(CO)(PPh3)2]. The trans geometry of the Ir-CHa=CHp-NEt3 moiety was inferred from the coupling constant J(H,Hp) (13-16 Hz) and confirmed by an X-ray diffraction study .2 Dehydrogenation of [Ir(H)2(F)(PBuL2Ph)2] occurs at 50 "C, producing ethene and the two spectroscopically characterised metallated species,

'

-

102

Orgunometallic Chemistry

[I~(o-C~H~PBU'~)(H)(F)(PBU'~P~)] and

[fr {CH2C(CH3)&ButPh)(H)(F)( P B U ' ~ P ~ ) Oxidation ].~'~ of the cationic species [Rh(cod)N3] and [Rh(q-C2H4)N4] (N3, N4 are tri- and tetra-dentate N-donor ligands, respectively) with H202 occurs selectively at the olefin t o give oxarhodatetracyclodecanes (e.g. 42) and 2rhodaoxetanes.220 Stoichiometric reactions between the phosphinoalkenes Ph2P(CH2),CH=CH2 (n = 1-3) and the complexes [(oC)4M(pPPh2)RhH(CO)(PPh3)] (M = Cr, Mo, W) gave mixtures of the species 43 and 44,which can be thought of as intermediates in hydroformylation reactions.22' Rhodium complexes of the first phosphino(stibino)methanes have been prepared and the salts [ R ~ ( R ~ P C H ~ S ~ R ' ~ ) ( C O ~ ) ] [ P F react with CH2N2 by insertion of the CH2 into the Rh-Sb bond to give [kh(CH2SbR'2CH2PR2)(cod)][PF6].222

L

(42) R = H,Me

(43) M = Cr, Mo, W n = 1-3

(44) M = Cr, Mo, W n = 1-3

The reaction of [ (RhC12(q-C5Me5))2]with tellurophene, TeCH=CHCH=CH, in the presence of Ag[OTf] gave [Rh(q5-C4H4Te)(q-C5Mes)][O$CF3], which in turn reacted with [Co(q-CgH5)2] to give the rhodacyclic complex [Rh(qCSMe5){qS-CSH4Rh(q-C5Me5))].A similar sequence of reactions using dibenzotellurophene (dbt) yielded 45, which upon reaction with [Fe3(CO)12]gave 46.223 At 60 "C selenophene and [RhH(Ph)(PMe,)(q-C5Me5)] gave the C-Se inserted product [rz'h(SeCH=CHCH=CH)(PMe3)(q-C~Mes)],which was characterised by The cobalt com77Se NMR spectroscopy and an X-ray diffraction pounds [ ~ O { C ( = C H ~ ) N ( R ) C ( = S ) $ } ( P M ~ ~ P ~ ) ( ~(R - C ,=H Me, , ) I Ph, CHZPh), having exocyclic C=C and C=S bonds, were obtained from the reactions of [Co{C(CH3)=NCH3)(PMe2Ph)(q-CsH5)]I with either CSdNa[OMe] or K[S2CNMe2]. Protonation and methylation occur at the exocyclic C=CH2 and C=S bonds, respectively, while treatment with C2(C02R1)2 (R'= Me, Et) leads to

2: Complexes Contuining Metul-Carbon a-Bonds of tlie Groups Iron, Cobalt und Nickel

103

insertion of the alkyne into the C=CH2 bond.225Cyclic cobalt dialkyls of the type [Co{CR(R')(C,H4N-2))2] 47 { RR'= (SiMe3)2, Ph(SiMe3), H(SiBu'Me2)) and [Co{CH(SiMe3)(C,H6N-8)}2]have been prepared from [CoC12] by reaction with organolithium reagents.226 The five-coordinate bis(viny1idene) complex [Rh(C= CPh)2(SnPh3)(PPr')2]was synthesised by the reaction of [Rh(q2-02CMe)(PPr'3)2]with PhC --= CSnPh3, and reacts with PMe3 to give the octahedral compound mer,truns[Rh(C=CPh)2(SnPh3)(PMe3)3], the structure of which was determined.227At 60 "C in the presence of phosphine, the alkyne complexes [Rh(acac){q2HC = CC(OH)Ph2}(PR3)] (R = Cy, Pr') transform into the acetylide complexes [Rh(acac)(H){C= CC(OH)Ph2}(PR3)2]. Protonation (HBF4OEt2) of the latter gave allenylphosphonium compounds.228 R'

R' (47)

RR' = (SiMe3)2,Ph(SiMe,) H(SiBu'Me2)

Ph (48)

The complex [dh { PPh2CH2C(But)=N -N=C(Ph)d}(CO)], containing a phosphino-N-benzoylhydrazone ligand, undergoes oxidative-addition with Me1 and HC CCH2Cl affording the complexes [dh{PPh2CH2C(But)=N-N=C(Ph)6}(X)(R)(CO)] (R = Me, X = I; R = CH=C=CH2, X = CI). Treatment with Me02CC=CC02Me gave the cyclometallated product [dh { PPh2CHC(CO2Me)=C(C02Me)]C(But)= N-N =C(Ph)d}{ q '-C(CO2Me)=CHC02Me)(CO)], which upon prolonged heating isomerised to 48.229Propargylic acid esters, HC=CCO2R (R = Me, Et), and [Co{C(CH3)=NCH3}(PMe2Ph)(q-C5H5)]I gave the alkenyl complexes [Co{C(CH+NCH3} (PMe2Ph)(C= CCO~R)(~-C~HS)]I and [do{ N(CH3)=C(CH3)C(H)=k(C02Me)}(PMe*Ph)(q-CSHS)]I. Heterocyclic complexes of the latter type were the only products obtained when terminal alkynes were used.230 A general method for the synthesis of aryl, methyl, vinyl and alkenyl(viny1idene) rhodium(1) complexes of the type ~ ~ ~ ~ S - [ R ~ ( = C = C H R ) ( R ' ) ( and PP~'~)~] trans-[Rh(=C=CMe2)(Rf)(PPri3)2]from the corresponding chloro(viny1idene) complex has been described. Some of these complexes were converted to q '-vinyland q '-butadienyl-carbonyl complexes by treatment with CO, or stereoselectively converted into the isocyanide derivatives trans-[Rh { q '-(Z)-C(R)= CHPh}(CNRf)(PPri3)2]by reaction with methyl- or r-butyl-isocyanide. In the absence of Lewis bases isomerisation to a-ally1 complexes occurs. The vinyl(vinylidene) complexes undergo an intramolecular rearrangement giving q3-2,3,4butadienyl or alkynyl(ethene) isomers depending on the condition^.^^' Thermal

104

Orgunometullic Chembtry

or photochemical reactions of the in situ generated species [IrCl(CgH 14)(PPri3)2] with alkynes Me3SiC=CR (R = Me, Ph, Bun, SiMe3, CH20H, CMezOSiMe3, C02Et) gave the complexes trans-[Ir{ =C=C(SiMe3)R)C1(PPri3)2], via n-alkyne complexes, while photolysis of [IrCl(H)2(PPri3)2] in the presence of Me3S i c = CC = CSiMe3 or HC 3 CC =CSiMe3 afforded trans-[Ir{ =C=C(SiMe3)C = CSiMe3}Cl(PPri3)2] or [IrCl(H)(C = CC 3 CSiMe3)(PPri3)2], respectively. Heating of the latter gave the vinylidene isomer trans[IrCl(=C=CHC=CSiMe3)(PPi3)2]. Propargylic alcohols, HC = CR(R')OH, and the dihydro complex gave [IrCl(H)(C=CC(Pr')=CMe2)(PPri3)2] (R = R' = Pr') or the carbonyl(hydrido)vinyl complex [IrCl(H){(E)-CH=CH(Ph))(CO)(PPr'3)2] (R = H; R' = Ph).232 The green vinylidene complex trans[RhCl(=C=CHFc)(PPri3)2] (F, = ferrocenyl) was prepared from [RhCl(PPri3)2]2 via the orange alkynyl(hydrid0) complex and et hynylferrocene [RhCl(H)(C zz CF,)(PPr'3)3]. With phenyl and vinyl Grignard reagents the vinylidene complex gave the corresponding phenyl or vinyl derivative, the latter of which was observed to rearrange to the q3-2,4-butadienyl complex

[Rh(q3-trans-CH2CHC=CHF,)(PPi3)2].233

Reaction between [Ir(diene)(OMe)(PR,)] (diene = cod, TFB; R = Pr', Cy) and 1 , l -diphenyl-2-propyn-l-01 affords the red hydroxyalkynyl compounds [Ir{C = CC(OH)Ph2)(diene)(PR,)] which upon protonation yield violet-red allenylidene species [Ir{=C=C=CPh2)(diene)(PR3)][BF4], providing the first examples of mixed ligand complexes of the type [IrL(diene)(PR3)]+ with an unsaturated q l carbon ligand.234The metallacumulene ~~~~S-[R~(=C=C=C=C=CP~~)CI(PP has been prepared in a stepwise manner from [RhCl(PPri3)2]2 and H C sCC =CCPh20SiMe3 and shown to react with diazomethane to give a complex containing the previously unseen hexapentaene ncoordinated to rhodium, trans-[Rh(H2C=C=C=C=C=CPh2)C1(PPri3)2], as a mixture of two isomers.235 The first example of an amidato complex in which the NHC(0)Me ligand links the metal-metal site forming a novel metallacycle, [Rh2(j~-CH2)2(p-q ':qlNHC(O)Me>(q-C5Me5)2][PF6], was obtained from the reaction of [Rh& CH2)2(p-02C0)(q-C5Me5)2]with acetonitrile in aqueous solution and subsequent treatment with KPF6.236Reaction of [IrCl(PPh3)3]with 2,6-bis(chloromethyl)pyridine gave the mononuclear complex cis-[IrCl2{ClCH2-C5H3N-CH2)(PPh3)2], which upon treatment with [RhCl(PPh3)3] gave the heterobinuclear complex 49.237Cobalt octacarbonyl, (MeSCS2)2 and PPh3 gave the crystallographically characterised complex [C02(1,3-q-S2CSMe)-(p- 1,2-q-SCSMe)(C0)2((PPh3)2], which has a 5-electron methyldithiofonnate l i g a ~ ~ d . ~The ~' vinylene-bridged dirhodium complex [ { K(MeOH)2) 2{(PPh3)(dmg)(dmgH)Rh-CH=CH-Rh(dmg)(dmgH)(PPh3))] (dmgH2 = dimethylgloxime) was obtained by the reaction of [Rh(dmgH)2(PPh3)J- with (E)-l,2-di~hloroethylene.~~~ Oxidative addition of Me1 to the compounds [ (Rh(j~-pz)(CNBu')~)2]and [(M(p-L)(CNBut)2>2]( M = Rh, L = SBu'; M = Ir, L = pyrazolate (pz)) affording the complexes [ ( Rh(p-pz)(Me)(CNBut)2)2(p-1)]1, [ {Rh(p-SBu')( Me)(CNBU')~} 2(p-I)]I and [ { 1r(p-pz)(Me)(CNBut),)2(p-I)]I, respectively, was found to be stereoselective and independent of the metal. This is not the case for

2: Complexes Containing Metul-Carbon o-Bonds oJthe Groups Iron, Cobalt und Nickel

105

reactions of the mixed ligand complexes [(cod)M(p-pz)2M(CNBut)2] (M = Rh, Ir) with Me1 which afford the mixed valence Rh(1)-Rh(II1) complex [(cod)Rh(p~ z ) ~ R ~ ( M ~ ) ( I ) ( C N Band U ~ )the ~ ] Ir(1II) complex [(cod)(Me)Ir(ppz)2(p-I)Ir (Me)(CNBu')~]I.240

2.3 The Nickel Triad - Two theoretical studies of the diime-nickel catalysed polymerisation of ethene with [(HNCH)2NiCH3]as catalyst have appeared and A theoretical the results compared with a zirconocene-based comparison between o-alkyl complexes of nickel, palladium and platinum with respect to the association of ethene and migratory insertion-b-hydrogen elimination was reported.243 An ab initio molecular orbital study on the chelate phosphine effect on oxidative addition of a C-H o-bond to model complexes [M(PH&] (M = Pd, Pt) demonstrated that very high activation energies are required for mondentate phosphines but the energy becomes quite low with chelating phosphines.244Metal-carbon bond enthalpies in the compounds trans[ P ~ C I ( C H Z Y M ~ ~ ) ( P(Y M= ~ ~C,) ~Si) ] have been determined from calorimetric measurements on the reactions with HCI, affording trans-[PtC12(PMe3)2] and YMe4. In accord with values for NMR coupling constants, it was found that the Pt-C bond is stronger by 14 k 6 kJ mol-'.245 A study of o-bond metathesis reactions of water and methanol with palladium methyl and hydride complexes by ab initio molecular orbital methods showed that such reactions are feasible and in some instances can compete with oxidative addition-reductive elimination processes.246The same group studied the reduction of water to H2 by the anionic species [Ph(CH2CH2CH2CI!12){ ( ~ z ) ~ B>I-, H concluding that the uncoordinated pyrazole group plays a major role as an intramolecular nucleophile in delivering A combined density functional and molecular two protons to the mechanics study of the role of the bulky ligands in the [(ArN=C(R)C(R)=NAr)NiCH3]+ catalysed ethylene polymerisation reactions suggests that the role of these ligands is two-fold: They sterically hinder the axial coordination site and stabilise the insertion transition state, thereby lowering the barrier to propagation while raising the termination barrier.248 The kinetics of the insertion of unsaturated hydrocarbons such as norbornadiene, propadiene and 1,Zheptadiene into Pd-C bonds of complexes of the type [PdX(R)(NN)] { NN = Ar-BIAN [bis(arylamino)acenaphthene], 8-PQ, Pr'-DAB, PiPyCa; R = Me, C(O)Me, C(O)Ph, C(0)Pr'; X = C1, Br} found that two pathways are involved, an alkene-dependent one and an alkene-independent one. For the complexes Mechanisms were proposed for both [MX(C,$5)(OPPynPh3_.)] (M = Pd, Pt; X = C6F5, halide; n = 1-3) the rate of

106

Orgunometallic Chemistry

rotation of the C6F5 group around the M-Cipsobond has been shown to vary with X in the order C6F5>CbBr>I.Associative exchange of free and coordinated Py groups occurs with OPPy3, the rate being Pd>Pt and C b C 6 F 5 and is faster than C6F5 rotation.252 Kinetic and thermodynamic data for the reversible oxidative addition reactions of E-X bonds (E = Sn, Ge) to various Pt(I1) complexes of type [PtMez(diimine)] have been determined.253The kinetics of arylaryl interchange reactions of complexes of the type [Pdl(aryl)(L)2] have been investigated,254as have cyclometallation reactions via oxidative addition of C-X bonds to Pt(1I) complexes as a function of pressure, temperature and solvent.255 Protonolysis reactions of the complexes ci~-[PtR(R’)(PEt3)~1 (R, R’ = Me, Et, Pr”, Bun, CH2CMe3, CH2SiMe3, C6H4Me-2, C6H2(Me)3-2,4,6) were studied by UV and low te*mperature NMR spectroscopy256 and substitution reactions of cis[PtMez(dmso)2]with pyridine were shown to occur in two steps.257 The first structurally characterised example of a Pt( IV) carbonyl complex, [B~~Nl[rrcrns-Pt(C~F~)~Br(CO)] was obtained by bromine oxidation of [ B u ~ N I ~ [ P ~ ( Cand ~ F subsequent ~)~] halide abstraction in the presence of CO. The value of v(C0) at 2166 cm-’ is higher than that of free CO implying that the CO ligand is primarily a o-donor, as expected.258 Low temperature oxidation of [Bu4N]2[Ni(C6F5)4]with Cl2 afforded [Bu4N][Ni(C,F,),] ,which was characterised by an X-ray diffraction study and repesents the first homoleptic organometallic complex of Ni(l11).259Sonication of [Pd1(R)(PPh3)2] and AgF, or reaction of [PdzMe2(PPh3)2(pOH)2] with Et3ND3HFin the presence of PPh3, gave the first organopalladium tertiary phosphine fluoride complexes trans-[PdF(R)(PPh,),] in high isolated yields.260In arene and alkane solvents (RH), the reaction between K[PtMez(Tp’)] with B(C6H5)3 led to intramolecular oxidative addition and formation of stable Pt(1V) complexes [PtMe(H)(R)(Tp’)], the first observation of such a process involving Pt(IV) complexes.26’ Treatment of the complexes [(PtI(PEt3)}2(aryl)] with a slight excess of silver triflate gave the bimetallic species [(Pt(OTf)(PEt3)}2(aryl)] (aryl = 4,4‘-C&, C6H4C6H4, C ~ H ~ C ~ H ~ C which S H ~have ) been used to prepare six nanoscale molecular squares through spontaneous self-assembly of programmed 90 angular units.262The dinuclear compounds [ P ~ ~ P ~ ~ ( P R ~ ) * ( P(R - O=HPh, ) ~ Cy) ] react with the complexes [M(C0)3(q-C5H5)] (M = Cr, Mo, W) giving H20 and the trinuclear compounds [P~~P~~(PR~)~(~-OH)(~-CO)~(J.~~-CO which are the first examples of complexes of palladium containing o-phenyl, carbonyl and hydroxyl ligands within the same coordination sphere.263 The first carbohydrate complexes of platinum(1V) were prepared from the stoichiometric reactions of [PtMe3(OCMe2)3][BF4] with 1,2:5,6-di-o-isopropylidene-a-D-glucofuranose and -u-D-allufuranose. The structures were confirmed by X-ray crystallography (50).264 Reaction of cis-[PdClZ(PPh3)2] with sodium 8(methy1thio)theophyllinato (NaL) gave trans-[PdCl(L)(PPh3)2], which upon heating in a H20/CH2C12 mixture in the presence of NaOH afforded trans[Pd(L)(L’)(PPh&] (HL’ = theophylline). The structure of the latter was established and provided the first example of a C(8)-Pd(II) purine complex, i.e. an analogue of guanine with Pd-C(8) binding.265Rare organometallic compounds of nickel(II1) (51) were obtained from the one-electron oxidation of the species O

2: Complexes Containing Metal-Carbon a-Bonds of the Groups Iron, Cobalt and Nickel

107

H

N-

H

(50)

0x0 (51) X = Br, NO2,OH, CN

[Ni(CTPP)] and [Ni(MeCTPP)] (CTTP = 5,10,15,20-tetraary~-2-aza-21-carbaporphyrin) and studied by electron spin resonance and 2H NMR spectroscopy.266 The pincer type complexes 52 were synthesised by reaction of [Pd(OCOCF3)2] with the appropriate diphosphine and were shown to exhibit high catalytic activity in the Heck reaction.267Similar bis(oxazo1ine)aryl complexes 53, obtained through oxidative addition of the appropriate bis(oxazo1ine) to [Pdz(dba)J, are good catalysts for cyclopropanation reactions.268

(52) R = P i , Bu'

(53) R = CMe2Ph,CMe3, CHZPh

Activation of either C-F or C-H bonds of Me2NCH2CH2N=CH(C6H2F3) occurred upon reaction with [Pt2Me4(p-SMe2)2]producing the cyclometallated Pt(IV) or Pt(I1) complexes [h(Me2NCH2CH2NHCH(CH2COMe))(C6H2F2)F(Me)2] and [fitMe2NCH2CH2N=CHb6HF3)Me], respectively. The latter is formed when no more than one ortho-F is present while the former results from addition of acetone to the iminic bond of the newly coordinated l i g i ~ n d . ~ ~ ~ Reaction of the potentially tridentate compound bis(2-pyridyl-methy1)amine (BPMA) with [Pt2Me&-SMe2)2] gave the complex [PtMe2(BPMA)] in which the BPMA acts as a bidentate ligand. Treatment of the dimethyl complex with HX (X = C1, BF4) afforded thermally unstable cationic hydrido species [PtMe2(H)(BPMA)][X], containing tridentate BPMA. At room temperature, elimination of methane occurs to give [PtMe(BPMA)][X] 54, the chloride salt of which was characterised by an X-ray diffraction The and formyl groups of the complexes [PdCl{C6H3(CHO)2-2,5}(NN)] truns-[PdC1(C6H~(CHO),-2,5)(PPh3)2] (NN = tmeda, bpy) can be oxidised with potassium permangenate, while reactions with amines and Na[CI04] or Tl[CF3S03] gave the cyclopalladated derivatives

108

Orgunometullic Chemistry

(55) M = Pd, Pt

[Pd{C,H,(CH=Nk)-2-(CH=NR)-5} (N N)]+ or [I‘d { C6H3(CH=fiR)-2-(CHO)5)(tmeda)]’, and the reaction between [PdCl{C6H3(CH0)2-2,5f(tmeda)] and N H20Me produced [Pd { C6H3(CH=&OMe)-2-(CH=NOMe)-5} (N N)][C104].27’ Four- and five-coordinate complexes [Ph { CH(C02Me)CH( Me)Cd(OMe)}(phen)][BF4] and [PdMe(dmf )(dmphen)(OH2)][BF4] were obtained from [Pd(dmf)(NN)] and [Me30][BF4] (NN = I , 10-phenanthroline (phen), 2,9-Me21,lO-phenanthroline (dmphen)}. The methyl complex reacts with electron rich alkenes to give unstable adducts of the type [PdMe(q-RCH=CH2)(dmphen)(OH2)][BF4] which slowly eliminate alkene.272Addition of alkenes to the methyl complexes [PdX(Me)(NN)] {X = CI, CH(C02Me); NN = bidentate N-donor ligand) was found to occur via a five-coordinate species of distorted trigonal bipyramidal geometry with the methyl and nitrogen atom in axial positions. This normally rearranges to the more stable isomer in which both axial sites are occupied by the anionic l i g a n d ~ . ~Reactions ~’ of [PdC12(PhCN)2] and K2[PtC14] with the poten tially t ridentate ligand 4’-[4-(dodecyloxy)phenyl]-6‘-phenyl-2,2’bypyridine (HL) leads to metallation and formation of the rod-like complexes 55. The structures and photophysical properties have been studied and both exhibit ~uminescence.~~~ Optically active complexes of primary benzylamine derivatives, (R)-( - )-2phenylglycine methyl ester and (&)- 1-phenylethylamine (e.g. 56) were obtained through cyclopalladation reactions.275Chiral cyclometallated complexes of Pt( 11) and Pd(I1) containing ligands derived from thienylpyridine (e.g. 57) have been prepared and structurally ~ h a r a c t e r i s e d . ~ ~ ~ The reactions of the cyclometallated complexes [Pd(C6H4CH2NMe2-2)(L)(L’)][C104] and [Pd { R-C6kf&H(Me)NMe2-2}(L)(L’)][C104] (L, L’ = PPh3, py, thf, NCMe) with a-keto-stabilised phosphorus ylides Ph3P=CH(COR) (R = OMe, Me2Ph) give one of two types of product depending on L and L’: the ylide can coordinate through the carbonyl oxygen atom or through the ylide carbon atom to give cationic species of the type [$d{ C6H3CH(R)NMe2}(OC(R’)=CH(PPh3)}(L)]+ and [pd { C 6 H 3 C H ( R )Me$ ~ {CH(CO2Me)(PPh3))(L)]+, respectively.277 [n the presence of a tertiary phosphine, [Ni(cod)Z] and the ylide Ph3P=NC(=NPh)Ph gave the phenyl complexes [di(Ph2PN=C(Ph)&Ph){NPh[=CPh(N=PPh3)]}Ph] and [I’Ji{Ph2PN=C(Ph)kPh}Ph(PR3)] (PR3 = PMe3, PMe2Ph, PMePh2). The Nmethylated ylide Ph3P=NC[=N(o-C6H4)NMe] and P(tolyl)3 gave 58 .278 Reac-

2: Complexes Contoining Metul-Curhon o-Bonds ofthe Groups Iron, Cobult and Nickel

109

tions of the cyano-stabilised ylide Ph,P=C( H)CN with ortho-metallated(C,N ) compounds of the type [Pd(C,N)(PPh3)(thf)][C104]and [Pd(C,IV)(NCM~)~][CIO~] afforded complexes [Pd(C,N)(PPh3){N =C(H)=PPh3)] and [Pd(C,N)(Ph3PCHCN)2][C104],respectively. In the latter type of complex one of the ylides is C-coordinated and the other N-coordinated. The structure of

[Pd(dmba){P(OMe)3f{ N = CC(H)=PPh2}]was reported.279 A mixture of the isomeric platinacycles 59 and 60, containing C,S-chelating ligands, was obtained from the reaction between [Pt2CI,(PEt&] and CH2(PPh2=S)(PPh2=N-aryl). Deprotonation of this mixture with NaH gave ~ ~ ~ ~ ~ - [ P ~ ( C H ( P P ~ ~ = ~ - ~ - ~ O ~ ~ I ) ( P P ~which ~ = S )upon - C , protonation NJCI(PE~~)~, yielded the geometric isomer of 59 trans-[Pi { CH(PPh2=$(PPh2=NH-tolyl)C,S}CI(PEt3)].28*Related four- and six-membered C,N - and N , N-chelate complexes [bd fCH(PPh2=karyl)(PPh2-N H-aryl))CI2] and tolyl)=PPh2CH(Me)PPh2=fi-p-tolyl) C12] were prepared from [PdC12L2] (L = PhCN, MeCN, cod) and the iminophosphines BIPM and 1 , l -BIPE, respectively. In contrast the platinum complexes [PtC12(RCN)2](R = Ph, p-tolyl) afforded the six-membered metallacycles [P\{aryI-N=C(R)-N=PPh&HPPh2-(NHary I)- C,N )CI(RC N)][Cl] [Pt { aryl- N =C(R)-N =PPh2-kHPPh2-(N Hand aryl)-C,N}CI(RCN)C12],resulting from [2+2] cycloaddition of a nitrile and a P= N group.28 The synthesis of cationic methyl palladium complexes with N, 0-, P, 0-and P,0,N-chelating ligands of the type [PdMe(Y,O)(L)][BF4] and [PdMe(P,O,N)][BF4] {Y,O = methyl picolinate, Ph2PCH2C02Et; L = PPh3; P,O,N = Ph2PCH2C02CH2(NCSH4-2))have been reported, and the structure of [Pd{O= C(OMe)C5H4N-2) Me(PPh3)] was determined. These compounds readily react

[w

'

R ,C=NR'

+ \

[59) R = ptolyl, panisyl

(SO) R = ptolyl, ganisyl

dmso

(6la) M = Pt; R = Me;R' = aryl (61b) M = Pd; R = H, Me; R' = OH

Orgunomrtullic Chemistry

I10

with CO to give the corresponding acyl complex and also catalyse the copolymerisation of CO and ethylene.282 Cyclometallated ferrocenylketimines 61 a are the products of the reaction between cis-[PtC12(dmso)2] and the ferrocenylketimines [(q-C5H5)Fe(qC5H4CMe=NAr)]283while the related palladium complexes 61b were prepared from Na2[PdCI4] by reaction with ferrocenyloximes and t r i p h e n y l p h ~ s p h i n e . ~ ~ ~ Aryne nickel complexes [Ni(q2-C6H4)L42]{ L2= (PEt&, Gy2P(CH2)2PCyz (dcpe)) and [Ni(q2-CloH6)(PEt3)2]react with C2F4 to give the nickelacycles [ii(C6H4CF2CF2-2)L2J and [fii(2-CloH6CF2eF2-3)(PEt3)2],respectively. Insertion of CO into the Ni-aryl bond of the former gave six-membered acyl complexes [ d i { C(0)C6H4CF26F2-2)L2], while the carboxylato complex [hi{OC(0)C6H4CF2CF2-2}(dcpe)]was produced on exposure to air. Alkynes also insert into the metal-aryl bonds yielding species such as 62.285Treatment of [Pd(hfx)2] (hfac = hexafluoroacetylacetonato) with monooximes results in C - 0 bond formation between the C-bonded hfac and the N-bonded monooxime affording palladacycles of type 63 having a hfac 0,O-chelate and a hfac-oxime C,N-chelate.286Metal containing liquid crystals 64 were prepared by cyclopalladation of di-Schiff's bases and subsequent reaction with a p-diketone. Employing

(64) R' = (n = 4-8, 10) R2 = ButtCrnH2,,,+' (m = 1,4,6,8)

suitable alkyl substituted diketones can significantly reduce the melting and clearing points.287 The first platina-p-diketonato complexes of platina-P-diketones [ {( N H2R)ClPt(p-COMe)2Pt[(COMe)2H])2](R = Ph, C6H4Me-4) were prepared by the reaction of aniline or p-toluidine with [Pt2(p-C1)2{(COMe)2H}2].The Xray crystal structures of both compounds were determined and show head-tohead dimers with zig-zag chains of metal atoms.*" A very rare example of oxidative-cleavage of a C-Se bond was observed in the reaction of cyclohepteno-

2: Complexes Contuining Metal-Curhon o-Bonds of the Groups Iron, Cobalt unii Nickel

11 I

1,4-diselenin with rrans-[PtC12(PhCN)2] to give the structurally characterised complex 65.289 Treatment of the 2-alkoxyallyl cations [Pt { q3-CH2C(OR)CH2)(PPh3)2][X] (R = Et, Pr’; X = OTf, halide, BF4) with hydrogen sulfide (HS-) gave the metallathiacyclobutane [Pt {q2-CH2C(OR)(Me)i}(PPh3)2], the structure of one of which (R = Et) was established by an X-ray diffraction I Metallacyclic complexes of the type [Pd{C(O)N(Ph)C(O)O)(NN)] (NN = phen, 4,7-dimethylphen, 3,4,7,8-tetramethylphen)were prepared from [Pd(MeC02)2(NN)] and nitrobenzene or nitrosobenzene at room temperature and 1 atmosphere CO.*’’ The thermal and oxidatively-induced reactions of the I 1 oxametallacycles [Ni(OCH2CH2CMe2-o-C6H4)L2](L2= dmpe, bpy) have been studied and both C,O-reductive eliminations to give 2,4-dimethylchroman and thermally induced P-H-elimination affording 3-methyl-3-phenylbutyraldehyde were observed.292 Silanes o-[Me2(R)SiCH20]C6H41 (R = Me, Ph, F) react with [Pd(PPh3)4] or [Pd2(dba)(A~Ph~)~] to give oxidative-addition products [Pd(o-Me2(R)siCH20CsH4) I(L)2] (L = PPh3, AsPh3). Fluorides and carbonates promote Pd-Si transmetallation in these complexes, with formation of [ P ~ ( O - C H ~ O C ~ H &thus ~ ] , allowing a key step in the Hiyama coupling reaction to be studied.293 The first examples of alkyl(sily1)palladium species r [ P ~ ( C H ~ C H ~ C H ~ S ~ R(R ~ )=( ~Me, ~ P Ph) ~ ) ] were obtained from reactions of silacyclobutanes with [PdMez(dmpe)] or [Pd(~-pCH=CH~)(dmpe)].~~~ Insertion of a Pt(cod) fragment into a Si-Fe bond of [Fe(q-C5H4)2SiMe2]gave the complex [Fe(q-C5H&Pt(cod)SiMe2] which was shown to function as a precatalyst for the ring-opening polymerisation of [Fe(q-C5H4)2SiMe2]yielding the poly(ferroceny1silane) [{ Fe(q-C5H&SiMe2} n].295 t Oxadimethylenemethane complexes [M { CH2C(O)CH2}(PPh3)2](M = Pd, Pt) have been synthesised by treatment of the allyl complexes [M($CH2C(OR)CH,>(PPh&] with base. This reactivity is explained in terms of a large contribution to the electronic structure of the allyl complexes from the oxonium resonance Reaction of the cyclopropane Ph02CC(CMe2)CC02Phwith [Pdz(dba)3] and crystallisation of the product from acetone gave the chiral complex 66, the structure determination of which was the first for a bis(acetone) complex of Pd( II).297 Enantiomerically pure palladatricycloheptanes were obtained by the same method and complexes with bis(dipheny1phosphino)ferrocene prepared. i

t

-

1

1

i

Orgonotnetnllic Chemistry

112

The structures of these complexes show a dramatic deviation from square-planar geometry with the C-Pd-C and P-Pd-P planes being tipped toward each other by as much as 30.4 As a result the metal centres in these complexes define helical chirality.298 Treat men t of [PtCI( C HCIC02Me)(cod)] with (2R,3 R)-bis(d ipheny1phosphino)butane [( R,R)-chiraphos] gave a separable mixture of the two diastereoisomers of [PtCI(CHCIC02Me){(R,R)-chiraphos}]. Two isomers of the platinaoxaphospholanes [Pt { CH(CI)P(OMe)(O)O~H[P(O)(OMe)2]~(cod)] were obtained from the reaction between [PtCI2(cod)] and N2CHP(0)(OMe)2and the structure of [Pt(CHCISiMe3)(CHClP(0)(OMe)2)],the major product of the reaction of [ PtCI( CH ClSi Me3)(cod)] with N *CH P(O)(OMe)2, was determined.299 Optically active complexes trans-[PtC12{Ph2PCH(OMe)Ph}21 and tmns-[PtC12{Ph,PCH(OMe)Ph}(PPh,)] were prepared by ligand transfer reactions involving [PtCI,] or trans-[PtC12 { Ph,PCH(OMe)Ph} (PPh,)] and [PdX{C6H4CH(Me)NH2)f Ph2PCH(OMe)Ph)] (X = C1, Br), the latter species being obtained by treating the homochiral complex ( R)-[PdX(C6H4CH(Me)NH2)]2 with Ph*PCH(OMe)Ph. This process allows the one step preparation of optically active complexes of platinum and regeneration of the resolving Metal-substituted fulvenes [Pd(C(NHBu')=CC4H3R) { CH(SiMe&}(CNBu')(PMe3)] were synthesised by stepwise reaction of [Pd2(CH(SiMe3)2}2(PMe3)2(j.~-CI)~]with CNBu' and Na[CSH4R] (R = H, Me) at low temperatures and the structures confirmed by an X-ray diffraction study (R = Me)."' Pyridine-functionalised phosphaalkenes, [Mes*P=C(R)(py)] (Mes* = 2,4,6-tri-t-butylphenyl; R = H, SiMq), have been reacted with [PdCI(Me)(cod)] to give the structurally characterised complexes 67."' The cationic sulfur ylides ~~u~~-[P~CI(CH~SR~)(PBU'~H)~][X] (SR2= tht, SEt2; X = PF6, CF3S03) were obtained by reaction of trcms-[PdC1(CH2C1)(PBu12H)~] with tht or SEt2 in the presence of TI[PF6] o r Ag[CF3S03] and the structures of two complexes determined.303 Reaction of Ph2Te with the complexes [M(PEt3),] (n = 3,4; M = Ni, Pd, Pt) afforded the complexes [MPh(TePh)(PEt3)2],providing the first example of oxidative addition of a C-Te bond to zerovalent Group 10 metal c o m p ~ e x e s . ~ " ~ A series of methyl dithiolate complexes of the type [PdMe(SS)(ER3)] (SS = S2CNR2 with R = Me, Et; SzCOEt, S2P(OR)2 with R = Et, Pr", Pr'; S2PPh2; EPR3 = PMePh2, PPh3, AsPh3) were prepared either by reaction of [Pd2Me2(PMePh2)2(~.t-C1)~]with salts of the dithio acid o r by stepwise reaction of [PdCI(Me)(cod)] with ER3 and the salt of the dithio l i g a r ~ d . ~Similarly, '~ reaction of phosphine(nicke1)halide complexes with thiomethyl salts Li[CHZSR] in a 1 :2 or 1 :4 molar ratio gave, respectively, the thiomethyl complexes [Ni(CH2SR)2(PBu3)2] (R = Me, Bu', Ph) and the homoleptic derivatives [Li(Et,0)~ N ~ ( C H ~ S B U[Li2Ni(CH2SMe)4]*xthf ')~], and [Li2Ni(CH2SPh)4l0xOEt2. Structures were confirmed by X-ray diffraction studies.30h Oxidative addition of bromothiophenes, C4H4- ,S (n = 1-4), to [Pd(PPh3)4] affords o-thienyl complexes ~~U~~-[P~B~(C~H~_,SC)(PP~~)~], which may be viewed as intermediates in the palladium catalysed regioselective reduction of b r o m ~ t h i o p h e n e s . ~The " ~ synthesis and NMR spectroscopy of the complexes cis-{Pt(CH2SR)2L2] and cisI .

2: Complexes Contuining Metul-Curbon a-Bonds of”(he Groups Iron, Cobult and Nickel

1 13

[Pt(CH2SR)2R’(PPhn)] (R = Me, Ph, C6H4Me-4, L = PPh3, PMe3, PMe2Ph, PMePh2; L2 = dppe, dmpe, dcpe, dppm; R’ = Me, C6H4Bu‘-4, CHZCMezPh, CH2SiMe2Ph, CH2SiMe3) have been described.308 The solution dynamics of a trimethyl platinum( IV) thiomethyl-substituted oxaline complex were studied in detail by NMR spectroscopy309 and the kinetics of the substitution reactions of the complexes trans-[PtCl(R)(SR’2),1 (R = panisyl, mesityl) with a variety of nucleophiles were investigated by variable temperature and pressure stopped flow ~ p e c t r o p h o t o m e t r y . ~Hydrosilylation ’~ and dehydrogenative silylation reactions catalysed by the methyl complexes [PdMe(L)(phen)][B{C6H3(CF3)2-3,5}4](L = OEt2, Me3SiC = CSiMe) were studied by NMR and labelling experiment^.^" A family of o,n-bimetallic complexes, [Cr((q5-SC4H1)PtL2(q‘-SC4H3)}(C0)3] (L = CO, PMe3; L2 = dppe) were obtained by reaction of cis-[PtC12L2] with [Cr(q5-SC4H3Li)(C0),1 and characterised by an X-ray diffraction analysis for the compound having L2 = (CO)(PMe3).312 Phosphorus coordinated, substituted (2-aminopheny1)phosphine complexes cis-[PtMe2L2] (L = 2-H2NC6H4PPhR; R = H, Me, Ph) have been prepared by reaction of [PtMe2(cod)] with L. A novel facile rearrangement of cis-[PtMe2(2H 2N C6H4PPh2)] to cis-[Pt Me(2- H N C6H4PPh2)(2-H2NC6H4PPh2)] with elimination of methane was observed. Monomethyl complexes [PtCl(Me)(L)] were similarly prepared from[PtCI( Me)(cod)] and react with HCI t o give dichloro derivatives [PtC12(L)]. These in turn afford the potential anticancer agents [Pt(C204)(L)]upon treatment with sodium ~ x a l a t e . ~ ’ ~ cis-Bis(heteroaryl) complexes cis-[1\5i { CN (CH3)N=C(CI)c(R ) } (bpy)] (R = CH3, CH3C02) have been prepared from the corresponding 3,5-dichloro-lmethylpyrazole by reaction with [ N i ( ~ o d ) ~ viu ] , oxidative addition of a C-Cl bond. l 4 The palkidiwm(11) azido complexes [PdMe(N3)L2] ( L = PMe3; L2 = dppm, dppe, dppp, bpy) were synthesised by reaction of NaN3 with [PdMe(OCOCF3)(tmeda)] followed by addition of L or L2. 1,3-Dipolar addition of isocyanides, RNC, to the azido ligand affords complexes of the type trans[PdMe{C=NN=NN(R)}(PMe3)2] (R = CMe3, C6H11 , C6H3Me2).3’5A series of and [Pd(Ar)(NAr’,)(dppf)] { dppf amido complexes, tran~-[Pd(Ar)(NAr’~)(PPh~)~] = bis(dipheny1phosphino)ferrocene) , have been prepared by reaction of aryl(halide)palladium complexes with the metal amide. Thermolysis of these compounds in the presence of PPh3 leads to C-N bond-forming reductive elimination affording arylamines and zerovalent palladium Activation of a C-H bond of acetone was observed in the reaction of cis[PtC12(NCMe)2] with bpy in acetone, yielding the acetonyl complex [PtCl(CH2COCH3)( bpy)] which was characterised by an X-ray diffraction Reaction of methyl vinyl ketone and methyl acrylate with [Pt(q3C H 3CHC6H 5 ) { Bu12P(CH 2)3PBuL2I[BF4] gave the complexes [Pt R(dbbp)][ BF4] (R = CH2CH2COCH3, CH2CH2C02CH3), while dimethyl maleate or dimethyl fumarate afforded [Pt { CH(C02CH3)CH2CO(OCH3)}( d b b ~ ) ] [ B F q ] . ~ ’ ~ Isocyanides, CNR (R = But, CH2Tosyl, C6H3Me2-2,6), insert into the Pd-C bonds of complexes of the type [PdCI(Me)(NN)] affording

114

Organometallic Clzemistry

[PdCI(C(=NR)Mef(NN)] viu a mechanism involving reversible substitution of the halide by the isocyanide, followed by rate-determining methyl migration.319 Reactions of [PdX2(cod)](X = CI, Br) with Ph3Sb result in C-Sb bond activation with formation of the complexes trcms-[PdX(Ph)(SbPh3)2].320 The bulky alkyl groups mesityl and trimethylsilylmethyl have been used to stabilise the mononuclear compounds [PdR2(dppm)] which are obtained from reactions of [PdX2(dppm)](X = C1, Br) with the appropriate Grignard reagent. With smaller groups, the A-frame complexes [Pd2R2(p-X)(p-dppm)2]were obtained. 32 A variety of cationic alkyl(a1kene) complexes of platinum( II), [PtR(alkene)(NN)] ( N N = phen, daph, daethyph, daproph) were prepared by treating the species [PtCIMe(NN)] with Ag[BF4] in the presence of the alkene, or by oxidative addition of a trialkyloxonium salt to the compound [Pt(phen)(dmf)] and subsequent reaction with the alkene. The fluxionality of these species in solution was discussed.322 The ability of new aryl(nicke1)phosphine complexes containing bidentate N,Ocoordinated ligands (4-nitropyridine-2-carboxylate,2-pyrazinecarboxylate1 4methoxypyridine-2-carboxylate)to polymerise ethene was demonstrated. The nature of the product, high molecular weight or a mixture of polymer and oligomer, is dependent on the basicity of the chelate l i g a r ~ d . ~ ~ ~ The non-linear optical properties of a number of new mono- and di-nuclear nickel(11) o-acetylide complexes, [Ni(C = CR)(PPh3)(q-C5H5)] and [ f Ni(PPh3)(q326 CSHS)(C= C)}2CR], have been in~estigated.’~~

Reaction c f 2,2‘-diethynyltolan with [PtC12(tht)] yielded the yellow tetraalkenyl complex 68,which upon treatment with HgC12 gave a ‘double tweezer’ compound with HgC12 moieties bridging cis C = C bonds.327The platinadehydrobenzoannulene 69 was obtained from the corresponding polyyne by treatment with Me3SnNMe2 and cis-[PtCI,(PEt3)2]. The trtrns geometry was confirmed by an Xray crystal structure.328Dialkynyl and trialkynyl ethenes have been synthesised in less than six steps from 1-alkynes and either [Ni(cod)(PMe3)2] or [Ni(PMe3)4] with isolated yields better than 50%. A key step in these reactions is elimination

2: Complexes Contuining Metal-Curbonrr-Bonds of the Groups Iron, Cobult untl Nickel

I I5

of the metal by reductive C,C coupling from complexes like 70.329Zwitterionic complexes of the type [Ni{C(PMe3)=C(CICR)R}12(PMe3)](R = CMe3, SiMe3) are formed by the reactiou of lithium acetylides with [NiC12(PMe3)2]in the presence of iodine. These compounds provided the first examples with a Group I0 metal showing monodentate a-phosphonio-o-vinyl groups.330

A mixture of the aryl(acety1ide) complexes trans-[Pd(C= CPh)(C6H4R4)(PEt3)2] (R = Me, OMe, F) and the acetylene PhCrCCbH4X-4 were obtained from the reaction between rrans-[PdI(C~H4X-4)(PEt3)~] and [Cu(C = CPh)(PPh3)I4,and the structures were confirmed by X-ray crystallog ~ a p h y . Bis(acety1ide) ~~' complexes of the type [Pt(C z CC6H4R-4)2(Me2bpy)] (R = H, Me, NO2) have been prepared from [PtC12(Me2bpy)] by reaction with the acetylene in the presence of C U I / H N P ~ ~The ~ . ~related ~~ compounds [ P ~ ( C G C R ) ~ ( L (R ) ~ ] = But, Ph; L = PPh2CrCCPh, PPh2C=CBu') were obtained by displacement of cod from [Pt(C =CR)2(cod)]. Reactions of the latter species with the complexes cis-[M(C6~;5)2(thf)2] (M = Pd, Pt) led to a variety of polynuclear compounds.333Disubstituted electron rich alkynes react with truns(PtR(q2-E-Me02CCH=CHC02Me)(phen)][BF4] (R = Me, Et) to give stable alkyl(alkyne) complexes but the electron poor alkyne Me02CC = CC02Me inserts into the Pt-C(R) bond affording the o-vinyl complex [Pt{C(C02Me)=

C(Me)C02Me}(OH2)(phen)][BF4].334 Reactions of the 1-(alkynyl)platinum complexes cis-[Pt(C= CR)2L2] (L2 = dppe, dmpe, depe; R = Me, But, C(Me)=CH2, PhSiMe3) and cis-, truns[Pt(C= CR)(R')(PEt&] with trialkylboranes have been studied by "B, "P and ''Pt NMR spectroscopy and proceed by 1,l-organoboration involving cleavage of a Pt-C(acetylide) bond and formation of an alkenyl-borate likc intermediate. In most cases the resulting alkynyl complexes are not stable and decompose to either q2-alkyne or q 3-borylalkenePt(0) complexes.335 The q '-(exo-a1kylidene)cyclobutenone platinum complex trans[Pt{&C(CMe3)C(O)&C(CMe3))(H)(PPh3)2] was prepared by reaction of trans-[PtCl(H)(PPh3)2(thf)] with Ag[SbF6] followed by O=C(C = CMe& via addition of the Pt-H bond to one of the alkenyl substituents of the ketone and subsequent insertion of the second alkenyl substituent into the resulting Pt-C(a1kenyl) bond.336 Reaction of the aryl(triflate) [(S-B1NAP)PdPh(&H2CH2CH2kH2)][CF3SO3] with 2,3-dihydrofuran gave two isomers of [(S-BINAP)Pd(rl'-CHCH2CH2CH2~)(~CH2CH2CH2CH2)][CF3SO3] resulting

1 I6

Organomctallic Cliernistry

from addition of Pd-H to the dihydrofuran. Low temperature and mass spectroscopy experiments detected the intermediate complex [(S-BINAP)Pd { q I eHCH2CH(Ph)b}dCH2CH2CH2cH2][CF3SO3] formed by insertion of the dihydrofuran into the Pd-Ph bond.337 A new palladium catalysed three-component synthesis of conjugated dienes by coupling of alkynes with an organic halide and trimethyltin was described and the intermediate complexes characterised. Thus, reaction of €Pdz(dba)3] with dimethylbutynediolate and a bidentate amine (NN = Ar-bian, Ph-bip) gave the palladacycles [Pd{C(E)==C(E)d(E)=C(E)}(NN)]which oxidatively adds organic halides (RX) to give [PdX{q'-C(E)=C(E)C(E)=C(E)R}(NN)]. Treatment with Me4Sn then results in selective formation of 2,5-difunctionalised 2,4-hexadierioates.338 Treatment of the dianions mns-[Pt(C6F5)2(C = CBu1)2I2- with TI[N03] afforded the compounds t r a r ~ s - [ P t T l ~ ( C ~ F= ~ CBU')~] ) ~ ( C which were shown to have polymeric structures with alkynyl bridging ligands and Pt-TI interactions.339 and [Bu~N]~[P~(C,F,)~(S)] Similarly, the salts [BU~N][P~(C~F,)~(OCOCH~)(PP~~)(PP~~)] {S = MeOH, (CH3)2O} react with TI[N03] or TI[OCOCH3] to give the dimeric (C6F5)3Pt} 2{ (p2-O)(p3-OCCH3)T1} 21, which also displays Pt-TI salt [ B u ~ N ]{ ~ [ bonding.340 3

Carbene and Carbyne Complexes of Groups 8 , 9 and 10

The mechanism of formation of methoxy(amin0) and bis(amino) carbene complexes of platinum(I1) by nucleophilic attack of methoxide and amines on spectroscopy coordinated isocyanide has been i n v e ~ t i g a t e d 7342 . ~ ~ Photoelectron ' and density functional calculations on the electronic structure of bis(carbene) complexes of palladium and platinum showed that the bonding primarily involves o-donation from the carbene lone pairs into a metal (dz2+s) hybrid Electrochemical studies on the cobaltadithiolene complex [Co{S2C2(C02Me)2}(C(C02Me)2(q-C5H5)],which exists as an equilibrium mixture of alkylidene-bridged and ylide forms in solution, showed that both isomers undergo a one electron reduction but the radical anion from the alkylidenebridged form rapidly and irreversibly isomerises to the anion of the ylide form.344 Both C-CI bonds of CH2C12 oxidatively add to the complex [ R u ( H ) ~ ( H ~ ) ( P C Ygiving ~ ) ~ ] [RuCI2(CH2)(PCy3)2],providing the first example of such a process.345 A one-pot synthesis of heterocyclic carbene complexes of rhodium and iridium of the type [M(LCarb)(X)(cod)](&arb = imidazole, triazole, pyrazole, benzimidazole; X = halide) was reported and involves successive treatment of [MCl(cod)]2 with an excess of sodium methoxide and the heteroaromatic azolium salt. Carbonyl and phosphine derivatives are readily obtained.3467347 Stable palladium complexes [Pd12{ =cN(CH3)CH=Nfi(CH3)}2] were similarly obtained from [Pd(a~ac)2].~~* N-Functionalised carbene complexes of Rh(1) and Ru(II), [RhCI(L)(PPh3)2], [RhCl(L)(cod)] and [RuC12(L)(arene)] {L = CN(Me)CH2CH2NCH2CH20Me, CN(CH*CH20Me)CH2CH2NCH*CH2OMe}

2: Complexes Contuining Metul-Curbon a-Bonds oftlie Groups Iron, Cobalt and Nickel

I 17

were synthesised by reactions of [RhCI(PPh3)3],[RhCl(cod)]2 and [RuC12(arene)]2 with the electron rich alkenes L=L. The new complexes are efficient catalysts for the cyclopropanation of diazoalkane derivatives with styrene.349 A new series of carbene complexes of rhodium, rruns-[RhCI(=CRR')(L)z] (L = tertiary phosphine, arsine or stibene), have been prepared through reactions of diazoalkanes, RR'CN2, with the complexes ~rans-[RhCI(q-C2H~)(SbPr'~)~] and subsequent displacement of the stibine with phosphines, arsines or SbEt3.350 Diazoalkanes and [OsCI(H)(CO)(PPr'3)2] gave the hydrido(carbene) complexes [OSCI(H)(=CHR)(CO)(PP~'~)~] (R = H, Ph, C02Et, SiMe3) which have a distorted octahedral geometry with the hydride and carbene ligands in trans afforded the first highsites.35' Reaction of Ph2CN2 with [cali~[4](0Me)2(O)~Fe] spin iron(I1) carbene supported exclusively by an oxygen donor set, [calix[4](0Me)2(0)2Fe(=CPh2)].352 Tetramethyldibenzotetraazaannulene (H2tmtaa) stabilised carbene complexes [Fe(=CR2)(tmtaa)] have also been prepared and the stability of such complexes is dependent on the carbene s ~ b s t i t u e n t Novel .~~~ palladium, platinum and rhodium carbene complexes were obtained by reactions of dithiones and diselenones with [Pd(PPh3)4], [Pt(PPh3)4] and [RhCI(PPh&] and the structures were confirmed by X-ray diffraction The (C,X)-chelate methoxycarbene complexes [Fk{q2-C(OMe)C6H4-oX)(CO)(q-C5Me5)][OTf] (X = OMe, CI) were prepared from the corresponding carbene complexes [Fe { =C(OMe)C6H4-a-X 1(CO)(q-C5Me5)][0Tf]. Treatment with [Bun4N]I gave the neutral iodo(carbene) complexes [Fe{q '-C(OMe)C6H4-& X>I(CO)(q-C5Me5)]. Various substituted complexes were formed by ligand exchange reactions of the chelate complexes.355Alkylation of the acyl complexes generated by reaction of [Fe2(CO),] with isobutene diol afforded the chelated allyl(iron)carbene complexes 71, having a centrally tethered x-ligdnd. These react with nucleophiles to give either 4-substituted alkene(carbene) complexes or

(71) X = 0, NMe, NCH2Ph, NBu'

substituted tricarbonyliron derivatives.356."' Reaction of [PtMe2(tmeda)] with [B{C6H3(CF3)2-3,5J4]at -70 OC gives the cationic complex [PtMe(OEt2)(tmeda)]+ which at room temperature eliminates methane to yield the hydrido(carbene) complex [Pt { =C(OEt)Me) H(tmeda)]B {C6H3(CF3)2-3,5)4],via intermolecular C-H activation as demonstrated by labelling experiments.358 The neutral bis(carbene) complexes trans[Pt{=C(NPr2)NHC6H4Me-4)212] and rrans-[Pt f =C(NHPr)NHC6H3Me-4}{ =C(NHPr)NHC6H4Me-4)21] were prepared by treatment of truns[Pt12(CNC6H4Me-4)2] with the amines HNPr2 and H*NPr, respectively.

118

Orgunornerullic Chemistry

Dialkoxy(amino)carbene complexes were similarly prepared by treatment with alcohols.359 Propargyl alcohols, H C = CCRR'(OH), react with [Fe(CO).~(q-CsMe5)1+to give the a,&unsaturated acyl complexes [Fe(C(0)CH2CRR'(OMe))(CO)2(qC5Me5)]and [Fe(CH=CRR')(C0)2(q-C5Me5)],which are converted to the corresponding alkenyl(carbene) complexes cisand trans-[Fe{ =C(OMe)CH=CRR'}(C0)2(r)-C5Me5)], via o-methylation with CF3S03Me.360 The ruthenium alkenyl(carbene) complex [Ru { =C(OMe)CH=CH(2-MeOC6H4))Cl(PMe3)(q6-C6Me6)][PF6] was prepared from the reaction of [RuC12(PMe3)(q6-C6Me6)] with H C = CCH(OH)(2-MeO-C6H4) and Na[PF6]. Bimetallic derivatives [(q6-C6Me6)(PMe3)ClRu{ =C(OMe)CH=CH(q6-2-MeC6H4)Cr(CO)3}][PF6] and [(qh-C6Me6)(PMe3)CIRu{ =C(OMe)CH=CMe( q6C6H5)Cr(CO)3}][PF6] were similarly obtained by activation of the substituted arene chromium tricarbonyl complexes with [RuCI2(PMe3)( Ferrocene containing methoxy carbene complexes [Ru {=C(OMe)CH*R)CI(L)(qh-C6Me6)][PF6] have been synthesised by reaction of [RuC12(L)(q6-ChMe6)]with alkynes in the presence of Na[PF6].362 An improved ~ ~ ) been ~] high yield synthesis of the hydride complex [ R u ( H ) ~ ( H ~ ) ( P C has reported and its use t o prepare vinyl and alkyl carbene complexes demon~ t r a t e d . ' " ~Reaction , ~ ~ ~ of complexes of this type with cyclobutenes gave alkyli-

dene complexes (e.g. 72) which were shown to be active olefin metathesis catalysts. 365 The ethoxy(ary1)carbene complexes [(OC)3Fe(1,4-q:5,8-q-C8H,)Fe(=C(OEt)Ar}(C0)2]were formed in the reaction of [ { Fe(C0)3}2(q4-C8H8)] with aryllithium reagents and subsequent alkylation with [Et3O][BF4] in aqueous solution.366 Treatment of the vinyl(carbene) complex [Fe{ q3-C(OMe)C(C02Me)=CH(C02Me)}(C0)3]with bidentate aromatic amines (l,lO-phen, 2,2'-dipyridyl) afforded the ferracyclopentenone complexes 73.367Stepwise reaction of [FeBr(CO)z(qMe02C

Moue

(73) NN = 1,lO-phen, 2,2'-dipyridyl

2: Complexes Contuining Metal-Curhon IT- Bonds of’tlie Groups Iron, Cohult cmcl Nickel

1 19

C5H5)]with 2-trimethylstanyl- 1,3,5-cycloheptatriene and [Cr(CO),(NCEt),] gave the heterobimetallic complex [(CO)z(q-C5H5)Fe(p-q1:q6-C7H&h(CO),].

L

(74)

Hydride abstraction with [Ph3C][BF4]yielded the first heterobimetallic cycloheptatrienylidene complex 74.368 Treatment of the q2-aldehyde complexes [Os{q2-OCH(R)}(NH,)5][(OTf),l (R = H, Me, But, Ph, C3H5) with CH30Tf affords the carbyne complexes [OS(ECR)(NH~)~][(OT~)~].~~~

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2: chnplexes Contuining Metul-Ccirhon 6 -Bonds of the Groups Iron, Cobult cind Nickel

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2: Complexes Containing Melul-Carbon a-Bonds of the Groups Iron, Cobalt and Nickel 110.

111.

112.

113. 114. 115. 116. 117. 118.

119. 120. 121. 122. 123. 124. 125. 126. 127. 128. 129. 130. 131.

132. 133. 134. 135. 136. 137.

123

M. I. Bruce, P. Hinterding, M. Ke, P. J. Low, B. W. Skelton and A. H. White, Chem. Cummun., 1997, 715. C. Slugovc, V. N. Sapunov, P. Wiede, K. Mereiter, R. Schmid and K. Kirchner, J. Chem. Soc., Dalton Trans., 1997,4209. C. Gemel, G. Kickelbick, R. Schmid and K. Kirchner, J. Chem. Soc., Dulton Truns., 1997,2113. H. Werner, T. Brdun, T. Daniel, 0. Gevert and M. Schulz, J. Organomet, Chem., 1997,541, 127. T.-F. Wang and C.-Y. Lai, J. Organomet. Chem., 1997,545-546, 179. R. D. Arasasingham, A. L. Balch, M. M. Olmstead and S. L. Phillips, Inorg. Chim. Acta, 1997, 263, 16 1 . C. J. Zeigler and K. S. Suslick, J. Organomet. Cliem., 1997,528,83. F. Coat, M.-A. Guillevic, L. Toupet, F. Paul and C. Lapinte, Organometallics, 1997, 16, 5988. 0.Garca-Mellado, R. Gutiirrez-Perez, C. Alvarez-Toledano, R. A. Toscano and A. Cabrera, Polyhedron, 1997, 16,2979. P. P. Patel, M. E. Welker, L. M. Liable-Sands and A. L. Rheingold, Organornetallit's, 1997,16,4519. C. Bianchini, J. A. Casares, R. Osman, D. I. Pattison, M. Peruzzini, R. N. Perutz and F. Zanobini, Orgunometallics, 1997, 16,461 1 . M. Bourgalt, A. Castillo, M. A. Esteruelas, E. Ofiate and N. Ruiz, Orgunometullics, 1997, 16, 636. A. Gisler, M. Schaade, E. J. M. Meier, A. Linden and W. von Philipsborn, J. Orgunomet. Chem., 1997,545546, 3 1 5. M. J. Albeniz, M. L. Buil, M. A. Esteruelas and A. M. Lopez, J. Organomet. Chem., 1997,545546,495. M. J. Albeniz, M. A. Esteruelas, A. Lledos, F. Maserus, E. Oiiate, L. A. Oro, E. Sola and B. Zeier, J. Chem. Sot'., Dalton Trans., 1997, 181. Y. Kawata and M. Sato, Orgunometallics, 1997, 16, 1093. 1.-Y. Wu, J. T. Lin, J. Luo, S.-S.Sun, C.-S. Li, K. J. Lin, C. Tsai, C.-C. Hsu and J.L. Lin, Orgunornetallit's, 1997, 16,2038. M. Olivan, 0.Eisenstein and K. G. Caulton, Orgunometallics, 1997, 16,2227. M. P. Gamasa, J. Gimeno, C. Gonzalez-Bernardo, J. Borge and S. Garca-Granda, Organometullics, 1997, 16, 2483. M . A. Esteruelas, F. Liu, E. Ofiate, E. Sola and B. Zeier, Orgunometallics, 1997, 16, 29 19. V. Cadierno, M. P. Gamasa, J. Gimeno, J. Borge and S. Garca-Granda, Organometallies, 1997, 16, 3178. A. Santos, J. Lopez, A. Galan, J. J. Gonzrilez, P. Tinoco and A. M. Echavarren, Organometullics, 1997, 16, 3482. D. Touchard, P. Haquette, S. Guesmi, L. Le Pichon, A. Daridon, L. Toupet and P. H. Dixneuf, Organornetallit's,1997, 16,3640. R. F. Winter and F. M. Hornung, Organometullics, 1997, 16,4248. M. Akita, M.-C. Chung, A. Sakurai, S. Sugimoto, M. Terada, M. Tanaka and Y. Moro-oka, Orgunometullics, 1997, 16,4882. M. Bassetti, P. Casellato, M. P. Gamasa, J. Gimeno, C. Gonzalez-Bernard0 and B. Martn-Vaca, Organometallics, 1997, 16, 5470. M. A. J. Tenorio, M. J. Tenorio, M. C. Peurta and P. Valerga, Organometallics, 1997,16,5528. M. Sato, Y. Hayashi, T. Tsuda and M. Katada, Inorg. Cliim. Acta, 1997,261, 11 3.

124 138. 139. 140. 141. 142. 143. 144. 145. 146. 147. 148. 149. 150.

151. 152. 153. 154. 155. 156. 157. 158. 159. 160. 161. 162. 163. 164. 165. 166. 167. 168. 169. 170. 171. 172. 173. 174.

Orgunometullic Cliemistry

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2: Complexes Contuining Metul-Curbon a-Bonds of the Groups Iron, Cobalt and Nickel

I25

175. J.-Y. Watanabe and J.-I. Setsune, Orgunometullics, 1997, 16, 3679. 176. Y. Cao, J. L. Petersen and A. M. Stolzenberg, Inorg. Chim. Actu, 1997,263,97. 177. N. E. Brasch, M. S. A. Hamza and R. van Eldik, Inorg. Cliem., 1997,36, 3216; N. E. Brasch, F. Miiller, A. Zahl and R. van Eldik, Inorg. Chem., 1997,36,4891. 178. T. M. Brown, A. T. Dronsfield and A.-S. Wilkinson, Inorg. Chim. Actu, 1997, 262, 97. 179. A. I. Kruppa, M. B. Taraban, T. V. Leshina, E. Natarajan and C. B. Grissom, Inorg. Chem., 1997,36, 758. 180. L. Rosi, A. Salvini, M. Bianchi, P. Frediani and F. Piacenti, J. Orgunomet. Chem., 1997,535, 143. 181. A. van Rooy, P. C. J. Kamer and P. W. N. M. van Leeuwen, J. Orgunomet. Chem., I997,535,20 I , 182. E. Fooladi and M. Tilset, Inorg. Chem., 1997,36, 6021. 183. J. C. M. Rilter and R. G. Bergman, J. Am. Chem. Soc., 1997,119,2580. 184. C . Hinderling, D. A. Plattner and P. Chen., Angew. Cliem. Int. Ed. Engl., 1997, 36, 243. 185. D. P. Paterniti and J. D. Atwood, Chem. Commun., 1997, 1665. 186. N. Dunwoody and A. J. Lees, Organometullics, 1997, 16, 5770. 187. J. S. Bridgewater, B. Lee, S. Bernhard, J. R. Schoonover and P. C. Ford, Orgunometullics, 1997, 16, 5592. 188. M. J. Tanner, M. Brookhart and J. M. DeSimone, J. Am. Chem. Soc., 1997, 119, 761 7. 189. M, P. Garcia, M. V. Jimenez, A. Cuesta, C. Siurana, L. A. Oro, F. J. Lahoz, J. A. Lopez, M. P. Catalan, A. Tripicchio and M. Lanfranchi, Orgunometullics, 1997, 16, 1026. 190. M.-A. Guillevic, A. M. Arif, I. T. Horvath and J. A. Gladysz, Angew. Chem. Int. Ed. Engl., 1997,36, 1612. 191. R. P. Hughes, T. Le Husebo, B. J. Holliday, A. L. Rheingold and L. M. LiabieSands, Orgunometullics, 1997, 16, 5 . 192. R. P. Hughes, T. Le Husebo, B. J. Holliday, A. L. Rheingold and L. M. LiableSands, J. Orgunomet. Chem., 1997,548, 109. 193. B. L. Edelbach and W. D. Jones, J. Am. Chem. Sue., 1997,119,7734. 194. R. P. Hughes, D. C. Lindner, A. L. Rheingold and L. M. Liable-Sands, J. Am. Chem. Sue., 1997,119, 11544. 195. B. Bogdanovc, W. Leitner, C. Six, U. Wilczok and K.Wittmann, Angew. Chem. Int. Ed Engl., 1997,36,502. 196. D. D. Wick and W. D. Jones, Inorg. Chem., 1997,36,2723. 197. R Zhou, C. Wang, Y. Hu and T. C. Flood, Orgunometullics, 1997,16,434. 198. P. J. Alaimo, B. A. Arndtsen and R. G. Bergman, J. Am. Chem. Soc., 1997, 119, 5269. 199. A. Vigalok, H.-B. Kraatz, L. Konstantinovsky and D. Milstein, Chem. Eur. J . , 1997, 3,253. 200. X. Yan, R. J. Batchelor, F. W. B. Einstein, X. Zhang, R. Nagelkerte and D. Sutton, Inorg. Chem., 1997,36, 1237. 201. I. Nagy-Gergely, G. Szalontai, F. Ungvary, L. Marko, M. Moret, A. Sironi, C. Zucchi, A. Sisak, C. M. Tschoerner, A. Martinelli, A. Sorkau and G. Palyi, Orgunometullics, 1997, 16,2740. 202. H. F. Haarman, J. M. Ernsting, M. Kranenburg, H. Kooijman, N. Veldman, A. L. Spek, P. W. N. M. van Leeuwen and K. Vriezu, Orgunometullics, 1997, 16, 887.

126

Orgunomerullic Chemistry

203.

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204. 205. 206. 207. 208. 209. 210. 21 1. 212. 213. 214. 215. 216. 217. 21 8. 219. 220.

221. 222. 223. 224. 225. 226. 227. 228. 229. 230.

2: Complexes Containing Metul-Curbon a-Bonds of lhe Groups Iron, Cobult and Nickel 231. 232. 233. 234. 235. 236. 237. 238. 239. 240. 241. 242. 243. 244. 245. 246. 247. 248. 249. 250. 251. 252. 253. 254. 255. 256. 257. 258. 259. 260. 261. 262.

127

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128

Orgunometullic Chemistry

263.

V. F. Kuznetsov, C. Bensimon, G. A. Facey, V. V. Grushin and H. Alper, Orgunometullics, 1997, 16,97. D. Steinborn, H. Junicke and C. Bruhn, Angew. Chem. Int. Ed Engl., 1997,36, 2686. A. Romerosa, J. Suarnez-Varela, M. A. Hidalgo, J. C. Avila-Roson and E. Colacia, Inorg. Chem., 1997, 36, 3784. P. J. Chmielewski and L. Latos-Grazynski, Inorg. Chem., 1997,36, 840. M. Ohff, A. Ohff, M. E. van der Boom and D. Milstein, J. Am. Chem. Soc., 1997, 119, 11687. S. E. Denmark, R. A. Stavenger, A.-M. Fauscher and J. P. Edwards, J. Org. Clzem., 1997,62,3375. 0. Lopez, M. Crespo, M. Font-Bardia and X. Solans, Orgunometullics, 1997, 16, 1233. H. A. Jenkins, G . P. A. Yap and R. J. Puddephatt, Orgunometullics, 1997, 16, 1946. J. Vicente, J.-A. Abad, B. Rink, F.-S. Hernandez and M. C. R. de Arellano, Orgunometullics, 1997, 16, 5269. A. de Renzi, I. Orabona and F. Ruffo, Inorg. Chim. Actu, 1997,258, 105. V. G. Albano, M. Monari, I. Orabona, F. Ruffo and A. Vitagliano, Inorg. Chitn. Actu, 1997,265, 35. F. Neve, A. Crispini and S. Campagna, Inorg. Chem., 1997,36,6150. Y. Fuchita, K. Yoshinaga, Y. Ikeda and J. Kinoshita-Kawashima, J. Cizem. Soc., Dalton Truns., 1997,2495. M. Gianini, A. von Zelewsky and H. Stoeckli-Evans, Inorg. Chem., 1997,36,6094. L. R. Falvello, S. Fernandez, R . Navarro, 1. Pascual and E. P. Urriolabeita, J. Chem. Sue., Dalton Truns., 1997, 763. P. Braunstein, J. Pietsch, Y. Chauvin, A. Decian and J. Fischer, J. Orgunomet. Chem., 1997,529, 387. L. R . Falvello, S. Fernandez, R. Navarro and E. P. Urriolabeitia, Inorg. Chem., 1997,36, 1 136. M. W. Avis, M. Goosen, C. J. Elsevier, N. Veldman, H. Kooijman and A. L. Spek, Inorg. Chim. Actu, 1997,264,43. M. W. Avis, M. E. van der Boom, C. J. Elsevier, W. J. J. Smeets and A. L. Spek, J. Orgunornet. Clzem., 1997,527,263. G. J. P. Britovsek, K. J. Cavell, M. J. Green, F. Gerhards, B. W. Skelton and A. H. White, J. Orgunomet. Chem.. 1997,533, 201. Y . J. Wu, L. Ding, H. X. Wang, Y. H. Liu, H. Z. Yuan and X. A. Mao, J. Organomet. Chem., 1997,53549. C. Lopez, R . Bosque, X. Solans and M. Font-Barda, J. Orgunornet. Cizem., 1997, 539,99. M. A. Bennett, M. Glewis, D. C. R. Hockliss and E. Wenger, J. Chem. Soc., Dalton Truns., 1997,2955. S. Okeya, K . Taniguchi, J. Nishimura, Y. Kusuyama, 1. Nagasdwa and Y. Kushi, Chem. Lett., 1997, 1095. D. P. Lydon and J. P. Rourke, Chem. Cummun., 1997, 1741. D. Steinborn, M. Gerish, F. W. Heinemann and C. Bruhn, Cizem. Cummun., 1997, 843. C. M. Bates, P. K. Khanna, C. P. Morley and M. Di Vaira, Chem. Commun., 1997, 913. D. Zhang, D. B. McConville, C. A. Tessier and W. J. Youngs, Orgunometullics, 1997, 16,824.

264. 265. 266. 267. 268. 269. 270. 271. 272. 273. 274. 275. 276. 277. 278. 279. 280. 281. 282. 283. 284. 285. 286. 287. 288. 289. 290.

2: Cumplexes Containing Metul-Curbon a-Bonds of the Groups Iron, Cobalt and Nickel 291. 292. 293. 294. 295. 296. 297. 298. 299. 300. 301. 302. 303. 304. 305. 306. 307. 308. 309. 310. 31 I . 312. 313.

314. 315. 316. 317. 318. 319. 320.

129

A. Santi, B. Milani, G. Mestroni, E. Zangrdndo and L. Randaccio, J. Organomet. Chem., 1997,545,89. R. Han and G. L. Hillhouse, J. Am. Chem. Soc., 1997,119,8135. C. Mateo, C. Fernandez-Rivas, A. M. Echavarren and D. J. Cardenas, Organometallics, 1997, 16, 1997. Y. Tanaka, H. Yamashita, S. Shimada and M. Tanaka, Organometallics, 1997, 16, 3246. J. B. Sheridan, K. Temple, A. J. Lough and I. Manners, J. Chem. Soc., Dulton Trans., 1997,7 I 1. A. Ohsuka, T. W. Wardhana, H. Kurosawa and I. Ikeda, Organometallics, 1997, 16, 3038. A. S. K. Hashmi, F. Naumann and J. W.Bats, Chem. Ber., 1997,130, 1457. A. S. K. Hashmi, F. Naumann, R. Probst and J. W. Bats, Angew. Chem. Int. Ed Engl., 1997,36, 104. G. Ferguson, J. F. Gallagher, A. J. McAlees and R. McCrindle, Orgunometullics, 1997,16, 1053. J. Albert, J. Cranell, J. Manguez, G. Muller, D. Sainz and P. Valerga, Organometullics, 1997, 16, 3566. F. M. Alas, T. R. Belderran, M. Paneque, M. L. Poveda, E. Carmona and P. Valerga, Orgunometallics, 1997, 16, 301. M. van der Sluis, V. Beverwijk, A. Termaten, E. Gavrilova, F. Bickelhaupt, H. Kooijman, N. Veldman and A. L. Spek, Orgunomefullics, 1997, 16, 1144. P. Leoni, F. Marchetti and M. Paoletti, Orgunometallics, 1997, 16,2146. L.-B. Han, N. Choi and M. Tanaka, J. Am. Chem. Sue., 1997,119, 1795. S. Narayan, V. K. Jain and S. Chaudhury, J. Organomet. Chem., 1997,530,101. F. Becke, T. Riifer, R. Boese, D. Blaser and D. Steinborn, J. Orgunomel. Chem., 1997,545-546, 169. Y. Xie, S. C. Ng, B.-M. Wu, F. Xue, T. C. W. Mak and T. S. A. Hor, J. Orgunornet. Chem., 1997,531, 175. D. G. Griffiths, D. I. MacTavish, N. A. H. Male, D. A. Tocher and G. B. Young, J. Chem. Soc., Dalton Truns., 1997, 3373. P. J. Heard an! D. A. Tocher, J. Orgunornet. Chem., 1997,549,295. 0.F. Wendt, A. Oskarsson, J. G. Leipoldt and L. I. Elding, Inorg. Chem., 1997, 36, 4514. A. M. Lapointe, F. C. Rix and M. Brookhart, J. Am. Chem. Soc., 1997,119,906. A. du Toit, M. Landman and S. Lotz, J. Chem. Sue., Dulton Truns., 1997,2955. S . Chatterjee, D. C. R. Hockless, G. Salem and P. Waring, J. Chem. Soc., Dulton Truns., 1997,3889. Y . Murakami and T. Yamamoto, fnorg. Chem., 1997,36,5682. Y.-J. Kim, D.-H. Kim. J.-Y. Lee and S.-W. Lee, J. Orgunomet. Chem., 1997, 538, 189. M. S. Driver and J. F. Hartwig, J. Am. Chem. Soc., 1997,119,8232. L. R. Falvello, R. Garde, E. M. Miqueeiz, M. Tomas and E. P. Urriolabeitia, Inorg. Chim. Actu, 1997,264, 297. G. S. Mhinzi, L. E. Crascall and J. L. Spencer, Inorg. Chim. Acta, 1997,265, 83. J. G. P. Delis, P. G . Aubel, K. Vrieze, P. W. N. M. van Leeuwen, N. Veldman, A. L. Spek and F. J. R. van Neer, Orgunometallics, 1997,16,2948. A. Mentes, R. D. W. Kemmitt, J. Fawcatt and D. R. Russell. J. Organomel. Chem., 1997,528, 59.

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321.

R. A. Stockland, Jr., G. K. Anderson and N. P. Rath, Orgunometullics, 1997, 16, 5096. M. Fusto, F. Giordano, I. Orabona, F. Ruffo and A. Panunzi, Orgunometullics, 1997,16,598 1. S. Y. Desjardins, K. J. Cavell, J. L. Hoare, B. W. Skelton, A. N. Sobolev, A. H. White and W. Keim, J. Orgunomet. Chem., 1997,544, 163. I. R. Whittall, M. G. Humphrey, S. Houbrechts, J. Maes, A. Persoons, S. Schmid and D. C. R. Hockless, J. Orgummet. Chem., 1997,544, 277. I. R. Whittall, M. P. Cifuentes, M. G. Humphrey, B. Luther-Davies, M. Smaoc, S. Houbrechts, A. Persoons, G. A. Heath, and D. Bogsanyi, Orgunometallics, 1997, 16, 263 1. R. H. Nuulty, M. P. Cifuentes, M. G. Humphrey, S. Houbrechts, C. Boutton, A. Persoons. G. A. Heath, D. C. R. Hochless, B. Luther-Davies, and M. Smaoc, J. Chem. Soc., Dulton Truns., 1997,4167. D. Zhang, D. B. McConville, C. A. Tessier and W. J. Youngs, Orgunometullics, 1997, 16, 824. H.-F. Kiein and A. Petermann, Inorg. Cliim. Actu, 1997,261, 187. H.-F. Klein, M. Heiden, M. He, T. Jung and Rohr, Orgunometullics, 1997, 16, 2003. K. Osakada, R. Sakata and T. Yamamoto, Organometallics, 1997, 16,5354. S. L. James, M. Younus, P. R. Raithby and J. Lewis, J. Orgunomet. Chem., 1997, 543, 145. T. Afra, L. R. Falvello, S. Fernandez, J. Fornies, E. Lalinde, A. Martin and M. T. Moreno, Orgunometullics, 1997, 16, 5923. M. E. Cucciolito, V. De Felice, I. Orabona and F. Ruffo, J. Chem. Soc., Dolton Trans., 1997, 1351. B. Wrackmeyer and A. Sebdld, J. Orgunomet. Chem., 1997,544, 105. A. C. Dema and C. M. Lukehart, Inorg. Cliim. Actu, 1997,264, 193. K. K. Hii, T. D. W. Claridge and J. M. Brown, Angew. Clzem. Int. Ed. Engl., 1997, 36,984. R. van Belzen, H. Hoffmann and C. J. Elsevier, Angew. Clwm. Int. Ed Engl., i 997, 36, 1743. I. Ara, J. R. Berenger, J. Fornies, J. Gomez, E. Lalinde and R. 1. Merino, Inorg. Chem., 1997,36,6461. R. Uson, J. Fornies, M. Tomas and R. Garde, Inorg. Chem., 1997,36, 1383. L. Canovese, F. Visentin, P. Uguagliati and B. Crociani, J. Orgunornet. Chem., 1997, 543, 145. L. Canovese, F. Visentin, P. Uguagliati, B. Crociani, and F. Di Bianca, J. Orgunornet. Clwm., 1997,53569. J. C. Green, R. G. Scurr, P. L. Arnold and F. G. N. Cloke, Cliem. Commun., 1997, 1963. C. Takayama, M. Kajitani, T. Sugiyami, T. Akiyama, K. Simizu and A. Sugimoni, Orgunometullics, 1997, 16, 3503. M. Olivan and K. G. Caulton, Chem. Commun., 1997,1733. C. Kocher and W. A. Herrmann, J. Orgunomet. Chem., 1997,532,261. W. A. Herrmann, L. J. Gooben and M. Spiegler, J. Orgunomet. Chem., 1997, 547, 357. W. A. Herrmann, J. Fischer, K. Ofele and G. R. J. Artus, J. Orgunomet. Chem., 1997,530,259. B. Cetinkaya, 1. Ozdemir and P. H. Dixneuf, J. Orgunomet. Chem., 1997, 534,

322. 323. 324. 325.

326.

328. 329. 330. 331. 332. 333. 334. 335. 336. 337. 338. 339. 340. 341. 342. 343. 344. 345. 346. 347. 348. 349.

153.

2: Complexes Contuining Metal-Curhon a-Bonds of the Groups Irun. Cobalt uncl Nickel

350. 351. 352. 353. 354. 355. 356. 357. 358. 359. 360. 361. 362. 363. 364. 365. 366. 367. 368. 369.

I3 1

H. Werner, P. Schwab. E. Bleuel, N. Mahr, P. Steinert and J. Wolf, Chem. Eur. J., 1997,3, 1375. H. Werner, W. Stuer, M. Laubender. C. Lehmann and R . Herbst-Irmer, Orgunometullics, 1997, 16, 2236. M. Giusti, E. Solari, L. Giannini, C. Floriani, A. Chiessi-Villa and C. Rizzoli, Orgunometullics, 1997, 16, 56 10. A. Klose, E. Solari, C. Floriani, N. Re, A. Chiessi-Villa and C. Rizzoli, Chem. Commun., 1997,2297. F. Iwasaki, H. Nishiyama. M. Yasui. M. Kusamiya and N. Matsumura, Bull. Chem. Soc. Jpn., 1997,70, 1277. G. Poignant, S. Nlate, V. Guerchais, A. J. Edwards and P. R. Raithby, Orgunomelullics, 1997, 16, 124. W. Fortsch, F. Hampel and R . Schobert, Chem. Ber., 1997,130,863. J. Bohmer, F. Hampel and R. Schobert, Synthesis, 1997,661. M. W. Holtcamp, J. A. Labinger and J. E. Bercaw, J. Am. Chem. Soc., 1997, 119, 848. S.-W. Zang, R. Ishii, F. Motoori, T. Tanaka, Y. Takai, M. Sawada and S. Takahashi, Inorg. Chim. Actu, 1997,265,75. C. Poignant, F. Martin and V. Guerchais, Synlett., 1997,913. N. Ruiz, D. Peron, S. Sinbandith, P. H. Dixneuf, C. Baldoli and S. Maiorana, J. Orgunomet. Chem., 1997,533,2 13. P. Stepnicka, R. Gyepes, 0. Lavastre and P. H. Dixneuf, Orgunometullics, 1997, 16, 5089. T. E. Wilhelm, T. R. Belerrain, S. N. Brown and R. H. Grubbs, Orgunumetullics, 1997,16,3867. T. R. Belderrain and R.H. Grubbs, Orgunometullics, 1997, 16, 4001. J. A. Tallanico, P. J. Bonitatebus Jr. and M. L. Snapper, J. Am. Chem. Soc., 1997, 119,7157. Y. Yu, J. Sun and J. Chen. J. Orgunomet. Chem., 1997,533, 13. H.4. Fujita, K. Ito, T. Kodo and T.-A. Mitsudo, J. Orgunomel. Cliem., 1997, 533, 161. M. Tamm, A. Grzegorzewski, I. Brudgam and H. Hartl, Chem. Cornmun., 1997, 2227. M. L. Spera, H. Chen, M. W. Moody, M. M. Hill and W. D. Harman, J. Am. Chem. Soc., 1997, 119, 12772.

3 Metal Carbonyls BY JOHN A. TIMNEY

1

Introduction

This report begins on a rather sad note. In 1996, Professor Sir Geoffrey Wilkinson FRS (1 921-1 996) died. His contribution to inorganic chemistry was enormous and his work is rightly recognised in a review of his contributions] and a list of his publications.* Throughout the chemical world he was known as the co-author of the standard textbook on inorganic chemistry cherished by an army of undergraduates. In the preface to the first edition of Advanced Inorganic Chemistry, Wilkinson noted that ‘. . .inorganic chemistry has experienced up2 impressive renaissance’. A major player in that renaissance was Geoffrey Wilkinson and he will be greatly missed. Also, in 1997, Professor Jeremy Burdett (University of Chicago) died just before his 50Lhbirthday. Jeremy contributed a great deal to chemistry in general and to metal carbonyl chemistry in particular. Having worked with Jeremy at Newcastle University in the late 1970’s and, more recently, on the Encyclopaedia of Inorganic Chemistry ( 1994),3 with many others, I share in the loss of such a passionate, ideas-rich scientist who taught us a great deal about transition metal chemistry. This report deals with those publications describing advances in the chemistry of the metal carbonyls and metal carbonyl hydrides, halides and pseudohalides for 1997. Activity in this area continues at a high level. The general structure of this report is similar to previous years. Since 1993 this chapter has included information about the general chemistry of metal carbonyls which have Group 15 and/or Group 16 donor ligands. So, for example, the reactions of Ni(C0)2(PF3)2would be included in this chapter, but those of Ni( PF3)4 would be excluded unless a carbonyl-containing product was formed. Hydrocarbon-containing complexes are dealt with elsewhere, but where they specifically involve reactions of the CO ligands (with the hydrocarbon ligands merely being spectators to the chemistry) they will receive a mention here. The practice of including relevant papers from the year preceding the main focus of this report is continued. It does happen that one or two relevant papers are missed (often due to their publication in obscure journals or because they were awaiting a translation) and we feel that inclusion is justified on the ‘better late than never’ principle.

Organometallic Chemistry, Volume 27 @*; The Royal Society of Chemistry, 1999

132

3: Metul Curbonyls

2

133

Reviews

A number of reviews will interest organometallic chemists. One of the most interesting was that by Bond and Colton4 on recent electrochemical studies on metal carbonyls. The proceedings of the 1 lth International Symposium on the Photochemistry and Photophysics of Coordination Compounds contain much to interest readers here.5 In the same issue, Belser6 et al. review the synthesis and photophysical properties of chiral, binuclear metal complexes, Szymanska-Buzar7 reviews the photochemical reactions of the Group 6 carbonyls in the catalytic transformation of alkenes and alkynes, Langford and Shaw' explore the case of the sub-nanosecond photoprocesses of W(CO)5(pyridine). A survey, by Ungvary, of the application of transition metals in hydroformylation reactions during the year 1995 has been published' and, for the same year, an extremely detailed and thorough review of organometallic cluster chemistry has been made available." A similar study" of work carried out in 1996 has also been released. Both contain references to work of considerable interest for metal carbonyl chemists. UngvaryI2 has also written a review of acyl cobalt carbonyl complexes, dealing mainly with their synthesis, characterisation and reactions. On a more general theme, the position and standing of transition metals in organic synthesis has been reviewed by Hegedus." The June 1997 edition of Coordination Chemistry Reviews contained a comprehensive survey14of transition metal chemistry, element by element, mainly for the year 1994. There is, of course, much to interest carbonyl chemists in this collection of reviews. Similarly, the September" edition of the same journal covered work carried out in 1995. There are gleanings of interest for metal carbonyl chemists in a fascinating article by BruceI6 on complexes of all-carbon ligands (and their related chemistry), in a review of recent advances in arene-ruthenium(0) complexes. " Finally in this section, Farrugia" has authored a stimulating article about molecular dynamics and fluxionality in metal carbonyl clusters (with reference to some old and new problems). This is well worth reading.

3

Theoretical, Spectroscopic and General Studies

3.1. Theoretical Studies - Theoretical studies on carbonyl complexes are, for some reason, considerably more abundant than in previous years. A number of these studies take a density functional approach. Typical of these, is a paper by Gonzalez-Blanco and Branchadell" that explores the structure and fluxional behaviour of several (butadiene)Fe(C0)2L complexes (where L = CO, PH3, PMe3). A paper of fundamental interest to those working in this field has been published by Gonzalez-Blanco and BranchadelL2' They have investigated the bonding between iron and phosphorus in a range of Fe(C0)4PR3 complexes via density function techniques. Equally interesting is a theoretical study of the structure and bonding of the extremely long line of isoelectronic metal carbonyis: [Hf(cO)6l2-, [Ta(C0)6]-, w(co)6, [Re(CO)6]+, [oS(cO)6]*' and [Ir(C0)6]3+.It

134

Organometullic Chemistry

is most unusual to have an isoelectronic series with six members and this paper makes for good reading.21 In the mid-1970's there was a considerable amount of research carried out by Perutz and Turner on the structure and bonding of the matrix-isolated Group 6 pentacarbonyl-noble gas complexes, M(C0)5(Ng) where Ng was any of Ar, Kr, or Xe. In brief, photolysis of the parent hexacarbonyl in an noble gas matrix resulted in the formation of an unsaturated fragment of C4" symmetry with a noble gas atom occupying the vacant site. This work has been revisited by Ehlers22et al. from a theoretical standpoint. P e r u t ~as~ it~ happens has returned to the identification of metal carbonyl fragments in low temperature matrices with a study of the matrix photochemistry and room-temperature solution photochemistry of Ru(C0)3(Me2-PCH2CH2PMe2). Carbonyi complexes have long been used as catalysts and their effects measured. Sugihara et at. have added to this knowledge via an interesting study of of the rate enhancement of the Pauson-Khand reaction by primary amines using cobalt carbonyls." Gade25 has published an intriguing paper on a new class of open shell transition metal clusters. The competitive processes between electrical forces and steric requirements are mentioned elsewhere in this report. McArdle and O'Nei1126 have extended our knowledge on the subject by describing the steric limits of cis-[(C~R5)Fe(CO)2]2 complexes in solution. The osmium-silicon bond in the iso-structural set of five-coordinate complexes Os(SiR3)CI(CO)(PPh3)2 (where R = F, Cl, OH, Me) has been investigated using both theoretical and structural studies.27 The rearrangement of W(C0)5(phosphanobornadiene) has been analysed through detailed ab initio MO calculations.28Along the same algorithmic pathways, the full cycle of olefin hydroformylation catalysed by RhH(C0)2(PH3)2 has been a n a l y ~ e d . ~ ~ A theoretical model for the insertion of 16-electron species of the type CpM(L) into saturated hydrocarbons has been developed. In a detailed paper, the reactions of [CpRu(CO)]-, [CpOs(CO)]-, [CpRh(CO)], [CpIr(CO)], [CpPd(CO)]+and [CpPt(CO)]+with methane are con~idered.~'

3.2. Spectroscopic Studies - Time-resolved infrared spectroscopy has come of age in carbonyl chemistry over the past few years and the number and complexity of the chemical systems being studied by TRIR is steadily increasing. in 1997 TRIR was used to investigate3' the photochemically induced oxidative addition of benzene to trun~-RhCI(CO)(PMe3)2, to observe the ultrafast reductive eliminato tion of hydrogen from a metal carbonyl dihydride complex32 and, shed new light on the photogenerated intermediate Cp*Cr(p-CO)@Cp*. Lees and D u n ~ o o d yhave ~ ~ produced quantitative measurements of the photochemistry (re. ligand photosubstitution and intermolecular C-H and Si-H bond activation reactions) of C ~ R h ( c 0in ) ~various hydrocarbon solutions. The EPR spectra of several [Cr(C0)2L(C&k6)] complexes (L = PEt3, PPh3,

3: Metal Curbonyls

135

P(OEt)B, P(OPh)3) have been measured3’ with particular focus on the analysis of line widths and the determination of ground state configuration from an interpretation of the 3 1 Pcouplings. Chromium is again the spectroscopic focus in a (which includes both theoretical work and spectroscopic observations) of the complex Cr(CO)5(CNCN). Some of the same group have also released i n f ~ r m a t i o n on ~ ~ the spectroscopic properties of Ru(E)(E’)(CO)~(~P~-DAB) (where E = Me, SnPh3,Mn(CO)j, Re(CO)5;E’ = Mn(C0)5, Re(C0)S; ‘Pr-DAB = N ,N’-diisopropyl-1,4-diaza-1,3-butadiene). A relatively sophisticated battery of spectroscopic techniques has been brought to bear on the phenomenon of metal fragment rotation within triangular metal clusters. ‘H, 2H and 13C N M R studies of the fluxional behaviour of the anion [Re3(H)3(NC5H4)(CO)0]- have been published.38 The phosphorus-phosphorus coupling constants (from 3 1 PNMR) for a range of Fe(C0)3(L)(L’) complexes have been determined.39 The study includes the crystal structure of Fe(CO),(PEt3)(PPh3). The UPS spectra of a number of complexes containing metal-silicon bonds In particular the authors concentrated on Co(CO)4SiC13, have been p~blished.~’ Mn(CO)sSiC13 and Fe(C0)4(SiC13)2. Every few years carbonyl chemistry intrudes deep into the heart of organic chemistry and/or biochemistry where the unique spectroscopic characteristics of the metal-CO group make the unit ideal as a probe. We have, in recent years, seen carbonyl groups bound to proteins as probes at the nanomole level and carboxyhaemoglobin was under scrutiny even more recently. In 1997, the spectroscopic characteristics and oxidation behaviour of meso-tetraphenyl-tetrabenzoporphyrin carbonyl complexes of ruthenium(1I) were revealed,4’ using the CO group as a probe to elucidate the bonding characteristics of porphyrins.

3.3 General - Chirality tends not to figure largely in organometallic chemistry and so it is of interest to report that the chemistry of the chiral complex [Cp*Re(NO)(CO)(PPh3)]+(which is, of course, a Lewis acid) has been publ i ~ h e dChirality .~~ also crops up in the synthesis of novel cyclopentadienes using iron carbonyls as the mediators.43 Coat et a14 have produced a compound which has a string of four carbon atoms linking two iron centres. They describe the synthesis and spectroscopic properties of the novel complex [Cp*Fe-C4-Fe(C0)2Cp*].Even more fascinating is the fact that the iron atoms are in different oxidation states. New ligands are always interesting to note and a paper by Ganter4’ et ul. has announced the use of phosphanyl-substituted phosphaferrocenes as P,P-chelate ligands. The transformation of two alkyne molecules into new organometallic ligands by using an [Os(CO)(PiPr&] unit has also been noted?6 A study into the substitution into a cyclohexadienyl ligand (as part of [(q5-C6H,)Fe(Co)3]+and [(q5-C6H7)Ru(CO)3]+complexes) by aniline tricarbonyl chromium complexes to produce hydrocarbon-bridged metal complexes has also been published.47 As part of a long-running series on organophosphorus compounds (this current study being Part 1 18) the reactions of 1 -chloro-1H-phosphirenes with nucleophiles (including metal carbony1 complexes) have been in~estigated.~~ As Part 12

I36

Organometullic Chemistry

of a series of papers on the phosphinoalkylsilyl ligand, B r ~ s ett al. ~ ~have studied the stereochemistry of the tridentate bis(diphenylphosphinopropyl)silyl framework. This type of complexation introduces ‘face discrimination’ at coordinatively unsaturated metal centres. Another new type of ligand to emerge in 1997 was the arsinocarbene. Kreissl” and co-workers have synthesised and characterised the 2-arsinocarbene complex [Cp(CO);!W = C R - A S P ~ ~ ] + [ P-F. ~ ] The tetradentate phosphine ligand tetrakis(diphenylphosphin0)-p-xylene has been prepared” and used to bridge two Fe(C0)3 units. Complexes with quadruply-bridging carbonyl ligands have been prepared by Sus2 et ul. The molecules are based around pentanuclear ruthenium clusters. A detailed paper by we be^-^^ and co-workers describes new research into acyl phosphanes and phospha-alkenes, arsa-alkenes, metallodisilylphosphanes and arsanes. The production of homoleptic metal carbonyl cations has featured with some regularity in this chapter in recent years. An article spanning this work (by Aubke and Willners4) has been published that deals specifically with the generation of these complexes in superacid media and focusses on their spectroscopic and structural characterisation. The strength of the Ru-C bond (expressed in terms of bond enthalpy) is discussed by Li55 and co-workers in a paper focussed on the effect of ligand influence in Ru(C0)2(L)2 complexes. In a related paper (though by a different group) the competition between steric and electronic forces in Ru(C0)2L2L’ has been examined.56 Catalysis has been an enduring feature of metal carbonyl chemistry and the trend continues with a study focussed on rhodium carbonyl catalysed reactions of N-(2-pyridinyl)piperazineswith CO and ethene which results in a novel carbonylation at a C-H bond in the piperazine ring.’”

4

Chemistry of the Metal Carbonyls

4.1 Titanium, Zirconium and Hafnium - This group seldom figures much in this report and 1997 was no exception. Although it should strictly be in the mixedmetal section, a paper by Shimomura5’ rt ul. (the sixth in a series devoted to using clusters as ligands) on the cluster carboxylates of titanium and zirconium derived from C ~ T ~ ( C O ) ~ C O ~ ( C O ) ~ ( ~ & C O Oand H) C~Z~(CO)~CO~(CO)&~-CCOOH) makes for interesting reading. Quite legitimately in this section, a study of the titanocene dicarbonyl cation, [TiCp2(C0)2j2+has been completed by Calderazzos9 et ul. 4.2 Vanadium, Niobium and Tantalum - This group never contains more than a handful of papers and 1997 was, if anything, below average in this respect. The only paper noted that mentions vanadium carbonyl compounds is a technical note by Reinhold6’ that describes the character of the V-V bond in

3: Metul Curbonyls

I37

V2(CO)&-PR2) complexes. Chromium and manganese compounds of the same type are considered in this paper also. Chromium, Molybdenum and Tungsten - This group always produces a relatively high number of relevant studies and 1997 was no exception. The group continues to be dominated by mononuclear complexes, with di-, tri- or higher nuclearity complexes continuing to be scarce. At a relatively simple level, Scheer6' et al. have devised routes to phosphorusrich P, kgands using Cr(CO)5PC13as a starting material. Rather more complicated is the paper by Toyota62 and co-workers dealing with the synthesis and structures of all the possible (tripty~ene)Cr(CO)~ complexes. The photosubstitution reactions of Mo(CO)~(I , 10-phenanthroline) and W(CO)4(1,lO-phenanthroline) have been the subject of a study by Fu and van Eldik.63 In a very detailed and interesting paper, they consider the varying influences of the entering ligand, irradiation wavelength and pressure. The kinetics and mechanism of the ligand exchange processes in photogenerated (2-m0noaIkylarene)Cr(CO)~complexes with alkenes has been studied by Ladogam@ and co-workers. There is considerable evidence for the involvement of the aliphatic chains in both the arene and the alkene in the exchange process. Molybdenum carbonyls figure in a number of studies. The use of pendant arm polyazamacrocycles with molybdenum carbonyls is described by Ros~ i g n o l et i ~al. ~ In a series of complexes where two molybdenum atoms form the core of the molecule, Capon66 et al. have carried out some very detailed electrochemistry. The reactions of rner-Mo(H)(CO)(NO)(PMePh2)3 with ethene, propene and phenylethene have been studied.67 A molecule containing two molybdenum atoms linked by an organic chain, (C0)4Mo-(pentamethylenedia~irine)~-Mo(CO)~, has been investigated in relation to the relative rates of hgand substitution viu thermal or photochemical routes. Interesting mechanistic information was gleaned by changing the entering nucleophile and altering the pressure.68 Rather than splitting a dinuclear complex, a dimolybdenum complex is the r e ~ u l t ~of ~ 'the ~ ' cyclodimerizdtion of the tropylium ring by reduction of [(C7H7)Mo(CO)3J'. A mixed molybdenumtungsten compound, [ M o W ( C ~ ) ~ ( C O ) ~ ( P ~ ~ P C H has ~ P Pbeen ~ ~ )the ] , subject of an investigation7' into oxidative addition reactions and decarbonylation reactions. Two related papers have also been p ~ b l i s h e d ~ ~ . ~ ~ The synthesis of axially asymmetric N-functionalised metal dialkyls and bimetallic complexes has been attempted, with considerable success, and the complex Me2Sn[(CHSiMe3C5H3N)2]W(C0)4 has been prepared and fully chara~terised.~~ With so much functionality that it could reside in several sections of this review and several chapters of this book, the complex [hydridotris(3,5-dimethyl-1pyrdzolyi)borato](CO)2W(yl3-allyl) has been investigated75 to adumbrate its orientational and stereochemical preferences. Tungsten complexes have been used catalytically for many years. In 1997 the coupling of alkyne molecules was effected76 by W(C0)5(PhCCPh)3. Another

4.3

I38

Organometallic Chemistry

catalytic use for carbonyls of tungsten7’ was the transformations of thiiranes by (t hiirane)W(CO)s. Both molybdenum and tungsten have been studied in a paper78 focussed on the oxidative additions of coordinated ligands at unsaturated Mo and W centres within diphosphine-bridged carbonyl dimers and the tungsten complex CPW~(CO)~(~-P has P ~been ~ ) the focus of a study by Yeh79 and co-workers investigating its substitution chemistry when faced with incoming diphosphine ligands. 4.4 Manganese, Technetium and Rhenium - The rush of papers devoted to the chemistry of Re(C0)3X(di-amine) complexes has abated, but follow-up studies are now appearing with subtle changes to the molecular geography. Under this category, the electrochemical reactions off~c-[Re(CO)~(dpk)Cl] (where dpk is di2-pyridyl ketone) with electrophiles and Group 1 and 2 metal ions have been reported.80 Koike et al. have published an important paper on the nature of the key processes in the photocatalytic reduction of carbon monoxide using [Re(4,4’X2-bipyridine)(C0)3PR3]+ complexes (where X=Me, H, CF3 and PR3 = various phosphines). A major focus of this paper is the investigation into the reaction (without light) of the one-electron reduced complexes with C02. Broadening the scope somewhat, the synthesis, photophysics and electrochemistry of luminescent binuclear rhenium( I) complexes containing bridging thiolates has been published.8’ The solid state (Le. on a silica gel surface) photochemical isomerisation of compounds of the type (CSH4R)Re(CO)(L)X, (where L is a phosphine ligand and X is a halogen atom) has been described by Cheng and Coville.82 Complexes containing a single manganese atom have been notable by their absence in recent years. Reversing the trend, Bond83et al. have published a study of the redox and isomerisation processes for a number of [Mn(CO)z(pho~phine)]”~complexes. They used a number of techniques to investigate this system (voltammetry, specular I R reflectance and X-ray electron probes for s ~ ~coexample) and, all in all, this is a very detailed piece of work. S t ~ f k e n and workers have also used single manganese atoms in carbonyl complexes as the focus for a spectroelectrochemical study. Di-rhenium complexes are represented in this report by [Re2(C0)8{ p-q S2CPCy3}] and [Re2(C0)6{p-q2;q3-S2CPCy3)lrboth of which make use of the S2CPCy3 ligand which donates either four or eight electrons to the electron count.8s A new route to polyselenoether macrocycles has been developed86 using Re2(CO)9SeCH2CMe2CH2.In a related rhenium compounds have also been used catalytically: the macrocyclisation of 3,3-dimethylthietane by Re2(CO)g(SCH2CMe2CH2)has been reported. In other developments involving two rhenium atoms, a new structural isomer of the cation [RezC13(dppm)(CO)(CNC1)]’ has been discovered” and the molecule [Re2(C0)8{ pN2(C5H4)2}]has been prepared from the reaction of [Re2(C0)8(MeCN)2] and dia~ocyclopentadiene~~ and the reaction of Cp*(C0)2Re=Re(C0)2Cp* with alkynes has been shown” to produce dimetallacyclopentenoneswhich react with acids to form cationic vinyl bridging complexes.

’

3: Metal Curbonyls

I39

Larger rhenium complexes are represented” in this review by two hydridocarbonyl chain clusters (recalling that rhenium does have this ability to form chains of metal atoms rather that the more common clustering of atoms where other metals are concerned): [ R ~ ~ H ( ~ - H ) ~ ( C O and ) I ~[ R] -~ ~ ( ~ - H ) ( C O ) I , ] - . Iron, Ruthenium and Osmium - The mononuclear chemistry of this group is well represented with a good number of stimulating papers. Not many years ago the notion of molecular hydrogen acting as a ligand was in the realms of fantasy. In 1997 the next paper in a long line of studies dealing with carbonyl-containing complexes with molecular hydrogen attached to the metal was published. In this instance, the complex under i n ~ e s t i g a t i o nwas ~~ trans-[Fe( H2)(CO)(d~pe)~]~+ and the intriguing thesis put forward by the authors is that there is a certain degree of back-bonding from the Fe to the H2. In the grand tradition of the carbonyls of this group being very close to organic chemistry, the reaction of Grignard reagents, Fe(CO)5 and CuCl with alkynes has been found to result (via a novel double carbonylation) in butenolides and A similar theme (only this time involving photochemistry) is cycl~butenedione.~~ revealed in a of the reactions of RU(CO)~with nitrogen heterocycles under UV irradiation. New five-coordinate complexes of osmium and ruthenium in the shape of MHCI(CO)(PiPr3)2 (M = Ru, 0 s ) have been prepared95 as precursors for the preparation of new hydrido and alkenyl metallothiol and monothio-diketonato derivatives. The fluxional character of CpFe(CO)2(q I-CgH7) has been investigated,96 giving evidence for the [4+2] cycloaddition of a metal substituted isoindene with tetracyanoethene. An unprecedented number of metal atoms are linked into a ring in the molecule [OS(CO)~(S~P~ The ~ ) ]12-membered ~. ring has been fully c h a r a c t e r i ~ e d . ~ ~ Mononuclear iron complexes are represented also by a of the restricted rotation around the arene-iron bond in (arene)Fe(CO)(SiC13)2complexes and in the intramolecular cyclization of (diene)Fe(C0)3 complexes with functionalised side chains on the diene l i g a r ~ d . ~ ~ Dinuclear iron complexes make an appearancelooin the thermal rearrangement of [(MezSiSiMez)(indHq)Fe( CO)]2(p-C0)2. Ruthenium-boron bonds are relatively scarce and it is, therefore, interesting to see that ethyne insertion into an Ru-B bond has been achieved.”’ A single ruthenium atom is also in play as part of a study on the acid-base control of a migratory insertion reaction.Io2 A single ruthenium atom forms the core of a detailed spectroelectrochemical study by S t ~ f k e n s ”et~ ul. and again shows up in the reductionlW of (C5Ph4[2,5-benzoquinonyl])Ru(CO)~Br and the formation of several new formate complexes of ruthenium. ‘05 The silylation of phenylethene with vinylsilanes has been achievedIo6 by using RuCl(SiR3)(CO)(PPh& and RuHCI(CO)( PPhJ)2. Lastly, amongst the mononuclear ruthenium complexes, Huangto7and co-workers report the synthesis and structural characterisation of Ru(SiMe3)(CCSiMe3)(CO)(PtBu2Me)zwhich is short on CO groups, but contains enough to rate a mention in this chapter. Mononuclear osmium chemistry is rarely a major feature of this section, but a

4.5

140

Orgcrnometallic Ciwmistry

paper by Edwards'08 and co-workers on the synthesis and reactivity of the unusual five coordinate hydrido-hydroxo complex OsH(OH)(CO)(P'Pr& is of considerable curiosity. Dinuclear iron complexes are represented firstlyl0' in the reaction of phosphites with the electrophilic allenyl complex [Fe2(CO),(PPh2){HC=C=CH2 f ] which undergoes stepwise transformation from a 1 :2-allenyl ligand into a 1 :Zacetylide ligand (a second paper'" deals with related work, analogous ruthenium compounds are described in another paper' ' I and the generation of binuclear unsaturated esters are discussed in a further studyIi2),secondly in the formation of several novel tellurium containing anions,'I3 the reactions of m- and p divinylbenzene-diiron hexacarbonyl with awl-lithium reagents' l 4 and finally' l 5 in Fe2(CO),(E-E') complexes (E = S, Se, E' = Se, Te). A related paper to this last mentioned describes regioselective addition of mixed-chalcogenide iron carbonyl clusters to alkyne bonds.'16 Song' l 7 and co-workers describe an unexpected reaction between the anionic complex [(cl-RE)(cl-s=Cs)Fe2(co)6]- (where E = S or Se) and SO2C12. The resultant product is a dithioformato-bridged double cluster. Dinuclear iron and ruthenium complexes containing the ligand q5-C5Me4CF3 have been prepared by Barthel-Rosa and co-workers.'I8 There appears to be little structural difference between these complexes and the familiar ( C P F ~ C O ) ~ ( ~ CO), complexes. FeJ(C0)12, one of the longest-serving metal carbonyls, has been used"' in a number of reactions with tellurium-ni trogen heterocycles, leading to the preparation of a number of novel organoiron compounds. The same molecule is involved in the activation of methanol whilst reacting with 1-phenylprop-2-yn-1-01 where two new complexes appear to be formed.I2' Whether the carbide cubane cluster [Fe3(CO)gTe4(p-CTeBr4)]should be within this section or later, in the mixed metal carbonyls, depends on the classification of tellurium. Regardless of the semantics, this complex has been prepared and characterised by Whitmire and Eveland. 1 2 ' It contains the unusual CTe4 unit. Phospha-alkyne-bridged clusters of iron [namely Fe4Se2(p-Se2PCBut)(CO)I I ] were produced in 1997. Unusually, the non-linear optical properties of this complex were also reported as part of the study.'22 Ruthenium has been more distinguished by its cluster chemistry than for mononuclear species in recent years and 1997 was no exception to this general trend. The prototypical ruthenium cluster R U ~ ( C O )figures ,~ in a reaction of considerable complexity123with [RzP(E)],NH compounds (where R = Ph or 'Pr, E = S or Se). The same molecule is used in a study of the photochemistry of Ru3(CO)!2 with nitrogen heterocycles.'24 New hexaruthenium clusters are described in an interesting piece of work'25by Johnson et ul. and a related study is to be found elsewhere.'26 The somewhat smaller cluster [ R U ~ ( C O ) ~ ~ ( ~ has ~ - Pbeen P ~ )the ] focus of a aiming to prepare unsymmetrically capped bisphosphinidene complexes. The di-ruthenium cluster (Me,SiSiMe,)[(Cp)Ru(CO)]2(p-C0)2 has been the subject of a study looking at its thermal rearrangement. '28 The 2,2'-bis(dipheny1phosphino)-1, I '-binaphthyl ligand has been employed in

3: Metul Curhonyls

141

the preparation of several tri-ruthenium clusters.129 Three ruthenium atoms also form the core of a study13’ dealing with carbonyl-metal clusters with mixed 0,Ndonor ligands; specifically the reactivity of the ureato cluster [Ru3(p-H)(p3H NCON Me2)(CO),] with phosphines. The reversible interconversion of [HRu~(CO)I 11- and [ H ~ R U ~ ( C O )in~ the ~]presence of CO or hydrogen has been studied.’” The authors make use of fully hydroxylated magnesia surfaces that mimic the reactions of these complexes in solution. Tetra-ruthenium clusters are also described in a paper132devoted to the synthesis, characterisation and chemical behaviour of hydridoruthenium carbony1 clusters substituted with functionalised phosphines in the presence of hydrogen. Penta-ruthenium clusters make an appearance with a devoted to the substituent effects on associative reactions of Ru5C(CO)14[P(OPh)3]and Ru5C(CO)14[PCy3]with phosphorus-donor nucleophiles. With one more ruthenium into the apparent atom, R u ~ C ( C O ) ~ ~ ( P P ~ ~is (the C ~subject H ~ ) ~of a reversibility of the coordination of a phenyl group. The same number of ruthenium atoms are involved in the reactions of RugC(C0)17 with alkynes 1 3 5 and with 1,lO-phenanthrolineand 2.2’-bipyridyl.’36 The large ruthenium cluster [ R U ~ ~ C ~ ( C Ohas ) ~been ~ ] ~ used (as part of an oxidative substitution process with disubstituted alkynes) to prepare Rul o C ~ ( C O ) ~ ~ ( C ~complexes. RR’) I 37 Osmium clusters continue to make for interesting chemistry. The synthesis and characterisation of three hexaosmium clusters containing pyridine hgands, [os6(Co)15(p4-q2-CO)(C5HSN)3], [os6(co) 1 5(~-H)(11-Co)(p,-o)(c~H5N~(p-q2NC5H4)]and [OS~(CO),~(~-H)(~-CO)(M~CN)(C~H~N)(~-~~-NC&) (including crystallography data) has been described.138 The frontiers of surface-mediated organometallic synthesis have been pushed further with the publication of a detailed paper13’ on the role of silica in the preparation of a number of tetra-osmium complexes: [H40s4(CO)I2], [HOsdCO)ioOR], [HOsdCO)ioCI], [HOs3(CO)ioBr], [HOs3(CO)ioII, [HOs3(CO)lO02CR],[HOs3(CO)1oSCNI *

4.6 Cobalt, Rhodium and Iridium The number of papers published that relate directly to the metal carbonyl chemistry of this group has been tapering off in recent years. That said, the papers of 1997 are of great interest. A study of the in DMSO and water is a carbonylation of trans-Ir(CO)CI[P(m-C6H4SO3Na)3l2 typical example.I4O Hydroformylation reactions, for which rhodium and cobalt are both used as catalysts, have been investigated further by Buisman14’ et af. Their study concentrates on the fluxional processes in asymmetric hydroformylation catalysts (of the type HRhLL(C0)2) containing C2-symmetric diphosphite ligands. Phthalimidomethyl and phenoxymethyl cobalt carbonyls have been used in a devoted to extending our knowledge of CO insertion reactions in complexes such as these.

Organometallic Chemistry

142

Phospholyl dicobalt dicarbonyls have been prepared by C a f f ~ n et ’ ~al. ~ and their reactivity studied. The larger clusters from this group always provide interesting chemistry and are represented here by a related to the synthesis and structural characterisation of [IR4(CO),(Ph)(PhPC( H)CPh)(PPh2)] which has a phenyl group arising from the selective cleavage of a coordinated Ph2PC(H)CPh ligand. The reaction of metal fragment electrophiles with Ir3 complexes has been the subject of a thorough investigation. i 4 5

4.7 Nickel, Palladium and Platinum - This group rarely figures much in this chapter. The deluge of work on mononuclear nickel complexes is long past and the cluster chemistry of the group tends to be confined to mixed-metal complexes. It was therefore, interesting to note that small, carbonyl-containing clusters of Pd( 11) and Pt( 11) have been prepared by Falvello et cil. i46 Nickel clusters, although not as prominent as in recent years, still appear here in small numbers. The synthesisi4’ of the very bulky cluster [Ni&,(CO)36]6was missed in last years review. More recently, new nickel-antimony clusters have been prepared’4g(and are in this section rather than the mixed-metal carbonyl section because the Sb atoms do not carry CO ligands). The overall formula of these molecules is [Niio(SbR)2(C0)18]2-with various R groups attached to the Sb atoms. The same team have prepared analogous nickel-bismuth compoundsi49 and have devised a geometric analysis of the whole range of [Nilo(EMe)(CO)I,]’- (where E = P, As, Sb and Bi).

4.8 Copper, Silver and Gold Although gold appears in several mixed metal carbonyl species (usually attached to a triphenylphosphine ligand), no papers describing new Cu-CO, Ag-CO or Au-CO bonds have come to light in 1997. ~

4.9 Mixed Metal Carbonyls - The amount of work carried on in the synthesis and characterisation of mixed metal carbonyls shows no sign of abating. A healthy crop of new complexes has been described annually for several years now. A general paper in this fieldi5’ deals with the formation of heterobimetallic complexes by nucleophilic substitution making use of the differing reactivities of the ansa-bridged metallocene dichlorides towards metallophosphide anions. Equally generic are papers by Song”’ et ul. covering the isolobal reactions in transition metal cluster systems and the use of [(CIAu)3(triphos)] as a building block for the synthesis of heterobimetallic ~lusters.’~’ Molybdenum-cobalt clusters are relatively scarce. However, the oxidative substitution of carbonyl groups by halogen or sulfur-containing groups has been studied by M a n ~ o u r ”and ~ co-workers who have employed the electron deficient cubane cluster C P E ~ ~ M O ~ C O ~ Sas~ (a Cmodel O ) ~ system for an organometallic desulphurisation material. A related studyi54looks at the reaction of these types of molecule with diphosphines. With metals from the same groups, M a n t ~ v a n i ’ ~ ~ et a/. have studied heterobimetallic indenyl complexes containing chromium and rhodium.

3: Mctul Curhonyls

143

Stepwise formation of heterometallic clusters is described by Chao and coworkers.Is6 Starting with R U ~ C ( C O ) ~ ~they , have produced Cp*WRuSC(CCH2Ph)(H)2(C0)13and Cp*WRuSC(CCH2Ph)(H)4(CO)12. The unusual migration of a methyl group from an oxygen atom to an iron atom has been observedIs7 in the mixed-metal (Group 6 plus Group 8 combination) cluster Cp(CO)Fe(COCH-&p-CO)Cr(CO)(Bz). Combining metals from Groups 6 and 8 as above, Male15s and co-workers report the photochemical heterolysis of the metal-metal bond in ( Me3P)(C0)40s-W(CO)S. Starting with a relatively small cluster, the reaction of [Fe4C(CO)12J2-with AuPPh3+ and Hg{ Mo(C0)'Cp)' produces the interesting finding that these ostensibly similar cations attach themselves to different parts of the Fe4 cluster.'sI Also turning gold into base-metal carbonyls, Albano'60 and coworkers have described the synthesis and structural characterisation of [Au3Fe2(CO)8(dppm)]- and [ A ~ ~ F e ~ ( C 0 ) ~ ( d p p m and ) ~ iron-gold ]+ and iron-mercury clusters have been preparedI6' from [Fe6C(C0)16]2-. Uhl and Pohlmann'h2 have prepared Fe2(C0)(,[InC(SiMe3)3]3 which has the unusual trigonal bipyramidal Fe21n3 cluster with the iron atoms occupying the axial positions. Iron also figures in an interesting study"' of the reactivity of [SeFe3(C0)9J2with electrophiles. The authors report the formation of [SeFe2Ru3(C0)14]2-and [SeFex(CO)g(Hgl)]-. The combination of iron and chalcogen elements is extended further by M a t h ~ r and ' ~ ~ co-workers who have prepared inorganic quadricyclanes. They have reported the synthesis and characterisation of novel S and Se bridged mixed chromium-iron clusters, CrFez(C0) 10S4 and CrFez(CO)loSe4. Iron-molybdenum clusters (so-called 'hour glass clusters') have been prepared by and co-workers. Osmium, a favourite metal for mixed-metal clusters, appears in many of the papers of 1997. The osmium-rhodium clusters [ O S ~ ~ R ~ ~ ( C O ) & ~ - Cand I)] [ O S ~ R ~ ~ ( ~ ~ - H ) ( C ~ ) ~ ~ ( ~ ~have - C been O ) ( reported ~ ~ - C ~byH Hung166 ~ ) ~ J et d. Osmium and palladium are the c ~ m b i n a t i o n " ~ in the high nuclearity clusters [osSpd6(co)13(~-C0)5(pL-H)2(p-dppm)] and [os5pd6(co) 13(p-C0)6(~-dPpm)21. Ruthenium is well represented in this section with the cluster anion molecular structure, fluxionality and reactivity of [ R u ~ I ~ ( C O ) ~The ~ ] -synthesis, . this compound are described.I6' The same metal also emerges in a series of molecules containing two or more members of the Fe, Ru, 0 s group."' Ruthenium and iridium are further combined17oto make [Ru31rH~(CO)I 1 PPh31 and [Ru31rH(CO)IZ(PPh3)]. Ruthenium and osmium have been combined in carbonyl clusters containing vinyl, ally1 and related complexes.171 Ruthenium and rhodium are combined in a RuSRh cluster.172Osmium and palladium are likewise clustered in a number of OsSPd corn pound^.^^' A whole range of tetranuclear bimetallic sulphido, nitrosyl and carbonyl complexes containing molybdenum, tungsten, iron and cobalt have been prepared by Mans0u1-I~~ and co-workers. Continuing the theme, new Mo/Co/S cluster salts (containing surprisingly few C O groups) have been prepared.I7' The real mixed-metal heavyweights of 1997 include a copper-ruthenium 17' et a/. cluster, [ R U ~ O H ~ C U ~ C I ~ ( prepared C ~ ) ~ S ]by~ -Beswick ,

In recent years there has been a trend away from the simple synthesis of mixed metal clusters into areas of quite sophisticated and complex chemistry. This trend of the reversible C-C bond cleavage and the is exemplified by a interconversion of the resulting hydrocarbyl ligands on so-called butterfly frameworks for complexes such as C ~ * W O S ~ ( C C R ) ( C O )(,R~ R = Ph, "Bu, CH20Me, C H 2 0 Ph).

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66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84.

Orgunotnetullic Chemistry

L. Weber, S. Uthmann, B. Torwiehe, R. Kirchhoff, R. Boese and D. Blaser, Orgunotnc~(ullic~,s. 1997, 16, 3 188. €1. Willner and F. Aubke, Angcw. C'lzew. Inr. Ed. EngI.. 1997, 36, 2402. C. Li, M. Olivan, S. P. Nolan and K. G . Caulton, Orgunometullics. 1997, 16,4223. M. Ogasawara. F. Maseras, N. Gallege-Planas, K. Kawamura, K. Ito, K. Toyota, W.E. Streib, S. Komiya, 0. Eisenstein and K. G. Caulton, Orgunometullic*s,1997, 16, 1979. Y. Ishii. N . Chatani. F. Kakiuchi and S. Murai, Orgunometullics, 1997,16,3615. H. Shimomura, X. Lei, M. Shang and T. P. Fehlner, Orgunomc.tullic~s,1997, 16, 5302. F. Calderazzo, G. Pampaloni and G. Tripepi, Orgunomc~lullics,1997, 16,4943. A. J. Reinhold, B. Muller and U. Eichler, OrgunometullicGs,1997, 16. 1497. M. Scheer, K. Schuster. A. Krug and H.Ilartung, Clwm. Ber., 1997, 130, 1299. S. Toyota. H. Okuhara and M. Oki. Orgtinotnetullic~.s,1997, 16,4012. 1997, 16, 572. W-F. F u and R . van Eldik, Or~cinomc~tuNic~s, S. Ladogana, S. K. Nayak, J. P. Smit and G . R. Dobson, Orgunotnetullicx, 1997, 16, 305 I . M. Rossignoli, P. V . Bernhardt and G. A. Lawrance, J. Clwtn. Sot*., Dulton Trans., 1997.4247. J-F. Capon, R. Kergoat, N. Le Berre-Cosquer, S. Peron, J-Y. Saillard and J. 1997, 16, 4645. Talarmin, Org~inomc~t(illic..s, T-Y. Cheng, J. S. Southern and G . L. €fillhouse, Orgunumetullic:, 1997, 16,2335. W-F. Fu. H. Kirsch and R. van Eldik, Orgunometullics, 1997, 16, 3439. D. A. Brown, J. C. Burns, C. Mock-Knoblauch and W. K. Glass, Orgunometullic-s, 1997, 16,2756. D. A. Brown, J. C. Burns, C. Mock-Knoblauch and W. K. Glass, Urgunometullic*s, 1997, 16, 139. C. Alvarez, M. E. Garcia, V. Riera and M . A. Ruiz, Org~inomc~tullics, 1997, 16, 1378. G. Garcia, M. E. Garcia, S. Melon. V. Riera, M. A. Ruiz and F. Villafane, Orgunometullic:. 1997, 16, 624. M. A. Alvarez, M. E. Garcia, V. Riera, M. A. Ruiz, L. R. Favello and C. Bois, Orgunomc~tullics,1997, 16, 354. W-P. Leung, K. S. M. Poon, T. C. W. Mak, R-J Wang and Z-Y. Zhou, Orgunometullics, 1997, 16,4839. D. S. Frohnapfel, P. S. White, J. L. Templeton, €1. Ruegger and P. S. Pregosin, Or~cinotne~ullic*.s, 1997. 16, 3737. W-Y. Yeh, C-L. Ho, M. Y. Chiang arid I-T. Chen, OrgunomeruNic*s, 1997, 16, 2698. R. D. Adams. J. H Yamamoto, A. Holmes and B. J. Baker, Orgunurnefuflics, 1997, 16, 1430. M. A. Alvarez, C. Alvarez, M. E. Garcia. V. Riera, M. A. Ruiz and C. Bois, Urgunomc~tulliis,1997, 16, 258 1 . W-Y. J'eh, Y-J. Cheng and M. Y. Chiang. Orgunomrtullic:s, 1997, 16, 9 18. M. Bakir, J. A. M. NcKenzie, J C k t n . Soc.., Dulton Truns., 1997, 3571. V. U - W . Yam, K. M. C.. Wong. K-K. Cheung, Orgunometullic-s,1997, 16, 1729. L. Cheng and N. J. Coville, OrgunometuNic.s, 1997, 16, 591. A. M. Bond. R. Colton. F. Marken and J. N. Walter, Urgunumetullics, 1997, 16, 5006. B. D. Rossenaar, F. Hartl, D. J. Stufkens, C. Amatore, E. Maisonhaute and J-N. Verpeaux, Urgunometullit*s, 1997. 16.4675.

3: Metul Curhonyls 85. 86. 87.

88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. 99. 100. 101.

102. 103.

104. 105. 106. 107. 108. 109. 110. 111. 112.

113.

147

B. Alvarez, J. Li, D. Miguel, M. D. Modes, V. Riera and S. Garcia-Granda, Chem. Ber., 1997, 130, 1507. R. D. Adams, K. T. McBride and R. D. Rogers, Orgunome&ullics,1997, 16, 3895. R. D. Adams, J. L. Perrin, J. A. Quessier and J. B. Wolfe, Orgunometullics, 1997, 16, 2612 W. Wu, P. E. Fanwick and R. A. Walton, Orgunometullics, 1997, 16, 1538. Y. De Sanctis, A. J. Arce, R. Machado, M. V. Capparelli. R. Atencio, A J. Deeming and J. Manzur, Orgunometullics, 1997, 16, 1520 . C. P. Casey, R. S. Carino and H. Sakaba, Organometallics, 1997, 16,419. M. Bergamo, T. Beringhelli, G. D’Alfonso, P. Mercandelli, M. Moret and A. Sironi, Orgunometullics, 1997, 16,4129. C. E. Forde, S. E. Landau and R. H. Morris, J. Chem. Sue., Dalton Truns., 1997, 1663. U. Radhakrishnan and M. Periasamy, Orgunometullics, 1997, 16, 1800. G. R. Haire, N. E. Leadbeater, J. Lewis, P. R. Raithby, A. J. Edwards and E. C. Constable, J. Cltem. Sot.., Dulton Trans., 1997,2997. M. L. Buil, S. Elipe, M. A. Esteruelas, E. Onate, E. Peinado and N. Ruiz, Orgunometallics, 1997, 16,5748. M. Stradiotto, D. W. Highes, A. D. Bain, M. A. Brook and M. J. McGlinchey, Orgunometullics, 1997, 16, 5563. W. K . Leong, R. K. Pomeroy, R. J. Batchelor, F. W. B. Einstein and C. F. Campana, Orgunometullics, 1997, 16, 1079. V. M. Hansen, R. J. Batchelor, F. W. B. Einstein, J. L. Male and R. K. Pomeroy, Organometallics, 1997, 16,4875. M-C. P. Yeh. L-W. Chuang, S-C. Chang, M-L. Lai and C-C. Chou, Orgunometullics, 1997, 16,4435. B. Wang, Y. Zhang, S. Xu and X. Zhou, Orgunometullics, 1997, 16,4620. G. R. Clark, G. J. Irvine, W. R. Roper and L. J. Wright, Orgunometullics, 1997, 16. 5499. G. R. Clark, W. R. Roper, L. J. Wright and V. P. D. Yap, Orgunometallics, 1997, 16, 5 135. M. P. Arants, F. Hartl, K. Peelen, D. J. Stufkens. C. Amatore and J-N. Verpeaux, Orgunometullics, 1997, 16,4686. W. M. Harrison, C. Saadeh and S. B. Colbran, Orgunometullics, 1997, 16,4254. D. H. Gibson, B. A. Sleadd, M. S. Mashuta and J. F. Richardson, Orgunometullics, 1997, 16,442I . B. Marciniec and C. Pietraszuk, Orgunometullics, 1997, 16,4320. D. Huang, R. H. Heyn, J. C. Bollinger and K. G. Caulton, Organomefullics. 1997, 16,292. A. J. Edwards, S. Elipe, M. A. Esteruleas, F. J. Lahoz, L. A. Oro and C. Valero, Orgunometullics, 1997, 16, 3828. S. Doherty, M. R. J. Elsegood, W. Clegg, M. F. Ward and M. Waugh, Orgunometallies, 1997, 16,4251 . S. Doherty, M. R. J. Elsegood, W. Clegg, N. 14. Rees, T. H. Scanlan and M. Waugh, Orgunometullics, 1997, 16, 322 1. P. Blenkiron, J. F. Corrigan, N. J. Taylor, A. J. Carty, S. Doherty, M. R. J. Elsegood and W. Clegg, Orgunometullics, 1997, 16.297. S . Doherty, M. R. J. Elsegood, W. Clegg and D. Mampe, Orgunometullics, 1997, 16, 1186. L-C. Song, C-G. Yan, Q-M. Hu, and X-Y. Huang, Orgunometullics, 1997,16,3769.

I48 114.

115. 116. 117. 118. 119.

120.

121. 122. 123. 124. 125. 126. 127. 128. 129. 130. 131.

132. 133. 134. 135. 136. 137. 138. 139. 140. 141. 142.

Org~nome tcr llic Clzemist ry

J-B. Chen Y . Y u and J. Sun, Orgrmometullics, 1997, 16, 3608. P. Mathur, S. Ghosh, A. Sarkar. c'. V. V. Satyanarayana and V. G. Puranik, Or~tinom~~rtrllic's, 1997, 16, 4392. P. Mathur, S. Ghosh, A. Sarkar, C. V. V. Satyanarayana and A. L. Rheingold, 0r~iinotnct~rllic:s. 1997, 16, 3536. L-C. Song, C-G. Yan, Q-M. I l u , B-M. Wu and T. C. W. Mak, Organometullic*s, 1997, 16, 632. L. P. Barthel-Rosa, J. R. Sowa, P. G. Gassman, J. Fischer, B. M. McCarty, S. L. Goldsmith, M. T. Gibson and J. €1. Nelson, Urganomrlullic*s,1997, 16, 1595. K. Baydal, W. R. McWhinnie, T. A. FIamor and H. Chen, Organomc~talli~:s, 1997, 16, 3194. G. Gervasio, D. Marabello and E. Sappa, J. Clwm. Soc., Dalton Trans., 1997, 1851. J. R. Eveland and K. €4.Whitmire, Angew. Clwn. Int. Ed. Engl., 1997,36, 1193. P. Mathur, S. Ghosh, M . M. IIossain. C.V.V. Satayanarayana, S. Banerjee, G. R. Kumar, P. B. Hitchcock and J. F. Nixon, Organomefullics,1997, 16, 3815. A. M. Z. Slawin, M . B. Smith and J. D. Woollins, J. Cliem. Soc., Dalton Trans., 1997, 1877. N. E. Leadbeater, J. Lewis, P. R . Raithby and G . N. Ward, J. Chem. Soc., Dalton Truns,, 1997, 25 I 1. B. F. Ci. Johnson, D. S. Shephard, D. Braga, F. Grepioni and S. Parsons, J. Clwm. Soc., Dulton Truns., 1997, 3563, D. B. Brown, P. J. Dyson, B. F. G. Johnson, C. M. Martin, D. G. Parker and S. Parsons, J. Clwm. Soc.,Dalton Trans., 1997, 1909. M. Scheer, J. Krug, P. Kramkowski and .I. F. Corrigan, Ur~rincimetallic~s, 1997, 16, 59 17. Y . Zhang, S. X u and X. Zhou, Org~inomc~tiillic~s, 1997, 16, 6017. A. J. Deeming, D. M. Speel and M. Stichdroff, , Orgunometallics, 1997, 16,6004. J. A. Cabeza, I . Del Rio, V. Riera, S. Garcia-Granda and S. B. Sanni, Orgrinomctullics, 1997, 16, 3914 S-FI. Chun. T. B. Shay, S. E. Tomaszewski, P. H . Laswick. J-M. Basset and S. G. Shore, 0rgcinomc~tallic.r.1991, 16. 2627. M. Bianchi. P. Frediani, A. Salvini, L. Rosi, L.Pistolesi. F. Piacenti. S. Ianelli and M. Nardelli, 0rgrinomc~tullic.s.1997, 16, 482. D. i l . Farrar, J. Hao, 0. Mourad and A. J. Poe, Or~anot~ie~t~illic~s. 1997. 16. 5015. H-F. Hsu, S. R. Wilson and J. R. Shapley, Urganomr~ullir~s. 1997, 16.4937. R. L. Mallors, A. J. Blake, P. J. Dyson, B. F. G. Johnson and S. Parsons. Orgunometullics. 1991. 16, 1668. G. Freeman, S. L. Ingham, B. F. G . Johnson, M . McPartlin and I. J. Scowen, J. Cliem. Soc., Dalton Truns., 1997, 2105. J. W. Benson, T. Ishida, K . Lee, S. R. Wilson and J. R. Shapley, Orgcinonr~~~cillic.,v, 1997, 16,4929. K. S. Y. Leung and W-T. Wong, J. Clwm. Soc., Dalton Truns., 1997,4357. D. Roberto, E. Lucenti. C. Roveda and R. Ugo, Organomc~tallic~s, 1997. 16, 5974. P. J. Roman and J. D. Atwood, Organomctallic:s, 1997, 16, 5536. G. J. H . Buisman, L. A . van der Veen. P. C. J . Kamer and P. W. N . M . van Leeuwen, Organomettrllics, 1997, 16, 568 1. 1. Nagy-Gergely, G . Szalontai, F. Ungvary, M. Marko, M. Moret, A. Sironi, B Zucchi, A. Sisak, C. M. Tschoerner, A . Martinelli, A. Sorkau and G. Palyi, Organomc~tcrllic~s, 1997, 16, 2140.

3: MetuI Curhonyls 143. 144. 145. 146. 147. 148. 149. 150.

151. 152. 153. 154. 155. 156.

157. 158. 159. 160. 161. 162. 163. 164. 165. 166. 167. 168. 169.

170. 171.

149

A. J. M. Caffyn, D. Carmichael, F. Mathey and L. Ricard, Orgunomet(~llic~.s, 1997,

16,2049. R. M. S. Pereira, F. Y. Fujiwara, M. D. Vargas, D. Braga and F. Grepioni, Orgunometullics, 1997, 16,4833. M. C. Comstock, T. Prussak-Wieckowska, S. R . Wilson and J. R. Shapleyu, Orgunometullit-s, 1997, 16,4033. L. R. Falvello, J. Fornies, C. Fortuno, A. Martin and A. P. Martinez-Sarinena, Orgunometullics, 1997, 16, 5849. F. Calderoni, F. Demartin, M. C. Iapalucci and G. Longoni, Angew. Clicm. Int. Ed. EngI., 1996,35, 2225. P. D. Mlynek and L. F. Dahl, Orgunometullita, 1997, 16, 1641. P. D. Mlynek and L. F. Dahl, Orgunometullic~,1997, 16, 1655. V. Comte, 0.Blacque, M. M. Kubicki and C. Moise, Orgunomctullics, 1997, 16, 5763. L-C. Song, Y-B. Dong, Q-M. Flu, X-Y.Huang and J. Sun, Orgrmometallic8s,1997, 16,4540. M. Ferrer, A. Julia, 0. Rossell, M. Seco, M. A, Pellinghelli and A. Tiripicchio, Orgunometullics, 1997, 16, 37 15. M. A. Monsour, M. D. Curtis and J. W, Kampf, Orgunometullics, 1997, 16, 3363. 0. J. Curnow, M. D. Curtis and J. W. Kampf, Orgtmometullic:v, 1997, 16, 2523. L. Mantovani, A . Cesson, A. Gambaro, S. Santi, P. Ganis and A. Venzo, Orgunometullics, 1997, 16, 2682. W-J. Chao, Y. Chi, C-J. Way, I. J. Mavunkal, S-L. Wing, F-L. Liao and L. J. Farrugia, Orgunomrtullics, 1997, 16, 3523. W. Luo, R. H. Fong and W. H. Ilersh, Orgunometullics, 1997, 16,4192. J. L. Male, R. K. Pomeroy and D. R. Tyler, OrgunomrtuNics, 1997, 16, 3431. R . Reina, 0. Riba, 0. Rossell, M. Seco, P. Gomez-Sal and A. Martin, Orgunomctallics, 1997, 16, 51 13. V. G . Albano, M. C. Iapalucci, G. Longoni, L. Manzi and M. Monari, Orgunometullics, 1997, 16, 497. 0. Rossell, M. Seco. G. Segales, S. Alvarez, M. A. Pellinghelli, A. Tiripicchio and D. de Montauzon, Orgunomc~tullic:,1997, 16, 236. W. Uhl and M. Pohlmann, Orgunometullic-s,1997, 16, 2478. M. Shieh, Y-C. Tsai, J-J. Cheng, M-H. Shieh, H-S. Chen, C-11. Ueng, S-M. Peng and G-H. Lee, Orgunometullics, 1997, 16,456. P. Mathur, P. Sekar, A. L. Rheingold and L. M. Liable-Sands, Orgunometullics, 1997, 16, 142. P. Mathur, P. Sekar, A. L. Rheingold and L. M . L. Liable-Sands, J. C'hrm. Soc., Dalton Truns., 1997,2949. S. Y-W. Hung and W-T. Wong, J.Ciiem. Soc.,Clicm. Commun. 1991,2099 J. W. S. Hui and W-T. Wong, ,J.Clwm. Sot., Cliem. C'ommun. 1997, 2009. G. Suss-Fink, S. Haak. V. Ferrand and H. Stoeckli-Evans, J. Chem. Soc.. Dulton Truns., 1997, 386 I . A. A. Koridze, V. I. Zdanovich, A. M. Sheloumov. V. Y. Lagunova, P. V. Petrovskii, A. S. Peregudov, F. M. Dolgushin and A. I. Yanovsky, Orgunometullics, 1997, 16, 2285. A. U. Harkonen, M. Ahlgren, T. A. Pakkanen and J. Pursiainen, Orgunometullic:Y, 1997, 16,689. B. T. Sterenberg, R. McDonald and M. Cowie, Orgunometullit.s, 1997, 16,2297.

150

Orgunomrtullic Chivnistry

J. E. Davies, S. Nahar. P. R. Raithby and G. P. Shields, J. Ciwm. Soc., Dalton Truns., 1997, 13. 173. J. Hui and W-T. Wong, J. Chein. S i c . . , Dulton Truns., 1997. 2445. 174. M. A. Mansour, M. D. Curtis and J. W. Kampf, OrgunometuNic:v, 1997, 16, 275. 175. M. D. Curtis, S. H. Drucker. L. Goossen and J. W. Kampf. Orgunometallics, 1997, 16, 23 I . 176. M. A. Beswick, J. Lewis, P. R. Raithby and M. C . Ramirez de Arellano, Angeiv. Cliem. In[. G I . Engl., 1997, 36, 2227. 177. Y. Chi, C. Chung, Y-C. Chou, P-C. Su, S-J. Chiang, S-M. Peng and G-H. Lee, Or.gunomc~tullic~s, 1997, 16, 1702. 172.

4 Organo-Transition Metal Cluster Compounds MICHAEL I. BRUCE

1

Introduction

This chapter covers the chemistry of metal carbonyl and organometallic clusters containing three or more metal atoms. The treatment is in Periodic Group order, homometallic compounds being followed by heterometallic clusters. The majority of numbered compounds are illustrated, the few that are not being so indicated by an asterisk; in most cases, terminal CO groups are not shown. Coverage is essentially restricted to papers published during 1997, but some late appearing 1996 papers have also been included to preserve continuity with last year’s report; I have also been able to include several Russian publications appearing during the last three years. A survey of organometallic clusters for 1996 is available.’

2

General Reviews

A modified VESCF method has been applied to determine ligand stereochemistry for metal clusters containing x-bonded ligands, particularly M3(C0)3(L)3 (M = Co, Rh, Ir; L = q5-ligand; L3 = p3-q2:q2:q2-arene).2The site preferences for substitution of CO in t.b.p. metal clusters have been calculated using energy indices: differences in site electronegativity are important only for M5L, (n = 14, 15, but not 12) clusters.’ A survey of recent results in organometallic electrochemistry includes several cluster systems4 A qualitative theoretical study of ligand effects on the strength of M.-.M interactions in stacked $-ML4 complexes has rationalised much structural data, accounting for deviations in linearity of the stacks by electronic effect^.^ An understanding of the binding of ligands to metal complexes often enables a rationalisation of the reactivity of the resulting complexes to be obtained. In this regard, detailed studies of high nuclearity ( M,4) organometallic clusters containing exposed C2 ligands,6 and of thiophene complexes and clusters7 have appeared. Other general reviews include chalcogen-bridged metal carbonyl complexes8 and reactions and magnetic behaviour of chromium-sulfur clusters containing other metals.’ Alkyne-metal cluster complexes usually have the alkyne coordinated so that the C-C bond is parallel to one of the M-M bonds. The reactivity of clusters containing perpendicularly-coordinated alkyne ligands has

Organometallic Chemistry, Volume 27 6-j The Royal Society of Chemistry, 1999 151

152

Orgunometullic Chemistry

been discussed, with reference to their possible intermediacy in catalytic reactions. l o

3

Spectroscopic Studies

3.1 IR - The simplicity of metal cluster terminal v(C0) spectra has been addressed, whereby it was found that the closer that the distribution of the CO groups is to spherical, the closer the spectrum will approach a single IR-active band and two Raman-active bands; however, if coupling between CO groups on one metal atom is greater than that between CO groups on different metal atoms, a different pattern will result."

3.2 NMR - Dynamic NMR spectroscopy has been widely applied to examine the fluxional behaviour of metal cluster complexes, particularly of metal carbonyls. The techniques used (line-shape analysis, magnetisation transfer) have been reviewed with special attention to mechanisms of CO exchange in metal cluster carbonyls of Group 8 [M3(C0)12]and the structural flexibility of heteroplatinum clusters.

'*

4

Structural Studies

Studies of H-bonding with CO ligands in organometallic crystals have been reviewed." Hydrogen bonds can be formed between C O ligands and water, NH and CH groups, as well as with MH systems. A scale of CO ligand basicity has been established."' The recognition of packing motifs involving these bonds (partcularly C-H - .-OC)has allowed a rationalisation of the co-crystallisation of molecules on the basis of molecular size and shape.14 A review of structures of transition metal hydrides determined by neutron diffraction includes many diand polynuclear complexes. l 5 Powder X-ray diffraction studies are assuming increasing importance in the determination of structures of complexes which do not afford X-ray quality single crystals. Combination of X-ray and neutron diffraction analyses allowed location of the H atoms in a movophasic microcrystalline sample of Re4(psH)4(C0)12: they are found 1.99(2) A from the Re atoms.I6 The neutron diffraction structure of O S & - H ) ~ ( C O )(~I )~shows that the two H atoms bridge opposite but non-equivalent edges of the square base and coplanar with the respective OS~(CO groups. )~

'

H

H

1

4: Orguno-Trunsition Metal Cluster Conipoundv

5

I53

Large Clusters

Interest in clusters with nuclearity > I0 continues, but progress is relatively slow as a result of the comparative difficulties of characterisation, together with the lack of general methods of preparation. In this account, the chemistry of the more interesting large complexes is gathered together in one place; the metal cores are illustrated in Figure 1. A neutron diffraction study of [NMe433CRhl3H2(C0)24](2) has located the two H atoms in, but almost coplanar with the Rh4 faces of, square-pyramidal cavities in the metal core.33 Formal interaction with five Rh atoms occurs, with Rh-H distances of I.84(2) (central) and 1.97(2) (outer). This result confirms the expectation from X-ray structure that the H atoms are in theolarger cavities [average Rh-Rh distances 2.75(1) A for unoccupied, 2.78(1) A for occupied cavities]. Thermolysis of [Rh6N(CO)15]- (diglyme, 140-1 50 "C, 6-8 h) gives [Rh14N2(CO)2,l2-; under more vigorous conditions (I70 "C, 24-36 h) it gave several products, from which small amounts of [Rh28N4(H)(CO),1l5- (3) were isolated. This species was also isolated in 30% yield from [Rh14N2(C0)25]2- in basic solution (pH -I I , 100 "C, 3-5 h), but X-ray quality crystals could not be obtained. Reversible protonation gave the tetra-anion and the structure of [NEt&[Rh28N4(H)x(C0)4i] (x probably 2) was successfully determined.34 The Rh28 core consists of three layers (RhdRhl2/RhI0) forming essentially a ccp lattice enc!osing an Rh3 triangle. The 17 types of Rh-Rh distances range from 2.58-3.17 A, the four N atoms being in distorted octahedral cavities. There are 24 bridging, two semi-bridging and 15 terminal CO groups. There are two empty spaces in the Rhlo layer, which may be occupied by two H atoms. The c.v.e. count is 360 for x = 2. Non-centred 1 ,12-Ni10Sb2cages are prepared from [Ni6(C0)12]2-and SbBrR2 (R = Me, Et, Pr') or SbCIR2 (R = But, C6H4F-4).35 Of the 18 CO ligands in [Ni l&bR)2(CO)18]2- (4), ten are terminal, four bridging and four triply-bridging. Terminal-bridge exchange has AG' 52.5 kJ mol-' for the Pr' complex. Negative-ion ES MS gave parent M2- and derived ions. N o evidence for 1,2,12Ni19Sb3 or 1,2,9,12-NigSb4 clusters was obtained, although the P and As analogues are known. The related 1, 12-NiloBi2 clusters were obtained from [Ni6(C0)12I2- and BiC12R (R = Me, Et), completing the series of congeneric

A

I54

Orgunometullic Chernistry

N 2

3 n

Ni

- E 4

CI

6

7

C'

155

4: Orguno-TransitionMetul Cluster Cotnpounth

a

Ru

10

clusters, which are isolobal with the well-known [BIzH ]*I2- species.36This paper contains a detailed structural comparison of the four NilOEz (E = P, As, Sb, Bi) cages, together with the Ni-centered [NilI Bi2(CO)18]3- complex previously reported. Large Pd clusters have been made from Pd4(pCO)~(PEt3)4 and Pd10(C0)14(PEt3)4. The former reacts with Pd*(dba)3 to give Pd16(CO)13(PEt,),

156

Orgunomctullic Chemistry

and Pd34(C0)24(PEt3)12,while Pd3g(C0)28(PEt3)12is obtained from the Pdlo clusters and oxidising reagents such as Me 3NO/CF$02H, H202/CF3C02H or P ~ ( O A C ) ~ / M ~ Direct ~ N O .reaction ~~ of Pd 10(CO)14(PB~11~)4 with Me3NO gave Pd38(C0)28(PBU1'3)12. The 21 -atom cluster O S ~ ~ R ~ ~ ( ~ ~ - C( 5I )) was ( C Oisolated ) ~ ~ in 20% yield O ) ~and { Rh(pCl)(nbd)S2 in the from the reaction between [ O S ~ ( ~ - H ) ( C,Ipresence of AgPF(,.3s The core contains a central Rhg unit formed by fusion of two octahedra, to which four Os3 units are attached. The CI atom caps one RhJ face, the other Rh atoms being attached only to other metal atoms. The 268-e count does not conform to normal cluster electron counting rules. High nuclearity copper-containing clusters have been obtained from reactions of [Ru(,H(CO)Ig]- and [Cu(NCMe)4]' in CH2C12 in the presence of [ppn]CI: the anionic cluster [ C U ~ R U ~ H ~ ( ~ - C I ) ~ ((C 6 )Owas ) ~ ~isolated ] ~ - in 6070'%1yields.39 The core consists of a Cu7 unit formed by fusion of two square pyramids at a common Cu3face; the three CI atoms each bridge a pair of Cu atoms and may help stabilise the cluster. Two Ru4 tetrahedra sandwich the copper polyhedron; the H ligands could not be located. Individual Cu atoms have between five and eight M-M contacts. The products are solvent-dependent: if the reaction is carried out in MeCN, the l8-atom cluster [CubRul2(pH)2(p-C1)2(CO)23]2-(7) is isolated. In this cluster, two octahedral Rug clusters sandwich a Cu6 core formed from two edge-fused tetrahedra. The two CI ligands (originating from CH2C12) bridge Cu-Cu bonds, and the H atoms, while not located, are probably bridging Ru-Ru bonds (NMR). An alternative view of the core is as four edge-sharing octahedra, with bonds between the apical atoms of adjacent M6 units. Reactions of [ R U ~ ~ ( ~ - H ) ( C Owith )~~]~[Cu(NCMe)4]' gave 60-70'%,of another example of a large cluster formed by condensation of octahedra by edge- and face-sharing4" The Cu6 unit at the C Ois) ~similar ~ ] ~ - to that in the C U ~ R U ~ ~ centre of [ C U ( , R U ~ ~ H ~ ( ~ - C I ) ~ ((8) cluster; the Rule units are formed of face-sharing octahedra in which the butterfly cavity is capped. Again, the H atoms have not been located, but a broad signal at 6 -5 suggests that they are fluxional. Related studies have resulted in the synthesis and characterisation of [Ag3R~lo(C)2(pCI)(C0)28]~(9) from the reaction of [RUSC(CO)I~]~with Ag' ions.41The core is formed of two RuSC units linked by three Ag atoms: one AgAg vector is bridged by the C1 atom. Adsorption of this cluster o n an MCM-41 support, followed by pyrolysis at 473 K, gave a CO-free system which was catalytically active for hydrogenation of hex-1 -ene. TEM and EXAFS measurements showed the presence of Ag-Ru nanoparticles aligned in the channels of the support. Reduction of mixtures of PdCI2(PPh& and PtCI?(PMe3)2with [Ni6(C0)l2l2afforded 10-20'%,yields of the 41 -atom cluster Pd2,PtI3H12(C0)*7(PMe3)(PPh3)12 (10; c.v.e. count 358).42The metal core consists of a four-layer hcp Pd2,Pt core ( Pd3/Pd7/Pd12/PtPdh) which contains approximately square-pyramidal cavities each capped by a Pt(PPh3) fragment. The 12 H atoms each occupy one of these cavities (NMR and H/D exchange data). There are 18 p-CO and nine p3-CO

4: Orguno- Trunsition Metul Cluster Compounch

157

groups. The single PMe3 ligand is attached to the central Pt atom in the bottom layer.

6

Group4

Thermal decomposition of TiMenCp* in toluene gave the cubane cluster { Ti(p3CH)CP*}~and CH4, possibly by dimerisation of [Ti(=CH2)MeCp*] or tetramerisation of [Ti( = CH)Cp*] intermediate^.^^ The related cluster {Ti(p3NSnMe3)Cpj4 was isolated from the reaction between TiCI,(PEt&Cp and N ( S I I M ~ ~EH )~M . ~O~ calculations on this 52-e cluster predict two shorter and four longer Ti-Ti bonds, as found experimentally. Several 0x0 clusters have been reported: the cyclic trimer {Ti(p-O)(Cl)(q-C5Me,Ph)}3 and (Ti(qC5Me4Ph)f4(p-0)6,which has an adamantanoid Ti406 cage, were prepared by hydrolysis of TiC13(q-C5Me4Ph)in the presence of NHEt2 or Ag20,45while the reaction of TiMeC12Cp with PhCH2SH or EtSH gave pseudo-octahedral (TiCp}6(p3-O)3(p3-S)3and pseudo-tetrahedral fTiCp}4(p3-S)3(p-S)(p-SEt)2,respective~~.~~ The first zirconium cluster halide containing isocyanide ligands is the beryllium-centred Zr6BeCII 2(CN~y)6, which was isolated after dissolving K3Zr6BeCl15 in MeCN with C N X ~ . ~ ~

7

Group5

Three independent syntheses of paramagnetic { V(pCl)2L}3 (L = Cp*, C5Me4Et) were reported from VCl,(thf), and S ~ B U ~ ( L 50 ) . ~Sequential * reactions of TaCI4Cp* with CPh3(SH) and NaBH4 gave Ta3(p3-S3BH)(p-S)3Cp3,51 for which a niobium precedent exists.

8

Group6

Homo- and hetero-metallic Group 6 clusters MonW3-,(p3-P)(CO)6Cp3 (n = 0-3) were obtained from (M(C0)2Cp)2(M = Mo, W) and M'(p3-P3)(C0)2Cp (M' = Mo, W). Ready oxidation (air) in solution gave M o , , W ~ - , ( ~ ~ - P O ) ( C O ) & ~ ~ . ~ Similarly, sulfur adds to give the analogous p3-PS clusters, which readily lose sulfur to regenerate the p3-P corn pound^.^^ Tetranuckar clusters M04( p3S),(CO)4(CpR)4 (R = C02Me, COzEt) were formed as one of the products from { Mo(CO)2(CpR))2 and Fe2(p-SEt)z(C0)6.54All four non-hinge Mo-Mo bonds are unsymmetrically bridged by CO groups. Dihydrogen reacts with 1 ,2-W2B~i2(OPri)4 to give W6H(p-H)4(p-CPri)(pO P I - ' ) ~ ( O P ~as' ) ~the major product: the p-CPr' ligand occupies a unique site.55 The cluster is thought to be formed by a sequence of combinations of reactive dinuclear intermediates. The lack of intramolecular fluxionality has allowed determination of involvement of the terminal W-H in hydrogenation reactions

158

Organometallic. Chemistry

and specific alcoholysis reactions occurring a t the OPr' group next to three p-H ligands.

9

Group7

9.1 Manganese - Cubane clusters fMn(p3-NPEt3)R}4 (R = Me, C=CR', R' = Ph, tol, But, SiMe3) were obtained from { M ~ ( P ~ - N P E ~ ~and )BT LiR.56 ) ~ Hydro(so1vo)thermal reactions of Mn2(CO)lowith Na2E2 (E = S, Te) in EtOH gave [Mn3(p3-s2)(p-sH)(Co)9I2- and [Mn4(C14-Te2)(p3-Te2)2(Co)13I2I), -(1respect i ~ e l y . 'The ~ Na2S2 reaction in MeOH gave [Mr13(p-S2)2(p-SMe)(C0)9]~-.The anionic cluster [Mn3(p-Se)2(C0),]- is formed from Mn2(CO)lowith KOH and Se02 or Se powder in MeOH. With a large excess of S or Se, [Mn2fpEC(E)E2}(C0),l2- are formed, which readily transform into octahedral [Mn4(p4E)2(CO) I 212 - .'*

11 Mn = Mn(C0)3

9.2 Rhenium - Oxidative decarbonylation with Me3N0 has been used to synthesise Re3 clusters from Re2(CO)lo.59Thus, Re3(p-H)(C0)I4 is formed in 30%)yield from reactions run in thf-PhOH, together with [Re2(p-OPh)3(CO)6]-; in MeOH, [Re3(p3-OMe)(p-OH)2(p-OMe)(CO)9]- is formed. In the latter, Re...Re separations of 3.423 and 3.439 A preclude formal Re-Re bonding. Reactions of R ~ ~ ( P - O R ) ~ ( O(RR )=~ OCH2Bu') with unsaturated hydrocarbons have given organo-Re3 clusters. Ethene gives Re3(p-OCH2But)3(Et)( O C H ~ B U ' )which ~, exchanges with labelled ethene.60 Ethyne gives the adduct 12 in which the alkyne perpendicularly bridges one Re-Re vector, while substituted alkynes afford alkenyl complexes, Re3(p-OR)3(CR'=CHR2)(OR)5(R = R2 = Me, Et; R ' = H, R2 = But; R' = SiMe3, R2= H).600,61 Where insertion takes place, an accompanying product is pivaldehyde. Ethyne inserts into the Re-H bond of [Re3H(p-OR)3(OR)6]-,to give Re3(~-OR)3(CH=CH2)(0R)5.60 Similar reactions of Re3H(p-OPr')3(0Pr')5 with alkenes and alkynes proceeded by elimination of acetone and insertion of the unsaturated hydrocarbon into the Re-H bond so formed.62 Phenylethyne gave two isomers containing CPh=CH2 (minor) and CH=CHPh (major) ligands; the former eliminates a second molecule of acetone and inserts phenylethyne again to give Re3(p-OPri)3(CPh= CH2)2(OPr1)4. Fluxional processes in [Re3(p-H)3(p-C5H4N)(CO)lo]have been studied in detail and include synchronous ax-ax and eq-eq CO exchange on the apical Re

159

4: Orguno- Transition Metul Cluster Compoimtls

12

and exchange of the two H ligands, which is consistent with a rotation of the whole ReH2(C0)4 group about an axis passing through the mid-point of the bond between the other two Re atoms. A kinetic deuterium isotope effect supports involvement of the H hgands in the rate-determining step of the exchange.63 The anion is protonated by strong acids in MeCN to cisoid and transoid (major) isomers of Re3(p-H)3(CO)lo(NCMe)(py)(13*); the two isomers are in equilibrium and interconvert at rates dependent on the solvent. After protonation of the C5H4N ligand, various ligands show the following order of nucleophilicity towards the vacant site: BF4-, OEt2, OH2 < TfO- < Me2C0 << MeCN < CI, py

Reactions of 13 with C O and py give Re3(p-H)3(CO)Il(py) and Re3(pH)3(CO)Io(py)2, respectively, the latter being formed more quickly than the mono-pyridine complex. In these reactions, the kinetic cisltruns ratio is higher than the equilibrium ratio, with the result that intermediate risoid complexes can be seen in the conversion of trunsoid bis-MeCN complex into the trunsoid bispy ridine ~ o m p l e x . ' ~ A multitude of rhenium hydrido clusters are becoming available from reactions of ReH2(C0)4or [Re2H(CO)9]-. Thus, addition of the anion to the unsaturated complex Re2(p-H)2(C0)8 afforded the open chain cluster [Re4H(p-H)2(C0),,](14), in which fluxional processes involving terminal H atoms and the CO groups trans to them are observed, consistent with the 'windshield-wiper' motion of the ReH2(C0)4 fragment, as found in analogous Re2 and Re3 anions. Under CO, 14 readily breaks u p into ReH(C0)5 and [Re3H(p-H)(CO)13]-.65 This paper also describes a study of t'q-Re2(C0)9(L) species obtained from Re2(CO)lo and Me3NO in thf: labile complexes in which L = thf (major), H20 and NMe3 are present. Reactions of these with [Re2H(CO),]- gave [Re4(p-H)(C0)ls]-, also fluxional. 1

14

160

Orgunometullic Chemistry

The aqua complex [Re(C0)3(OH2)3]' is formed quantitatively when [NEt4]2[ReBr3(CO)3] is dissolved in water. Slow hydrolysis then occurs to give [Re&OH)3(CO)6]- and [Re3(p3-OH)(p-OH)3(C0)9]-. The cubane cluster { Re(p3OH)(C0)3), can be obtained by extraction of the aqueous solution of [Re(C0)3(OH2)3]' with Et20 after addition of base; formation of adducts with dmf and OPPh3 was reported.66 Reactions of Re2(p-H)(p-PCy2)(CO)8 with LiPh, followed by addition of HgC12 and PPh3, afforded Re2Hg(p-PCy2)(CI)(C0)7(PPh3) and Re2Hg(p-PCy2)(pCPhO)(CO),(PPh3), the latter being formed with an excess of LiPh.67Exchange of CI for OH in [Re7Hg(p6-C)(CI)(CO)21]2-was achieved with aqueous AgNO3; subsequent reaction with 4-BrC6H4SH gave [Re7Hg(p6-C)(SC6H4Br4)(CO),l]2- .68 In these complexes and in [Re7Tl(p6-C)(CO)21]2-,obtained from [Re7(p6-C)(C0)2,l3-and TIPF6,69the HgR ( R = OH, SC6H4Br)groups or the TI atom cap the Re3 face opposite that capped by the seventh Re atom.

10

Group8

10.1 M3(C0),2 Clusters - As mentioned above, the molecular structures and dynamic processes found in the various M3(CO)12 species have been reviewed.12 However, the interpretation of the results of these studies continues to be a source of contention, with detailed summaries and interpretations in terms of CO migration via concerted bridge-opening and bridge-closing reactions7' or libration of the metal core within the (CO), ligand polyhedron" being given. The first tetrasubstituted derivatives of Fe3(C0)12 have been obtained from reactions of Fe3(CO)loL'L2 [L', L2 = CO, P(OMe)3, P(OCH2)3CMe]with C N B U ' . ~ ~ ~

10.2 Iron -- Trinucleur clusters. Mixtures of di- and tri-nuclear complexes were obtained from reactions between Fe3(C0)12and (4-XC6H4)2C=CCI(SnBu'3) (X = H, Me, CI) or E- and Z-MePhC=CI(SnBu13),including ferraindenes such as 15,72 and from HC = CCHPh(OH), which afforded Fe3(p3-CCCHPh)(p-CO)(C0)9 in low yield.73With MeOH, the latter gave Fe2{p-CHPhCHC(0)OMe}(CO)6. Group 14 complexes were formed from Fe3(CO),2 and HSiC13 [Fe(Sic13)~(Co)~, 20'X)]74and from [Fe3(CO),'I2- and PbClPh3 (the first open Fe-FePb cluster anion, [Fe3(PbPh3)(p-CO)2(CO)9] -).75

15

16

4: Orguno-Trunsition Metul Cluster Compounds

161

Phosphinidene clusters have been obtained from Fe2(C0)9 and chloromethylphosphines containing bulky s u b ~ t i t u e n t s Systematic .~~~ studies of the clusters Fe3{p3-E[ML,])2(C0)9 [E = P, As, Sb; ML, = Cr(CO)5, Mn(CO)zCp], which are considered to be analogues of complexes of ligands ER3, have shown that their geometries and electrochemical properties are determined by the covalent radius of E, while v(C0) frequencies are determined by the relative electronegativities of E.77The Mn derivatives are reduced at potentials -400 mV more negative than the Cr analogues; the ligand properties of the E atom are changed by 2-e reduction, as shown by a 0.1 A lengthening of the P-Mn distance in the dianion compared with the neutral complex. Fenske-Hall MO calculations are used to rationalise the Fe-E bonding. Thermolysis of [NEt& [Fe4Bi4(CO)13] gave square-pyramidal [Fe3(p3-Bi)2(CO),l2- (ref. 78) while reactions with PC12Me gave mainly diiron complexes, as well as [Fe3Biz(pH)(CO) 101- ( The reaction of Fe3(C0)12with Bu'SH and NEt3 in the presence of zinc acetate gave F ~ ~ ( ~ - S B U ' ) ~ as ( Cthe O )main ~ product, accompanied by the unusual cluster Fe3(p3-SBut)(p-SH)(C0)9.80The major products from Fe3(p3-S)2(C0)9 and PdC12(PPr'3)2were Fe3(p3-S)2(C0)9-,(PPri3), (n = 1, 2), together with Fe2((pS)2Pd(PPri3)2}( c o ) ~ . Several ~' reactions of [Fe3(p3-Se)(C0)9I2- have been reported. The anion is formed from Fe(CO)5 and Na2Se in Pr'OH; protonation gave Fe3(pL-H)2(p3-Se)( CO)9.20Binuclear complexes were obtained from reactions with CH212 or CHC12Ph, while the p-HgI cluster [Fe3(p3-Se)(p-HgI)(C0)9]- was formed from The mixed-metal cluster [Fe2Ru3(p4-Se)(p-C0)(CO)~3]*was obtained with Ru3(C0)12.** Various diphosphine diselenides react with Fe3(C0)12 to give Fe&3-Se)2(CO)7(PP) (PP = dppm, dppe, dppf), as well as { Fe3(~3-S)2(C0)8)2(p-dppe).~~~Phosphine substitution occurs only at the two basal Fe atoms; fluxional behaviour of the dppm and dppe clusters may involve the Fe-Fe bond between atoms linked by the PP ligand. Se(C5Me~)zreacts with Fe2(C0)9 to give Fe3(p3-Se)2(C0)9.84The tetra-iron complex Fe3{ p3-SeCButPSe2[Fe(C0)3](p3-Se)}(C0)B (17) is formed from Fe2(pL-Se)2(CO)9and Bu'C = P and NaH; it shows significant third-order NLO proper tie^.^^ Organotellurolates LiTeR react with Fe3(C0),2to give [Fe2(p-TeR)(pL-Co)(c0)6]-(R = Bun, Ph, 2and 4-t0lyI).~~ Trinuclear clusters can be obtained from heterocyclic Te-N compounds such as benzoisotellurazole, which gives 18; 2-methylbenzotellurazole was detellurdted and gave 19.87 The unusual cubane cluster Fe3(p3-Te)3{ p3C[TeBr4])(C0)9 was obtained from F e & . ~ ~ - T e ) * ( cand 0 ) ~ CBr4; one of the Fe sites is occupied by the p3-CTeB1-4moiety.88 Detailed EH MO analyses of 50-e square pyramidal Fe3E2 ( E = Bi, S) clusters have shown that in the former, the square Fe2E2 moiety is flatter than found with the sulfur clusters.78 The angle Fe-E-Fe becomes larger when E bears a substituent; the E...E non-bonding distances are short. Although the latter interactions are involved, the most important feature which determines the geometry is the presence or absence of a lone pair on E. Whereas this electron pair has primarily s character in the absence of a substituent, as it becomes more involved in bonding and therefore more localised, the M-E-M angle widens.

162

Orgunorn~~tullis Chemistry

0

19

Higher nuclearity clusters. One of the most interesting systems has been obtained independently by two groups.89990Thermolysis of Fe2(p-PPh&K2Ph)(C0)6 gave the rectangular Fe4-diyne cluster 20 i n which the two C2Ph groups are coupled with a long C-C interaction (-1.60 A ) through the centre of the Fe4 face. Formally, the complex has 64-e (with two 5-e donor phenylethynyl ligands) or 68e [as an Fe4(p4-CR)2 system]. EH M O c a l c ~ l a t i o n suggest s ~ ~ that a 64-e count for the cluster is stable (the L U M O is 1.99 eV above the HOMO); the C . - . C overlap population is +0.66, i.e. a significant bonding interaction exists through the cluster.

/

Ph

20

A range of bonding interactions is available to the cluster [Fc4C(CO)12J2-in its reactions with electrophiles. For H', the hinge position is bridged, whereas the isolobal [Au(PPh3)]' fragment bridges the wingtip Fe atoms. A further site of attachment is found in the products obtained from [Hg{M}]+ [M = Mol W(CO),Cp, Mn(CO)5, Fe(CO)zCp, CO(CO)~], in which the Hg atom bridges an

4: Orguno-Trunsition Mecul Cluster Compounds

163

Fe(basa1)-Fe(wingtip) vector." Oxidation (with [FcH]+) gave a radical species in which the unpaired electron density is located within the Fe4Hg core. Similar complexes [Fe6C{ p-Hg[ MI) (CO),,] - [M = Mo/W(C0)3Cp, Mn(CO)s]were formed with [Fe6C(CO),6]2-; with Hg(N03)2, Hg{Fe6C(C0)16}2was isolated.92 The butterfly vinylidene-Fe4 cluster Fe4(p4-C=CMe(OMe)}(CO)~2has been converted into the analogous pq-C=CHMe cluster by treatment with Li[BHEt3] followed by SiMe3(0Tf).93 Comparison of observed geometries of p4-carbyne and p4-vinylidene clusters shows that only partial C=C double bonds are found in the p4-C=CR(OMe) (R = H, OMe) complexes, electron density shifting on to the 0 atoms. A consequence is that C, of the vinylidene in the p4-C=CHMe complex is below the wingtip Fe.-.Fe vector, bonding to these atoms involving the C=C n-bond rather than the Caporbital lone pair. Reactions of [Fe4S414]2-with ArNC (Ar = xy, mes) in the presence of CoCp2 afford cubanes Fe4(p3-S)41(CNAr)9in which I - can be exchanged for [S(mes)]-; treatment with K[B(C6H4Cl-4)4] gave the coupled cluster [{ Fe4(p3S)3(CNAr)9)2(p4-S)2]2+.94 Multiple oxidation states have been found in mixedligand clusters [Fe4(p3-S2)(p3-S)3(S2C2Ph2)Cp*3]"+ (n = 0-2); comparison of the Fe-Fe separations for the PF6 and By4 salts of the monocatiop shows the presence of three short [2.736-2.783(1) A] and one long [3.047(2) A], and four short [2.732-2.887(2)A] Fe-Fe bonds, respe~tively.~' 10.3 Ruthenium - The long-sought after complex Ru&H)~(CO)IO has been made by photolysis of Ru3(C0)]2 under H2 and characterised by its IR and NMR spectra (6 -13.6), which are similar to those of the 0 s analogue. Preliminary studies have demonstrated the formation of R u ~ H ~ ( C O ) ~ O ( P P ~ ~ ) , Ru3H(C2Ph)(CO) 10 and Ru(C0)3(q4-C6H8) in its reactions with PPh3, HC = CPh and 1,3-~yclohexadiene,r e ~ p e c t i v e l yConditions .~~ have been described for the high-yield syntheses of several ruthenium cluster carbonyls and related anions by the controlled reduction of RuCI3 supported on silica; an intermediate species RuC12(C0)3(HOSi = ) is the initial product.97 Variables include stoichiometries, the presence of Na2CO3 or K2CO3, reducing agent (CO, CO + H2, CO + H20) as well as temperature and time. Details are given for Ru3(C0)12, Ru3C12(CO)I2, RU4(p-H)4(C0)12, K[Ru4(p-H)3(CO)I2], K[RU6(p-H)(C0)18] and K2[Ru6C(CO)181. On hydroxylated magnesia, R U ~ ( C Ois) converted ~~ to [Ru3(p-H)(CO)l,]- and can be recovered as such by addition of [ppn]CI. Treatment of the adsorbed anion with H2 results in its conversion to [RU&-H)~(CO)~~]-, which is reversed when CO replaces the H2.98 These reactions are similar to those occurring in basic solution: the anions are mobile on the oxide surface. On high surface area rare earth oxides, R q ( C 0 ) 12 forms surface-adsorbed clusters, probably Ru&-H)(pOM -)(CO)l0, together with { Ru(0M =)2(CO)2)),.99 Trinucfeur clusters. Hydrocarbon ligunds. Reactions of Ru3(CO)I2 with unsaturated hydrocarbons continue to be a rich source of ruthenium cluster complexes containing novel ligands. For example, Ru3, Ru4 and Rug clusters have been obtained from styrenes: complexes containing p3-q ':q ':q2:q6-HCCHC6H3R, p4-

I64

Orgunomc~tullicChemistry

q1:q1:q2:q2-HC2C6H4R and q6-EtC6H4R ligands (R = H, Me, CF3) were obtained, together with Rug(p4-q :q I :q 2:q2-HC2C6H4R)(CO)1 ~ ( -EtC,H,R) q (21).looIsomeric clusters 22 and 23 were isolated from reactions with cycloocta1,3-diene: while the attachment of the Cg ligand in the former is conventional, the allenyl system in 23 is novel.'" EH MO calculations were reported for model clusters containing p3-q2-HC2CH=CH2 and p3-q3-HC=C=CHMe ligands: both systems form strong bonds to the cluster. The reactions between RC6H41-4 (R = H, Me) and R U ~ ( C Ogave ) ~ ~ Ru3(p3-q':qh-C6H4R)(p-I)(CO)s, formed by oxidative addition of the Ar-I bond across an Ru-Ru bond, followed by q6 coordination of the aryl group.Io2

'

21

22

23

The p-fulvalene complex R u ~p-qs:q ( 5-C~H4C~H4)(C0)4 is readily isomerised to { Ru(p-q I:qs-C5H4)(CO)2)2. Extended reaction under an N2 purge results in formation of the mixed fulvaleneKSH4 cluster 24, which can be formally viewed

24

as being formed by condensation of a molecule of each isomer. I"' Quantitative formation of Ru3(p3-H)2(p-H)3(p3-q2:q2:q2-C6Hb)Cp*3(25) occurs on teatment of R U ~ ( ~ ~ - H ) Z ( P - H )with ~ C Pan* ~excess of cyclohexa-l,3-diene in a reaction that probably proceeds viu an intermediate p3-q2:q2-C6H8complex; this hydrocarbon appears to fit the cavity above the metal cluster, whereas the 1,4-isomer requires heating to effect isomerisation before reaction occurs.lo4The CV of 25 shows two reversible I -e oxidations; chemical oxidation with [FcH]PF6 enabled the monoand dications to be isolated. In the latter (26), the benzene ligand is coordinated in the p3-q3:q3 mode, this conversion being the first example of an oxidationinduced hapticity change on a cluster. The first examples of cluster complexes containing C70 are found in Ru3(p3-

4: Orguno-Trunsition Metal Cluster Compoiinds

165

C70)(CO)9and { Ru3(C0)9}2(p3,p3-C70). Three isomers of the latter were isolated, the 1R v(C0) spectra of which suggest similar bonding in each; one, of C2 symmetry, was also structurally characterised and found to have the same p3q2:q2:q2bonding of the R u ~clusters to six-membered rings as in the mono substituted complex. While the reactions of alkynes with metal carbonyls have produced a multitude of unusual complexes, it is often difficult to produce and identify the simple q2alkyne intermediates. The chemistry of R U ~ ( C Ohas )~~ proved no exception, so the report of a versatile route to Ru3(CO)],(q2-alkyne)complexes from RujH(pH)(CO)I1 is of importance in this regard. The hydrido cluster can be regarded as a 'lightly-stabilised' Run(CO),I , although the detection of free C2H4 during the reaction with C2H2 suggests that other competitive reactions may be occurring. The preliminary report describes complexes obtained with ethyne and HC = CPh."' The former readily transforms to the p3-alkyne complex. The NMR spectrum indicates that the C2H2 occupies an axial positipn and 'H relaxation times were used to determine the H . . . H separation at 2.48 A. A considerable chemistry of ethynylferrocene derivatives of Ru3(CO)I2 is developing. Its reactions with R u ~ ( C O )afforded I~ RuZ, Ru3 and Ru4 clusters of familiar structural types. One product has since been shown to arise by formal cleavage of the C E C triple bond, being characterised as Ru&-H)(pC F C ) ( C O ) ~ ~The . " ~ reaction of Ru3(p-H)(p3-C2Fc)(C0)9with Ru3(C0)12 gave R u ~~( - H ) ( ~ & ~ F c ) ( C 2,O )which I shows CO and alkynyl migration processes. The Os3Ru cluster was obtained with the Os3 complex. However, comparison with the propynyl derivative showed that the H migrated back to the C2Me group to give O S ~ R U ( ~ ~ - H C ~ M ~ )in( Cthe O ) analogous ,~ reaction.398 With FcC = CC = CFc, binuclear complexes were obtained [all three isomers of R u f ~ pC ~ F C ~=( CFC)~}(CO), C and Ru2fp-[CFcC(C= CFC)]~CO)(CO),].'~* In these clusters, reversible I-e oxidation of the Fc nucleus occurs at between 0.15 and 0.25 V more positive potentials than free ferrocene. The electron-withdrawing power of M4 clusters is greater than that of M3 clusters and they undergo reversible 1 -e reduction to radical anions."' With PhC =CCH=CHPh, the usual bi- and tri-nuclear metallacyclopentadiene complexes were formed, together with Ru3{p3-C(CH=CHPh)CPhCPhC(q2(CH=CHPh)}(CO)8.Io8The free C r C triple bond in Fe2{p-SeCH=C(C3 CR)Se)(CO), (R = Me, Bun) reacts with M R ( C O ) , ~ ( N C Mto~ give ) ~ the usual p3q ':q':q2-alkyne cluster complexes. Thermolysis of Ru3(p3-PhC2C= CPh)(pCO)(CO)9resulted in fragmentation of the cluster. Two products were obtained:

'

Orgunometullic Chemistry

166

Ru4(p4-PhC2C E CPh)(CO)I2 containing a C2Ru4 core, formed by cluster expansion, and Ru4(p,p-PhCCCCPh)(CO)14, in which the organic ligand bridges two Ru~ fragments in p-2q':q4 and p-ql:ql modes.']' Reaction of RuJ(C0)12 with hexa-2,4-diyn-l,6-diol gave Ru3 {p3-q2-CH2(0H)C2C= CCH2(OH)>(pCO)(CO)9; the only reported product obtained from PhC ZE CC = CPh was R u ~ ( ~ - C P ~ CCPh)C(C (C ECP~)CP~)(CO)~."~ Insertion of C2Ph2 into one of the Ru-C 0-bonds of Ru3(p-H)(p3-q1:q1:q2C12H 17)(CO)9afforded 27, containing an open, bent Ru3 chain; the cluster-bound H atom migrates to the C12 ring during this reaction.lI3

27

Hydrogenation of acenaphthylene to 4,5-dihydroacenaphthylene,catalysed by R u ~ ( C O ) Iinvolves ~, the hydrocarbon being face-bonded in the p3-q2:q3:qsmode (28; Scheme 1) followed by hydrogenation and partial displacement to the pq1:q5mode in 29 (from the C5 and a c6 ring), before the product is displaced by CO. In the course of the final step, intramolecular oxidative addition also forms 30 in which the hydrocarbon is p3-q':q2:qs-bonded.1'4This complex is not an intermediate and is carbonylated to 31, in which the organic ligand is p-q':qs bonded from the C5 ring only. Labelling studies were used to determine some features of the proposed mechanism. Group 13 complexes. Reactions of R u ~ ( C O ) !with ~ Ga2Cl4 have given Ru{GaCl(thf)}{ GaCl~(thf))2(C0)3 and R u ~GaCl(thf))2(CO)p.' { l5

Other Group 14 systems. A review of organo-silicon and -tin complexes derived from Ru3(C0)12 and an aminopyridine cluster is available.' I 6 Reactions of R u ~ ( C O )with ' ~ HSi(OSiMe3)3and HSiMe(OSiMe3)2 have given clusters containing p-Si-0 bonded ligands which decompose to { Ru[Si(OR)3](C0)4}2 and Ru~(~-H)~(CO Irradiation )I~. of the reaction mixtures affords the truns-SiRuRuSi complexes cleanly.]l 7

Nitrogen-donor ligunds. The kinetic site of protonation of [Ru~(pNO)(CO)lo]- is the NO group in an anion-assisted intermolecular process: H migration to the cluster from first-formed Ru3(p3-N0H)(p3-CO)(C0)9 then

167

4: Orguno- Trunsition M e t d Clitsier Compounds

20

29

30

31

Scheme 1

affords Ru3(p-H)(p-NO)(CO) 10. 'I8 All three clusters exhibit C O group fluxionality. A detailed comparison of the ligand dynamics of p3-q2-imidoyl complexes of Ru and 0 s has been made."9 While molecular structures of congeneric complexes are identical, the Ru complexes have lower Ru-CO bond energies and are more sensitive to substituents on the RC=NR' group. Consequently, the 'windshieldwiper' motion of the latter across the Ru3 cluster is the lowest energy process, compared with tripodal rotation of the M(CO)3 group in the osmium compounds. Substitution with other 2-e donors (PR3, CNR) is achieved by hemilabile p2Ip3 interconversions of the imidoyl ligand: PR3 adds to the N-bonded 0 s atom. Sequential addition of PPh3 and CN Me gave Os3(p-H)(p-C=NC3Hs)(CO)8(CNMe)(PPh3), in which the isocyanide is found on the third 0 s atom. Both Ru and 0 s pJ-imidoyl clusters react with alkynes C2R2 (R = Me, Ph, C02Me) to give a variety of products: the 0 s clusters usually required activation by replacing one C O by MeCN before reaction occurred. Reactions include alkyne insertion into the M-H bond to give p-vinyl ligands or coupling to give metallacyclopentadienes; the third 0 s atom coordinates t o an ester 0 atom. With Os3(p-H)(pC=NC3H6)(CO)I *, a1kyne-imidoyl coupling gave Os3(p-q6-MeCH =CMeCMe=cMec=NC~H~)(c0)8. Two molecules of diphenylethyne insert into one of the Ru-N bonds of Ru3(pH)(p-N=CPh2)(CO),, t o give Ru2(p-ql,q',N:q2,q2-C6H4CPh=NCPh=CPhCPh=CPh)(p-CO)(CO)4 in which one of the azavinylidene Ph groups has been

'**

168

Orgunometullic Chemistry

metallated. Reactions of the unsaturated cluster Ru3(p-H){p-NS(0)MePh}(C0)9 with alkynes afford several different types of With the p-vinyl derivative Ru3 { p3-NS(0)MePh){ pH C = CCH2Ph, C(CH2Ph)=CH2}(p-CO)2(CO)6 is formed. Internal alkynes RC = CR' gave the unusual p3-vinyl complexes Ru3 { p3-NS( 0)MePh } (p3-CR=CH R')(p-CO)(CO)-I (32; R = R' = Pr; R = Ph, R' = Bu"), containing open R u ~clusters. With diphenylethyne, two molecules of alkyne react to form Ru3(p-H) { p3-NS(O)Me(C,H4)}(p3-C2Ph&p-CPh=CHPh)(C0)6, in which the sulfoximido Ph group has been metallated. With PhC 3 C(C6H4N02-4), unusual coupling and N 0 2 elimination reactions give Ru3 { pJ-NS(O)MePh)(p,-PhCCCCHPh)(CO)g (33) and Ru3{ p-NS(0)MePh}(p3-PhCCCCHPh)(CO)9 (34), in which the C4 groups are considered to be butatrienyl and butenynyl ligands, r e ~ p e c t i v e l y . ' The ~~ nitrophenyl group is retained in two minor isomeric products, R u ~p3-NS(O){ MePh}(p-CR=CHR')(p-C0)2(CO)6 (R = C6H4N02-4, R' = Ph and the reverse; analogous to the complex above).

32

33

34

Photolysis of M3(CO)I2 (M = Ru, 0s) with N-heterocycles results in substitution of C O rather than fragmentation of the clusters; further reactions, such as addition of C-H bonds to the clusters are found for the Ru complexes of pyridine and 2-methylpyridine. In xylene, pyridazine (pydz) gave Os3(p-H)(p-pydz H)(C0)lo.124Dynamic behaviour of pyrrolic ligands on Ru3 clusters has been studied.1251-Methylpyrrole is metallated at the 3-position to give Ru3(p-H)(p3C4H3N Me)(C0)9: two isomers are in equilibrium, interconversion involving H migration between Ru-Ru edges with concomitant electron reorganisation within the ligand. Isomerisation in refluxing cyclohexane gave Ru&~-H)2(p3-q'C4H2NMe)(C0)9, analogous to the 0 s complex; the reaction is reversed in more polar solvents. The C4H3NMe ligand shows a new type of coordination t o the R u cluster ~ in 35. In thf, similar products were obtained from 2,5-Me&HZNR (R = H, Me), but in PhMe, cleavage of N-H and C-H bonds with loss of H2 occurs t o give R u ~ ( ~ - H ) ( ~ ~ - C H = C ~ H ~ M ~ Nand )(CO Ru3(p-H)( )~ j.17-q~CHC4H2 MeN )(p-CO)(CO) Open R u j cores are present in two minor products obtained from reactions between Ru3(CO)I2 and I-nitroso-2-naphthol (Hnqo).126In one, two nqo ligands and in the other, two coupled quinone-imine ligands, bridge the open edge. Coordination of deprotonated 3-hydroxy- 1,2,3-benzotriazin-4(3H)-oneto the M3 cluster occurs in different ways for the ruthenium and osmium complexes M3(p-

4: Orguno-TransitionMetul Cluster Compounds

I69

H){NNN(0)C7H40)(CO)lo (36 and 37, respectively): in the former, p-N',N2 bonding is found, while in the latter the ligand is attached via ring N3 and azoxy o atorns.l2' Ru

35

36

37

Phosphorus-donor ligunds. Tertiary vinylphosphines react with M3(CO)I2 (M = Ru, 0 s ) to give, initially, the CO-substitution products M3(CO)12-n(L)n[L = PPh2(CH=CH2), PPh(CH=CH2)2]. Further transformation of the osmium complexes was not achieved, but the ruthenium analogues undergo oxidative addition reactions of the vinylic C-H bond to give Ru3(p-H) (p3-PPh2(CH=CH)J( C 0 ) g { PPh2(CH=CH2) or RuJ(p-H)(p3-PPh(CH=CH2)(CH=CH))(CO), { PPh(CH=CH2)2}, a process reported as being 'favoured by the TLC material'. The metallated vinylphosphine is p3-q':q2:fbonded.'28 With (R)-binap, the usual Me3NO-induced C O substitution reaction gives instead Ru3(p-binap)(p-OH)2(C0)8, which shows restricted rotation about four of the P-Ph bonds. The thermal reaction between Ru~(CO)IZ and (R)-binap gave Ru&-H)(p-binap - H)(CO)9, in which a Ph group has been metallated.129 Reactions of { C U ( ~ ~ - C I ) ( P H B Uwith '~)J~ R U ~ ( C O afforded )~~ products by phosphine and CI transfer, namely Ru3(p-H)2(p3-PBu1)(C0)8(PHBu12)2 (38), Ru~(~-H)(~-CI)(~-PBU'~)~(CO)~ and the 50-e cluster Ru3(p-C1)3(p-PBut2)(C0)6(PHB~'2).130 Bu' P

38 Complexes Ru3(p3-NPh)(p3-CO)(CO)9-n(PPh3)n (n = 1, 2) were obtained from both thermal and Me3NO-induced CO substitution reactions of Ru3(p3-NPh)(p3CO)(CO),. The first PPh3 ligand occupies an axial position, while the second takes up an equatorial position on an adjacent Ru atom.I3' Electrochemical studies of all three complexes showed irreversible reduction waves at - 1.47,

Orgunometullic Chemistry

170

- 1.67 and - I .89 V, respectively, probably to give radical anions which then lose CO and/or PPh3. have been prepared Several derivatives of RU~(~-H)(~-N=CP~~)(CO)~(PHP~Z) by conventional routes. 1 3 2 Thermolysis gives Ru3(p-H)&-PPh2)(pN=CPh2)(C0)*which with CO forms Ru,(p-PPh2)(p-N=CPh,)(CO), by loss of H2. Addition of PHPh2 gave Ru~(~-H)~(~-PP~~)(~-N=CP~~)(CO)~(PH Protonation of these three complexes afforded [Ru3(p-H)2(pN =CPh2)(CO),(PH Ph2)]+, [Ru3(p-PPh2)(p-N =CPh2)(CO),]+ and [ R u ~ ( ~ - H ) ~ ( ~ PPh*)(p-N=CPh,)(CO),(PHPh2)]+, the latter two being unusual examples of protonated p-phosphido complexes. ~ ~ } (PHPh2, C ~ ) ~ PPh3 or Ready reactions of R u ~ ( ~ H ) { ~ ~ - N H C ( O ) N M with dppm occur at r.t. to give the mono- or disubstituted complexes: the first ligand With dppm, a mixture occupies an equatorial position cis to the p-NH of symmetric and asymmetric isomers is obtained. Thermolysis of the PHPh2 complex afforded Ru3{p3-NHC(0)NMe2)(p-PPh2)(p-CO)(CO)6 and Ru~(~-H){~~-NHC(O)NM~~)(~-PP~~)~(CO)~. The reaction with two eq. of PPh3 in the presence of alumina gave the unusual p-phenyl cluster Ru3{p3NHC(0)NMe2>(p-PPh2)2(CL-Ph)(CO)6.A related complex was obtained by thermolysis of [Ru3(p3-ampy)(C0)8(PPh3)21+ (ampy = 2-NH-6-MeC5H3N) when [Ru3(~~3-ampy)(p-PPh2)(p-Ph)(CO)~(PPh3)]' is formed; addition of CO gives a 50e complex in the first reversible P-C bond activation process on a cluster to be reported. Treatment with [ppn]CI gave the neutral acyl Ru3(p3-ampy)(p-CI)(p-

PPh2)(p-PhCO)(CO),(PPh3). The complex Ru3(p-dppm)(CO) (39*) often offers enhanced reactivity and cleaner reactions than R u ~ ( C O ) , ~ although , on heating dephenylation of the dppm ligand (usually with elimination of benzene) may occur readily. Further reactions of 39 reported during 1997 include that with P=CBu' to give R u ~ { ~ J PC(C0)Bu') 2(p-dppm)(CO)7 in which the p3-ligand is formed by formal addition of CO to the phosphaalkyne. 135 The complexes Ru3(pJ-PhC2C= CPh)(pdppm)(p-CO)(C0)7 and Ru3(p-dppm){p-C4Ph2(C 3 CPh)2}(CO), (40) were obtained from 39 and PhC=CC-CPh, the first also being formed by direct reaction of Ru3(p3-PhC2C= CPh)(p-CO)(C0)9 with dppm.' I Thermolysis gave Ru3{ p3-CPhCHCC(C6H4)}(p-dppm)(CO)g (41) and Ru3(p3-C4HzPh2)(p C 0 ) (CO)s(dppm).

'

R

40 R=Ph,C=CPh 41

171

4: Orguno-Transition Metul Cluster Compounds

Ready addition of dppa to the unsubstituted Ru atom in 39 afforded { Ru3(pdppm)(C0)9}n(dppa)(n = 1, 2). On heating the latter in refluxing thf for 2.5 h, the major product was RU~(~~-PP~CH~PP~~)(CL~-~~':T~~ PPh2)(Ph)(co)6 (42).'36 The R u ~chain in 42 supports the dephenylated dppm ligand and C2Ph and PPh2 fragments formed by P-C(sp) bond cleavage in the dppa ligand. Unusually, the Ph group from the dppm has been trapped on the cluster and is bound at the end of the chain. A minor product was characterised as the phosphinoxy complex Ru3(p-H) { p3-CCHP(O)Ph2}(p-PPhz)(pdppm)(C0)6 (43).

42

43

Ph

Ph

Scheme 2

8Ph

172

Orgmometullic Chemistry

Group 16 donor ligancis. In contrast with the mononuclear products formed with iron carbonyls, a remarkable number of polynuclear complexes were obtained from reactions between R U ~ ( C O and ) ~ ~ PhCH=CHC(O)R (R = Me, Ph) (Scheme 2)."7 Several complexes were isolated from reactions of NHfP(E)R2}2(E = S, Se; R = Pr', Ph) with R U ~ ( C O )In~ general, ~. cleavage of the P-E bond occurred to give clusters of the types Ru3(p3-E)(p-(PR2)2NH)(C0)7 and R u 4 ( ~ 4 - E ) ~ ( p (PR2)2NH}(p-co)(Co)g containing pn-E (n = 3, 4) and p-(PR2)2NH ligands.'"' Reactions of benzo[b]tellurophene with M3(C0)12 ( M = Ru, 0 s ) have given RU~(P-CSH~)(CO)~ (already known), OSj(~ - C ~ H ~ T ~ ) ( C (4) O )and I ~ M4(~3T ~ ) ( ~ - C ~ H ~ ) ((459, C O )together I~ with several binuclear complexes.139

44

Tetrunucfeur clusters. A convenient synthesis of salts of [Ru4(p-H)3(C0)12]- is reaction of the cluster hydride with azamacrocycles (tacn, 1,4,7-Me3-tacn1tacd, 1 ,5,9-Me3-tacd). The N MR properties, fluxional behaviour of the anions, and their catalytic activity in the water gas shift and MeOH carbonylation reactions have been studied.I4' In contrast to iodoarenes (see above), reactions of 1 -iodonaphthalene and 9iodophenanthrene with R u ~ ( C O )afford ~ the p4-aryne complexes Ru4(p4-q2L)(c0)12( L = C10H6, C14H8, respectively) in which the polycyclic hydrocarbon forms part of a conventional C2Ru4cluster.Io2An interesting alkynyl coupling reaction occurs on heating Ru2(p-PPh2)(p-C2But)(CO)6, initial dimerisation affording the 64-e cluster Ru4(p-PPh2)2(p-C2But)2(C0)g (46; Scheme 3) which is further transformed into R u ~ ( ~ ~ - B u ~ C ~ C ~ ~ U ' ) ( ~ (47); - P Pcarbonylation ~~)~(CO)S then gives Ru3(p3-q2-Bu'C2C= CBut)(p-PPh2)2(C0)7.14' The structure of 47 contrasts with that of the iron analogue 20 in that the diyne is not threaded through the cluster. Several ruthenium-containing clusters obtained from reactions of R U ~ ( C O ) ~ ~ and Fez(p-SeCH=CPhSe)(C0)6 include R u & ~ - H C ~ P ~ ) ( CI 2,O Ru4( ) p4-Se)(p4HC,Ph)(p-C0)2(CO)q and FeR~2(p3-Se)2(CO)g.I~~ The complex Ru4(p-rl3:rl4-c,H7)2(p-c0)( CO)6, obtained from Ru3(CO)I2 and cycloheptatriene, is considered to be an example of a novel type of sandwich complex in which a cluster core is sandwiched between two almost planar C7 rings.143In the crystal the molecules pa$ with direct interactions between the rings, with inter-ring separations of 3.46 A. Similar reactions with cycloocta-l,3-

4: Orguno- Trunsition Metal Cluster Compounds

I73 Bu'

\

I

Pha

,But

h2

47

Scheme 3

diene have given two isomeric clusters which have different c.v.e. counts. In Ru4(p4-rl2-C8H~~)(C0)12 (60 c.v.e.), the hydrocarbon is a 2-e donor through two ring carbons, while in Ru4(p4-q2:q2-C8Hlo)(CO)12 (62 c.v.e.), the hydrocarbon is a 4-e donor using three carbon atoms.14 One of the products from reactions of R U ~ ( C O with ) ~ ~ cinnamic acid amides (amino-oxadienes) is the chain cluster Ru&-H)2 (p-CPh= CHC(NRR')0)2(CO)lo [R = R' = Me, Et; R = H, R' = Me; RR' = (CH2)4].I4' They are interconvertible with the binuclear Ru&-H)(p-CPh= CHC(N RR')O)(C0)6 complexes. Cluster expansion of R U ~ ( C O ) with ~ Ru(C0)4(dppp-P) afforded Ru4(pH)4(CO)I,-,(dppp).146Several novel complexes Ruq(p-H)4(C0)8(P(CH20COR)3)4 [R = Me, Et, Pr', Bu', (9-CHMeEt] have been prepared: under H2 (1 30 bar), the ester groups are cleaved to give the corresponding alcohols.147 Several clusters containing PPh, PPh2 and PPh3 ligands were obtained from either Ru4(pH)4(CO)8(PPh3)4, Ru(OAc)2(CO)2(PPh3)2 or Ru2(0Ac)2(C0)4(PPh3)2under H2 (100 bar, 80- 160 oC).22 Novel cluster complexes include Ru3(p-H)&-PPh)and (C0)8(PPh3), RU4(p4'PPh)2(p-PPh2)2(C0)8 (C0)7(PPh3). On photolysis, one, two and three PHPh2 ligands can be introduced into 12 on wing-tip and successive, different, hinge atoms. RQB(~-H)(~~-BH~)(CO) Thermolysis of the disubstituted complex gives R u ~ B ( c I - H ) ~ ( ~ ~ - B H ~ ) ( I ~ - P P ~ (C0)9(PHPh2).I4 Addition of [Ru(q6-arene)12' fragments (arene = CsH6, PhMe, p-cymene) to [Ru~(CO)~( BH4)]- and [Ru3(C0)9(B2H5)]- results in cluster expansion to give R~~(p-H)(p~-BH~)(CO)~(q~-arene) after deprotonation; some [RugB(C0)I7]- is also formed.'49

Orgunometullic Chemistry

174

The development of p3-PO and related chemistry on M4 (M = Ru, 0 s ) clusters has been reviewed. I5O This ligand is the phosphorus analogue of NO and was first obtained by hydrolysis of cluster-bound p3-P(N R2) ligdnds. Protonation of the p3-P(NR2) ligand, followed by reaction with base, gives hydroxyphosphinidene, p3-P(OH), which can be deprotonated to form anionic p3-P0 clusters.15' A mixture of the p3-P(OH) and p3-P(NPrI2) complexes gradually underwent elimination of HNPr'2 to give the P20 complex { RU~(CO)~~)~(~~,CL~-P,P originally characterised as a minor product from the hydrolysis of the aminop h ~ s p h i n i d e n e . ' In ~ ~ this complex, the novel POP ligand is bent (140.8"), probably by steric repulsion between the two large cluster moieties. Three types of complex were obtained from the square-pyramidal 62-e R U ~ ( ~ ~ - P P ~ )and ( C phosphaalkynes, O)~~ which in all cases formed ketenylphosphinidene 1igar1ds.I~~ At r.t. or 60 "C, P = CBu' affords Ru4(p3-P(CCO)BuL)(p3PPh)(C0)12 and R u ~~~-P(CCO)BU~)(~~-PP~)(CO)~~, { the conversion from open to closo cluster occurring with loss of CO. If a more bulky substituent is used, such as 2,4,6-Bu13C6H2(mes*), both the tetranuclear analogue and trinuclear R u {~p3-P(CCO)(mes*))(p3-PPh)(C0)9 are obtained. In the early stages of this reaction, 31PNMR evidence for a 0-or .n-bonded phosphaalkyne complex was obtained. Cluster R ~ ~ ( p ~ - H ) ( p ~ - c H ) ( p ~ - C(48) o ) ~ was C p ~ obtained with CH4 from R u ~ ( ~ - C H ~ ) ~ ( C O ) ( N C Munder ~ ) C ~H2 ; ! (1 bar, r.t.). With the CD2 precursor, 48(p3-D)(p3-CD) was formed, confirming cleavage of the C-H bond in a CH2 group. Carbonylation of 48 gave a mixture of {Ru(pCX)(CO)Cp)2 (X = H2, o ) . ~ ~ ~ + The ' ~ ~ fomation of the cluster is envisaged to result from combination of reactive intermediates containing Ru-Ru triple and quadruple bonds.

0

An extensive chemistry of Ru(q6-arene) clusters is being developed and recent results have been s ~ m m a r i s e d . 'The ~ ~ majority of these involve symmetrical dicationic Ru4 systems containing either four or six H atoms, formed by hydrogenation of { RuCI2(q6-arene))2 in water; trinuclear complexes containing p-Cl or p3-O ligands have also been obtained. The complexes are catalyst precursors for the hydrogenation of benzenes to cyclohexanes under biphasic conditions. Appropriate experiments have shown that four arene ligands can be successively replaced by other arenes (cg., p-cymene by CbH6) under the same conditions. '57 An unusual framework geometry resembling the sails of a windmill has been found for { ( P - C ~ ~ ) R U ) ~formed M O ~ from ~ ~ ~ { ,RuC12(P-cym)}2and N ~ ~ M O O ~ . ' ~ ~

4: Organo-Trunsition Metul C h e r Compounds

I75

Pentanuclear clusters. A small amount of RuS(p-H)Z{J A ~ - C C M ~ ( C O ~ M ~ ) ) ( C O ) (49) was obtained from R U ~ ( C O and ) ~ ~ ethyl methacrylate in octane (22h,

1 10°C).159The vinylidene ligand is attached across an open Ru4 face, with the ester 0 atom also bonded to one of the Ru atoms.

49

An improved synthesis of R U ~ C ( C O )from , ~ R U ~ C ( C Oand ) ~ ~CO (70 bar, M~) 90°C, 3.5 h) has been described.'@ Reactions of R U ~ C ( C O ) ~ ~ ( N Cwith dimethyl maleate or C2(C02Me)2 gave electron deficient clusters Ru5C{p-C2H2(C02Me)2}(CO),3 and Ru5C{p-C2(C02Me)2}(CO)15, respectively.I6l Addition of PPh3 to the product obtained from c60 and R u ~ C ( C O ) I ~ in refluxing chlorobenzene (1 h) gave Ru5C(p3-q2:q2:q2-C60)(CO)1 I(PPh3), the phosphine being attached to one of the Ru atoms not bonded to the c60 ligand.162 The synthesis of R~~C(CO)~~{(p-dppp)Ru(C0)~) has been described.'46 In the presence of Me3N0, Ru5C(CO)I5 reacts with 2,2'-bipyridyl or 1,lO-phenanthroline (LL) to give RuSC(CO)~~(LL).'~~ Also formed were small amounts of R u ~ C ( ~ - H ) ( C O ) ~ ~- (H), L Lcontaining the metallated N-heterocycles. All these Ru5C clusters contain wing-tip-bridged Rug clusters. Associative pathways are also found in the rapid reactions of RugC(C0)14(L) [L = PCy3, P(OPh)3] with several Pdonor ligands. 163 Steric and electronic effects on the reaction rates have been determined, with up to a 2800-fold decrease in rate being found with increasing size, but only a 20-fold increase as a result of electronic factors. This is related to difficulties in opening up the cluster. Compared with RuSC(C0)15, the substituted clusters react with P(OCH2),CEt 750 [L = P(OPh)3] or 3 x lo4 times slower (L = PCy3), a series of cluster reactivities being Ru5C(CO)rs(smaller PR3) > RU6C(CO)I7 RU5C(CO) I4 f P(OPh)3 > RU5C(C0)14(PCY3) Ru5C(CO)I 5 (larger PR3) > R U ~ ( C O ) ~ ~ The chemistry of R~5(p&)(p-SMe)2(p-PPh2)2(CO)~ I (50) has been summarised.lU Its preparation from the reaction of Ru~(~~-C~PP~~)(~-PP~~)( 3 (Sl), itself obtained in high yield from R U ~ ( C Oand ) ~ ~dppa, has been detailed (Scheme 4). 165 The conversion involves at least three intermediate complexes, which have been isolated and fully chardcterised. Two other clusters containing the C2 ligand have been obtained from this reaction. The reaction between 50 and CO has given 52 and 53, in which the C2 ligand has taken up unusual coordination geometries. These have been rationalised by EH M O calculations, using results obtained in a general study of the bonding of C2 in high nuclearity clusters.6

'

'

Orgunometullic Chemistry

I76

/ 52

50

53

Scheme 4

Hexanuclear clusters. Cluster expansion by reaction of [RuSC(CO)1412- with [Ru(NCMe)3Cp]' occurs to give [Ru6C(C0)14Cp]-.'~~ Heating of Ru3(C0)12 with cyclohexene or cycloocta-1,3-diene has given Rug clusters in which the hydrocarbon has undergone ring contraction to form either q-C5H4Me or q5trihydropentalenyl ligands attached to a doubly edge-bridged tetrahedal core. The two butterfly portions of the clusters contain p4-q2-C0 ligands.168A similar complex was obtained from Ru3(C0)12 and SiMe3(C5H5).'69 Rug clusters were also formed by coupling of preformed Ru3 complexes. Thus, reaction of [R~3(p3-ampy)(CO)~~]' with [ R U ~ ( ~ ~ - S ) ( C Ogave ) ~ ] ~Ru6(p-H)(p4S)(p3-ampy)(CO)17, in which two Ru3 triangles are linked by two Ru-Ru bonds.I7' Alternatively, thermolysis of { Ru3(p-H)(p3-C2Bu')(c0)8)2(p-dppa) was used to make 54 and 55, in each of which one of the p3-acetylide ligands has become partially hydrogenated."' In the former, cleavage of one of the P-C(sp) bonds of dppa has occurred, with coupling of the PPh2C2 fragment to a Bu'CH=CH moiety; in 55, both P-C(sp) bonds have been broken, the C2 unit again being found linked to a Bu'CH=CH group. Most Rug chemistry is centred on Ru6C clusters. An improved synthesis of RU&(CO)~, from Ru3fCO)12 and C2H4 (30 bar, 145"C, 3.5 h) has been described.'60 Reactions of this cluster with C2Me2 have given complexes containing one, two and three p3-q1:q1:q2-alkyneligands, together with one in which p-q2:q2- and p3-q':r)':q2-C2Me2groups are attached to a monocapped square

4: Orguno-Transition Metul Cluster Compounds

I77 But I

r""'

pyramidal core.172A sequence of reactions of R u ~ C ( C O with ) ~ ~ HCECPh has been e~tab1ished.l~~ With Me3NO inducing the reaction, the first-formed Ru6C(p3-q':q':q2-HC2Ph)(CO)15couples with an excess of the alkyne to give head-to-head and head-to-tail isomers of Ru6C(p3-PhCCHCRCR')(CO)14 (R, R' = H, Ph; Ph, H). The latter reacts with a third molecule of HC=CPh to give R U ~ C ( ~ ~ - C P ~ ) ( C O ) ~,3) ~ (by~C~=-CCbond ~ H ~breaking P ~ ~ -and ~ oligomerisawas obtained from tion. The cyclooctyne cluster Ru&(p3-q ':q :q2-C8H12)(C0)15 Ru3(CO)~2 and cyclooctene in refluxing octane (5 h).174 With NiCp2, Ru&(C0)17 gave Ru~C(~-CO)(CO)I 1Cp2, in which the c p groups are on adjacent Ru atoms. The reaction with HC5Me5 gave Ru&(pq ':q5-CH2C5Me4)(pL-C0)(CO)l3.75 Further examples of Ru&(CO) 14(q6-PhR) (R = Pr", CHMe2, Bun, CH2CH=CH2) have been described. A long Ru-Ru bond in the PhBu" complex is rationalised by EH MO calculations.176Yet other examples have been prepared from polyphenyls [R = C6H4Me-4 and C6H4Et-4 (two isomers of each), C6H4Ph-4,C&3Ph2-3,5].'77 Reactions of several areneRu6C clusters with C2Me2have given derivatives in which the p3-q ':q':q2-alkyne is on the face away from the Ru(q6-arene) atom; in Ru6C(p3-q2:q2:q2C16H 16)(P3'T) ':q':q2-C2Me2)(CO)12,opposite faces are capped by the two hydroc a r b o n ~ . 'The ~ ~ product obtained from Cm and R U ~ C ( C O )in I ~ refluxing chlorobenzene (5 h) reacts with dppm to give Ru6C(p3-q2:q2:q2-C6o)(pdppm)(CO)~~, the phosphine being attached to the Ru-Ru edge opposite that bridged by the c60 ligand.'62 Reactions of Ru~C(CO)~with 2,2'-bipyridyl and 1,lo-phenanthroline (LL) gave small amounts of Ru5C(CO)14(LL) (see above) and Ru&(CO)I~(LL).I6O In contrast, bidentate tertiary phosphines afforded 75-95% yields of Ru&(pPP)(CO)15 (PP = dppm, dppe, dppp) with up to three CH2 groups in the chain, but dppb gave only 10Y1 of Ru6C(p-PP)(CO)15, the major product being 179 The conversion of R u ~ C ( C O ) ~ ~ ( P toP Ru6(p-q6:P~~) Ru6C(CO)~6(dppb-P). PhPPh2)(C0)13 (refluxing PhCI, 24 h) can be reversed under CO; the related PMe2Ph complexes were also prepared.180 Reactions of SO2 with RU& clusters have been explored.I8' Only one CO is replaced in RU&(CO)~~, the reaction being reversed under CO. In the presence of Me3N0, [RU6C(p-SO2)n(CO)16-nI2- [n = 1, 2 (%*)I can both be obtained from

'

178

Orgcmometullic Chemistry

[Ru6C(C0),,l2-. Complex 56 reacts with NO to give [Ru6C(C0)14(NO)(S02)2]-, although SO2 does not react with [Ru~C(CO)I~(NO)]-. Methylation of 56 gave [ R U ~ C ( ~ - S O ~ M ~5)](- ,Cwhich O ) ~ with excess MeOTf or BF,(OEt,) underwent SO bond cleavage to form Ru~C(~~-SO)(CO)IS. The ally1 [ R u ~ C ( C O ) ~ ~ ( ~ - C ~ H , ) ] reacts with SO2 to give [RU~C(~-S~~)(~.I-C~H~)(CO)I~]-, also obtained from 56 and CH2=CHCH2Br.1 8 ' This complex and the related neutral allyls, Ru&(pCC2CRCH2)(C0)14(NO)(R = H, C02Me), are fluxional as a result of migration of the SO2 or NO ligands, respectively,over the Rug core.182

Higher nuclearity clusters. Good yields of Ru,C(C0)14Cp2 were obtained from [ R u ~ C ( C O ) ~and ~ ] ~two - equivalents of [ R u ( N C M ~ ) ~ C while ~ ] + , the related monoanion [ R U ~ C ( C O ) ~ ~ Cwas P I -formed from [ R U ~ C ( C O ) ~ ~In] ~both, - . one face of the Ru6C core is capped by an RuCp group.'67 A detailed study of the spectroscopic and magnetic properties of RuloC clusters, combined with EPR studies and DFT calculations, has been reported.Is3 In [RuIoC(CO)24J2-,there are two bands of occupied MOs, with MM and M-CO 'II based MOs being above a group of CO d/n-type MOs. The HOMO (M-CO rt bonding)-LUMO (M-CO 0 antibonding) gap is 1.07 eV (cf: 1.27 eV for the Osl& cluster). The UV-vis-near iR spectra have been interpreted with this model. The salt [ R U ~ ( ~ - H ) ( ~ - C , H ~ N ) ~ ( C O ) ~ ~ ~ ) ~ ] [ R U C)(CO)23(PPh3)] has a temperature-independent magnetic susceptibility of +1384 x cm3 mol-' (van Vleck paramagnetism). EPR shows a temperature-independent paramagnetism apparently sourced from radical cluster anions resulting from oxidation of the cluster anions. The conclusion from all of these results is that these ruthenium clusters are molecular rather than 'mesometallic' in nature. CV and spectroelectrochemical studies of RuloC cluster anions showed that 2-e - occurred, reduction of both [Ru 1O( p&)( p-H)(CO)24] - and [Ru I O( j~,-C)(C0)24]~ accompanied by structural change@)in the metal core, probably cleavage of an apical Ru-Ru bond.'84 The presence of a hydride ligand favours reduction. Reoxidation at low temperatures is reversible, 2-e processes generating new mono- and di-anions in which the new cluster structure is preserved. At r.t., however, the original anions are formed. The observed changes in core geometry differ from related Osl& chemistry, where either no change occurs or only cluster expansion accompanies the oxidations. Oxidation of [RulO(p6-C)2(C0)24l2-with [FcH]+ in the presence of alkynes has given the neutral complexes RU~O(~~-C)~(~-RC~R')(CO)~~ (57; R = Ph, R' = Me, Ph; R = R' = tol) which are readily reduced (OH-/MeOH) to the (C0)22 dianions, of which the C2Ph2complex has been reported b e f ~ r e . " ~ The alkyne bridges the apical Ru atoms of two fused Ru6C clusters which share an edge. Comparison of the structures of the 012- clusters shows significant but minor differences in the folding of tht bioctahedral cores. One Ru(ap)Ru(hinge) distance (dashed) is 0.216 A longer in the neutral complex. Differences are also found in the distribution of p-CO ligands. The NMR spectra of 57 indicate that facile CO migration occurs over all of the cluster framework.

4: Orgum- Trunsition Metui Cluster Compounds

179

Ph

57

Ruj(CO),J us u synthetic intermediate. The use of Ru3(C0)12 as a convenient source of Ru(CO), fragments is illustrated in many reactions which afford monoor di-nuclear products. Thus, R u ~ ( C O and ) ~ ~bis-tertiary phosphines under CO (1300 psi, 120°C) gave mono- and di-nuclear complexes Ru(C0)3(PP) and Ru~(~-PP)~(C (PP O )=~dmpm, dppm, dcypm);186R~(CO)~(dmpe) was obtained from a reaction carried out under CO for 1 week.I8' Ruthenium carbonyl fluorides have been obtained from Ru3(C0)12 and XeF2 in anhydrous HF.'88 Other syntheses include complexes containing metallated azabuta-l,3-diene ligands from MezC=CHCH=NR (R = Pr', But; senecialdimine),26 pyrid-2ylacetyl ligands from 2-CH2CIC5H4N,189 2,l -naphthoquinone-2-oximatoligands from 2-nitroso- 1-naphthol,'26*190 tetrabenzoporphyrin complexes,19' RuCl(ER3)(CO)2(Pri-dab)(E = Gel Sn, Pb; R = Me, Ph),'92 q5-cyclopentadienylruthenium derivatives from HC5Me4(CF3)'93and C5H5SiMe2SiMe2C5H5,'94 mono- and dinuclear complexes from enediones ArC(O)CH=CHC(O)Ar,I9' and { Ru(p-02PMe2)2(C0)4},, from CH(C02Me)=C=CH(C02Me),19' Me2P(0)(OH).'97 10.4 Osmium - CV of the anion [ O S ~ ( ~ - H ) ( C O ) shows ~ ~ ] - an irreversible oxidation wave at +0.66 V vs Ag/AgN03.38 A survey of available structural information for Os,H,(CO),, [Os,H,(CO),]- and [OS,(CO),]~- has been used to calculate the efficiency with which electrons are used for 0s-0s bonding.'98The bond enthalpies E(0s-0s) are related to the 0 s - 0 s separations: E(0s-0s) = 1.928 x 10'3[d(Os-Os)]-4.6

Various correlations between total bond enthalpy per metal atom, L!?(Os-Os)l x, and the number of ligand electrons per atom, the skeletal electron pair count,

and the number of formal two-electrodtwo-centre bonds were noted. The parameter C E ( 0 s - 0 s ) can be used to quantify the effects of small changes in Os0 s distances in the clusters. The most efficient use of electrons for 0s-0s bonding is found in larger clusters with relatively fewer ligands. Trinucleur clusters. Surface-activation of Os3(CO)12 by adsorption on silica and (Y = OH, OR, subsequent reaction is a high-yield route to OS~(~-H)(~-Y)(CO),O

180

Orgunometullic Chemistry

O;?CR, SCN, CI, Br, The silica-bonded intermediate [ O S ~ ( ~ - H ) ( C O ) I O ( ~ OSi = )] is formed quantitatively. Hydrolysis affords the p-OH complex, which itself is even more reactive; most reactions require simple refluxing with the nucleophile. Slight modification affords Os&-H)4(CO)I2. Mixed 0s-Hg clusters were obtained from reactions between O S ~ ( C O ) ~ ~ ( N C and M HgClR ~ ) ~ (R = Me, Et, Ph, Fc): the R group is eliminated and the products included {Os3(yCI)(CO)lo}2(p4-Hg) and c~~-OS{(~~-H~)O~~(~-C~)(CO)IO}~(CO) the latter formed by decomposition of 0s2( ( ~ ~ - H ~ ) O S ~ ( ~ - C ~ ) ( C ~ ) ~ ~ ) ~ ( ~ O As usual, the precursors for much of the osmium cluster chemistry described M ~or ) ~ Os3(p-H)2(CO)lo (C). below are O S ~ ( C O )(A), ~ ~ O S ~ ( C O ) ~ ~ ( N C(B) Methyl-substituted cyclohexa-1,3-dienes have shown pronounced differences in reactivity towards B [giving O S ~ ( C O ) ~ ~ ( ~probably ~ - L ) ] , as a result of interactions between the Os3cluster and the Me groups; not surprisingly, these effects are greater with the dimethyl derivatives.20' Activation of sp2 C-H bonds occurs in the thermal reaction between A and BunOCH=CHPEt3,from which Os3(~-H)(p3BunOC=CHPEt3)(C0)9(58) was isolated.202This and related y-CH=CHR (R = n-C6H13, Ph) complexes catalyse hydrosilation of olefins to rrans-triethylsilylethenes and alkanes at r.t. Reaction of HCrCC02Me with O S ~ ( C O ) ~ ~ (CNPr)(NCMe) resulted in C-C bond formation by addition of the alkyne to both CO and CNR ligands, giving isomeric C(OH)C(C02Me)=CHCNHPr and C(OH)CH=C(C02Me)CNHPr ligands on binuclear complexes.203

The synthesis of Os3(p-H){p3-C2CMe2(0H)} (C0)s from Os3(pH)(p-Cl)(CO)lo and LiC = CCMe2(0H) has been described.204Protonation at - 60 "C with HBF4.0Et2 afforded the cationic allenylidene [Os,(p-H)(p-C=C=CMe2)(CO)lo]+, in which the allenylidene undergoes 0,7c exchange about the two 0 s atoms it bridges. Exchange of CO groups on the Os(CO), moiety also occurs. At +lO°C, loss ofCO gave O S ~ ( ~ - H ) ( ~ ~ - C ~ C H M ~ ~ ) ( C ~ ) ~ . The ferrocenyl group is metallated when Os3{ p3-C(SiMe3CMeCHCFc}(CO),, and containing a face-bonded obtained from OS~(~~-HCZS~M~~)(~-CO)(C~)~ metallacyclopentadiene, is converted to Os3(p-H){ p3-C(SiMe3)CMeCH[(qC~H3)Fecp])(Co)8by t h e ~ ~ n o l y s i sThe . ~ ~ formation ~ of 0~3{p3-C(SiMe3)CMeC=CR(SiMe3))(CO)g(R = Me, Bu"), an intermediate in the dimerisation and rearrangement of MeCrCSiMe3 on an Os3 cluster, occurs by an alkynevinylidene coupling reaction.206 Clusters containing all-carbon chains were prepared from Re{(CrC)nH}(NO)(PPh3)Cp*(n = 1-3) and B; the initial products were formed by oxidative addition of the =C-H bond across an 0 s - 0 s bond to give Os3(p-H){p-

4: Orguno-Trunsition Metal Cluster Compounds

181

(C EC),[Re(NO)(PPh3)Cp*]>(CO)lo; on heating, decarbonylation to the usual p3-alkynyl complex occurred.207 Structural and N MR data indicate some contribution from a zwitterionic { Re+)=(C=C),={ O s 3 - } mesomer. Related reactions between Re(C = CLi)(NO)(PPh&Cp* and A, followed by [Me30]+, gave the carbene cluster Os3(CO)I I { =C(OMe)C = C[Re(NO)(PPh3)Cp*]}; however, the OMe group could not be removed with BF3 to give the C3 complex.208 (n = 0-2) suggest that Electrochemical studies of OS~(CO)~O_.(PP~~),(~~~-C~O) reduction occurs by initial addition of the electron to the c60 ligand, followed by delocalisation onto the Os3 cluster.209This is supported by the IR spectra, which show only a small shift in the v(C0) spectra for the mono-anion. More or less rapid decomposition of di- and tri-anionic clusters occurs. The borylidene cluster O S , ( ~ - H ) { ( ~ - H ) ~ B H > ( C isOformed )~ from C and BH3(SMe2)at r.t.; warming to 65 "C affords OS~(~-H)~(~~-BCO)(CO)~.~~' Comparison with the other Group 8 analogues shows that a similar structure has been proposed for one isomer of the Ru complex, but the Fe derivative has three FeH-B bridge bonds. The reaction between A and nido-7-NMe3-7-CBloH12 gave Os3(C0)~(q5-7-NMe3-7-CBIoHlo), in which one 0 s is attached to a CB4 face, while B-H-0s bridge bonds attach the other two 0 s atoms to the carborane cage.21 Low temperature NMR studies of O S ~ H ( ~ - H ) ( C O ) ~ ~ ( N(R2 H R=~ )HEt, Et2) suggest that the 0s-H(t) bond acts as a proton acceptor for an N-H bond, this feature stabilising the product (no reaction occurred between C and NEt3).212 Kinetic studies of the reaction of C with CF3CN, which affords the isomeric OS3(P-H)b-rl2complexes O S ~ ( ~ - H ) ( ~ - N = C H C F ~ )10( C O ) and NH=C(CF3)}(CO)lo reveal that the rate-determining step is formation of the unobserved adduct Os3H(p-H)(CO)lo(NCCF3).Larger kinetic deuterium isotope effects observed for the formation of the latter, which is favoured by decreasing temperatures, suggest that a significant barrier tunnelling effect is associated with its formation, but not that of the p-N=CH(CF3) complex.213The larger isotope effect may also reflect the importance of H-bonding in the H-migration reaction. Complexes derived from ethyl glycinate and ethyl L-a-alaninate were obtained from O S ~ ( ~ - H ) ( ~ - O H ) ( Coxidative O ) ~ ~ : addition of the N-H bond with loss of (R = H, Me). When Os3(p-H)(pwater gave Os3(p-H)(p-NHCHRC02Et)(CO)lo OPh)(CO)12 was used as precursor, the N-alaninato complex was accompanied by the related carboxamido cluster, Os3(p-H)(p-q2-OCNHCHMeC02Et)(CO),o.214L-Hydroxyproline esters react with Os3(p-H)(p-OH)(CO)~oto give initially Os3(p-H)(p-OH){NHCH(C02R)CH2CH(OH)CH2}(CO),(R = Et, Pr') which on heating are transformed into Os3(pL-H){p-OCHNHCH(C02R)CH2CH}(CO)9; both reactions are stereo~pecific.~'~ Allylamine and A react at 90 "C to give Os3(p-H)(p-q2-OCNHCH2CH=CH2)(CO)1o which on further heating is transformed into cis and frans isomers of the pOCNHCHzCHMe cluster, each of which exists in two configurations.216The reaction of B with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenolresults in cleavage of the azo link and formation of the bis-p-amido cluster Os3(p-2-NH-5BrC5H3N){ p-N =C6H3(0-2)(N Et2-4))(CO) o. 21 The p-acyl complex Os3(p-H)(pq2-OCC4H4N)(CO)10 is not converted to a pyrrole-coordinated cluster on treat-

'

Organometullic Chemistry

182

ment with Me3N0, but affords instead the NMe3 complex, Os3(p-H)(p-q2OCC4H4N)(C0)9(NMe3).218 Complex 59, containing a side-on bonded imine, was prepared from the related carbene complex by reaction with NH3. Deprotonation of the product with dbu in the presence of [ppn]CI gave the anionic aminocyclohexadienyl complex, from which [CPh3]' removed hydride to give 59. The complex is fluxional by rapid inversion of the NH group.219The reaction sequence again illustrates the increase in reactivity of the side-on carbene ligand resulting from delocalisation in the p3cyclohexadienyl part of the ligand.

60

61

Reactions of B with 7-azaindole (LH) gave the N , N - and C,N-isomers of Os3(p-H)(p-L)(CO)]~(60, 61), together with Os3(p-H)(p3-L)(C0)9, shown to be formed by thermolysis of Indazole and benzotriazole react with B to give similar N , N- and C,N-bonded isomers. Treatment of the N,N-benzotriazole complex with MeCN/Me3N0 results in replacement of C O by MeCN: thermolysis then gives a dimeric cluster, in which the metallated N-heterocycle bridges the two Os3 units.22' ) Os&The rates of decarbonylation of O S ~ H ( ~ - H ) ( C O ) I O ( PtoR ~form H)2(C0)9(PR3) are -lo5 times faster than those found for O S ~ ( C O ) I I ( P Rthe ~); rates decrease with increasing electron-donor power of PR3 and only for PBu'3 was any significant sterically-induced rate enhancement found.222Further addition of PR'-, probably gives OSH(~-H)(CO)~(PR~)(PR'~) in which both phosphines are on the same 0 s atom. However, isomerism can occur by virtue of the order of addition. The reaction between C and W(PMe)(CO)S (produced in situ) affords Os3(p-H)(p-PHMe)(CO)lo which undergoes H-migration and CO loss to form O S ~ ( ~ - H ) ~ ( ~ ~ - P M ~In) (the C Oearly ) ~ . stages ~ ~ ~ of the reaction, the 31P NMR spectrum contains a signal assigned to OS~H~(CO)~~(PM~[W(CO)~]). Fenske-Hall M O calculations on M3(p-H)(p-PXPh)(CO)12 (M = Ru, Os, X = H; M = Os, X = Ph) confirm that lengthening of the bridged 0 s - 0 s bond is electronic in origin, although in general steric effects are more important in determining bond lengths and angles.27 Reaction between B and Os3(CO)I I(PH3) gave the linked cluster complex Os3(CO)1I ((~-PH~)OS&I-H)(CO)~(NCM~)); comparison with three other bis-cluster complexes with p-PH2 groups shows that all OS~(CO)I l(L) moieties have a ligand environment distorted towards a D3 structure.224

4: Orguno-Trunsition Metul Cluster Compounds

I83

Addition of RSH (R = But, Cy) to B gave OS~(~-H)(~-SR)(CO)~O,~~~ while with c-S3CHMeCHMe, O S ~ ( ~ ~ - S ) ( C and O )Os2(p-SCHMeCHMeS)(C0)6 ~~ were obtained.226Irradiation of O S ~ ( C O )and , ~ Fe(C0)2(PR3)2(q2-SC=S) (R = Et, Ph) in .227 Two complexes are obMeCN gave O S ~ ( C O )(p-S=CS)[Fe(CO)2(PR3)2]j ~ tained from NH(P(S)Ph2l2 and Os3(CO)11(NCMe):in 62,the ligand H atom has migrated from N to S, while in 63,it is found on an S-bridged 0 s atom. Separate experiments confirm that 62 transforms to 63 on heating.228 The variety of bonding modes available to 1-hydroxypyridine-2-thioneis shown in its reactions with Os3(CO)12-n(NCMe)n (n = 1, 2 ) which have given 64, 65 and 66; the yield of the latter is increased with time or on treatment of the first two complexes with (X = Me3N0. Thermolysis of 64 or 66 at 80 "C gave OS~(~-X)(~~-SCSH~N)(CO)~ H, OH).229With Os3(CO)Io(CNR)(NCMe)(R = Pr, CHZPh), analogous isocyanide-containing clusters were obtained.

H 62

63

O'* \

64

66

Thiols react with the 46-e cluster Os3(p-H)(p3-q2-4-MeCgHgN)(C0)9 (from 4methylquinoline) to give several products.230 With RSH (R = Et, Ph), OS#(J.LH ) ( ~ - S R ) ( P - M ~ C ~ H ~ N ) ( are C O )formed, ~ which with CCl4 give Os3(pSR)(pM ~ C ~ H S N ) C ~ ~ (Thermal C O ) ~ . decarbonylation of the SEt complex gave OS~(J.LH)2(pSEt)(pMeC9H5N)(C0)8 together with Os3(p-H)(p-SEt)(CO)10 and oS3(J.LH)~(p3-S)(C0)9.The latter is also formed, with loss of the quinoline ligand, in the reaction of the 46-e cluster with H2S. Fragmentation of PhN=S=O occurs in reactions with Os3 clusters. With A, 0 ~ ~ ( p ~ - S ) ( p ~ - N P h ) (isC formed 0)~ which with Me3NO/MeCN gives Os3(p3S)(p3-N Ph)(CO)g(N CMe), while B gives 0s3(p3-S) { p-( NP h)zSO1(C0)g. 23 The higher nuclearity clusters found in analogous reactions with R u ~ ( C O )were I ~ not detected here.

'

Organometallic Chemistry

184

Clusters of nuclearity >3. As with Os3(CO)12, Osq(p-H)4(C0)12 can be activated towards substitution with Me3NO/MeCN, the bis-MeCN derivative being isolable. Reactions with bidentate tertiary phosphines have given Os&H)4(ppp)(co)lO (pp = dppm, dppee, dppp, dppf) and OS4(p-H)4(CO)IO(dppee), all in 30-50‘%yields and chardcterised by X-ray structures.232The dppf-bridged bis-Os5 cluster (Os5C(CO)14}2(p-dppf) was formed by thermolysis (refluxing CHC13, 48 h) of O~~PdC(p-dppf)(CO)~~.~~~ The three complexes 67,68 and 69 were obtained from O S ~ ( C O ) ~ ~ ( N Cand M ~~) ~ y r i d i n e Notable . ~ ~ ~ features of the structures include a p,+-C,U-COligand in 67, and the p3-O ligand in 68;both 68 and 69 contain metallated p-C5H4Nligands. In (Os(p-SnPh*)(C0)4)6(from [Os(CO),] and SnC12Ph2),the Os6Sn6 ring is nearly planar: all CO groups are equivalent, indicating free rotation about the 0s-Sn bonds.235

68

67

69

Mixed-metal clusters contuining only Group 8 metals. The mixed Fe-0s clusters FeOs&X)2(CO) 1 0 were obtained from either {OsC12(CO)3}2and Naz[Fe(CO)4] in water (X = OH) or ( O S ( ~ - I ) ( C O )and ~ ) ~FeZ(C0)g (X = I). The latter slowly decomposes in solution to a mixture containing F ~ O S ~ ( C Owhich ) ~ ~ was , isolated as the mixed crystal with Os3(CO)12 ( ~ 0 . 4 1 ) . ~ ~ ~ Unstable butterfly clusters M3Ru(p-H)(p4-C2Fc)(C0)l2 (M = Ru, 0s) have been obtained from M3(CO) and R u ~ ( ~ - H ) ( ~ ~ - C ~ F C )on ( Cstanding O ) ~ ; they decompose to form the precursor complexes; the Ru complex was obtained as a mixed crystal RU~(~~-C~FC)(CO)~~.RU~(~-H)(~~-C~FC)(CO)~. These complexes are fluxional by CO exchange and a ‘windshield-wiper’motion of the p4-alkynyl ligand. The products from the ferrocenylethynyl derivatives are unusual: the

4: Orguno-Trunsition Metal Cluster Compounds

I85

common C2M4 core is found in Os3Ru(p4-HC2Me)(CO)12,formed from Ru3(C0)12 and OS~(~-H)(~~-C~M~)(CO)~.*~~ Cluster build-up occurs in the reaction between [RU(NCMe)3(rl-c6H6)l2+and [ O S ~ ( ~ - H ) ~ ( C Oto) ~give ~ ] ~Os4R~(p-H)2(C0)~2(7-c6H6), which with P(OMe)3 gave O S ~ R U ( ~ - H ) ~ ( C P(OMe)3}(q-C6H6).239 O)~~{ The benzene ligand in the latter adds to the cluster to give 70, in which the q6-phenylgroup now bridges an Os0 s bond.

70

11

Group9

11.1 Cobalt - Polynuclear cobalt-alkyne complexes have been reviewed.240The paramagnetic complex C03(p-C0)3(PMe3)3, obtained from Co(q-C2H4)(PMe3)3 H2 (or D2) to give C03(~3-H)2(p-H)(pand C O ~ ( C O ) ~ ( P Mreacts ~ ~ ) ~with , C0)3(PMe3)3with more or less amounts of the monohydride. No evidence for the formation of the dihydrido cluster was obtained. The Co-Co separations increase with the number of H atoms. The complexes show molecular paramagnetism with effective magnetic moments between 1.9 and 3.1 pe.241 The reaction between C02(C0)8, thioacetamide and Zn powder afforded C O ~ ( ~ ~ - S ) ( ~ - N H C M ~ S )Cluster ( C O ) ~formation .~~~ was also found in the reaction between N~[CO(CO)~] and FcPC12, which gave Co3(p3-PFc)(pL-PFc2)(CO)7, which exhibits only a single reversible oxidation wave at +0.33 V.243 With 2mercaptopyridine, Na[Co(CO)4] gave Co5(p3-S)3(C0)2(SC5H4N-2)7,in which a C O ~raft is present.244 Complexes Coj(pj-CR) (C0)y. The Pduson-Khand reaction is promoted by polar solvents; attempts to use LiC104 in Et20 in the bicyclisation of Co2(pcomplexes O)~ HC2CR I R2CH2CH=CH2)(C0)6gave instead three C O ~ ( ~ ~ - C R ) ( C 71 containing unusual R Reactions of the parent complex with Sdonor ligands gave C O ~ ( ~ ~ - C P ~ ) ( C O ) ~ _(n ~ (=S M 1, 2, ~ ~3); ) , the face-capped derivatives C O ~ ( ~ L ~ - C P ~ ) ( ~ ~were - L ) (formed C O ) ~with L = CH(SMe)3 and 1,3,5trithiacyclohexane.246 Complexes Co3(p3-C[P(0)(OR)2]}(C0)9(R = Et, SiMe3)were obtained from C02(C0)8 and CC13(P(O)(OR)2},followed by protonation; with MC12Cp2 in the presence of TlPF6, the Et compound gave the mixed TdZr-Co3 complexes [CO~{~~-C[P(O[MC~C~~]}(OE~)~}(CO)~]+ by coordination of the P=O moiety to the Group 4

Orgunometullic Chemistry

Reactions of Co3(p3-CR)(C0)9(R = Me, C02Me) with PHPh2 gave monoP H=P ~ ~ ) , - , and di-substituted products; thermolysis of C O ~ ( ~ ~ - C M ~ ) ( C O ) ~ _ ~ ( (n 1, 2) gave Co3(p-H)(p3-CMe)(p-PPh2)(CO),- n(PHPh2)n- I in reversible react i o n ~A. minor ~ ~ ~ product from the initial reaction of the CMe complex is C03(p3CMe)(p-PPh20PPh2)(CO)6(PHPh2), from which the PHPh2 can be displaced by CO. P - 0 bond formation also occurs in the reactions of C O ~ ( ~ ~ - C R ) ( with CO)~ P2Ph4 via the intermediates C O ~ ( ~ ~ - C R ) ( C O ) ~ and ( P ~ PCo3(p3-CR)(p~~) P2Ph4)(C0)7. Cluster carboxylate complexes M4(p-02CRC')2(02CRCo)2(L)4 [Rco = Co3(p3CC02)(CO)9;M = Mn, Fe, Co, L = thf;249M = Cd, L4 = tetragl~me~~'] were obtained from the cluster acid and M(02CMe)2; the cobalt complexes were also formed by slow decomposition of Hg(02CRC0)2 and crystallographically characterised. With MeOH, the Mn and Fe compounds form cubane clusters M ~ C O ~ ( ~ ~ - O M ~ ) ~ ( ~ - O ~ C R ~ ~ in)which ~ ( Othere M~)~(M~ is weak antiferromagnetic coupling between the core atoms.249 Yet more complex structures, most containing bridging 0 ligands, were obtained from Group 4 alk(ary1)oxides: a representative example is Ti4(p3-0)4(OR)4(p02CRC0)4 (R = Pr', Bun, Ph, X Y ) . ~ ~ ' M3Cp3 dusters ( M = Co, Rh, I r ) . Interconversion of the two isomers of Co2Ir(C0)3Cp2Cp* [(CO)(p-C0)2 and (p-CO),] is slow in the neutral 48-e cluster, but electron transfer-catalysis results in very rapid isomerisation via the 47-e monocation.2s2 The 49-e monoanion was also studied: relative rates of isomerisation are 1: -lo4: -lo8 for the 48-e << 49-e << 47-e species, respectively, a result rationalised in terms of electron occupation of M-M cluster bonding or antibonding orbitals. Cobalt vapour reactions with the HC5Me4Et isomer mixture have afforded complexes containing between one and four metal atoms, including ConH4(~C5Me4Et), (n = 3, 4).253Diazomethane reacts with Co2Rh(C0)2Cp2Cp* to give Co2Rh(p-C0)2(p-CH2)Cp2Cp*,in which a Co-Rh edge is bridged by the carbene. On standing in solution, isomerisation to an isomer in which the carbene bridges a Co-Co edge occurs. NMR studies show the two are in equilibrium and that the CH2 group migrates between the two Co-Rh edges. At 300 K, a third species (maximum concentration -1%) was identified as 72, an intermediate in the CH2 migration process: the 6(C) value of 145.3 is consistent with a p3-CH2 l i g a ~ ~ d . ~ ' ~ A detailed study of internal rotations in several bis-carbyne complexes, C O ~ ( ~ ~ - C R ) ( ~ ~ - C(R, R ' )R' C P=~Ph or substituted phenyl) has been reported:

4: Urguno-Trunsition Metul Cluster Compounds

187

there is significantly slower rotation of Ph rings adjacent to the metal core compared with those attached to C = C triple bonds.255

72

Protonation of Co3(p3-q2:q2:q2-arene)Cp3 complexes occurs at the C03 centre unless the arene contains unsaturated substituents. Thus, the CPh2=CH2complex gives [Co3(p3-H)(p3-PhCPh=CH2)Cp3]+,while styrene derivatives afford clusterCp3]'. The difstabilised benzyl cations, [ C O{ ~p3-q2:q3:q3-R'C6H4CR2(CH2R3)} ferences were rationalised by EH MO studies. With a-methylstyrene, paramagnetic [Co3(p3-q2: q2:q2-C6H5CMe=CH2)Cp3]+was obtained.256 Cycloalkenes react with CoCp fragments [from Co(q-C2H4)2Cp or CoCpzK], activation of C-H bonds resulting in formation of C0~(p-H)~(p~-cycloalkyne)Cp3, accompanied by smaller amounts of C04(p~-cycIoalkyne)Cp~.~~~ These complexes were structurally characterised and have p3-ll-alkyne and C2c04 (butterfly C O ~ ) skeletons, respectively. In the trinuclear complexes, p-H migration, pJp3-H exchange and 'windshield-wiper' alkyne migration processes were identified. At r.t., irreversible redox behaviour is found, although the processes become more reversible on cooling. Similar furyne complexes were obtained by thermolysis of butynediol derivatives Co3(p3-C2R2)(p3-CO)Cp2Cp' (R = CH20H, Cp' = Cp or C P * ) . ~ 'Again, ~ migration of the cycloalkyne is observed. Both complexes show reversible 1-e oxidation and 1-e reduction waves. Reactions of Co3(P - H ) Z ( ~ ~ - B ~ H ~with ) C Pmetal * ~ halides result in chlorination of one or both B atoms; hydrolysis of the original cluster gave closo-l-OH-2,3,4{CO~CP*~}(~-H)~B Cluster ~ H . ~cations " [ { C O C ~ ~ ) ~ A(CpR S ~ ]=+ Cp*, CpBu') were obtained from { CoCICpR}2 and As7(SiMe3)3,accompanied by triple-decker c o 2 systems.260 - In the synthesis of Rh3(p-C0)3Cp3 from Rh(C0)zCp and Me3N0, small amounts of Rh3(p3-O)(p3-CO)Cp3 were isolated. Reactions of Rh(r\-C2H&Cp and Rh2(p-CO)(C0)2Cp2 have given Rh3(p-C0)3Cp3. Related clusters containing Cp' groups have also been described, together with the * } ~= Rh, Ir) putative [Rh6(p6-C)Cp6]C.26'The cubane clusters { M ( P ~ - S ) C ~(M were obtained from { M(l-SH)ClCp*}2 and NEt3; with { Rh(p-Cl)(cod)}2, the cationic homo- and mixed-metal clusters [M2Rh(p3-S)2(cod)Cp*2]f were formed.262 Heterocubane clusters { Rh(p3-I)(q-C4H4BR))4 (R = Me, Ph) were formed in reactions of triple-decker Rh2(C4H4BR)3complexes with 12.263 Exchange of RhI(q-C4H4BR) fragments occurs rapidly on the NMR time scale. The cubanes

11.2 Rhodium

Orgunometullic Chemistry

188

add Lewis bases, L, to form mono- and di-nuclear complexes RhI(L)z(qC4H4BR) and { Rh(p-I)(L)(q-C4H4BR)}2.2m The reaction between { Rh(pI)2Cp*)2 and the cubane (R = Ph) affords Cp*Rh(p-I)3Rh(q-C4H4BPh).The planar butterfly Rh4(p-N(tol))2(CO)7(cod)(73)reacts with dppm to liberate a trinuclear anion, isolated as [Rh(CO)(dppm)2][Rh3{ p-N(tol)}2(C0)6]; EH MO calculations confirm that the cluster is electron-rich and can coordinate a further metal atom.265 The reaction between 73 and HgC12 gives (Rh3[pN(t01)]2(C0)~]2Hg,and a palladium complex is described below.

73 74 11.3 Iridium - Tetranuclear iridium carbonyl clusters can be enriched in I3CO by reactions of [Ir4X(CO)I (X = Br, I) with an excess of I3CO, which displaces X- to give Ir4(l3C0)(CO)I1. Further exchange of CO with X-, followed by treatment with I3CO, can be repeated as many times as required: about 10"h enrichment occurs per cycle. Alternatively, '2CO/' 3 C 0 exchange can be promoted by Me3NO in a one-pot procedure.266 The fluxional behaviour of Ir4(p-dppee),(CO)12-2n (n = I , 2) has been studied. For n = 1, two geometrical isomers are each fluxional by CO exchange, and interconvert by P atom migration. Pairwise P atom exchange for n = 2 occurs via CO exchange only.267 Thermolysis of Ir4(p3-PPh2CHCPh)(p-PPh2)(C0)9 gives II-&~-PP~CHCP~)(~-PP~~)(P~)(CO)~.~~~ In the minor isomer, the Ph group is on a wing-tip Ir atom; the major isomer is thought to have Ph trans to the vinylidene P atom. Carbonylation results in formation of the benzoyl complex by Ph migration. The reaction of Ir4(C0)]2 with dppf gave 74 by dehydrogenation and metallation of Ph and C5 l i g a n d ~ . * ~ ~ Mercury electrophiles, HgR+ [R = Ph, W(CO)3Cp] add to Ir3(p-CO)3(q5C9H7)3to give butterfly clusters with the Hg atom in a wing-tip position. The related h3T1cation has a tetrahedral core with the Ir-Ir edges bridged by C0.270

12

Group 10

12.1 Nickel - The I3C CP MAS NMR spectra of a series of salts containing the [Ni6(CO)12l2- dianion have been recorded; the site symmetries of the anions differ, leading to differences in the spectra: only the "Me4]+ salt gave high signal-to-noise ratios. The structure of the [AsPh4]'- salt was also reported.27I Reactions of nickelocene with organolithiums in the presence of olefins have

4: Orguno-Trunsitiun Metal Cluster Compounch

189

been reported as sources of tri- and tetra-nuclear clusters. Thus, with LiPh and 1decene, Ni3(p3-CR)Cp3(R = Me, CgH19) were isolated, together with Ni4H2Cp4 (X-ray).272Other organic products were identified. A linear Ni-Hg-Ni sequence is present in { Ni(PEt3)Cp)zHg, obtained from (Ni(PEt3)Cp)z and Hg or magnesium amalgam.273 12.2 Palladium - Trinuclear A-frame complexes 75 were obtained from [Pd3(CNR)pJ2+ (R = xy, mes) and dpmp274or from unri-[Pd2(p-dpmp)2(CNR)2J2+ (76*) and M3(CNR)6 (M = Pd, Pt).275Insertion of the doM(CNR)2 fragment into the M-M bond of 76 gives the bent PtMPt array.274The Pd3 complex reacts with I2 to give Pd12{(p-dpmp)Pd12}2 which has no Pd-Pd bonds.275

Addition of NaBH4 to solutions of K2PdC16 or K2PtCl4 and dppm while passing CO through the mixture is a convenient one-pot synthesis of [M3(p3CO)(p-dppm)3C1]C1 (M = Pd or Pt, respectively).276Use of Pd(0Ac)z as (n = 1 or 2); a minor amount of a precursor afforded (Pd3(p-dppm)2(pL-C0)3},, second crystalline modification of Pd6(p-dppm)3(p-CO)3was also obtained.277 Electrochemical reduction of [Pd(p3-CO)(p-dppm)3]2+ (2-e wave at - 0.5 V vs. SCE) gave the neutral cluster, for which DFT calculations were presented.278 The occurrence of square and rectangular geometries for Pd4(p-C0)4(pOZCR)4 (R = Bu', Ph) has been rationalised by EH MO calculations: the differences are traced to vibronic interactions within the clusters.279The clusters Pd4(p3-CF)(p-X)3(PB~13)4 (X = C1, Br) (77) are formed when a mixture of Pd2(dba)3and PBu'3 reacts with CFX3 in toluene.280With H2/NEt3 and PBu'3, cluster degradation to P ~ ( P B U 'and ~ ) ~CFH3 occurred; however, the cluster is not an effective catalyst for the hydrogenation of CFC13. Homo- or hetero-nuclear clusters were obtained by halide abstraction from [Pt(p-PPh2)~(cl)(c6F5)2(co)]2- or [ ((CsF5)2Pt(p-PPh2)2Pd(p-C1)}2J2- with Ag+.281 The products are Pt4(~-PPh2)4(C6F5)4(C0)2 (78a) and Pd2Pt2(pPPh2)3(C6F5)3( PPh2(C6F5))(79), respectively; treatment of the latter with co gave Pd& ( p3-PPh2)(~-PPh2)2(C6F5)3(CO)( PPh2(C6F5)} (80). Unusual reductive coupling of PPh2 and C6F5groups produced the fluorinated phosphine, while in 79, one of the PPh2groups bridges a third metal atom by q2-Ph bonding. A different arrangement of six Pd atoms is found in Pd6(p-Br)4(p-C0)4(PB~'3)4

190

Orgunometullic Chemistry

(81), obtained from Pd2(p-Br)2(PBut3)2 and iron or cobalt carbonyls, or from 78

and C O ~ ( C O ) ~ . ~ ~ ~

78

Ph2

Ph2

79

Pd-Pd

80

\ Br/ 81

12.3 Platinum - Zinc reduction of PtC12(CO)(PPhNpR) (R = Ph, Np) in thf afforded one day the clusters Pt,(p-CO),(PPhNpR),; the dinaphthyl compound is less stable and decomposes in solution.283 The synthesis of Pt4(HgX)& C0)4(PR3)4 (X = Cl, Br, I, CF3, CC13; R = Et, Ph) from HgX2 and Pt3(pC0)3(PPh3) or Pt5(p-C0)5(PEt3)4have been reported.284 COnVerSiOtl Of 84-e Pt6(p-dppm)3(p-C0)6 to 86-e Pt&l-dPPm)3(P-C0)6(P(OCH2)3CMe) occurs on addition of the phosphite. The added ligand is fluxional by migration around a triangular face of the cluster via a symmetrical p3 transition state.285EH MO calculations indicate that addition of the phosphite ligdnd results in stronger inter-triangle bonding and build-up of negative charge on the open face, precluding addition of a second ligand to this face. Either the 84-e cluster or its derived 82-e dication react with [SnX3]- or Hg2X2 to give trigonal prismatic Pt6(p3-M)2(pL-dpprn)3(p-C0)6 (M = SnX3, X = F, CI, Br; M = HgX, X = Cl, Br, I).286 Separations of the Pt, triangles (Pt-Pt 2.910-2.948 are as predicted by the EH longer than the inter-triangle distances (2.634-2.687 MO calculations. The reactions used to form these complexes have been termed 'bicluster oxidative addition'. Under CO, Pt(dba), afforded colloidal Pt: the solution in thf gave fcc 12 A particles. Addition of PPh3 gave a new colloid containing icosahedral 12 A

A),

A)

4: Orguno- Trunsition Metal Cluster Compounds

191

particles, while Pt~(Co)~(PPh3)4 was formed with excess PPh3, together with mononuclear

13

Group 11

13.1 Copper - Tetra- and penta-meric forms of Cu(mes) have been characterised by X-ray studies and are in equilibrium in ether and aromatic solvent systems.288 Homoleptic cubane {Cu(p3-R))4 (R = C6H4CH=CH2-2), in which R was attached through the aryl carbons only, was obtained from CuCl and MgR2; mixed arylhalide complexes containing [Cu5Br4R2J- and [Cu5Br2R4]- were also isolated, coordination also occurring through the vinyl Reactions of [Cu3(p3-C= CR')(p-dppm)3]2+ with isocyanides have given [Cu3(p3-C= CR')(p-dppm)3(p-CNR2)]2+ (R = Ph, tol; R2 = CH,Ph, Cy, tol), while [C~(p3-Cl)(p-dppm),(CI-CNR~)]~+ were obtained from [Cu3(p-C1)2(pdppm)3]+ and CNR2 in the presence of Agf. The isocyanide ligands undergo p2/ p3 exchange.290 The luminescent hexanuclear complexes [ 1,4-(M3(p3-C= C)(pdppm)3) 2C6H4I4+ (M = Cu, Ag) were formed from [M2(p-dppm)2(NCMe)2I2+, LiBu and 1,4-(HC = C)2C6H4.29"399

13.2 Silver - There are two Ag environments in { A ~ ( c I - C ~ H ~ C H ~ None M~~))~ being attached only to carbon and the other having interactions with two NMe2 groups in addition. The Ag4 unit is a p a r a l l e l ~ g r a m . ~ ~ ~ Reactions of Au(mes)(dppm) with AgC104 or [Au(tht)zJ(OTf) gave [MAu(pdppm)2(mes)2]X (X = C104, OTf, respectively); in the AgAuz cation, weak Ag-..Au bonds result in a distorted Ag geometry.293

13.3 Gold - Many of the reports appearing during 1997 relate to the weak 'aurophilic' interactions found in gold([) complexes. Aurophilicity is a relativistic effect, although as a recent survey points out, the origin of the effect is still a matter of debate.294 The theory of d"-d" closed shell attraction in AuX(PR3) complexes has been explored in depth by ab initio methods, the strength of the interaction depending on the softness of X: if relativistic effects are ignored, the ) . ~ ~ ~di- and triAu...Au bond strength decreases by 27% for A u C ~ ( P H ~Similar nuclear systems have been examined,296 and the topic has been reviewed.297 Redistribution of AuX(PH3) to form ( [ A U ( P H ~ ) ~ ] [ A U X(n~ = ] ] ~1, 2) shows that the different observed structures of the di- and tetra-nuclear complexes are similar in energy.298 Perhaps one of the most interesting reports describes the solvent-stimulated yellow luminescence of Au3{p-(MeO)C=NMe)3, which occurs when crystals which have been UV-irradiated come into contact with a liquid such as chloroform. The cyclic trimers form an extended supramolecular aggregate in the The unexpected product from the reaction between MeOTf and Au&C6H4PPh2) was the pentanuclear cluster [ A ~ ~ ( p - c ~ H ~ p P(82); h ~ )one ~ ] of + the Au atoms has no bond to phosphorus.301

Orgunometullic Chemistry

192

82 Showing Au-bonded aromatic C only

Other species containing aurophilic interactions between three or more gold (ref. atoms include: [Au4(p-dppm)(p-PPh2CHPPh2){p-CHCH2S(0)NMe2}]+ 302), [ { A u ~ ( ~ - P P ) [ C ~ H ~ S ( O ) N M ~(PP ~ ] } ~=] ~ dppm, + d ~ p e ) , ~ {[AutCN'~ (mes))2][Au(GeC13)2]1n,303 {[Au(CNMe)2][OTf]1 [{S[Au2(p-dppf)]1(Au(C6F5)2)110Tfl,305 "Et412f :2(c6FS)} 3(113-s)1,306 and [ Au(PPh3))3 { p3C(PPh3)(C5H4N-2))][OTfl2. A new synthesis of [ ( A U ( P P ~ ~ ) } ~ C from ]~' [ { Au(PPh3))30]+and CH(SiMe3)N2proceeds by desilylation, deprotonation and deazotisation of the C atom.308 ny304

14

r

Mixed-metal Clusters

As in previous accounts, the chemistry of clusters containing metals from more than one group of the Periodic Table is considered in this section. With the exception of clusters containing one or more Group 11 metal atoms, complexes are arranged in order of lowest Periodic group number. 14.1 Group 6 - Cr, W-Re. The paramagnetic cluster cations [Cr4(p3-S)4Cp4]+ were the only products isolated from reactions of and [Cr2(p-SBuL)2(p-SMe)Cp2]+ Cr2(p-SBut)2(p-S)Cp2 and a variety of complex Re triflates." In contrast, Cr2Re(p3-S)2(pSB~f)(CO)(N)Cp2 was formed from halide precursors by loss of CrXzCp to form the transmetallation products, which then add CrSCp.' O ) ~RC ~ =*Ph, CMe=CH2) have The 0x0 clusters W R ~ ~ ( ~ L - C ~ R ) ( O ) ( C (83; been prepared by direct oxidation of WRe2(p3-C2R)(CO)&p* with 0 2 ; it adds CO in a reversible reaction to give WRe2(p-C2R)(p-CO)(0)(co)&p*.309 Reactions with H2 give successively WRe2(p-H)2(p3-C2R)(jt-o)(co)6cp*, WR~~(CI-CH=CHR)(O)(CO)~C~* and WRe&H)(pCHCH2R)(O)(CO)&p*; the vinylacetylide also gives the allenyl cluster WRe2(p3-CH=C=CMe2)(p-O)(pCO)(CO),Cp*. Cr, Mo, W-Fe. Reactions between M(CO)s(thf) (M = Cr,310Mo3") and Fe2(p-EE)(CO)6(EE = S2, Se2, SSe, STe, SeTe) have given CrFe2(E)4(CO)loand a range of M o F ~ ~ ( ~ ~ - E ) ( ~ ~ - E ' ) ( ~ - E E1 ' )and ( C O )'hour-glass' I clusters Mo{ Fe2(113-E)(113-E')(Co)6}2(C0)2 (84). Treatment of [Fe{(p-S)2Fe(SEt)2},13with M(C0)3(NCMe)3 (M = Mo, W) afforded cubane clusters [MFe3(p3-S)4(SEt)3(C0)3]3-, from which the M(CO)3group can be displaced by

193

4: Organo-Trunsition Metul Cluster Compounds

84

CO or NaPF6. Replacement of the SEt groups by other thiolates was demon~ t r a t e d . The ~ ' ~ v(C0) frequencies depend on the oxidation states, showing that intracluster electronic coupling occurs. Other cuboidal MoFe3 clusters were obtained by treatment of the fused double-cubane { MoFe3(p3-S)3(02C6C14)(PEt3)2()lg-S))2 with CO. The cores in the two products, MoFe&S)3(O)"(O2C6Cl4)(CO)6-n(PEt3)2+n (n = 0, I), resemble the MoFe3S3 unit in the cofiactor of n i t r ~ g e n a s e . ~ ' ~ Several clusters Mo2Fe(p3-S)(CO)7(CpR)2 were obtained from {Mo(CO)2(CpR)}2(R = C02Me, C02Et) and Fe2(p-SR')2(C0)6 (R' = Et, Ph).54 Reactions of Fe2(p-S)2(CO)6 with { M(C0)2(CpR))2 (R = MeCO, C02Me, the W reactions also gave W2Fe(p3C02Et) gave M2Fe2(~3-s)2(p3-Co)2(co)6; S)(C0),(CpR)2 (R = C02Me, C02Et).3'4Organic transformations of the acetyl groups [to CHMe(0H) with NaBH4 and to the 2,4-dinitrophenyIhydrazonewith the hydrazine] were carried out on the Mo complex. Isolobal replacement of one and two FeH(C0)3 groups by M(CO)*Cp (M = Mo, W) occurs when Fe3(pH)2(p3-E)(C0)9 (E = Se,20 Te3") is treated with {M(C0)3Cp)2. The W system also gave W~F~~(~~-S~)~(JA~-CO)(~-CO)(CO)~C~~.~'~ Several Mo-Fe clusters were identified in mixtures obtained from { Mo(C0)3Cp>2 and Fe3(p3-E)(p3-Se)(C0)9 (El = Se, E2 = Se, (E = S, Te), including Mo2Fe2(p4-E1)(p3-E2)(p3-E3)(CO)gCP2 E3 = Se, Te; E' = Se, E2 = S, E3 = S, Se; E' = Te, E2 = Se, E3 = Se, Te) and Mo2Fe2(p3-Se)(p3-E)(C0)7Cp2 (E = S, Te). Tellurium could be replaced by lower E atoms when the clusters were treated with S or Se The nitrosyl-containing clusters M2Fe2(p3-S)4(N0)2CpR2have been obtained from M & ( C P ~ ) ~(M = Mo, CpR =CpE'; M = W, CpR = Cp*) and Fe(C0)2(N0)2.318 An alternative approach to building up novel Mo-Fe clusters has been the oxidative cleavage of S-C bonds with FeCl3; with Mo(SBu')&p*, redox-active cubane core, was obtained.319 M o ~ F ~ ~ ( ~ ~ - S )containing ~ C ~ ~ C aP *distorted ~ Chloride could be replaced by polysulfide, whereupon the tricubane cluster { Mo2Fe&-S)&p*2) 3(p-S4)3 was obtained. This complex shows three reversible oxidation waves at +0.69, +0.26 and -0.1 1 V (vs SCE) and one irreversible reduction wave at -0.85 V. Mo, W-Ru.The electronic structure of MoRu2 { ~-(NH)2C6H4}2(C0)6(PPh3)2has been calculated by the EH method to shed light on the nature of the Mo-Ru interaction (bent) and the oxidation states of the metal atoms.320

194

Orgunometullic Chemistry

Thermal substitution of CO by PMePh2 in M o ~ R u ( ~ ~ - C C H R ) ( C O(R) ~=C ~ ~ H, Me, Ph, C02Me) is site-selective, occurring at the Ru atom.32' With PHPh2, however, depending on conditions, the 46-e M o ~ R u ( ~ ~ - C C H ~ R ) ( ~ PPh2)(CO)SCp2 and 48-e Mo2Ru(p3-CCHR)(p-PPh2)2(CO)4Cp2are isolated in addition to the CO substitution product. Their formation demonstrates sequential vinylidene/aIkylidene/vinylidene conversions. Reaction of MoZ(p-O)(pC4Ph4)(0)Cp2 with Ru3(C0)12 results in redistribution of the C4 ligand to give the twisted (dihedral 88 ") bow-tie cluster Mo2Ru3(p3-0)(p3-CPh)(pC3Ph3)(CO)&p2 (85).322

Complexes with mixed p-S, p-SR and p P R 2 ligands have been used for cluster ~ ~Et, ) CPr', P ~But, assembly. Thus, the reactions of M O ~ ( ~ - S ) ~ ( ~ - S R ) ( ~ - P(RP = tol) with Ru3(C0)12 have given MO~RU~(~~-S)~(~-SR)(~-PP~~)(CO)~ W-Ru, 0s. The reactions between Ru3(CO)I2 and WH(CO)3(CpR) [CpR = C5H3(SiMe3)2,CSH4SiMe3, C5H4Pri]afforded WRu6(p3-H)(CO)18(CpR)in which the tetrahedral WRu3 core is edge-bridged by three Ru atoms. As is now becoming common, the butterfly cavities so formed each contain p4-q2-co Hydrogenation gave the trihydride WRu&-H)2(p3-H)(Co)17(CpR), containing a double edge-bridged trigonal bipyramidal core, retaining two p4-co ligands. Unusual H-migration behaviour was shown by VT NMR. A series of studies of C-C bond cleavage in mixed W-Ru or W-0s clusters containing acetylide ligands has revealed that a plethora of unusual complexes is formed. Thus, on treating WRu&-C2Ph)(C0)&p* with WH(C0)3Cp*, the carbido-alkylidyne cluster W3Ru2(p4-C)(p3-CPh)(C0)&p*3 (86) is formed as main product; byproducts include WRu3(p-H)3(CO)l lCp*, W~Ruz(pCCHPh)(CO)&p*2 and the 0x0-carbido cluster W~RU~C(O)(CO)I 1Cp*2(87).325 The But derivative reacts differently, affording only the acetylide cluster W3Ru2(p3-C2But)(C0)gCP*3 (88). However, the two pentanuclear clusters have similar core structures, the butterfly portion being occupied by p4-C or p4-C0 ligdnds in 86 and 88, respectively. The C-C bond cleavage occurs readily with larger clusters. Reactions of Ru5C(CO)l5 with W(C= CPh)(C0)3(L) (L = Cp, Cp*) gave WRu&-C)(p4C2Ph)(CO),(L) [n = 13 (89-L), 151, the latter giving 89 on t h e r m ~ l y s i s . ~ ~ ~

4: Orguno-TrunsitionMetal Cluster Compounds

87

86

Hydrogenation

195

88

of 89-Cp* gave WRu,C(p-H)(p-CCH2Ph)(CO) I 3Cp* and

WRU,(~-H)~(~~-C)(~~-CCH~P~)(CO)~~C~* (90); with CO, the former gives octahedral WRU~C(~-CCH~P~)(CO)I~CP*.

09

90

Reactions of Os3(CO)Io(NCMe)2 with W(C=CR)(CO)&p* (R = Bun, Ph, CH20Me, CH20Ph) gave two interchangeable isomers of WOs3(pC2R)(CO)1ICp* (W in wing-tip or hinge position^).^^' Reversible formation of W O S ~ C ( ~ - C P ~ ) ( C Ooccurs ) ~ ~ Cby ~ *thermal elimination of CO, whereas for R = Bun or CH20Me, subsequent C-H activation afforded vinylidene clusters WOS,C(~-H)(~-CCHR')(CO)~C~* (R'= Pr, OMe). The CH20Ph complex undergoes metalation of the Ph group, C-C bond formation and H migration to give a benzofuryl cluster W O S ~ C ( ~ - H ) ~ ( ~ - C ~ H ~ ~ ) All (CO these ) ~ Calteration ~*. compounds were obtained as isomeric mixtures. Hydrogenation of the CH20Me oCp* ~ ) ( Cand O ) WOs3C(pH)z(pcomplex gave W O S ~ ( ~ - H ) ~ ( ~ - C ~ C H ~ O IM CCH20Me)(CO)&p* (91) sequentially; the latter isomerises to WOs3C(p-H)&CH=CHOMe)(C0)9Cp* (92) on heating. Addition of CO gave WOs3(p3CCH2CH20Me)(CO)11Cp* (93). Condensation of W(C = CPh)(0)2Cp* with Os3(CO)10(NCMe)2 afforded WOs3(~~-0)2(p-C2Ph)(CO)&p*,which reacts with H2 or CO to give woS3(pH)(p-O)2(p-C2Ph)(CO),Cp* (94) and W O S ~ ( ~ - O ) ( C ~ P ~ ) ( O ) ( C O(99, ) ~ C ~re* ~pectively.~~' Similar reactions with Ru&3-PPh)(CO) 13 gave WRu&4-PPh)(p0)2(p-C2Ph)(CO)1o-~,Cp*(q-PhMe), [n = 0 (96), 1 (97)] and WRu5(p4-PPh)(p0)2(P-C2Ph)(CO) 12 (98).329

Mo, W-Co. Exchange of one Co in C03(p3-CPh)(C0)9 occurs on treatment with [M(CO)3(CpR)J- (M = Mo, W; R = CHO, MeCO, C02Et).330Similarly obtained were the acids M C O ~ ( ~ ~ - C C O ~ H ) ( C O ) ~ C ~ ( which R~CO were ~ H then )

Organometullic Chemistry

196

91

93 Ph

I

Ph

94

95

Ph

97 Ru' = Ru(CO)~ 96

Ph

98 Ru' = Ru(q-PhMe)

used in reactions with Group 4 alkoxides to give Zr@-OH)2(p02CRM*)2(02CRM0)4 and Ti4(p3-0)4(p-02CRM)4(OR')g (R' = Et, Pr'). Detailed comparisons with the related RCoC02 complexes (see above), particularly in terms of differing electronic effects of the M3 cluster, are reported.33' Continuing studies on hydro-desulfurisation catalysts have concentrated on Co-Mo clusters. Sulfur compounds react with M O Z C O ~ ( ~ ~ - S ) ~ ( C O(99*; )~(CP~~) CpE' = q-CsMe4Et) to give hydrocarbons and intractable Mo-Co containing

4: Organo- Trunsition M e t d Cluster Compounds

197

materials, possibly polymeric sulfur-bridged clusters. Oxidation of 99 gave 58-e clusters Mo2C02(p3-S)4(X)2(CpEt)2(X = CI, Br, I, SPh) which showed either complex spin equilibria (X = halogen) or paramagnetism (X = SPh), which is related to the Co.-Co separation. Under CO (1000 psi, 15O"C), an excess of PhSH was converted to PhC(0)SPh and Ph2S2.332The corresponding trisulfide, M o ~ C O ~ ( ~ ~ - S ) ~ ( (loo*; C O ) ~Cp' C ~=' ~q-CSH4Me) reacts with dppm or dppe (PP) to give M o ~ C O ~ ( ~ ~ - S ) ~ ( C O ) ~ (the P Pdppe ) C ~ 'complex ~; removes S or PR from thiols and tertiary phosphines, respectively, to give M02C02(p3S)&-dppe)Cp'2 and { Mo2C02(p3-S)3(p3-PPh)(p-dppe)Cp'2)n.333 Addition of two molecules of dmpe to 100 gave Mo2Co2(p3-S)3(p3-C0)(dmpe)2Cp12, which in CH2CI2.Reduction of was converted to M~~Co~(p~-S)~(p~-CH)(drnpe)~Cp'~ 99 with NdHg or reaction of 100 with NaS(to1) afforded paramagnetic [ M o ~ C O ~ ( ~ ~ - S ) ~ ( C O )(Cp ~ C P=~CpE' ] - and Cp', respectively), with formation of [M0&02(p3-S)3 {S(tol)}(C0)3Cp'2]- as a minor product in the latter reaction.334 Reactions of thiols with 100 are first order in both reactants: initial q 1 coordination of thiol was found at -40°C. At -25"C, conversion to a p-q'-SR group occurs, which is fluxional by migration in concert with a p-S atom. Radical cleavage of the S-C bond occurs at 35°C to give R and [Mo~CO~(~~-S)~(CO)~C~'~]-.~~~ Reactions of M2S4(CpR)2 (MCpR = WCp*, MoCpEL)with CO(CO)~(NO)gave M ~ C O ~ ( ~ ~ - S ) ~ ( N O )the ~ ( mixed C P ~ )W-Co ~; clusters W2C02(p3-S)4(CO)2Cp*2 and W2C02(p3-S)3(CO)5(CpEt)2 were also described.3' Ma-Zr. A considerable amount of chemistry of tetrahedral Mo-Ir clusters has been described. Reactions of MoIr3(p-C0)3(CO)&p with PR3 (R = Me, Ph) have given fluxional mono-, di- and tri-substituted (R = Me only) products; at low temperatures, isomer separation is possible.336 Structural and NMR studies enabled configurations for all complexes to be suggested: in the mono- and disubstituted complexes, the PR3 ligand is found in a carbonyl-bridged MoIr2 face, although the third (PMe3) ligand substitutes at the third Ir atom. Cluster MO~I~~(~~-CO)(~-CO)~(CO)~C~~ has been made from [Mo(C0)3Cp]- and IrC1(CO)2{NH2(tol)).In contrast to the W cluster, all edges are bridged by CO: with a CO group that leans across one face, the molecule is unusually crowded.337 Phosphine mono- and disubstitution takes place at Ir; in some cases, interconverting isomer mixtures were ~ h a r a c t e r i s e d . With ~ ~ ~ alkynes, clusters with C2M021r2 cores were obtained: the Mo atoms were in wing-tip positions of the metal butterfly, formal insertion of the alkyne into an Mo-Mo bond having occurred.

Cr, Mo, W-Ni, Pd, Pt. The unusual complex 101, formally produced by addition of cyclopentadienylidene to a PhC= fragment, was obtained from the reaction between { Mo(C0)3Cp}2 and Ni2(p-HC2Ph)Cp2.339Synthesis of a cluster conO ) ~= C~#~ taining PS ligands was achieved by oxidation of W N ~ & . L ~ - P ) ~ ( C(Cp' q-C5HPri4)with Sg. On heating at lOO"C, loss of CO afforded the chain cluster W N ~ ~ ( ~ - T ~ ~ - P S ) ~ ( CinOthe ) ~ Ccrystal, P # ~ ; both enantiomers of the chiral cluster are present.340Reactions of Cr2(p-SBut)2(p-S)Cp2 with PdC12(PPri3)2and { Pt(p3-

Orgunometutlic Chemistry

198

I)Me3)4 have given antiferromagnetic Cr2Pd(p3-S)2(pSBu')(CI)(PPh3)Cp2S1 and 1 0 2 , respectively ~~~ .

102

Reactions of MH(C0)3Cp (M = Cr, Mo, W) with one equivalent of {Pd(pOH)(Ph)(PR3)t2 (103*; R = Ph, Cy) gave the MPd2 clusters (104) in high yield by ~ ~ ' W complex decomformal neutralisation of the Group 6 acidic h ~ d r i d e . The poses to Ph2, 103 and a tetranuclear cluster 105, also obtained directly from 103 and an excess of MH(C0)3Cp or WH(CO)&p*. However, the latter reactions proceed by H/Ph exchange, which produces C6H6 and MPh(C0)3Cp or WH(C0)3Cp*; these processes are faster than neutralisation and M-M bond formation. CD

104

CD

CP

105

14.2 Group 7 - Mn,Re-Ru. Reactions of Ru12(CO)2(Pri-dab) with [M(C0)5](M = Mn, Re) gave Ru{ M(CO)5)2(CO)2(Pri-dab).The Re2Ru complex contains a bent Re-Ru-Re chain (1 56.7 0).342Detailed spectroscopic properties have been investigated, the deep colours of the complexes being attributed to a nb-(M-RuM) + x*-(dab) transition.343

Re-lr. The triangular cluster Re21r(p-H)2(C0)9(q5-CgH7) was prepared from Substitution by PPh3 occurred at Re2(p-H)2(CO)8 and Ir(CO)(~oe)(rl~-C9H~).~~ Re, while deprotonation gave the monohydrido anion, in which the Re-Re edge is bridged by H.

4: Orguno-TrunsitionMetal Cluster Compounds

1 99

Re-Pt. Adsorption of RezPt(CO)12 on y-alumina gave a catalyst active in the dehydrogenation of methylcyclohexane. EXAFS spectroscopy characterised the formation of Re4Pt2 aggregates attached to the support by the oxophilic Re atoms and stabilising the Pt dispersion.345 Reactions of RezPt(pH)2(CO)8(cod)with ReH(C0)5-n(PPh3)n (n = 1, 2) under CO result in displacement of cod by the rhenium hydrido complex to give novel Re-spiked triangular clusters Re3Pt(p-H)3(CO)14-,,(PPh3), (106). With CO, the Re2Pt cluster affords the 'parent' cluster Re3Pt(p-H)3(C0)14,in which the spike ReH(CO)5 'ligand' readily exchanges with free ReH(C0)5.346

has been used as a model for Re-Pt/ The cluster [Pt3{Re(C0)3}(p-dppm)3]+ alumina catalysts. Reactions with propylene sulfide have given [ P t 3 (Re(CO)3S)(p-dppm)3)]+ and [Pt3{Re(C0)3)(p3-S)2(p-dppm)3]+;oxidation with Me3NO gave [Pf3{ Re(C0)3S)(p3-0)(p-dppm)31+ and [Pt{ Re(C0)3)(P3-0W3S)2(p-dppm)3]+,respectively.347The related 0x0 clusters [Pt3{ Re(CO)3}(p3-O)(p3and [Pt3(Re03)(p3'S)2(p1S)(p-dppm)31f, [Pt{ Re(C0)31(~3-0)2(~3-S)(~-dppm)]+ d ~ p m ) ~were ] + also described.347 14.3 Group 8 - Fe-Co, Rh, Ir. Large optical non-linearity of Fe2Co(p3-S)(p3Se)(C0)6Cp has been measured: the optical limiting characteristics are much Reactions of Fe2Co(p3-Se)2(C0)6Cp with dppm or better than those of C~O.'~' dppe (PP) have given F~~CO(~~-S~)~(~-PP)(CO)~C~ in which the PP ligand bridges a Co-Fe bond.349The novel functional phosphinoethyl-oligosiloxane P P ~ ~ ( C H ~ ) ~ { T ~ ( C(L; - CT ~ H=~SiO312) ) ~ ) has been used to form FeCo3(pH)(CO)g-n(L)n (n = 1, 2).350Exchange of a cobalt fragment for Fe(C0)3 occurs in the reaction of Co3(p3-S)(pL-NHCMeS)(C0)7with [Fe(C0),l2- to give FeCoz(p3-S)(p-N,S- N HCMeS)(C0)7 .242 Reactions of cobalt- and rhodium-ethene complexes with { M(C0)2Cp}2 (M = Fe, Ru; Cp = Cp, Cp*) have given a wide range of tri- and tetranuclear = PCO, clusters M2M'(p3-CO)(p-C0)3Cp3 and M ~ - ~ M ' ~ ( P ~ - C O(M' )~C ~ Rh; n = 1-4).26' Octahedral'cluster anions [Fe5MN(CO),5J2-(M = Rh, Ir) were obtained from reactions between [Fe4N(CO),z]- and [Rh(C0)4]- or [Fe6N(CO),5l3- and {Ir(pCl)(coe)2)2, respectiveiy; oxidation of the Fe5Rh anion with RhC13 afforded - .35' The relatively greater electron density on the Group 9 [Fe4Rh2N(CO)15] atoms is redistributed over the cluster by a larger number of bridging CO ligands. The dianions are oxidised to short-lived paramagnetic mono-anions, while a 2-e reduction of [Fe4Rh2N(C0)15]-gave an unstable trianion. The interstitial nitride resonates at between S 514 and 470 ppm. Reactions of [Fe3(p3-O)(CO)9l2-with

Organometallic Chemistry

200

( Rh(p-CI)(C0)2)2 gave [Fe3Rh3(p3-O)(CO)15]-,containing an octahedral core formed by staggered Fe3 and Rh3 units; the 0 atom caps the Fe3 face.352

Ru-Co. Treatment of C O ~ ( ~ ~ - C B T ) (with C O )[Ru(C0)2Cp]~ gave a low yield of the carbide cluster CO~RU(~~-C)(~-H~[RU(CO)~C~])(CO)~ 3 (107); fragmentation of the C03C cluster was prevented by using Co3(p3-CBr){p3-(PPh2)3CH)(C0)6, which afforded Cog { p4-C[Ru(C0)2Cp]}{ p3-(PPh&CH) (CO)6 (108); the tetrahedral carbide can be regarded as a permetallated methane.353

H

107

108

Ru-Rh, Ir. The major product from R U ~ ( C Oand ) ~ ~either RhCI(PHBut2)3 or (Rh(p-CI)(PHBu12)2)2is Ru3Rh(p3-H)(p-CI)(p-PBut2)2(CO)$PHBu'2) in which the butterfly core contains a long Ru-Ru hinge bond (3.231 A); some Ru3Rh(p3H)(p-H)2(p3-PBu')(p-PBu12)2(CO)g is also formed.354 With IrC1(PHBut2)3, RU~I~(~-H)~(~~-C~)(~-PBU'~)~(CO)~(PHB~~~) was isolated.355 interestingly, the positions of the p3-X ligands (X = H, CI) are reversed in these two complexes. Homo-metallic 38 was obtained from both reactions. Replacement of one Ru atom by Rh occurs in the reaction of [Ru6(CO),gl2with [Rh(NCMe)3Cp*I2+:in the resulting Ru5Rh(p4-q2-C0)2(p-CO)(CO)]2Cp* (lW),the butterfly portions of the 88-e doubly edge-bridged tetrahedral core contain p4-q2-C0 l i g a n d ~ . ' ~The ~ 86-e pb-boride cluster cis-Ru4Rh2B(pH)(CO)12(nbd) was obtained from [Ru4(p-H)(p4-BH)(C0),2]- and (Rh(pCl)(nbd)}2; it can be deprotonated and neither cluster isomerises to the trans form [as found for the nbd-free (CO)16

109 Ru' = Ru(CO)~

The clusters [Ru2M(p3-S2)2(NCMe)Cp*3I2+(M = Rh, Ir) have been prepared from Ru&Cp*4 and [M(NCMe)3Cp*]2+;the S2 ligands are bonded in the

4: Organo-Transition Metal Cluster Compouncis

201

qi(Rh):q2:q2(Ru)mode.358Reaction with acetone affords [Ru2RhS3{S(CH2COM~)}CP*~]+ containing a trigonal prismatic M3S3 core. Fluxional processes were ) C ~ * ~ C ~occurs ~ ' ]via ~ +clea: explored with [ R u ~ R ~ ( ~ ~ - S ~ ) ~ ( N C M ~racemisation vage of one S-S bond. Ru-lr. Two isomers of the anion, with two or four p-CO groups, are present in the crystal of [ppn][Ru3Ir(CO)13],obtained from Ru3(CO)12 and [Ir(C0)4]-. In solution, both isomers interconvert. Protonation afforded neutral Ru31r(pH)(CO)13;addition of H2 then gave R U ~ I ~ ( ~ - H ) ~ (also C Oobtained ) ~ ~ , by protonation of [Ru31r(p-H)2(CO)l2]-, itself formed by hydrogenation of [ R u ~ I ~ ( C O ) ,.359 ~ ] -Several related clusters have been prepared from reactions between [ R u ~ ( ~ - H ) ( CI]O ) ~and IrCl(CO)(PPh3)2, the products including R u ~ I ~ ( ~ - H ) ( C O ) I ~ ( Ptwo P ~ ~ isomers ), of R U ~ I T ( ~ - H ) ~ (I(PPh3) C O ) ~ and RU~-~I~,(~-H)~_~(CO)IO(PP~& (n = I , 2).25*360

0s-Rh. In addition to the Os12Rh9 cluster 5 mentioned above, the reaction I]- and (Rh(p-Cl)(nbd)>2in the presence of AgPF6 between [OS~(~-H)(CO)~ afforded Os4Rh3(p3-H)(p3-CO)(CO)I4(nbd)2,which contains an Os-capped Os3Rh3 octahedral core. The nbd ligands remain bonded to Rh.38 Fe-Pd. Addition of PdC12(SEt2), to { Fe(p-SnBun2)(CO)3(dppmP)}2 afforded two intermediates which on standing changed to two new products, one of which was identified as Fe2Pd(p-SnBun2)(p-dppm)2(C0)6 (110); a similar product was obtained from PtC12(NCPh)2.36'

110

Phi

111

Ru-Ni, Pt. As an example of a general route converting trigonal pyramidal Ptz(pS)2M assemblies to Pt2M(p3-S) cluster cores, R ~ c l ~ ( P P hand 3 ) ~Pt,(p-S)2(PPh3)4 react to give the sulfur-bridged complex [{ [RuCl(PPh3)2][pt(PPh3)2]2)(p3-S)2]+. Under CO, this condenses to [RUP~~(~~-S)(CI)(CO)~(PP~~)~]+.~~~ Heteronuclear complexes were obtained via reactions of the p-buta-l,3-diynyl ligand in RuZ(pPPh&p-C2C = CR)(C0)6 (R = Bu', Ph) with Ni(CO)4, Ni(cod)2, Pt(qC2H4)(PPh3)2 or P t ( ~ l - C ~ H ~ ) ( d p pThe b).~ first ~ ~ two reagents gave R ~ N i ( p 4 (1 11) by dimerisation of the R u ~ Bu'C =CC4C =CBU')(~-PP~~)(CO)~~(PP~~) complex and head-to-head coupling of the two butadiynyl groups. In contrast,

202

Orgunometallic Chemistry

the reaction with the Pt complexes gave Ru2Pt(p3-C2C = CR)(pPPh2)(CO)&)(L') [(L)(L') = (CO)(PPh.3), dppb]. The reaction of Pt(qC2H4)(PPh3)2 with R u ~ { ~ ~ - P ( O H ) } ( C O afforded ),~ 74-e Ru4Pt (p4P(OH)}(C0)13(PPh3) by capping the Ru3P face with the Pt(CO)(PPh,) fragment.I5' At r.t., reactions of PR3 (R = Me, Ph) with R~6Pt3(p3-H)(p-H)3(c0)21 gave the salts [PtH(PR3)3][R~6Pt3(p3-H)(p-H)2(C0)2 while the Me3NO-induced reaction with PPh3 resulted in substitution to form Ru6Pf3(p3-H)(pH)3(C0)20(PPh3).In these products, the Ru3/Pt3/Pf3 layer structure of the core is preserved.364 0s-Pd, Pt. Reactions between O S ~ ( ~ - H ) ~ ( Cand O ) ~truns-Pd12(NH3)2 ~ gave moderate yields of 0~4Pd(p-H)4-n(p'I),+n(C0)~2[n = 0 (112), I] and OS6Pd(pH)8(CO)l8; in which two Os3Pd tetrahedra are joined by a common Pd atom.365 In refluxing CHC13, 112 was converted into n = 1 and the bis-cluster {Os3Pd(pH)3(CO)9}2(p-I)2. Thermolysis of O~~PdC(p-dppf)(CO)~~, from [OS~C(CO),~]~ and [Pd(OH2)2(dppf)][CF3CO2]2, gave the bis-cluster { Os5C(CO)14}2(p-dppf), while 12 afforded the macrocycle {os~(~-~)~(co)~)(p-dppf)2{Pd~(pL-I)2~2} .233T i angular OSP~~(~-I)~(~-CO)(CO)~(PP~~)~ is formed by the reaction of { Os(pI)(C0)3}2 with Pt (dba)(PPh3) or Pt(q2-C2Ph 2)(PPh3)2.366

112 0s' = Os(CO),

113 L = PBu"~

114

14.4 Group 9 -- Co-Pd. Mixed Co-Pd clusters 113 have been obtained from Co2(CO)8 and { Pd(p-X)(PBut3))2(X = C1, Br) or P&(p3-CH)(p-?1)3(PBut3)4; one Pd-Pd bond in the Pd3 face capped by the halogen is long (3.324 A).282 Rh, Ir-Pd, Pt. Reactions of syn-[Pt2(p-dpmp)2(CNxy)2I2+ with { M(p-Cl)(cod)}2 (M = Rh, Ir) gave linear-[MPt2(p3-dprnp)2(Cl)(CN~y)2]~+ and A-frarne-[MPt~(pC1)(p-dpmp)2(CNy)2I2+;in the former, the M-Pt-Pt sequence is considered to involve ds-to-d9 dative and d9-d9covalent bonding.367The reaction of planar Rh4{p-N(toI)}~(CO)~(cod) with PdC12(NCPh)2 affords {Rh3[pN(t01)]2(C0)6}2Pd(CO)(NCPh)(114), which has a planar Rh3PdRh3 raft-like core.265 Palladium can also be incorporated into a sulfido cluster by reaction of Pd(PPh3)4 is obtained.262 with { Ir(p-SH)ClCp*}2, when [Ir2Pd(p3-S)2(C1)(PPh3)Cp*2]+ from [Ir(CO)4]- and [Pt3(p3Air-sensitive [IrPt3(pdppm)3(p-CO)3(CO)]+7 CO)(~~-dppm)~]~+, has a butterfly core (Ir at ~ i n g - t i p ) Ready . ~ ~ ~ substitution of

203

4: Orguno- Transition Metul Cluster Compounh

the terminal CO by P(OPh)3 occurred: the wing-tip separation in the product is 3.002 Both complexes are fluxional by a 'walk of the Ir fragment around the Pt3 face.

A.

14.5 Group 11 - Mo, W. Reactions of CuNCS and CuBr with [WS3Cp*]- have 2(p4-SCN)2I2- and given the double-cubane clusters [{ Cu3W(~~-S)~(NCS)~CP*} [ (Cu3W(p3-S)3Br2Cp*}2(p-Br)2I2- in high yields by ~elf-assembly.~~~ Similar reactions with AgBr gave {Ag2W(p3-S)3BrCp*},,which with PPh3 afforded triangular Ag2W(p3-S)(p-Br)(p-S)2(PPh3)2Cp*.370 The halide-elimination reaction between AuCI(PPh3) and [Mo(C0)3Cp]- gave Mo (Au(PPh3))(CO),Cp, which on irradiation with Au(N3)(PPh3) afforded [AuqMo(CO)~(PP~~)~ (1C ~ ] + Reactions of MoH(C0)2(PR3)Cp (R = Me, Ph) with [Au(PPh3)]' at -40 "C gave directly [AU~MO(CO),(PR~)(PP~~)~]+. At lower temperatures, an intermediate [AUMO(~-H)(CO)~(PM~~)(PP~~)CP]+ was observed; deprotonation occurred with 2,6-lutidine. Three eq. of [Au(PPh3)]' add to the Mo centre to give [AU~MO(CO)~(PM~~)(PP~~)~]~+. Build-up of Au-Mo clusters is aided by the hydride ligand and greater aurophilicity of the PMe3 complexes.372

115 P=PPh%

Re. The anion formed by addition of LiPh to Re2(p-H)(p-PCy2)(C0)8at -100°C reacts with two eq. of AuX(PPh3) (X = CI, Br, I) to give A U Z R ~ ~ ( ~ - P C ~ ~ ) ( X ) (C0)7(PPh3)2 (116) via intermediates isolable as [ppn][AuRe2(p-PCy2)(X)(CO),(PPh3)].373

116 Au' = A u ( P P ~ )

117

Fe, Ru, 0s. The unusual polyrnetallic mesocyclic cation 117 was built up from Hg( Fe[Si(OMe)3](CO),(dppm-P)} 2, which contains an Fe-Hg-Fe sequence, and [ C U ( N C M ~ ) ~ Initially, ] + . ~ ~ ~the dppm ligdnds coordinate to the Cu in a manner

Organometallic Chemistry

204

similar to that found in the bis-AuBr complex; however, in polar solvents, elimination of [Cu(NCMe)4]+gives 117 containing the first Cu-Hg bond. An EH MO calculation has clarified the bonding in this system. Fe-Au clusters have been built up using { AuCl(PPh&H2)} 3CMe[ = (AuC1)3(L = CHzCHPh, (triphos)]. Reactions with [Fe&L)(p-CO)(C0)6]CPh=CHPh, PPh2) have given { A~Fe~(p-L)(p-Co)(Co)~}~(p~-triphos); with [Fe2(Co)812-, [ { Fe2(p-C0)2(C0)6)3(p3-triphos)]3- was obtained.375 The product from (A~CI)~(p-dppm)and either [Fe(C0),l2- or [AuFe2(CO)8I3- is the raft cluster anion [Au3Fe2(p-dppm)(Co)8]- (118), which itself is a bidentate ligand isolobal with dppm. This was shown by further condensation with (AuCl)(p-dppm) to give the cation [Au5Fe2(p-dpprn)2(C0)8]+ (119).376Auration of the 0x0 cluster anion [Fe3(p3-O)(CO),12- with AuCl(PPh3) resulted in addition of two Au(PPh3) units to give trigonal pyramidal AuzFe3(p3O)(CO)9(PPh3)2,with the oxygen atom capping the Fe3 face.352Reactions of [Fe6C(C0)16]2- with AuCl(PPh3) have given [ A u F ~ ~ C ( C O ) ~ ~ -, (PP ~~)] which with NOBF4 gave either AuFe6C(CO)~,(NO)(PPh3)(with one equivalent) or AuFe&(CO)I I(NO)(PPh3)(with an excess).92The structural differences between the AuFesC cluster (where the Au atom spans the wing-tip Fe atoms) and its formally isolobal hydrido analogue (in which the H bridges the hinge Fe-Fe bond) have been examined using EH MO calculations which show optimum orbital overlap occurs in each case.

‘ 1-

PhzPPh2p-!pb I

1

PPh2

I

Au-Au

/\/\

(OC)3Fe-

Au-

118 Ph2P-

PPhp

119

An unusual elimination of copper from CU~RU~(~~-C)(CO)~~(NCM~)~ occurs upon addition of [ 121-ane-S3(1,5,9-trithiacyclododecane)to give [Cu(ql-[121-aneS3)(q3-[ 12]-ane-S3)]2[RU6C(CO),6].377 The use of [O{AU(PR~))~]+ to introduce one or two Au(PR3) units into ruthenium clusters has been commented on in earlier reviews. Further developments have seen it used to add three Au(PPh3) units to a variety of Ru3 cluster~.~ The ’ ~Au3(PPh3)3 group acts as a 3-e donor and may be incorporated as an open (bent) or closed triangular unit; the former is favoured with a higher ~(= PP~~)~ electron density on the cluster. The structures of A u ~ R u ~ ( ~ ~ - L ) ( C O ) (L C2Ph, CMeCHCMe) were reported. Addition of C2Ph2 to the precursor of the latter cluster affords RU~(~CE~CM~CP~CP~)(~-CO)~(CO)~, which was aurated

4: Organo-TransitionMetal Clirster Compounds

205

to give the A u ~ R cluster u~ 120; the structure determination allowed a minor revision of the substituent sequence in the central C4Ru cycle.379

120

121 0s’ = Os(CO),

The first Au4Os4 cluster is 121 was obtained from [0s4(v-H)2(CO),2l2- and two eq. of (AuCl)2(pdppm); the core is an Os4 tetrahedron, of which one face is capped by three Au atoms, the fourth Au atom capping one of the resulting Au20s faces.380 Co, Ir. Treatment of Co3H4Cp3(Cp = Cp*, CpE‘) with AgBF4 in the presence of PEt3 gave the tetrahedral clusters [AgCo3H4(PEt3)Cp3]+ by addition of an [Ag(PEt3)]’ fragment to the C03 face.253Addition of electrophilic metal fragments to Ir3(p-C0)3(q5-C9H7)3 has given [MIr3(C0)3(PPh3)(q5-C9H7)3]+ (M = Cu, Ag, Au), in which the metal core is a butterfly with the Group I 1 atom in a wing-tip position.270

Pz.Under CO (4 bar), the complex Pt2(p-S)2(PPh3)4reacts with AgCI(PPh3) or CuCl to give MPt2(p3-S)(Cl)(CO)(PPh3)3 (122; M = Ag, C U ) . Several ~ ~ ~ noncluster intermediates were seen, which underwent cdrbonylation, desulfurisation and M-M bond formation. Further examples of the use of [Pt2(pdprnp)2(CN~y)~]’+ to build up linear or bent MPt2 sequences are found in its reactions with CuX (X = C1, Br, I) to give [CuPt2(p3-dpmp)2(X)(CNxy)2I2+, which contains a rhombic CuBrPt2 moiety, and with MPF6 (M = Ag, Au) to give [MPt2(p3-dpmp)2(CN~y)~]~+, in which the M atoms are trapped by the third P

122

Orgunometullic Chemistry

206

donor atom in the dpmp ligands to form bent MPt2 arrays (angles at central Pt 136.4, 1 10.7”,re~pectively).~~’ The trinuclear clusters P t ~ ( p - C o P ) ~C( Y ~ and ) ~ Pt3(p-CNxy)2(pL-C0)(CNxy)(PCy& react with Group 1 1 metal cations containing bifunctional phosphines (PR2)ZR’ [R = Cy, Ph; R’ = C6H4, (CH2)2C6H4,Fe(q-CsH4)2]to give many dicationic phosphine-linked bis-MPt, clusters. The X-ray structure of one, { AuPtJ(p-C0)3(PCy3)3}2 { p-l14-(CH2)2C6H4}, is reported.382

14.6 Clusters Containing Three Different Metals Rapid exchange of the Group 6 metals occurs on teatment of the MPd2 or M2Pd2 clusters (104 and 105) with [M(CO),Cp]-; in this way, the CrWPd2 and MoWPd2 clusters MM’PdZ(p3C0)2(p-C0)4(PPh&Cp2 were prepared.34’ Successive metal exchange reactions afforded chiral clusters, as exemplified by the synthesis of C ~ F e M ( p ~ - s ) ( C o ) ~ ( [M c p ~= ) Mo, W; R = PhCO, MeOC(0)C6H4CO] by thermal exchange of C O ~ F ~ ( ~ ~ - S ) ( with CO)~ [M(CO),(CpR)]-. The benzoyl-Cp-Mo cluster was reduced with NaBH4 to the CHPh(0H) derivative.383Reactions of FeMoNi(p3-S)(C0),Cp(CpR) (R = H, MeCO, C02Me) with Fe2(C0)9 resulted in addition of a second Fe(CO)3 the bis-cluster group to give F~~MO{~~-S[N~(CO)C~]}(CO)~&~(C~~); { F ~ M O N ~ ( ~ ~ - S ) ( C O{ ~) ~- C T ~~ }C*~ H ~ C ( Oreacted ) C H ~in} ~similar fashion.384 Isolobal displacement of Co by Ni occurred in the contrasting reaction between { C O F ~ M O ( ~ ~ - ~ ) ( C O ) ~ } ~ { ~ - ~ - C ~and H ~ NiCp2 C(O)C to Hgive ~ } ~the { FeMoNiS}{ CoFeMoS} and bis-{FeMoNiS} clusters.384The trimetallic cluster FeMoW(p~-Se)(C0)7Cp2was prepared by successive reactions of Fe3(p-H)2(p3Se)(CO)9 with [W(CO)$p]- and [Mo(CO)3Cp]- . 3 1 Related clusters containing K u in place of Fe were made from C O ~ R U ( ~ ~ - S ) (and C O [Mo(CO)3(CpR)])~ [R = CHO, MeCO, PhCO, MeOC(0)C6H4C(O)]; reduction of the CsH&(O)Me complex with NaBH4 gave the corresponding C5H4CHMe(OH) M(C0)3[qderi~ative.’~~ Similar reactions of C O ~ R U ( ~ ~ - S ) ( with C O ) ~[ 1,4-{ c5H4c(o)]}2c6H4]2- (M = Mo, W) afforded 1,4-(CoRuM(p3-S)(CO)*[qc5H4c(o)]>2C6H4.386 Pentanuclear clusters Fe3MM’C(C0)12(L)(M = Co, Rh; M’ = Rh, Pd, Au) were obtained from reactions between [Fe3MC(CO)12]-(M = Co, Rh) and either { Rh(p-CI)(C0)2}2,{ Pd(p-CI)(L)), (L = q-C3H5, q3-P-pinenyl)or A u C I ( P P ~ ~ ) . ~ ~ ~ The M’L groups bridge the wing-tips of Fe3M clusters. Successive introduction of Rh and Au into ruthenium-boride clusters was achieved by reaction of [Ru4(pH)(p4-BH)(CO),2]- with (Rh(p-Cl)(nbd)}2, followed by addition of AuCI(PR3) (R = Ph, 2-MeC6H4, Cy), when cis-AuRh2Ru4B(CO),(PR3)(nbd)2 (n = 12, 14) were obtained.3s7 Replacement of cod or ReH(CO)5 groups in Re2Pt(p-H)2(CO),(cod) or Re2Pt(p-H)2(CO)9{ (p-H)Re(CO)s}, respectively, by a series of metallo-ligands has been used as a general route to bi- and trimetallic complexes.346The first reaction is generally run under CO. The metallo-ligands may be carbonyl metal anions ([Mn(CO)s]-, [W(CO)3Cp]-, [CO(CO)~]-)or metal carbonyl hydrides [MnH(CO)5];the latter product was also obtained by protonation of the anionic MnPtRe2 cluster. These complexes contain metal-spiked triangular PtRe2 cores. ~

4: Orguno-Trunsition Metul CIusler Compuuncis

207

The entering metallo-ligands are more-or-less labile, the following relative (thermodynamic) nucleophilicities being established:

14.7 Clusters in Catalysis - The intramolecular Pauson-Khand reaction of CH2=CHCH2C(C02Me)2CH2C = CEt and related molecules to give bicyclic cyclopentenones is efficently catalysed by R u ~ ( C O ) ~ ~Reactions .~" of CC14 with to give hex-1 -ene or N-( trans-cinnamoy1)-L-proline methyl ester CCI3CH2CHC1Bu and PhCHC1CH(CCl3)COR', respectively, are catalysed by M3(CO)12 (M = Fe, Ru, 0 s ) in dmf.389Selective formation of monoenes from H2 and cyclohexa-I,6diene or hex-3-yne is catalysed by solid phase clusters depos[RU3(CO)12, RU4(p-H)4(CO)12, RU3(~3-C2Ph2)(CL3'CO?(~-CO)(C0)3CP21 ited on porous glass discs; the reactions are similar to those found in homogeneous systems.390 A variety of derived cluster complexes were formed during the reactions. Hydrogenation of olefins, dienes and benzenes is catalysed by Chromosorb P on which tetrahedral Ru4, FeRu3 or RuCo3 hydrido clusters have been adsorbed and activated by H,; metal particles (- 7.5 nm) are present after reaction.391 Silylformylation of alkynes to SiR3CR'=CR2(CHO) is achieved by reaction of the alkyne (terminal or internal) and SiHR3 under C O (>lo kg cm-2) with Rh4(C0)12as catalyst.392With two equivalents of 1-alkyne, cyclopentenones are obtained. Reactions of N-(2-pyridinyl)piperdzines with CO (1 5 bar) and ethene, catalysed by Rh4(CO)I2, give the corresponding propionyldehydr~piperdzines.~~~ The reactions of { Pd(pOAc)(pCO)1 with alcohols proceed by several routes, involving alkoxy, alkoxycarbonyl and acyl-Pd complexes, to give dialkyl carbon a t e ~ Hydrogen . ~ ~ ~ reduction of Ru5PtC(CO) I supported on carbon afforded Pt-Ru nanoparticles with average diameter -1.5 nm, EXAFS data indicating that surface atoms are preferentially Pt. The oxide layer produced in 0 2 is reduced to metal in H ~ . ~ ~ ~ References 1. 2. 3. 4. 5. 6.

7. 8. 9.

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12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41.

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Orgunometullic Chemistry

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4: Orguno-Trunsition Metd Cluster Compoimtls 43. 44.

45. 46. 47. 48. 49.

50. 51.

52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63.

64. 65.

66.

67. 68. 69.

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209

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210 74. 75. 76. 77. 78. 79. 80. 81. 82.

83. 84. 85. 86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. 99. 100.

101. 102. 103.

104.

Organometullic Chemistry

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4: Orguno-Trunsition Metal Cluster Compounds

105. 106. 107. 108.

109. 110.

111. 112. 113. 114. 115. 116. 117. 118. 119. 120. 121. 122. 123. 124. 125. 126. 127. 128. 129. 130. 131.

21 I

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A.R. Kudinov, D.V. Muratov, M.I. Rybinskaya, P.V. Petrovskii, Russ. Chem. Bull,, 1997,46, 559. Z. Tang, Y. Nomura, Y. Ishii, Y. Mizobe, M. Hidai, Orgunometullics, 1997, 16, 151. G.E. Herberich, H.J. Eckenrath, U. Englert, Orgunometullics, 1997, 16,4292. G.E. Herberich, H.J. Eckenrath, U. Englert, Orgunometullics, 1997, 16,4800. C. Tejel, Y.-M. Shi, M.A. Ciriano, A.J. Edwards, F.J. Lahoz, J. Modrego, L.A. Oro, J. Am. Cliem. Soc.., 1997, 119, 6678. R. Ros, A, Tassan, Inorg. Chim. Ac-tu, 1997, 260, 89 G. Laurenczy, G. Bondietti, R. Ros, R. Roulet, Inorg. Chim. Actu, 1996,247,65. R.M.S. Pereira, F.Y. Fujiwara, M.D. Vargas, D. Braga, F. Grepioni, Orgunometulfics, 1997, 16,4833. C.-H. Ueng, S.-M. Lu, Inorg. Chim. Actu, 1997,262, I 1 3. M.C. Comstock, T. Prussak-Wieckowska, S.R. Wilson, J.R. Shapley, Orgunometuflies, 1997, 16,4033. T. Eguchi. R.A. Harding, B.T. Heaton, G. Longoni, K. Miyagi, J. Nahring, N. Nakamura, H. Nakayama, A.K. Smith, J. Clzem. Soc., Dalton Truns., 1997,479. S . Pasynkiewicz, W. Buchowicz, A. Pietrzykowski, T. Glowiak, J. Orgunomel. Cliem., 1997,536-537, 249. J.J. Schneider, U. Denninger, J. Hagen, C. Kruger, D. Blaser, R. Boese, Cliem. Ber./ Recueil, 1997, 130, 1433 T. Tanase, H. Takahata, H. Ukaji, M. Hasegawa, Y. Yamamoto, J. Orgunomel. Chem., 1997,538,247. T. Tanase, H. Takahata, M . Hasegawa, Y. Yamamoto, J. Orgummet. Chem., 1997, s45-546,53 1. D.G. Holah, A.N. Hughes, E. Krysa, G.J. Spivak, M.D. Havighurat, V.R. Magnuson, Polyliec/ron, 1997, 16, 2353. D.G. Holah, A.N. Hughes, E. Krysa, R.T. Markewich, M.D. Havighurst, V.R. Magnuson, Polyhedron, 1997, 16, 2789. I. Gauthron, Y. Mugnier, K. Hierso, P.D. Harvey, Cun. J. Chem., 1997,75, 1182. A.A. Levin, P.N. D’yachkov, Doklurly Akurl. Nuuk, 1996,347,493. R. Vilar, S.E. Lawrence, D.M.P. Mingos, D.J. Williams, Cliem. Commun., 1997, 285. L.R. Falvello, J. Fornies, C. Fortuiio, A. Martn, A.P. Martinez-Sariiiena, Orgunometullics, 1997, 16, 5849. R. Vilar, S.E. Lawrence, S. Menzer, D.M.P. Mingos, D.J. Williams, J. Chem. Soc., Dulton Truns., 1997, 3305. T.E. Muller, F. Ingold, S. Menzer, D.M.P. Mingos, D.J. Williams, J. Orgunomel. Chem., 1997,528, 163, N.K. Eremenko, S.S. Kurasov, A.V. Virovets, Yu.T. Struchkov, V.V. Bashilov, V.1. Sokolov, Russ. Chem. Bull., 1997.46, 164. G.J. Spivak, R.J. Puddephatt, Inorg. Chim. Actu, 1997,264, 1. L. Hao, L. Manojlovic-Muir, K.W. Muir, R.J. Puddephatt, G.J. Spivak, J.J. Vittal, D. Yufit, Inorg. Chim. Actu, 1997, 265,65. A. Rodriguez, C. Amiens, B. Chaudret, M.-J. Casanova, P. Lecante, J.S. Bradley, Chem. Muter., 1996,8, 1978. H. Eriksson, M.Hikansson, Orgunometullics, 1997, 16,4243. H. Eriksson, M. Ortendahl, M. HAkansson. Orgunometullics, 1996, 15, 4823. J. Diez, M.P. Gamasa, .I.Gimeno, A. Aguirre, S. Garcia-Granda, Orgutiometullics, 1997,16,3684. V.W.-W. Yam, W.K.-M. Fung, K.-K. Cheung, Chem. Commun., 1997,963.

262. 263. 264. 265. 266. 267. 268. 269. 270. 271. 272. 273. 274. 275. 276. 277. 278. 279. 280. 281. 282. 283. 284. 285. 286. 287. 288. 289. 290. 291.

4: Orguno- Trunsition Metul C1irstc.r Compouncls

292. 293. 294. 295. 296. 297. 298. 299. 300. 301. 302. 303. 304. 305.

306. 307. 308. 309. 310. 31 I . 312. 31 3. 314. 315. 316. 317. 318. 319. 320. 321.

217

D.A. Edwards, R.M. Harker, M.F. Mahon, K.C. Molloy, J. Chem. SOL'.,Ddton Truns., 1997, 3509. M. Contel, J. Garrido, M.C. Gimeno, J. Jimlnez, P.G. Jones, A. Laguna, M. Laguna, Inorg. Chim. Actu, 1997,254, 157. N. Kaltsoyannis, J. Chem. Soc., Dalton Truns., 1997. 1. P. Pyykko, N. Runeberg, F. Mendizabal, Chem. Eirr. J., 1997,3, 1451. P. Pyykko, F. Mendizabal, Chem. Eur. J., 1997,3, 1458. P. Pyykko,Chem. Rev., 1997,97,597. P. Pyykko, W. Schneider, A. Bauer, A. Bayler, H. Schmidbdur, Chem. Commun., 1997, 1 1 1 1 . L.H. Gade, Angeiv. Chem., 1997, 109, 1219; Angew. Chem., Int. E d Engl., 1997, 36, 1171. J.C. Vickery, M.M. Olmstead, E.Y. Fung, A.L. Ralch. Angeiv. Chem., 1997, 109, 1227; Angew. Chem., Int. Ed. EngI., 1997,36, 1 1 79. M.A. Bennett, L.L. Welling, A.C. Willis, Inorg. Chem., 1997,36, 5670. D.-F. Feng, S.S. Tang, C.W. Liu, I.J.B. Lin, Y.-S. Wen, L.-K. Liu, Orgunometullics, 1997, 16,901. A. Bauer, W. Schneider, H. Schmidbaur, Inorg. Cliem., 1997,36,2225. W. Schneider, A. Sladek, A. Bauer, K. Angermeier, H . Schmidbaur, Z. Nuturforsch., 1997,52b, 53. M.J. Calhorda, F . Canales, M.C. Gimeno, J. Jimenez, P.G. Jones, A. Laguna, L.F. Veiros, Orgunometullics, 1997, 16, 3837. J. Vicente, M.-T. Chicote, P. Gonzalez-Herrero, C. Grunwald, P.G. Jones, Orgunometullics, 1997, 16, 3381. J. Vicente, M.-T. Chicote, M.-C. Lagunas, P.G. Jones, B. Ahrens, Inorg. Chem., 1997,36,4938. F.P. Gabbai, A. Schier, J. Riede, H. Schmidbaur, Clzem. Ber.lRecuei1, 1997, 130, 111. Y. Chi, H.-L. Wu, C.-C. Chen, C.-J. Su, S.-M. Peng, G.-H. Lee, Orgunometullics, 1997,16,2434. P. Mathur, P. Sekar, A.L. Rheingold, L.M. Liable-Sands, Orgunometullics, 1997, 16, 142. P. Mathur, P. Sekar, A.L. Rheingold, L.M. Liable-Sands, J. Chem. Soc., Dalton Truns., 1997,2949. J.W. Raebiger, C.A. Crawford, J. Zhou, R.H. Holm, Inorg. Chem., 1997,36,994. M.A. Tyson, D. Coucouvanis, Inorg. Chem., 1997,36,3808. L.-C. Song, J.-Q. Wang, Q.-M. Hu, W.-Q. Gao, B.-S. Han, Polyhedron. 1997, 16, 481. S.N. Konchenko, A.V. Virovets, S.V. Tkachev, N.V. Podberezskaya, Polyheciron, 1997,16, 1549. S.N. Konchenko, A.V. Virovets, N.V. Podberezskaya, Polyhedron, 1997,16, 1689. P. Mathur, S. Ghose, Md.M. Hossain, C.V.V. Satyanarayana, M.F. Mahon, J. Orgunomet. Chem., 1997,543, 189. M.A. Mansour, M.D Curtis, J.W. Kampf, Orgunometullics, 1997, 16,275 H. Kawaguchi, K. Yamada, S. Ohnishi, K. Tatsumi, J. Am. Chem. Soc., 1997, 119, 10871. C. Mealli, A. Ienco, A. Anillo, S. Garcia-Granda, R. Obeso-Rosete, J. Chem. Sue., Dalton Truns., 1997, 1441. H. Adams, N.A. Bailey, L.J. Gill, M.J. Morris, N.D. Sadler, J. Chem. Soc., Dalfon Truns., 1997, 304 I .

218 322. 323. 324. 325. 326. 327. 328. 329. 330. 331. 332. 333. 334. 335. 336. 337. 338. 339. 340. 341. 342. 343. 344. 345. 346. 347. 348. 349. 350. 351.

352.

Orgunometollic Chemistry

H. Adams. L.J. Gill, M.J. Morris, J. Orgmotnet. Chem.. 1997. 533, 117. H. Adams. N.A. Bailey, M.N. Bancroft, A.P. Bisson, M.J. Morris, J. Orgunomet. Chem., 1997,542, I 3 I. Y. Chi, C.-J. Su, S.-M. Peng, G.-H. Lee, J. Am. Chern. Soc., 1997, 119, 1 1 114. P.-C. Su, Y. Chi, C.-J. Su, S.-M. Peng, C.-H Lee, Orgunomefullics,1997, 16, 1870. W.-J. Chao, Y. Chi, C.-J. Way, I.J. Mavunkal, S.-L. Wang, F.-L. Liao, L.J. Farrugia, Orgunometallic~s.1997, 16, 3523. Y. Chi, C. Chung, Y.-C. Chou, P.-C. Su, S.-J. Chiang, S.-M. Peng, G.-H. Lee, Orgunometallics, 1997, 16, 1702. C.-W. Shiu, Y. Chi, A.J. Carty, S.-M. Peng, G.-H. Lee, Organornetullics, 1997, 16, 5368. P. Blenkiron. A.J. Carty, S.-M. Peng, G.-H. Lee. C.-J. Su, C.-W. Shiu, Y. Chi, Orgunomefullics,1997, 16, 5 19. H.-P. Wu, Y.-Q. Yin, X.-Y. Huang, Inorg. C'him. Actu, 1997, 255, 167. H. Shimomura, X. Lei, M. Shang, T.P. Fehlner, Orgunometullics, 1997, 16, 5302. M.A. Mansour, M.D. Curtis, J.W. Kampf, Orgunometullics, 1997, 16, 3363. O.J. Curnow, M.D. Curtis, J.W. Kampf, Orgunometallics, 1997, 16, 2523. M.D. Curtis, S.H. Druker, L. Goossen, J.W. Kampf, Orgunometullics, 1997, 16,231. M.D. Curtis, S.H. Druker, J. Am. Chern. Soc., 1997, 119, 1027. N.T. Lucas, I.R. Whittall, M.G. Humphrey, D.C.R. Hockless, M.P. Seneka Perera, M.L. Williams, J. Orgunornet. Chem., 1997, 540, 147. N.T. Lucas, M.G. Humphrey, D.C.R. Hockless, J Orgunomet. Chem., 1997, 535, 175. N.T. Lucas, M.G. Humphrey, P.C. Healy. M.L. Williams, J. Organomet. Clzem., 1997,545-546, 5 19. A.D. Shaposhnikova, M.V. Teplova, G.L. Kamalov, A.A. Pasynskii, T.L. Eremenko, Yu.T. Struchkov, A.I. Yanovskii, Zh. Neorg. Khitn., 1997,42, 1824. O.J. Scherer, C. Vondung, G. Wolmershguser, Angrw. Cllrvn., 1997, 109, 1360; Angew. Chem., Int. Ed Engl., 1997,36, 1303. V.F. Kuznetsov, C. Bensimon, G.A. Facey, V.V. Grushin, H. Alper, Orgunometullics, 1997, 16, 97. M.P. Aarnts, A. Oskam, D.J. Stufkens, J. Fraanje. K. Goubitz, N. Veldman, A.L. Spek, J. Orgunornet. C/wm., 1997,531. 191. M.P. Aarnts. M.P. Wilms, D.J. Stufkens, E.J. Baerends, A. Vlcek, Jr, Orgunometullics, 1997, 16, 2055. M.C. Comstock, T. Prussak-Wieckowska, S.R. Wilson, J.R. Shapley, Inorg. Chena., 1997,36,4397. A.S. Fung, M.J. Kelley, D.C. Koningsberger, B.C. Gates, J. Am. C'hem. Sot.., 1997, 119,5877. M. Bergamo, T. Beringhelli, G. Ciani, G . D'Alfonso, M. Moret, A. Sironi, Inorg. Chim. Actu, 1997, 259, 29 I. L. Hao, J. Xiao, J.J. Vittal, R.J. Puddephatt. Orgrmot?ic~tallir~s. 1997, 16, 2165. S. Banerjee, G.R. Kumar, P. Mathur, P. Sekar, Them. Commrm.. 1997. 299. P. Mathur, P. Sekar, J. Orgunomet. Chern., 1997,527,29. V. Ruffieux, G. Schmid, P. Braunstein, J. Rose. C h n . Eirr. J., 1997.3,900. R. Della Pergola, A. Cinquantini. E. Diana. L. Garlaschelli, F. Laschi. P. Luzzini, M. Manassero, A. Repossi, M. Sansoni, P. L. Stanghellini, P. Zanello. Inorg. Them., 1997,36,3761. L.A. Poliakova, S.P. Gubin, O.A. Belyakova, Y.V. Zubavichus, Yu.L. Slovokhotov, Orgunornetulliis, 1997, 16,4527.

4: Orguno-Trunsitiun Metal Cluster Compounds

353. 354. 355. 356. 357. 358. 359. 360. 361. 362. 363. 364. 365. 366. 367. 368. 369. 370. 371. 372. 373. 374. 375. 376. 377. 378. 379. 380. 381. 382. 383. 384. 385. 386. 387.

219

Y. Takahashi, M. Akita, Y. Moro-oka, Chem. Cummun., 1997, 1557. H.-C. Bottcher, M. Graf, K. Merzweiler, J. Orgunomet. Clzem., 1997,534,43. H.-C. Bottcher, M. Graf, K.Merzweiler, J. Orgunomet. Chem., 1997,531, 107. J.E. Davies, S. Nahar, P.R. Raithby, G.P. Shields, J. Chem. Sue., Dulton Truns., 1997, 13. A.D. Hattersley, C.E. Housecroft, A.L. Rheingold, J. Cluster Sci., 1997,8, 329. A. Venturelli, T.B. Rauchfuss, A.K. Verma, Inorg. Chem., 1997,36, 1360. G. Suss-Fink, S. Haak, V. Ferrand, H. Stoeckli-Evans, J. Clzem. Sue., Dulton Truns., 1997,3861. A.U. Harkonen, M. Ahlgren, T.A. Pakkanen, J. Pursiainen, Orgunometullics, 1997, 16,689. P. Braunstein, C. Charles, G . Kickelbick, U. Schubert, Clzem. Commun., 1997, 2093. H. Liu, A.L. Tan, K.F. Mok, T.C.W. Mak, A S . Batsanov, J.A.K. Howard, T.S.A. Hor, J. Am. Chem. Soc., 1997,119, 11006. P. Blenkiron, G.D. Enright, A.J. Carty, Chem. Cummun., 1997,483. R.D. Adams, T.S. Barnard, Z. Li, L. Zhang, Clzem. Ber.lRecuei1, 1997,130, 729. J.W.-S. Hui, W.-T. Wong, J. Cliem. Soc., Dulton Truns., 1997, 1515 . V.A. Maksakov, V.P. Kirin, A.V. Virovets, S.V. Tkachev, V.I. Alekseev, N.V. Podberezskaya, J. Orgunomet. Chem., 1997,539, 27. T. Tanase, H. Toda, K. Kobayashi, Y. Yamamoto,Orgunornetullics, 1996, 15, 5272. G.J. Spivak, G.P.A. Yap, R.J. Puddephatt, Polyheciron, 1997, 16, 3861. J. Lang, H. Kawaguchi, S. Ohnishi, K. Tatsumi, Chem. Commun., 1997,405. J.-P. Lang, H. Kawaguchi, K. Tatsumi, Inorg. Chem., 1997,36,6447. J. Pethe, C. Maichle-Mossmer, J. Strahle, Z. Anurg. Clzem., 1997,623, 1413. R. Galassi, R. Poli, E.A. Quadrelli, J.C. Fettinger, Inorg. Clzem., 1997,36, 3001. H.-J. Haupt, M. Schwefer, H . Egold, U. Florke, Inorg. Chem., 1997,36, 184. M. Benard, U. Bodensieck, P. Braunstein, M . Knorr, M. Strampfer, C. Strohmann, Angew. Chem., 1997, 109, 2890; Angew. Chem., Int. Ed. Engl., 1997,36,2758. M. Ferrer, A. Julili, 0. Rossell, M. Seco, M.A. Pellinghelli, A. Tiripicchio, Orgunometullics, 1997, 16,3715. V.G. Albano, M.C. Iapalucci, G. Longoni, L. Manzi, M. Monari, Orgunometullics, 1997, 16,497. R.D. Adams, R. Layland, K. McBride, Orgunometullics, 1996, 15, 5425. M.I. Bruce, P.A. Humphrey, B.W. Skelton, A.H. White, J, Orgunomet. Chem., 1997, 545--546,207. M.I. Bruce, J.M. Gulbis, P.A. Humphrey, R.J. Surynt, E.R.T. Tiekink, Aust. J. Chem., 1997,50, 875. M.R.A. Al-Mandhary, J. Lewis, P.R. Raithby, J. Orgunomet. Chem., 1997,536-537, 549. T. Tanase, H. Toda, Y. Yamamoto, Inorg. Chem., 1997,36, 1571. D. Tmhof, U. Burckhardt, K.-H. Dahmen, F. Joho, R. Nesper, Inorg. Chem., 1997, 36, 1813. E.-R. Ding, S.-M. Liu, Y.-Q. Yin, J. Sun, Polyhedron, 1997, 16, 3273. L.-C. Song, Y.-B. Dong, Q.-M. Hu, X.-Y. Huang, J. Sun, Orgunometullics, 1997, 16, 4540. E.-R. Ding, S.-M. Liu, Z.-Y. Zhao, Y.-Q. Yin, J. Shun, Polyhedron, 1997, 16,2387. E.-R. Ding, Y.-Q. Yin, J. Sun, Polyhedron, 1997, 16, 3067. S.P. Gubin, T.V. Galuzina, I.F. Golovaneva, A.P. Klyagina, L.A. Polyakova, O.A. Belyakova, Ya.V. Zubavichus, Yu.L. Slovokhotov, J. Orgunomet. Chem., 1997,549, 55.

220

Orgunometallic Chemistry

T. Kondo, N. Suzuki, T. Okada, T. Mitsudo, J. Am. Chem. Soc., 1997,119,6187. R.G. Gasanov, F.M. Dolgushin, A.1. Yanovsky, Z.S. Klemenkova, B.V. Lokshin, P.V. Petrovskii, M.I. Rybinskaya, Russ. Cliem. Bull., 1997,46, 1125. 390. D. Campagnola, M. Castiglioni, W. Dastru, S. Deabate, R. Giordano, P.J. King, E. Sappa, Inorg. Chim. Acta, 1997, 262, 1 57. 391. M. Castiglioni, S. Deabate, E. Garrone, R. Giordano, B. Onida, G. Predieri, E. Sappa, J. Cluster Sci., 1997, 8, 381. 392. I. Matsuda, Y. Fukuta, T. Tsuchihashi, 13. Nagashima, K. Itoh, Organometallic~s, 1997,16,4327. 393. Y. Ishii, N. Chatani, F. Kakiuchi, S. Mural, OrgunometulIics, 1997, 16,3615. 394. T.V. Chernysheva, T.A. Stromnova, M.N. Vargaftik, 1.1. Moiseev, Izu. Akud Nuuk, Ser. Kliim., 1996, 2456. 395. M.S. Nashner, A.I. Frenkel, D.L. Adler, J.R. Shapley, R.G. Nuzzo, J. Am. Chem. Scw., 1997, 119, 7760. 396. D. Braga, F. Grepini, E. Tedesco, H. Wadepohl, S. Gebert, J. Clzem. Soc., Dalton Trans., 1997, 1727. 397. X. Chen, B.E. Mann, Clzem. Commun., 1997,2233. 398. A.A. Koridze, V.I. Zdanovich, V.Y. Lagunova, A.M. Sheloumov, F.M. Dolgushin, A.I. Yanovsky, Yu.T. Struchkov, M.G. Ezernitskaya, E.V. Vorontsov, P.V. Petrovskii, Russ. Chem. Bull., 1995,44,2198. 399. V.W.-W. Yam, W.K.-M. Fung, K.-K. Cheung, Organometullics, 1997, 16,2032. 400. A.A. Pasynskii, Y.V. Torubaev, S.E. Nefedov, I.L. Eremenko, O.G. Ellert, V.K. Belsky, A.I. Stastch, J. Orgunomet. Chem., 1997, 536-537,433.

388. 389.

5 Hydrocarbon Transition Metal n-Complexes other than q=&H5 and q-Arene Complexes BY K.R. FLOWER

1

Introduction

This survey of the 1997 literature relating to mhydrocarbon complexes of the transition elements other than q-C5H5 and q-arene complexes is similar in nature to previous reports.' This chapter is sub-divided into the following sections dealing with: reviews; complexes containing allyls or monoalkenes; unconjugated alkenes; conjugated alkenes; acyclic alkenes; alkynes and polymetallic complexes.

2

Reviews

Reviews covering organometallic cluster chemistry in 1995,2 and transition metal chemistry covering the years 1985, 1986, 1991-1994 and 1994-1995 have appeared and contain material of The use of ab initio calculations to probe the nature of the chemical bond in transition metal organometallic complexes containing species. such as alkynes and alkenes has been r e ~ i e w e d . ~ The periodic trends in d orbital energies observed by photoelectron spectroscopy has been discussed.6 The reactions of Group 6 metal carbonyls with alkynes, alkenes under photochemical conditions that induce polymerisation and isomerisation reactions was r e p ~ r t e d .The ~ organometallic carbide structural units found in solid state transition metal carbides have been discussed at lengths8The use of solid state structural techniques to investigate x-bound silacarbocyclic ligands to obtain an understanding of the diverse variety of coordination modes has appeared.' The structural and stereochemical relationships of over 40 [FeL3(q4-diene)]complexes has been reported. Included in the discussion was a Berry plot and the explanation of the possible turnstile isomerisation process of the ligated carbonyl ligands using EHMO calculations. l o Reviews on the preparation of small ring cyclophanes and their transition metal complexes,' the synthesis of fenestranes and their transition metal complexes, l 2 the preparation of alkynylated cyclobutadiene complexes,' the use of pentalene as a x-bound ligand in transition metal chemistryi4have all appeared and contain material of interest. The use of Ir and Rh fragments to cleave n-bound thiophene or annulated thiophene ligands to ultimately yield highly conjugated sulfur containing ligands has been reviewed.I5 The reactivity of Ni(0) and Pt(0) benzyne and related small Organometallic Chemistry, Volume 27 0The Royal Society of Chemistry, 1999

22 1

222

Organometullic Chemistry

ring alkyne complexes has been discussed as have Ru(0) and Ru(I1) arene complexes that contain q-bound hydrocarbon ancillary ligands.'6917Discussions on the chemistry of allenylidenes and the preparation of acyl cobalt carbonyl complexes have appeared and contain some material of intere~t.'~"'A series of reviews covering the use of transition metals in organic synthesis have been reported and include: activation of aromatic molecules by q2-coordination to pentaammineosmium(II);20 metal assisted cycloaddition reactions;2' the preparation of highly enantio enriched compounds via iron mediated allylic substitutions;22the use of allylic protecting groups in a complex e n ~ i r o n m e n t alkene ;~~ carbonylation as effected with cationic Pd complexes;24 and the use of alkene metathesis in organic chemistry*' all of which contain material of interest.

3

Complexes Containing Allyls or Monoalkenes

3.1 Cr, Mo, W - During a study on the Cr catalysed trimerisation of ethene to hex-1-ene the compound [CpCr(PMe3)2(q2-C2H4)]was isolated and structurally characterised.26 Pulsed laser flash photolysis has been used to elucidate the mechanism of ligand exchange in photogenerated [Cr(C0)5(q2-C6HSR)] with . ~ ~complexes [M(C0)2(q2alkenes such as hex-1-ene, dec-1-ene e t ~ The C6*)(phen)(dbm)] (M = Mo, W; dbm = dibutylmaleate) were prepared from [M(C0)4(phen)] in good yield.28 Treatment of the compounds [M(PMe3)4(q2C2H4)2](M = Mo, W) with the tripodal phosphine 1 , l , l -tris(dimethylphosphino)methane or ethane afforded the complexes [M(PMe&(q2-P3CH2R)(q2-C2H4)]. The molecular dynamics of these complexes were studied by VT NMR spectros c ~ p yThe . ~ ~reaction of [ M O H ( C O ) ( N O ) ( P M ~ P ~with ~ ) ~ ]ethene, propene and styrene has been investigated and the results obtained showed that coupling reactions involving H, CO and alkene occur affording acyl and alkyl ligands affording some insight into alternating CO/alkene oligomerisation ~hemistry.~' n +0+n allyl interconversion in a series of Mo-x-ally1 complexes containing the Tp* ancillary ligand have been investigated. The fluxional process was observed via the exchange of the syn and anti resonances of the terminal substituents in the VT 'H NMR ~ p e c t r a . ~A' series of Mo(II)-n-allyl complexes that contain a conjugated double bond and hydrotris(pyrazo1-1-yl)borate as a co-ligand have been prepared. N o evidence was obtained for conversion of the q3-allyl into an q5-pentadienyl ligand.32 A collection of Mo(I1) and Mo(II1) cyclopentadienyl, allyl, butadiene containing complexes have been prepared. Isomerisation of the organic moieties was observed, i.e. cis-trans isomerisation of the butadiene moiety. Many of the compounds prepared were characterised by single crystal Xray diffraction studies.33 Some water soluble n-ally1 complexes of Mo(I1) that contain sulfonate are carboxylated pyridine ligands have been reported.34 The compound [Mo(C0)3(py)3] was used to prepared a diverse range of Mo(I1) IT-ally1 complexes via oxidative addition of allylic precursors in good yield.35A series of Mo( 11) n-ally1 complexes were prepared that contain tris(pyrazo1- 1-yl)borate as an ancillary ligand. The reactivity of a double bond or carbinol moiety adjacent to the x-bound allyl moiety has been investigated and rationalisation of the

5: Hyclrocarbon Trunsition Metal rc-Complexesother than q-C5H5anciq-Arene Complexes 223

products was obtained from molecular mechanics calculation^.^^ Some Mo(I1) allyl complexes of the type [Mo(tfiao)(CO)2(N-N)(q3-allyl)] which contain functionalised 1,lO-phenanthrolene ligands have been prepared and their use as substrates in allylic substitution reactions investigated. The influence of the phenanthrolene hgand on the reaction selectivity has been discussed.37 A collection of q3-bound cycloheptatrienyl complexes of the type [MoX(C0)2L2(q3C~HS)](X = C1, NCO; L2 = bidentate phosphine) have been prepared from [Mo(C0)2Lz(q3-C7H9)][BF4] and characterised by a variety of spectroscopic technique^.^' Some heptamethylindenyl molybdenum complexes containing allyl and alkyne co-ligands have been prepared and spectroscopically c h a r a ~ t e r i s e d . ~ ~ The preparation of bis(a1lyl) tris(trimethy1)phosphine molybdenum(1I) has been reported and the allyl ligands shown to coordinate in an q1:q2fashion. Treatment of this compound with CO resulted in the elimination of 1 S-he~adiene.~' Treatment of the metallate ions [CP*M(CO)~(CNR)]-(M = Mo, W) with Me1 initially forms the alkylated products [Cp*MMe(C0)2(CNR)] which then rearrange, depending on the solvent, to either q*-iminoacyls or q3-aza allyl containing compound^.^' A similar pattern of reactivity was observed for the analogous indenyl containing compounds.42The activation of hydrocarbons by W+ has been studied by cyclotron resonance mass spectrometry. The results showed C-H activation occurs in a variety of substrates and the structures of many intermediates and products were reported.43 Photo-reversible isomerisation of !rans-[W(C0)4(q2-alkene)2]to the cis isomer was induced in an argon matrix at low temperature. A dissociative mechanism was proposed in which the alkene was expelled and then r e - c ~ o r d i n a t e d Compound .~~ 1 has been prepared by two routes: photolysis of the carbyne complex [CpW(Co)(PMe3)(C,H,)] in CHC13 or treatment of the carbyne complex with HC1/Et20.45Thermal activation of a C-H bond has been observed that is a direct reversal of a-hydrogen elimination. Heating of [Cp*W(NO)(Np)] at 70 "C causes a-elimination and formation of the alkylidene complex [Cp*W(NO)(CHCMe3)] which in the presence of cyclohexane and PMe3 affords Me& and 2 via C-H activation of cyclohexane>6 A mixture of the mer and Sac isomers of [w(co)3(dppb)(q2-c60)]was obtained on treatment of [W(C0)3(NCMe)(dppb)]with Cm.47The reaction of [WH(dppe)2(q3-C3H5)]with acid has been investigated and the most favoured site of protonation is on the allyl moiety to give the cationic species [WH(q2-MeCHCH2)(dppe)2]+; at high acid concentration, however, protonation of the metal centre predominates. The X-ray crystal structures of [MH(dppe)2(q3-C3H5)](M = Mo, W) were also reported.48 The o-vinyl complex [CPW(CO)~{ q2-CHCH(COMe))] readily converts to the lactone containing complexes [CpW(CO), { q3-CHCHC(Me)OC(0))] via an insertion cyclisation reaction. The lactones can be readily ring opened on treatment with a variety of n u ~ l e o p h i l e s The . ~ ~ tungsten complex 3 has been shown to undergo enantioselective aminocarbonylation which was shown to be useful in the preparation of an optically pure n-ally1 bound a-methylene butyrolactone complex 4.50 Treatment of [Cp*W(C0)3(o-propargyl)] with CF3C02H afforded mixtures of q '-2,5-dihydrofurans and q3-yn-y-lactones. The product ratios were found to be dependent upon the alkyl or d o x y groups present in the propargyl m ~ i e t y . ~ The ' anionic acetylide complexes

Orgunometullic Chemistry

224

1

2

W

[CpM(NO)(CO)(qI-CCR)] react with allylic iodides affording q I-acetylide q3ally1 containing compounds. The reaction was rationalised in terms of electrophilic attack at the metal centre affording a o-vinyl complex that rearranged to ~ ~ tungsten allyl complexes of the type the n-ally1 via CO e l i m i n a t i ~ n .Some [Tp*W(CO)2(q3-CH(R)CHCHR'i] (Tp* = 3,5-dimethyl-pyrazol-l -yl borate) have been prepared by the irradiation of [Tp*WH(C0)3] in the presence of alkynes or unconjugated dienes. The syn and anti isomers of [Tp*W(CO)2{q3CH2CHCHCH3}] have been structurally characterised by single crystal X-ray diffraction studies and the allyl orientation in the two isomers varies by 90". The change in orientation was also accompanied by a change in the OC-W-CO angle from acute to obtuse; this observation was explained in terms of maximising xdonation from the rc-non-bonding MO of the allyl moiety and was confirmed by EH MO calculations on the model compound [WH 3(C0)2(q 3-C3Hs)].53

Fe, Ru, 0 s -- The reaction of [Fe(o-C2H5)]+ and its tautomer [FeH(q-C2H4)]+have been examined by a hybrid of density functional theory and the Hartree-Fock approach (BECKE3LYP). Mass spectral data was also obtained to demonstrate the facile interconversion of [Fe(C2H5)]' and [FeH(C2H4)]+.54The interaction of allyl chloride with one carbon ligands in cationic iron complexes has been investigated and the allylic interaction was shown to be strongly dependent on the one carbon ligand.55Infrared multiphoton dissociation of the two isomeric products [M( 1,3-butadiene)]+ and [M(C2H&]+ (M = Fe, Co, Ni) have been i n ~ e s t i g a t e dThe . ~ ~ reactivity of n-ally1 iron carbonyl complexes which contain a tethered lactone were investigated. The complexes have been reacted with nucleophiles, for example allyl stannanes and organoaluminium reagents. The functionality present in the tethered ally1 moiety influences the out come of the reaction. In general good stereo-control was obtained on nucleophile addition5' 59 Nucleophilic attack by amines and carbanions on chiral planar q3-allyl(dicarbonyl)nitrosyliron complexes in which the allyl moiety carries an ester or amide group has been investigated and shown to afford y-functionalised a$-unsaturated carboxylic acids.60 A series of ester functionalised allyl iron tetracarbonyl complexes have been prepared and reacted with nucleophiles yielding alkene bound products;61 a further example of nucleophilic

3.2

5: Hyclrocurbon Trunsition Metal n-Complexes olher than q-CsHs and q- Arene Complexes 225

attack on ally1 iron tricarbonyl complexes was also reported.62 A collection of allyl iron carbene complexes of the type 5 have been prepared and their interaction with nucleophiles in~estigated.~’ The reaction between lithium dimethylcuprate and ct,&unsaturated ketone complexes was reported.64 In one instance an unusual (q3:q3-l,6-diphenyl-3,4-(distyryl)-1,3,5-hexatriene moiety bound to an Fe(C0)2 fragment was observed 6. Photo excitation of complexes of the type 7 have been investigated. In some instances 0-TC rearrangement was

5

6

7

observed with loss of CO or migration of the allyl moiety to the Cp ring occurred with concomitant change in bonding the mode of the C p ring to q4.65 An intermediate in the ROMP process using Grubb’s catalyst has been isolated and structurally characterised, it was shown to contain an alkylidene moiety 11along with a tethered alkene.66 A series of q3-N-methoxy-7-azabicyc~o[2.2. hepta-2’5-dienyl ruthenium complexes were prepared from [Cp*RuCl(q4-cod)] in which complexation occurs through one double bond and the bridgehead nitrogen.67 The reaction between [Ru{q2:q5-C5Me4CH2(CH2),,CH2CHR}(CO)2][BF4]with NaBH4 and OR- have been investigated and afford either a hydride complex in which the alkene is not coordinated or an alkoxy complex in which the alkene is coordinated. In each case there was no evidence for the nucleophile attacking the alkene.68 Treatment of [Cp*RuC12]2 with Ph2PCHCHZ in the presence of Zn and Na[PF6] afforded the q’-phosphaallyl containing complex [Cp*Ru(q3-CH2CHPPh2)(PPh2CHCH2)]+. The phosphaallyl moiety was readily displaced on treatment of the complex with a variety of neutral and anionic l i g a n d ~ Reaction .~~ of either enantiomer of the naturally occurring ketonic diterpine carvone or its trimethylsilyl enolate with [Cp*Ru(p-0Me)l2 affords TC-ally1complexes. Complexation occurred through the exocyclic double bond 8 or from an enone tautomer 9.70 The allylic

8

10

9

11

226

Orgunometullic Chemistry

complex 10 is prepared in several steps from [RUHCI(CO)(PP~'&].~* The compounds [Cp*RuBr2{q3-CH2CHC(H)SR2}] were prepared by attack of thioethers on the ligated butadiene in the Ru(IV) compound [Cp*RuBr2{q4C4H6)]f.72 The complexes [Ru f P~'~P(CH~),PP~'~}(T~~-~~I~I)~] (allyl = C3H5 or C3H4-2Me) were prepared by either phosphine displacement of cod in a his allyl complex or reaction of a phosphine halide with allylMgCI. The compound [Ru f Pri2P(CH2)nPPr'2}(q3-allyl)2] was converted to the pentadienyl complex [RuH { Pr'2P(CH2)nPPr'2}(~3-C5H8)].73 The ruthenium acetylide complex [Cp*Ru(cr-C2Ph)(PPh3)] was found to catalyse the dimerisation of terminal acetylenes, mainly in the head to head fashion. During the course of the study an q3-butadienyl complex [Cp*Rufq3-PhCHChCC(Ph)CCPh]] was isolated and structurally ~ h a r a c t e r i s e dA . ~ series ~ of ruthenium complexes containing 0acetylides and vinylidene iigands have been prepared that contain 1,4,7trimethyl- 1,4,7-triazacycIononane.These complexes were shown to react with alkynes to afford C-C coupled products such as q3-butadienyl moieties. A hydrogen shift was proposed to be an important part in the reaction pathway.75 Treatment of [Ru(cod)(cot)] with PMe3 effected selective displacement of cod yielding fac-[Ru(q3:q '-C8H lo)(PMe3)2].76Thermal activation of aliphatic C-H bonds was observed in a series of Ru and Rh allyl complexes such as 11. Activation was observed for cyclooctane to cyclooctene, some activation of the ligand cyclohexyl rings was also observed.77 The first example of a water soluble enediyne complex was prepared by treatment of [O~(OH~)(en2)(q~-H~)][oTf]~ with cis- 1,6-bis(trimethylsilyI)-3-ene-1,5-diyne. Coordination occurs exclusively through the alkene moiety by displacement of H2. Treatment of the complex with LiBr afforded [OsBr(en)2(q2-enediyne)][Br] which was structurally c h a r a c t e r i ~ e d .The ~ ~ compound [ O S H ~ C ~ ~ ( Pwas P~~~)~] converted into a series of Cp containing compounds with ancillary ligands such as alkenes and alkynes. In the case of terminal alkyne containing compounds conversion to vinylidenes was facile and subsequent modification afforded carbyne complexes.79 The reactivity of [OsHz(q2-CH2CHEt)(CO)(PPr'3)2] towards a variety of unsaturated organic moieties has been investigated affording a range of alkene, alkyne and butenyl containing complexes.80 Several reports on the use of the [OS(NH~),L]~'fragment have appeared. Thus treatment of [Os(NH3)5(q2-C6H50Me)I2' with Michael acceptors affords after deprotonation a series of q2-coordinated 4-substituted anisoles which can be liberated from the metal by oxidation." Further a series of naphthalene complexes of the type [OS(NH,)~L]*' were prepared and shown to be a mixture of linkage isomers; generally though one linkage isomer can be obtained by a protonation deprotonation sequenceg2 Alkylation of the sulfur in [Os(NH&( q2-thiophene)12' occurs essentially quantitatively. Treatment of these complexes with nucleophiles causes ring opening by cleavage of an S-C bond yielding an q4-4-alkyl-thio- 1,3-butadiene complex.83 The complexes [OS(NH~),L]~'( L = arene or polyaromatic hydrocarbon) were shown to be readily protonated with triflic acid to generate arenium, naphthalenium and anthrocenium complexes. Most of the organic cations were stabilised by complexation to the metal in a ~-allylfashion. In the corresponding anisolium

5: Hydrocurbon Transition Metal n-Complexes other thun q-CsHs and q- Arene Complexes 227

system q2-coordination was proposed. It became apparent during the discussion that the complexes prepared represented a continuum between distorted and pseudo ally1 complexes.84 When the complex [0s(NH,),(OTf)l2' was reacted with a variety of aldehydes affording q2-(C=O) aldehyde complexes. All except for a crotonaldehyde containing complex were readily converted to Fischer carbyne species. In the case of crotonaldehyde protonation occurred followed by linkage isomerisation to afford an q3-hydroxyallyl complex.85 The [Os(CO)(PPri3)2] moiety has been shown to ligate to a variety of organic fragments including R-ally1 derived from the rearrangement of the two alkynl ligands in [Os(o - C ~ P ~ ) ( C O ) ( P P ~ ' ~ ) ~ ] . ~ ~ Co, Rh, Ir - The process of P-hydride and methyl migratory insertion into the Group 9 metal complexes [CpM(PH3)(q2-CH2CH2)R]+(R = H or Me) was investigated by density functional theory.87 On heating the alkene complexes [Cp*Co(q2-CH2CHR),] to 60 "C for R = H or 20 "C for R = TMS in C6D6 lead to the incorporation of 2D into the alkenes. This observation was interpreted in terms of alkene dissociation, oxidative addition of C6D6 insertion of the alkene into the M-D bond followed by P-hydrogen elimination from the 0-ethyl complex and finally reductive elimination of benzene. The process can then repeat until per-deuteration is observed.88 The reduction of 12 affords an equilibrium mixture of 13 and 14. The interconversion between 13 and 14 has 3.3

12

13

14

been studied and N2 can force the double bond to insert into the Rh-H bond.89A series of cationic Rh ethylene and styrene containing complexes have been prepared and their reactivity towards secondary amines examined.g0 [RhCI(PMe3)3] reacts with 1.2 mole equivalents of diphenylallene to give the structuralIy characterised q2- allene complex [RhCl(PMe3)3{ q2-H2CCCH(Ph)}]; however, when [RhCl(PMe3)3] was treated with an excess of diphenylallene a rhodacyclopentane containing product was obtained: this was not obtained on treatment of the q2-allene complex with excess diphenylallene as only starting materials were recovered." The penta-ene fragment H2CCCCCCPh2 has been prepared in the coordination sphere of [RhCI(PPr'3)3]and shown to coordinate through C ~ - c 3 . The ~ * compounds [TpM(q2-C2H4)2](M = Rh, Ir) react with PPh3 to give trigonal bipyramidal products in which the PPh3 is axial and the ethene equatorial. The molecules are fluxional and react with hydrogen to give alkene free M(II1) complexes.93 The reversal in stability of Rh and Ir ethene and hydrovinyl complexes containing Tp co-ligands was studied by a variety of ab initio methods. The equilibrium between the two forms was shown to be sensitive to the steric and electronic influences at the metal centre.94The reaction between

228

Orgunometlrllic Chcmislry

[RhH(PPh3)3] and the allene H2CCCH(C6H4-4-OMe) affords 15 where four consecutive insertions of the allene has occurred. This complex has been structurally characterised and shown to undergo co-polymerisation processes with ot he; unsaturated fragments. 95 The anion [3,5-bis(trifluoromethyl)pheny1]4

borate has been shown to coordinate in an q3-, q4-, q6-Pashion in cationic Rh and Ag complexes.96 A series of Rh(1) assisted stereoselective coupling reactions between an allyl, aryl, or vinyl group with a vinylidene ligand afforded novel synthetic routes to .rc-allyl and butadienyl containing complexes.97 A collection of carbonyl, alkene, alkyne, hydrido and vinyl Ir(1) and (111) complexes were prepared that contained bulky bifunctional phosphine ligands. C-H activation of the alkene ligands was observed.98 The reversible binding of c60 to a dendrimer containing [IrCI(CO)(PPh2R)2] has been reported.99 Treatment of complex 16 which contains a tripodal phosphine ligand with terminal acetylenes in the presence of Ag[BF4] leads to ligand coupling and the formation of an q2bound fulvalene compound 17.loo The reaction between [Cp*IrMe(PMe3)(0Tf)] and aldehydes affords a kinetic product in which the aldehyde is q2-bound. On warming C-H activation is observed causing reductive elimination of CH4 followed by a migratory de-insertion reaction affording [Cp*Ir(o-R)(CO)(PMe3)]'[(OTf)]. When an a$-unsaturated aldehyde is used C-H activation is immediate."' [Cp*Ir(Me),{ P(OPri)3)] reacts with triflic acid to afford [Cp*Ir{ P(0Pr')ZOH )(q3-C3H5)]. The reaction proceeds by protonation of the methyl group with loss of CH4 followed by cyclometallation of an Pr' group and loss of the second Me ligand. The cyclometallated Pr' moiety then rearranges to the ITallyl. The complex [IrCI(OTf)(CO)(PPh3)2(q '-CHCCH2)] undergoes regioselective addition of water or alcohols at the central carbon to give q3-2-hydroxyl alkoxy-ally1 containing complexes of the type [IrCI(PPh3)2(CO){q3CH2C(OR)CH2}][OTfl. The hydroxy group can be readily deprotonated to afford q3-oxoallyl species. The alkoxy group can be readily displaced via nucleophilic attack by ammonia.'03 Reaction of the allenyl complex [IrCl(OTf)(CO)(PPh3)2(q'-CHCCH2)] with functionalised anilines lead to the preparation of a series of aza-trimethylenemethane compounds of the type [IrC(PPh3)2(CO){q3-CH2C(NR)CH2}][OTfl. Mechanistic studies showed that the initial site of attack was the metal centre with displacement of OTf not attack at the allenyl ligand.Io4 The complex [ T p l r ( ~ l ~ - C ~ H 4undergoes )~] a thermal rearrangement to an allyl hydrido species viu C-H activation to afford a 0-vinyl which couples with the second ethene to yield the observed allyl hydride complex. ' 0 5

5: Hydrocurbon Trunsition Metul x-Complexes other thun q-CjH5 und q- Arene Complexes 229

Ni, Pd, Pt - Density functional B3LYP calculations have been performed on diimine s-methyl metal (1+) complexes (metal = Ni, Pd, Pt) to examine their ability to coordinate ethene and undergo p-elimination and migratory insertion reactions. The results obtained agreed well with recognised experimental data. '06 Further the ability of the complexes [MCI,(NH3)3-x(q2-C2H4)] { M = Ni(II), Pd(II), Pt(I1)) to coordinate ethene has been investigated by density functional theory B3LYP. Generally the expected trend Pt > Pd > Ni is observed.'07 A nonlocal density functional method has been applied to study the polymerisation processes instigated by Ni(I1) with diimine ligand sets. Chain initialisation, propagation, isomerisation and termination were studied. '08 The role of bulky substituents on imine nitrogens in Brookhart Ni diimine catalysed polymerisation was studied by density functional theory and molecular mechanics. Io9 Reaction of the Ni complexes [Ni{R2P(CH2)2PR2}(q2-C2H4)]with cot afford mononuclear complexes where the cot ring is planar with alternating double and single bonds corresponding to a semi aromatic system [C8Hs]-. A series of dinuclear complexes were also prepared with the cot @and displaying unusual conformations.' lo The complex [Ni(n-allyl)(OCOCF3)]was shown to polymerise a series of monoalkenes by a living process. I The ammonium and imminium tetraphenyl borates (CH2CHCH2NH4)BPh4 and (CH2CHCH2NHCMe2)BPh4 react with either [Ni(C0)2(PCy3)2]or [(Cy3P)2NiNNNi(PCy3)2] to afford good yields of the cationic n-ally1 complexes [Ni(NH3)(PCy3)(q3-C,H,)I[BPh4] and [Ni{q IN(H)CMe2)(PCy3)(q3-C3Hs)][BPh4].' I 2 An ab initio study on the Pd(I1) catalysed hydroesterification of ethene has been carried out. The results suggested a hydrido species rather than an alkoxycarbonyl compound is the key intermediate.'13 A theoretical study using density functional theory at the B3LYP level has been used to study the Pd(0) catalysed hydroboration of alkenes and alkynes.'14 Density functional theory at the B3LYP has been further used to study the polymerisation of ethene by cationic Pd cations of the type [Pd(NN)(Me)]+ (NN = bidentate nitrogen). The rate determining step was shown to be ethene insertion into the allyl-Pd bond.'15 A collection of Pd(0) tetracyanoethene complexes that contain bidentate phosphines along with a dipyridene ligand with large steric requirements have been prepared and studied crystallographically. The electronic influence of the phosphines has been studied using MOPAC calculations. I 6 Some new chiral Pd(0) alkene complexes containing either phosphine or phosphinehlfur chelates have been prepared. The solution dynamics of these complexes were investigated by 2D exchange spectroscopy.' I7 Pd catalysed allylic alkylation reactions were carried out in the presence of phosphinoarylhydrooxazole ligdnds and studied by 2D N M R. Evidence was obtained for a primary alkene Pd(0) complex. l 8 A collection of functionalised alkene complexes of the type [Pt(PPh3)2(q2-C2H4)]have been prepared. The complexes have been characterised spectroscopically and in some cases crystallographically.' I9 Treatment of the compound [Pd(dmf)(l,lO-phen-2,9Me2)] (dmf = dimethyl fumarate) with Me30[BF4] yields [Pd(Me)(dmf)(l,lO-phen-2,9Me2)] which then reacts with electron rich alkenes by displacement of dmf. The alkene complexes formed are not particularly stable in solution for long.'20 A collection of bis-q2-phosphinoalkene Pd(0) complexes have been prepared from [Pd(dba)2]

3.4

'

230

OrganomefallicChemistry

(dba = dibenzylidene acetone) with trans-[RHCCHPPh3][Br]. Ancillary ligand substitution reactions were done and afforded mono-alkene complexes.12' The stereoselectivity observed on coordination of 2-methyl-3-buten-2-01 in cis[PtCl(sarcosine)(alkene)] has been attributed to H bonding between the OH group of the alkene with the NH of sarcosine stabilising one rotamer.122The Pd(I1) oxidation of alkenes (the Wacker process) has been studied using chirality transfer.123A theoretical study at the MP2 level was carried out on the complexes [ P ~ ~ ( P - B ~ ) ( ~ - C ~ H ~and ) ( P [PdCl(PH3)(q3-C3H5)]. H~)~] The geometrical characteristics were very similar to those obtained experimentally.124 The influences on stereoselectivity in Pd catalysed allylation reactions has been studied using molecular mechanics and QSAR techniques using the product distribution obtained from nucleophilic attack on q3-allyl complexes as a starting point. The model developed displayed good predictive power. 12' The nature of the interaction between polar p-substituents and the Pd centre in a-ally1complexes has been investigated by both experimental and theoretical techniques.i26Nucleophilic attack by PhO- was shown to occur mainly on the central carbon on haloallyl Pd complexes.127 The attack on [PdL2{q3-CH2C(Cl)CH2}]by stabilised carbanions has been investigated. Attack on the central or terminal carbon was shown to be dependent upon whether o-donor or a-acceptor ligands were present in the coordination sphere: o-donors direct to the central carbon a-acceptors to the terminal. Correlation with I3C allyl carbon shifts was also noted and used as a predictive tool. Ab initio calculations were carried out and concurred with the experimental results.I** The complex [CpPd {q3-CH2CH(CH2Cl)CH2)] was readily prepared from [PdCl{q3-CH2CH(CH2Cl)CH2)]on the addition of TlCp. This complex is stable in benzene but unstable in CD3N02 or other polar solvents. Rearrangement occurred to 18, 19. The mechanism for the rearrange-

18

19

ment process was discussed in terms of a trimethylenemethane intermediate.129 A series of Pd q3-allyl complexes derived from 3,17-dioxo-4-androstone were prepared that contained a range of chiral chelating ligands. The complexes have been spectroscopically and structurally ~haracterised.'~'A collection of cationic [Pd(q3-C3H3-1,3-R) {Ph2P(CH2)2PPh2)](R = aryl) complexes were prepared. The I3C NMR shifts of the terminal carbons were correlated to o-Hammett substituent constants; a chemical shift at lower field was indicative of the A series of preferred site of nucleophilic attack in the Tsuji-Trost rea~ti0n.I~' cationic Pd a-ally1 complexes were studied by X-ray crystallography and VT NMR. X-ray studies showed the allyl moieties adopted a coordination mode ranging from q1:q2- to q3-.132The molecular structure of [Pd{S-S-chiraphos) {q3-PhCC(H)CPh)][PFs]has been determined and shows the five membered chelate ring of the phosphine adopts an envelope conformation; whereas, in solution circular dichroism implies the ring adopts the gauche form.'33A

5: HycfrocurbonTrunsilion Metul n- Complexes other thun q-C5Hs uncl q-Arene Complexes 23 1

cationic Pd complex containing 1,3-diphenylallyl and a chiral phosphinoamine hgand was prepared. Some inferences about allylic allylation reactions were drawn from NMR and crystallographic data.'34 Treatment of [PdBr(oC6F&NCMe)2] with hexa-i ,5-diene, hepta-l,6-diene, or octa-l,7-diene at low temperature afforded a series of q1:q2-enylcomplexes which isomerised over a period of time to n-ally1 complexes. The major product obtained had the allyl moiety at the terminus of the chain. Some internal allyl coordination was observed and implied the metal centre could migrate along the chain.'35 The compound [PdCl(q3-CPh3)]2was prepared by treatment of [PdC12(q4-cod)]with Ph3C in benzene. Confirmation of the synthesis was by comparison with spectral data of an authentic specimen.'36 A series of cationic n-ally1 Pd complexes containing substituted imino pyridine ligands were prepared. They were shown by N M R spectroscopy to exist in solution as a mixture of isomers and the dynamics of the isomer interchange was investigated.'37Propadiene and hepta1 ,Zdiene have been shown to insert into Pd-C bonds affording ultimately n-ally1 complexes of the type [Pd(X)(R)(N-N)] {X = C1, Br; N-N = bidentate nitrogen donors; R = Me, C(O)Me, C(O)Ph, C(O)Pr'}. Kinetic data have been obtained and used to elucidate the mechanism. There was good evidence for R migration on to a pre-coordinated allene.I3' Treatment of [Pd(OAc)2] with allylbenzylamines was investigated and n-ally1 formation was shown to be in competition with ortho-C-H activation.139 A series of chiral and non-chiral 1,3-dimethylallyl Pd complexes containing 2-[2-(dipheny1phosphino)phenyll oxazoline ancillary ligands were prepared and characterised by X-ray crystallography, 1 and 2D NMR spectroscopy.14' A collection of 3,7-diazobicyclo[3.3.llnonane derivatives were prepared and their utility as ligands in n-ally1 complexes has been investigated. A single crystal X-ray diffraction study showed large steric interactions and further work in solution suggested N,N'-diphenylbispidinone could be used as a chemical shift reagent in this type of ~omplex.'~' Single crystal X-ray diffraction studies on the complexes [M(PPh3)2{q3-CH2C(Oc5H~o)cH~>][PF6] (M = Pd, Pt) and [M(PPh3)2{q3-CH2C(OCH20CH3)}][PF6]revealed that a large amount of the oxonium structure is present. Their reactivity towards MeO- and OH- were investigated and discussed with the aid of OI8 labelling studies.'42A theoretical study at the MO/MP4SQD level was carried out on the Pt catalysed disilylation of alkenes. The rate determining step was shown to be ethene insertion into the Pt-Si bond. 143 The platinum complex [Pt(PPh&(q2-C2H4)] has been reacted with propeonoate and 2-methylpropeonoate esters to give the substituted complexes [Pt(PPh3)2(q2-propeonoate)]. Reaction of these compounds with ,PCy3 lead to the substitution of a PPh3 ligand.IM The addition of alkenes to the square planar complex [Pt(Me)X(N-N)](X = CI, malonate; N-N = bidentate nitrogen ligand) afforded trigonal bipyramidal complexes viu two successive steps. The anionic ligand was found to occupy the axial position.'45A series of 'J(Pt-P) values have been measured for Pt(I1) and Pt(0) alkene complexes. The value of the 'J(Pt-P) have been plotted against the Hammett substituent constant and two trends were observed: for Pt(I1) the more electron withdrawing the substituent the smaller the coupling; for Pt(0) the reverse was observed. The observations were rationalised in terms of CT and 7t bonding

232

Orgunome ullic Chemistry

characteristics of the Pt-P bond.'41 Some new Pt(0) cyclopropene complexes containing bulky phosphine ligands have been prepared.'47 The Pt fullerene (n = 2, 3) have been prepared by two complexes [Pt{Ph2P(CH2),PPh2)(q2-C60)] different routes from [Pt(cod)2].'41 Treatment of frun~-[PtH2(PCy3)2]with c 6 0 induces reductive elimination of H2 and complexation of c60 yielding [Pt(PCy3)2(q2-C~)].This reaction was shown not to be general for electron deficient a l k e n e ~ .A' ~series ~ of cationic Pt(I1) complexes that contain an alkyl and alkene ligand in the same coordination sphere have been prepared by several different routes. The complexes prepared are fluxional and have been investigated by VT NMR spectro~copy.'~~ A mechanistic study utilising kinetic data into the isomerisation of propargyl Pt(I I) complexes truns-[PtX(CH2CCPh)(PPh,),l into the more stable allenyl isomers rruns-[PtX(CPhCCH2)(PPh3)2]was reported. It was shown that when isomerically pure materials were heated under the same conditions re-equilibration between isomers occurred.1 5 ' A series of Pt(I I) allyl and propargyl complexes have been prepared viu protonation of eneyne and diyne complexes. The eneyne complexes furnished x-ally1 compounds and the diynes propargyl complexes. The reactions were said to proceed via platinum hydride species. 152 Treatment of the cationic complexes [Pt(PPh3)2(q3CH2C(OE)CH2)] with soft carbon nucleophiles lead to regioselective OE substitution the central carbon yielding q3-trimethylenemethanecompounds.'53

Other Metals - The energetics and mechanism for dehydrogenation of ethene by early transition metals have been investigated. Bond energies were calculated using statistical kinetic energy release distribution^.'^^ Treatment of [(CP*~YH)~] with 3,3-dimethyl-l,4-~entadienein Dl4 methylcyclohexane at - 78 OC afforded a pentenyl chelate [CP*~Y { q':q2-CH2CH2C(Me)2CHCH2)]. The tethered alkene could be readily displaced on addition of thf to form the thf adduct.'55The reaction between [CpzZrX2] (X = CI, Br) and KC5H3But2afforded [Cp2ZrX(q2-C5H3Bu'2)]which has been characterised spectroscopically and by a single crystal X-ray diffraction study. Thermal decomposition of the [Cp2ZrC12]+ 2 BuLi system afforded [Cp2Zr(q3-C3H5)]that was characterised by ESR. Similarly a Zr(II1) species was prepared on treatment of [CpzZrCl2] with PriMgBr.'57Compound 20 has been prepared and shown to polymerise ethene in the presence of MAO? The zwitterionic complex 21 has been prepared and its polymerisation and deactivation characteristics reported. 159 Treatment of [ C P * ~ Z ~ ( ~ ~ - with C ~ HB(C6F5)3 ~)] afforded a betaine complex in which the CH2CHCHCH2BAr3 moiety was shown by X-ray crystallography to be bound as a distorted x-allyl. The complex was active as a polymerisation catalyst.'60 Treatment of [Zr(q4-C4H6)(q8-cot)]with B(C6F5)3afforded the x-allyl complex 22 which from crystallographic data the authors suggest an ion pair interaction giving a five membered metallacycle.'6' Reaction of the group 4 metallocenes with the Lewis acid B(C6F5)3afforded the betaine complexes 23.The complexes have all been shown to strongly interact with one of the six orrho-fluorine has been atoms.162 The compound [Cp*ZrCI{q5-C4H4B(CHNMe2)2)].LiC1 shown to react with allyl magnesium bromide affording [Cp*Zr(q3-C3H5){ q5C4H4B(CHNMe2)2)].The complex does not appear fluxional even at elevated

3.5

5: Hydrocurbon Trunsition Metal n-Complexes other tliun q-CsH5undq-Arene Complexes 233

21

20

R

22

23

temperatures although addition of PMe3 causes rapid q3-q'-intercon~ersion.'~~ Treatment of a zirconocene but- 1 -ene complex with vinylcyclopropane derivatives resulted in ring opening of the cyclopropyl ring giving n-allylic or o-allylic complexes. The CT or n coordination was determined by the bulkiness of the substituents on the cyclopropyl ring. '64 The compounds [Cp*Hf(q3-C3H4-2Me)2][MeB(C6F5)3] and [Cp*Hf(q3-C3H4-2Me)2][B(C6F5)4] have been prepared. The former polymerises ethene and the latter polymerises propene to atactic Voligomers. 165 The do solvated cation [ {q5:q'-C5H4(CH2)2NPri} (N B ~ ' ) ( B r c ~ D ~ ) ] [ b f e B ( creversibly ~ F ~ ) ~ ] binds propene or ethene. The complex is fluxional. Rapid propeller rotation of the alkene is observed and the rate of alkene exchange is slow suggesting a strong interaction with the metal centre.166 Some half sandwich Ta imido complexes were prepared and shown to polymerise ethene. The complexes that contained both ql- and q3-allyl ligands were shown to be active in the presence of [Ph3C][B(C6F5)4]and [B(C6F5)3]. The reactivity though appeared dependent upon the substituents on the imido moieties.'67 The carbene complex [Cp*Mn{C(OEt)CHR)(CO)2]undergo Michael additions with a,fbunsaturated ketones. After warming to room temperature and reaction with H + substituted cyclohexenone complexes of the type [Cp*Mn{q2CH2CHCH(R)CH(R')CH2O}(CO)2]are obtained. The cyclohexeneones can be liberated on treatment of the complex with either CO or PPh3.I6' Microcdlorimetric measurements, at elevated temperatures, of the enthalpies of sublimation of [Mn(CO),(q'-C3H5)] and [Mn(C0)4(q3-C3H5)]have been carried out to provide thermochemical information on the irreversible isomerisation involved in o to n conversion of ally1 complexes.169The fluxional behaviour observed in butenyl manganese tricarbonyl complexes has been investigated using MollerPlesset second order perturbation theory and density functional theory: the density functional theory results were more comparable with experimental data. I7O Treatment of orthomanganated 2-arylpyridine and quinoline tetracarbony1 complexes with aryl lithium reagents followed by alkyl triflates afforded q3-benzyl tricarbonyl manganese complexes.''I The structures and fluxional characteristics of the q2-hexafluorobenzenecomplexes [(q5-C5H4R)Re(C0)2(q2C6H6)] (R = H, Me) and [Cp*Rh(PMe3)(q2-C6H6)]have been reported. The

234

Organometallic Chemistry

structure of [CpRe(C0)2(q2-C6H6)] suggests coordination occurs as an alkene leaving the remaining fragment as a non-complexed diene.'72 The isomerisation of substituted allylketones at a [CpRe(CO)] core have been investigated using 2D labelling studies and NMR spectroscopy. 173 Allylic substitution reactions have been found to be highly regioselective in the chiral rhenium complexes [CpRe(CO)(PPh3)(q2-CH2CHCH20H)]. The regioselectivity associated with the addition of thiols, alcohols and allyltrimethylsilane was confirmed using isotopic labelling studies. 174 The compound [Cp*Re(C0)2(q3-C3H5)]has been reacted with a variety of oxygen, sulfur, nitrogen and carbon nucleophiles. In all cases attack occurred at the terminal carbon of the allyl ligand to give functionalised propene containing complexes. When NH2- and Ph- were used, however, some attack at a CO ligand was observed particularly at low temperature.'75 The complex [Cp*ReCI(CO)(q3-C3H5)] was prepared either by treatment of [CP*R~(CO)~] with allyl chloride under photolytic conditions or from the reaction of [Cp*Re(C0)2(q3-C3H5)]+with P h i 0 and Me4NCI. The halide is easily exchanged for H, a-aryl or alkyl groups.'76

4

Complexes Containing Unconjugated Alkenes

The molecular structure of [Mo(CO)4(q4-cod)] has been determined. 177 The complex [WCI(SnC13)(CO)3(q4-nbd)]was prepared by diene displacement of two acetonitrile ligands from [WCl(SnC13)(CO)3(NCMe)2].The compound was spectroscopically and crystallographically characterised. 178 A density functional theory study was carried out on [Fe(CO)3(q4-nbd)] to investigate the value of rotational barriers of the alkene and the effect of the torsion angles on CO stretching frequencies. '79 The Fe( 11) complexes [FeC12(PriP2(CH2),,PPri2)] have been reduced with Mg in the presence of dienes. Depending on the length of the hydrocarbon chain either hydrido hexadieneyl or q2::q2-diene complexes are isolated. EHMO calculations were carried out and used to elucidate the electronic factors influencing the course of the reaction.'" Treatment of [RuC12(q4cod)(bzpm)] (bzpm = bis pyazol-l -ylmethane) with MeMgCl followed by AgCF3S03 and KTp afforded compounds of the type [TpRuMe(q4-cod)]. A single crystal X-ray diffraction study showed an unusual coordination mode for 3,5-dimethyl-pyrazol-l-y~ borate: a 3c B(m-H)Rh bond was observed.'8' The alkylation of [TpRuC1(q4-cod)] with AIR3 reagents was reported.lS2 A synthetic procedure that leads to a stereoselective preparation of complexed benzyl alcohols in [Ru (q4-cod)(q6-arene)] was r e ~ 0 r t e d . IA~ series ~ of enantiomerically pure asymmetric [Ru (q4-cod)(q6-arene)] complexes were prepared by replacement of 1,3,5 cyclooctatriene or naphthalene from [Ru (q4-cod)(q6-L)]. Brominated arenes can be utilised in a Li/Br exchange process and quenched with alkylchloroformates. Chiral electrophiles were also used which produced useful alkene hydrogenating agents. 184 The complex [OsH2C12(PPri3)2]was reacted with cyclic dienes and depending on the reaction conditions C-H and C-C bond activation processes were observed in conjunction with C-C and C-P bond formation. Several of the compounds prepared were structurally characterised.

5: Hydrocurbon Trunsition Metal 7c-Complexesother than q-CjHj uncl q- Arene Complexes 235

The complex [OsH6(PPri3)2] reacts with diene to afford compounds of the type [OsH2(PPri3)2(q4-alkene)]and 2 mole equivalents of the hydrogenated alkene. The complexes were readily protonated to form trihydride complexes and some evidence for agostic H interactions were reported. Tetracyclo [7.3.1 .02*s.04,'2] trideca-5,lO-diene was practically resolved by reversible ligand exchange with its diene complex [Rh(hfacac)(q4-diene)]in the presence of a chiral auxillary. Is7 The ability of squarate to participate in Rh(1) chemistry has been investigated and in some of the complexes prepared dienes appear as co-ligands.ls8 The reduction of [ R h ( ~ ~ - c o(q4-C9H7)] d)~ was investigated using single electron transfer. Initially a radical forms then a dianion which readily coordinated another cod to give [ R h ( ~ ~ - c o das ) ~the ] final product.'89 A collection of Rh(cod) complexes that contain chelating phosphino(stibin0) methanes have been reported. The molecular structure of 24 has been determined.'" A molecular structure of a Rh(cod)

24

complex with a chiral bidentate phosphine containing an OH group in a remote position was determined. 192 Bis(diary1phosphino)methylamino Rd(cod) complexes have been shown to be active hydroformylation catalysts. 193 Preparation of triazolidene Rh(cod) complexes and their use as chiral hydrosilylation catalysts collection of cationic Rh(cod) complexes containing chiral was r e ~ 0 r t e d . IA~ ~ tripodal ligands have been prepared. Their activity as hydrogenation catalysts has been investigated and showed the complexes to be less active than their bidentate analogue^.'^^ A collection of TpRh diene complexes have been prepared from [ { Rh(p-C1)(q4-diene))2]. Some fluxionality was observed by NMR whereas, on the IR timescale the molecules appeared static.'96 The bonding properties of chiral ligands at phosphorus as well as achiral ligands towards the [Rh(q4-cod)] fragments were investigated in the solid and solution states. 197 The complexes [{RhCl(q4-diene)2}2]have been reacted with a wide range of bi- and terdentate nitrogen donor ligands yielding a series of fluxional five coordinate complexes. In some cases cationic complexes as well as the expected neutral products were prepared. 198 A spectrochemical study on the mechanism of complex formation between [{ RhCl(q4-diene)*}23 and PR3 + SnC12 was studied. Penta-coordination was favoured at high dilution, but the products slowly decompose on concentration and SnC12 was also shown to insert into the RhCl bond.'99 The molecular structures of [Rh(SnC13)(dppb)L2]{dppb = bis(dipheny1phosphino)butane; L2 = cod and nbd) have been determined and shown to be distorted square pyramidal with the tin moiety A collection of cationic Ir diene allenylidene complexes have been reported. 20' The preparation of [Ir(PPr'3)dtet rafluoro barreIene)]' and its molecular structure and catalytic activity were reported.202The

236

Orgunometullic Chemistry

synthesis of some [Ir(I)(cod)] complexes containing chiral thioether ligands was reported. Their potential activity as asymmetric hydrogenation catalysts was in~estigated.~'~ A series of cationic complexes of the type [h-(py)L(q4-cod)][PF6] {L = P ( C G H ~ - ~ - C FAsPh3) ~ ) ~ , were reported along with their ability to act as imine hydrogenation catalysts.2M A collection of functionalised [TpIr(q4-cod)] complexes have been reported. The hapticity of the Tp ligands varied affording a mixture of 4 and 5 coordinate Ir complexes in solution.205The redox properties of some Pd(0) complexes containing bidentate a-imine and Ir-bound quinone ligands have been studied electrochemically.2o6A series of [Pt(q4-cod)]containing complexes have been synthesised and reacted with diazo ~ornpounds.~'~ Treatment of [(Pt(LL)}2(p-LL)] {LL = (CHCHSiMe2)20}with phosphines afford the monomeric complexes [Pt(LL)(PR3)]. Similar complexes of Ni were prepared by the Zn reduction of [NiC12(PPh3)2] in the presence of the siloxane.208A collection of Cu(1) complexes have been prepared and used as photosensitisers for the isomerisation of quadricyclene. Some success was reported and the mechanism was discussed in terms of n-bound cornplexe~.~'~

5

Complexes Containing Cyclic Conjugated Alkenes

5.1 Cr, Mo, W - Alkyne tethered cycloheptatriene chromium tricarbonyl complexes have been prepared and shown to undergo metal promoted [6x + 2x1 cycloaddition reactions.210 In one instance this methodology was used in a natural product synthesis.2' Similarly photochemical induced addition of dienes to q6-cot bound to Cr(CO)3 afforded a series of bicyclo-complexes. The organic fragments were removed by cerium oxidation.212Evidence for metal induced bond localisation in cyclobutabenzenes was obtained from low temperature crystallographic studies in Fe, and Cr carbonyl c o m p l e x e ~ .Cyclodimerisation ~'~ of the tropilium ring in [Mo(CO),(q7-C7H7)]' was achieved by addition of potassium n a ~ h t h a l i d e . Reaction ~'~ of [Cp2W(CO)] with CF3CFICF3 afforded the dienyl complex 2?i215Nucleophilic attack on cationic polyarene manganese

'

25

26

carbonyl complexes afforded neutral cyclohexadienyl complexes.2w217Treatment of the A ring steroid complex 26 with Me or Ph Grignard reagents afforded the stable hexadienyl complex where nucleophilic attack occurred at C1 meta to the OMe when the metal fragment was on the p-face: addition when the metal is on

5: Hydrocarbon Trunsition MeiaI n-Compksesother than q-C5H5 und q-Arene Complexes 237

the a-face was less regiospecific.2'* A collection of cyclohexadienyl manganese complexes containing a chiral non-racemic 2,5-dimethylpyrrolidine sustituent were prepared by nucleophilic attack on cationic arene complexes.219Addition of imminium salts to the activated complex [K][Mn(Co)3(q4-C6H,)]affords the exocyclohexadienyl complexes [Mn(C0)3(q5-C6H6CH2N R2)] in variable yields.220 The complex [Mn(CO), {q5-(SC4H3)-2-N(CH2CH20)}]has been prepared and shown to be unstable in solution. Its reactivity towards nucleophiles was investigated and showed a preference for alkylyation on the C adjacent to S.22' Further in a related study chemical reduction of some Mn thiophene complexes has led to the observation of a Mn(C0)4 fragment inserting into a C-S bond; alkylation at sulfur was also observed on treatment of these compounds with nucleophiles.222 Treatment of [CpReBr2(C0)2] with PhCzPh afforded [CpReBr2(q4-C4Ph4)].Reaction of the intermediate [CpReBr2(q2-PhC2Ph)]with o-diphenylphosphinostyrenein the presence of Ag[BF4] afforded a cisoid butenyl complex [CpRe(CPh-q3-C(R)CHCHC6H4-o-PPh2)][BF4]. Hydride reduction at the carbene centre afforded an q4-diene complex: the reaction can be reversed with [Ph3C][BF4].223

Fe, Ru, 0 s - Reaction of the heterocyclohexadienyl anions [CSH5ER2] (E =Si, Sn) with FeCI2 gave the sandwich compounds [(q5-C5H5ER2)2Fe]:where E = Si the complex was structurally c h a ~ a c t e r i s e d A . ~ ~cyclohexadienyl ~ iron complex containing a tethered alkyne has been shown to direct incoming nucleophiles o rather than a except when the nucleophile is CN-.225 Several other examples of nucleophilic attack on cyclohexadienyl complexes have been reported.226229 The crystal and molecular structure of [Fe(CO)3(q4-2-methoxycyclohexadieny l)][BF4] was reported .230The [5.5.5.Slfenestradiene was reacted with [Fe2(CO),]. The coordination mode of the [Fe(CO),] (n = 3, 4) fragments was shown to be dependent upon which face complexation took place.23' The reactions between HC5Me4CF3and [ R u ~ ( C O )or ~ ~[Fe(CO)5] ] was reported. For iron if the reaction was carried out in refluxing heptane an q4- coordination was observed, whereas in refluxing octane the q5-cyclopentadienyl complex was obtained.232Photolysis of [ C ~ * F ~ ( O - C C P ~ ) ( Cwith O ) ~primary ] alkynes afforded I 7e paramagnetic complexes containing a cyclopentadieneone ring formed by acetylide, alkyne and CO coupling.233Treatment of [Fe(CO)3(q4-1,2-a,P-dibenzoylethene)] or an q2-analogue with MeLi under a CO atmosphere led to the formation of a pyrone containing complex viu a ketene.2341: 1 adducts formed between [Fe(CO)3(q4-vinylketene)]and alkynes have been prepared and their conversion to cyclohexadieneone complexes was achieved with retention of chirality.235Treatment of [Fe(C0)3(q4-2,4-cyclohexadiene-1-one)] with (i) higher order cuprates, (ii) acetic anhydride, (iii) CO yielded [Fe(CO)3(q4-1-acetoxy-5endo-acyl 1,3-~ycIohexadiene)].~~~ The reactions of [Fe(CO)3(q4-p-ionone)]with a variety of carbanions has been carried out to investigate methods for stereoselectively preparing retinoic acids. Two stereochemically different acids were successfully prepared.237The [Fe(C0)3] complex of ergosterol acetate was prepared and on treatment with LiAIH4 selective reduction of the 5,6-double bond occurred.238 Kinetic resolution of eurocarvone was successfully achieved on complexation to 5.2

Orgunomet ullic Cliemistr y

238

[Fe(C0)3] using spateine N-oxides in upto 64% ee.239The use of [Fe(C0)3(q5-4MeO- 1,3-dimethylcyclohexadienyl)][PFb] as the A ring precursor in the preparation of a racemic mixture of stemodinone was reported.24*The preparation of the antibiotics carbazomycin C and D was achieved via nucleophilic attack on a cyclohexadienyl Fe(C0)3 complex followed by several other steps.241Other examples of the use of cyclohexadienyl Fe(C0)3 moieties being used in the total synthesis of natural products have appeared.242244 The microwave spectrum of [Fe(CO)3(q4-CsHs)]was measured in the 4--12 GHz range. The data obtained were consistent for the molecule being a rigid rotor.245 The synthesis and fluxional characteristics of [Ru(q6-cot) (q4-cot)] was reported. The reactivity of this complex towards monodentate ligands was also investigated.246Treatment of { (6,6'-dimethoxybiphenyl)bis(di-3,5-dibutyl1phenyl)the compound [RU(OAC)~ phosphine)] with cod in the presence of H[BF4] afforded 27.247The reaction between [Cp*RuCI{ Me2N(CH2)2NMe2)]and Na[BAr4]followed by 0 2 oxidation afforded a hydroxytetramethylfulvalene complex that was structurally characterisd.248

5.3 Other Metals - [CPCO(CO)~] mediated [2 +2] cyclisation of acyclic diynes has been achieved. Careful choice of terminal R groups in the diyne allowed regiocontrol of the [2 + 21 reaction, thus n-face: n-edge or n-face: It-face geometries were observed in the products.249 Reaction of the compounds [CpCoL2] (L = CO, PMe3) with ICF2CF2CF3 has been investigated. For L = CO alkylation occurs at the metal centre, whereas for L = PMe3 alkylation occurs on the Cp ring.250 The preparation of a metallocene complex that contains a molecular gear has been reported.2s1Ni(0) catalysed polycondensation of bifunctional Co cyclobutadiene complexes was reported to afford complexes with liquid crystalline properties.252 The tetra alkynylated complex [CpCo(q4-1,2,3,4-

28

HC&)] has been prepared by fvp.253A collection of sterically congested cyclic diynes have been shown to undergo [2 + 21 cyclisation reactions at C o and Fe centres yielding cyclobutadiene complexes.254Simultaneous electrolysis of Cp and PhC2Ph in NCMe containing 0.5% H20 using a Co anode afforded [RCpCo(q4-C4Ph4)]complexes.255The complexes [ C P M ( ~ ~ - C * H(M ~ )=~ Rh, ] Ir) were treated with alkynes under photolytic conditions. In both instances q4benzene complexes were isolated. In the Rh case a mixed alkene /alkyne complex was isolated too.256The reaction of the Rh complexes [CpRh(L)2] (L = CO, PMe3)with fluoroalkyl halides was investigated. Similar results to those obtained

5: Hycirocarbon Trunsition Metal n-Complexes other thun q-C5Hjand q- Arene Complexes 239

for analogous Co complexes were reported thus: for L = CO alkylation at the metal centre occurs; alkyation of the Cp ring occurs for L = PMe3.257Compound 28 was isolated when [Zr(dmpe)(q6-PhBC5H6)2](dmpe = bis(dimethy1phosphiof monopentalene complexes no)ethane) was reacted with a l k y n e ~ . A ~ ~collection * of Ti, Zr, Hf have been prepared from re-distribution reactions between bispentalene M compounds with MX4,259The complex [Cp2V(q8-pentalene)] was prepared from the reaction between [Cp*VX] and Li2(~entalene).'~'The complex [TaCI2Me3]reacted with Li(cot') (cot' = I ,4-bistrimethylsilyIcyclooctatetraene)to give [(q8-cot')TaMe3]. Treatment of this compound with [NHPri2Et]CIin CH2C12 afforded the pentalene complex [(q8-1,4-TMS-pentalene)TaC13].26'The vanadium complexes [(q7-C7H7)V(q4-C5H4C02H)] and [ ((q7-C7H7)V(q4C5H4CO)}2 0 1 have been prepared and structurally characterised. The solid state structures showed hydrogen bond interactions which were still evident from EPR spectral data in aprotic non-polar solvents.262The alkoxy-cyclohexadiene complexes [M(OC6H3-2,6-Pri2)3(r14-c6H8)] (M = Nb, Ta) were prepared by Na/Hg reduction of the trichloride analogues. Solid state structures showed the hexadiene moiety was strongly bound and consistent with a metallanorbornadiene description of the A collection of monomeric Pd cyclobutadiene complexes with dithiolene co-ligands have been prepared.264

6

Complexes Containing Acyclic Alkenes

A collection of Ti(0) and Ti(I1) butadiene complexes with bidentate phosphine ancillary hgands have been prepared. In both the structurally characterised complexes [TiMe2(dmpe)(q4-C4H4Ph4)]and [Ti(dmpe)(q4-C4H6)2]the butadiene fragments are best described as q4-n-bound not the often observed c ~ ~ - 7 cA. ~ series of half sandwich Zr and Hf diene and dienyl complexes have been prepared and their polymerisation properties and de-activation pathways were discussed in A general synthetic route to trimethylenemethane Zr complexes was reported. The complexes were shown to polymerise ethene in the presence of MA0.267 Warming of [Cp*NbMe2(q4-C4H6)] caused elimination of CH4 and the formation of a methylidene ligand. The complex was trapped on the addition of norbornene etc.268The interconversion between 02, R and planar 02-enediamide coordination in the compounds 29, and 30 was

achieved by addition of Mgbutadiene and confirmed by crystallographic studies.269Tantalum butadiene complexes that contain borapin and boratabenzene co-ligands have been prepared. The butadiene adopts the trans orientation and is more strongly bound than in analogous Cp containing complexes.270

~ ~

Orgunomet ullic C/iem ist ry

240

The structure and fluxional behaviour of [Fe(C0)2L(q4-butadiene)] (L = CO, PH3, PMe3) have been studied by density functional theory. All the results obtained compared well to those obtained experimentally. Some assignments of IR and Raman bands have been reassigned as a result of these calculation^.^^' Some new optically active cyclopentadienes have been prepared and used as ancillary ligands in cationic [CpFe(CO)(q4-butadiene)]' complexes.272 The preparation of a collection of sulfinyl diene Fe(C0)3 complexes was reported. 3E-1,3-dienes have Complexation was shown to be highly stereo~elective.~~~ been prepared by treatment of allylironcarbene complexes with K[eneoxyborates] one of which was structurally c h a r a ~ t e r i s e d In . ~ ~a ~similar report diene containing complexes were decomplexed by oxidation affording 2-ally1 alcoh o l ~ Trimethylsilylenolether . ~ ~ ~ iron dieneone complexes have been shown to under go Tic14 aldol and cross aldol reactions in some instances as a step in the synthesis of a natural product.276278 The diene complex 31 was shown to under go an enolate Classian rearrangement to 32.279Substituted q4-1-oxira-

31

32

nyldiene Fe(C0)3 complexes have been prepared and converted to cc-allyl-Phydroxydienes which are sub-units of natural products.280[(q4-dienal)Fe(CO)3] complexes have been reduced with NaBD4 and studied by 2D N M R which enabled complete stereoisomeric analysis.28' Catalytic hydrogenation of an alkyne bond p to a diene Fe(C0)3 moiety using Pd on C was shown to stop at the alkene stage. This was independent of: stereochemistry; nature of the vicinal group; substitution of the alkyne and its electrophilicity.282Addition of AIC13 to acyclic diene Fe(C0)3 complexes was shown to induce intramolecular cyclisation. Examples include cyclisation of dienes containing aldehyde, ester, and nitrile functional groups.283 Diastereoselective preparation of a series of 2 3 , 2,4-, and 1,5-diol diene complexes of Fe(C0)J have been prepared.284 Alkylation of 4,6-heptadiene-3-one and 3,Sdimethyl hexadieneoate coordinated to Fe(C0)3 were investigated.285The nucleophilic attack by malonate anion on a series of cationic I -substituted pentadienyl iron complexes has been carried out. The results inferred that strongly electron withdrawing groups direct attack to the internal sites, whereas strongly electron donating groups directed attack to the terminal positions.286The ability of [Fe(C0)3(q4-formyltrimethylenemethane)] complexes to undergo hetero Diels-Alder reactions in the presence of BF3 etherate has been investigated affording eventually organometallic complexed sugars such as 33.287A series of trimethylenemethane Fe(C0)3 complexes were prepared from functionalisat ion 3-butenyltrimethylenemethaneor formyltrimethylenemethaneFe(C0)3 complexes. During the reactions with nucleophilic reagents no reactivity at the metal centre was observed.288 A detailed investigation into chirality transfer in [Fe(C0)3(pentadienyl)] com-

5: Hydrocurbon Trunsition Metul n-Complexes o h - than &Hs

and v- Arcwe Complexes 24 1

plexes was reported.289 A mechanistic study on the combination of vinyl, aryl, and carbonyl ligands in Ru(I1) phosphine complexes was reported; in one case an q4-coordinated vinylarylketone was ~ynthesised.~~'Reaction of [TpRuCl(cod)] with acyclic dienes yielded [TpRuCI(q4-diene)] in which the diene is coordinated in the s-truns-fashion. When cyclohexadiene was used as the diene elimination of HCI is observed affording a cyclohexadienyl complex.29' Some Ru(1I) diene complexes have been oxidised to the analogous Ru(1V) compounds. The diene fragment in the Ru(IV) complexes commonly displays the gauche conformation which increases the diene's susceptibility to nucleophilic attack. The gauche conformation can be disfavoured by substitution in the 3,4 positions: this has been further studied by EHMO calculaof the complex [ { MeSi(CH2PMe&) RuCI2(PMe3)] with 2 t i o n ~ Treatment .~~~ equivalents of neopentyl Grignard affords a ruthenacyclobutane complex; on

thermolysis affords the n-ally1 complex 34 as a mixture of isomers which on further heating yields the trimethylenemethane complex 35 by methane eliminat i ~ nThe . ~ pentadienyl ~ ~ complex [Cp*Ru(qs-CsH6-3-Me)] was protonated with H BF4. Protonation occurred at the terminal carbon affording the cationic diene complex [Cp*Ru(q4-CSH7-3-Me)]' which was structurally characterised and shown to contain an agostic H interaction.294A series of highly functionalised conjugated dienes were prepared with good control of the stereochemistry by the treatment of [CpCo(PPh3)(q2-RC2R)] with two mole equivalents of a d i a ~ o k e t o n eThe . ~ ~ cobalt ~ mediated addition of two carbenes to a complexed alkyne afforded a butadiene ligand. The stereochemistry of the reaction could be controlled by F- isomerisation of the resulting complex.296A series of Ir(1) complexes of the type [Tp*Ir(H4-C4H4-2,3-RR')] (R = R' =H, Me; R = Me, R' =H)were prepared. These complexes were shown to undergo photochemical C-H activation at either allylic or vinylic positions. These activations led to butadienyl and ally1 containing complexes.297 The molecular structure of [K igC6][PtC13(q4-C4Me4)] has been determined by a single crystal X-ray diffraction study.298

Orgunometullic Chemistry

242

7

Complexes Containing Alkynes

Ab inifio calculations carried out on [Cp2Ti~q2-trans-Bu'C2Si(H)Me2)1 showed a

strong bending of the Si-H bond towards the metal centre. The calculations showed the Si-H bond has strong o* accepting properties.299 Treatment of [Cp2Ti(q2-Me3SiC2SiMe3)]with 1,4-diphenylbuta-l,3-diyneafforded an unstable alkyne complex which was in equilibrium with a titanocumulene complex which could be made the major component by complexation to Ni(0).300 Silylated alkyne complexes of Ti and Zr were shown to be effective catalysts for dehydrocoupling of ~ilanes.~"A collection of propynylzirconocene complexes were reacted with B(C&5)3 affording C-C coupled products [CpZM(p-RC4R B(C,F&]. These complexes were shown to be chiral and intramolecular enantiomerisation was studied by VT N MR spectroscopy.302 Treatment of [(por)ZrC12] (por = octaethylporphyrinato or tetraphenylporphyrinato) with PhCzPh in the presence of Na/Hg afforded [(por)Zr(q2-Ph2Ph)]. Structural and spectroscopic data are best interpreted as the alkyne being a 4e donor at a Zr(I1) centre.303 Paramagnetic complexes of the type [N b( q2-RC2R)(q5-C5H4SiMe&] were prepared from [N bCl(q2-RC2R)(q5-C5H4SiMe3)2]and then converted to the cationic complexes [N bL(q2-RC2R)(q5-C5H4SiMe3)2If by oxidation in the presence of ligands L (L = NCMe, CNBu', thf) at low temperature. If the oxidation was carried out at high temperatures vinylidene bridged compounds were obtained.304 Treatment of the complex [NbC13(q2-PhC2SiMe3)]with a tripodal trisaminopyridinato ligand afforded the structurally characterised product [Nb(tripod)(q2PhC2SiMe3)].3"5 The alkyne containing complexes [Tp*NbC1(CH2R)(q2PhCZSiR')] (R =Me, R' =Me, Et, Pr"; R = Et, R' = Me, Et; R = SiMe3, R' = Me) all show cr-agostic interactions in the solid state. The phenyl propynyl complex undergoes a thermally induced rearrangement to a methyl complex.306 Ion four sector and Fourier transform ion cyclotron resonance mass spectrometry was used to study the reactions between acetylene and butadiene that were complexed to the atomic metal cations Cr', Mn', Fe', Cu'. All the reactions proceeded by [4 + 21 cycloaddition reactions apart from that on copper.307 A series of chromium carbene complexes of the type 36 where the alkyne is stabilised

OR

36

R

through coordination to the phenyl ring were prepared and considered t o be arrested intermediates in the benzannulation reaction. The reactivity of these complexes was studied further,308 In another related report the moleculad structure of one example was reported showing the Cr-alkyne distance at 2.4A confirming a weak interaction that was inferred from spectroscopic data.309 Treatment of the complexes [TpML(C0)(q2-OCzPh-4-Me)] {M = Mo, W; L =

5: Hydrocurbon Trunsitiun Metal n-Compleses other thun 9- C, H5 und q-Arefie Complexes 243

PMe2Ph, PPh3, P(OMe)3} with Woollins’ reagent afforded selenoketyl ligands which on alkylation afforded selenoalkyne containing complexes.”’ A comparative study on the bonding of 4e alkynes and 4e nitriles in tungsten fluoride containing complexes that contain strong Ir-donor and acceptor ligands was reported. It was found that the q2-nitrile ligand like an q2-alkyne ligand coordinates parallel to the M-CO vector thus maximising orbital overlap for electron donation and a~ceptance.~’The complex [W(CNRCH2CH2NR)(q2PhCzPh)3] has been prepared in which there are only alkyne and carbene ligands in the coordination sphere.3i2The reactions of the alkyne complexes [W(L)(q2PhC2Ph)3] (L = CO, NCMe) with phosphine donors has been reported.3137 3 i 4 In another related report heating of the tris alkyne complexes in the presence of PhC2Ph afforded q4-cyclobutadiene and q 5-cyclopentadienyl containing comp l e ~ e s . ~Treatment ” of [Tp*WMe(CO)(q2-MeC2Ph)] with [CPh3J[PFh] afforded the methylidene complex [Tp*W(CH2)(CO)(q2-MeC2Ph)][PF,Iwhich behaves as a Fischer carbene, i.e. it readily adds nucleophiles such as PMe3. It also reacted 317 with alkenes and imines to give cyclopropenes and aziridenes respe~tively.~’~. The preparation and reactivity of [TpW(NPh)(CO)(q2-MeC2Ph)]’ was reported.318 The complex [Tp*WI(CO)(q2-HC2H)]has been prepared and on treatment with base and alkylation with Me1 affords a propyne containing complex. Further deprotonation alkylation reactions were carried out reported and in some cases cyclisation around the alkyne triple bond was observed.”’ A series of hydroxy, amido and sulfhydryl Re(1) tris-alkyne complexes have been prepared. The hydroxy and amido complexes were shown to rearrange to Re(II1) oxide and nitrido containing compounds: the kinetics of the rearrangement were in~estigated.~~’ When the compound [Fe(CO)*(PEt3)N2] is reacted with HC2H a mixture of three compounds is obtained one of which contains an q2-ethyne. Attempted chromatographic separation yields only a vinylidene containing complex.32’ The mechanism of insertion of alkynes into orthoruthenated complexes has been investigated and compared to that of analogous insertions in Pd chemistry. The major difference in the Ru system was the need for the creation of a vacant coordination site.322The mechanism of alkyne to vinylidene rearrangement in half sandwich Ru(I1) cations was reported. The effects on the tautomerisation were discussed in terms of C p ligand, phosphines present and the alkyne R An ab initio study at the MP2 level was carried out on the ethyne vinylidene ligand tautomerism. The mechanism was discussed in terms of interand intramolecular proton t r a n ~ f e r . ’The ~ ~ complex [RhI(PPr’3)2(q2-PhC2C2Ph)] has been prepared from [R~(OAC)(PPI-’~)~] by treatment with alkynyl tin reagents followed by 12 which caused reductive coupling of two o-acetylide ligands into the 1,6diphenylbutadiyne hgand.325 Treatment of [Rh(acac)(PR~)(q2-cyclooctene)] (R = Cy, Pr’) with 1,l-diphenylpropyn-1-01 afforded [Rh(acac)(PRB){q2HC2C(OH)Ph2}], which on reaction with PR3 gave a o-acetylide complex which was converted to an allenyl complex on reaction with H[BF4].326A method was developed which incorporated Rh onto a polysiloxane/phosphine containing polymer. This polymer was shown to act as a hydrogenation catalyst towards alkynes and a l k e n e ~ A . ~ collection ~~ of complexes of the type [Ir(CO)(q2RC2R)(q5-C,H7)] have been prepared and their reactivity investigated.328 The

Orgunometallic Chemistry

244

complex [IrC1(PPri3)2(q2-Me3SiC2C02Et)] has been prepared in good yield. It was shown to rearrange under photolytic conditions to a vinylidene containing complex.329A series of cyclic triynes containing a silyl of germyl moiety 37 have been prepared and complexed to Ni centres. Several of the compounds have been structurally ~haracterised.~~’ A collection of silylated alkyne complexes of Ni have been prepared by successive cod displacement from [Ni(q4-cod)2]. The Ni

37

38

centre was shown by single crystal X-ray diffraction studies to be in a distorted tetrahedral en~ironment.~”A wide range of Pd alk-1-yne complexes were prepared on the treatment of Pd(0)complexes with alkynes at low temperature. The complexes prepared contained diynes and eneynes which enabled the synthesis of some polymetallic species.332The reaction of [Pt(PPh3)2(q2-CIC2CI)] with P(OPh)3 was investigated.323 The compound 5,6,11,12-tetrahydrodibenzo[a,e]cyclooctene was reacted with sources of [Pt(PPh3)2], complexation readily occurred through the C-C triple bonds. Attempts to induce double hydrosilation of the triple bonds were also disclosed.334 A collection of Pt primary alkyne complexes analogous to Zeisse’s salt have been prepared by displacement of a coordinated b ~ t - 2 - y n e . ~An ~ ’ alkynyl copper adduct obtained on conjugated addition of Me2CuLi to methyI-4,4-dimethyl-2-pentyneoatereadily forms rcalkyne complexes of type 38 in the presence of an excess of the starting a l k ~ n e . ~ ~ ~

8

Polymetallic Complexes

8.1 Bimetallic Complexes The dienyl complex 39 has been prepared and its catalytic properties investigated.337The Zr eneyne complex 40 which contains a planar 4 coordinate C has been prepared and is stabilised by a 3c-2e bond involving the two metal centres;338in a related study the Zr metals are bridged by an acetylide instead of an imido Thermolysis of (2-phosphininy1)methylzirconocenes in benzene at 80 %’Cyielded -q2-phosphabenzene bridged of the compounds [C:p2ZrRz] (R = Me, Et, Bu) with d i m e r ~ . ~Reaction ~’

Me

39

40

41

5: Hydrocarbon Trunsition Metal n-Complexe.s other than q-C5HS und q- Arene Complexes 245

[Cp2ZrX(o-C(Me)CH2}] (X = Br, CI) afforded the dimeric species 41. The reaction was monitored by NMR and revealed the initial step was alkyl for halide e~change.’~’ Homobimetallic vanadium diyne complexes have been prepared on treatment of [CpZV] and RC2C2R (R = Me$&, PPh2). The alkyne oxidatively adds to the vanadocene affording a d ’ metal centre. This has been confirmed by magnetic measurements.342 A collection of di- and trimeric 2-substituted q3butadienyl Mo(I1) complexes have been prepared. The butadienyl ligands were linked by forming either ester or amide linkages via acid chloride chemistry.343 towards weak aroThe reactivity of [FVMO~(CO)~(~-T)~:~’-CH~C~CH~)][BF~]~ matic nucleophiles was reported. Singular attack at the carbenium centre was observed and reduction with NaBH4 delivers the hydride to the second carbenium centre. The final result was an alkyne containing dimeric c o r n p l e ~ . ’ An ~ electrochemical study of the reduction process in [ C ~ ~ M o ~ ( C O ) ~ f r n - q ~ : q ~ HC$(R)(R’)}] was investigated. The rationalisation of the two electron versus one electron reduction processes were investigated using EH MO calculations.345 The reactions between [Cp2Mo2(C0)4] and [Co(CO),] with mono and diallylsilylalkynes was investigated. Treatment of the alkyne complexes prepared afforded elimination of propene: no metal stabilised cationic silyl intermediate was observed.346Trimethylamine-N-oxide was shown to promote oxidation and CO substitution in [Cp2M~2(CO)4(p-~2-RC2R)].347 The structure of 42 has been determined. Of interest is that the alkyne is neither parallel nor perpendicular to

-0R 42

43

‘Ar

46

47

246

Orgunornetullic Chemistry

the W-W bond.’48 Treatment of [Tp*W(CHZ)(CO)(q2-MeC2Ph)][PF6]with either an excess of NaOH of NaH affords the ally1 bridged complex [Tp*(q2-MeC2Ph)(CO)W(CH2CHCH2)W(CO)(q2-MeC2Ph)Tp*][PF6] which is inert towards nucleophiles. The nature of the bonding in the hydrocarbyl fragment was also discu~sed.”~ The photochemical reaction between [Mn2(C0)5(p-q6:q2-1,4-Me2naphthalene)] and but-2-yne afforded an alkyne bridged Mn-Mn bonded complex amongst other^.'^' Treatment of [Mn(CO)5][BF4]with styrene afforded the expected cationic K-arene complex, which on oxidation with [Cp2Co] afforded 43. If 1,l-diphenylstyrene complexes were used a raft of other bonding modes were ~bserved.’~’ The reaction between [Cp*(CO)*ReRe(C0)2Cp*] and alkynes affords dimetallacyclopentenones which can be readily protonated to afford bridging vinyl species.352The reaction between [Fe3(CO)12]and stannylethenes has been investigated and shown to yield a collection of di- and trinuclear c o m p l e x e ~ . ~Nucleophilic ~’ attack by ArLi reagents on [Fe2(CO)6(p-q4:q4-cot)] occurred at a carbonyl carbon affording two structurally characterised products 44, 45.’54 Compounds 46, 47 were prepared from the diironhexacarbonyl complexes of m- or p-divinylbenzene by reaction with ArLi followed by [Et30][BF4]. The alkoxycarbene then reacts with the vinyl moiety to give the observed products.355Phenylacetylene inserts into the p-H of [Fe2(C0)4(p-H)(ptCO)(p-PPh2)(p-dppm)] affording the two isomers [ Fe2(CO)4(p-PhCCH2)(pPPh2)(p-dppm)] and [Fe2(CO),{p-HCC(H)Ph}(p-PPh2)(p-dppm)], These com.~~~ pounds display windscreen wiper fluxionality on the N MR t i m e ~ c a l e The complexes [Fe2(C0)4- n( Ph2PC2Ph,)(p-q I:q2-C2Ph)(p-Ph)(p-dppm)] were reported. Comparisons of the structural data were made with related phosphido bridged diiron systems and used to elucidate structural changes bought about by O-TCacetylide fl~xionality.’~’ The compounds [M2(C0)4(p-q5:q5-CpCH2Cp)](M = Fe, Ru) were reacted with alkynes and the iron complex formed a vinylketone bridged dimer; whereas, the ruthenium complex formed a Ru-Ru bond bridged alkyne complex which on exposure to air oxygen inserts into the R u - C ( ~ ~ ~ ~ ~ bond.358 Treatment of [Fe2(CO),(p-PPh2)] with bromoprop-2-yne afforded [Fe2(Co)6(p-PPh2)(p-q ‘:q2-HCCCH2)]which on further reaction with organolithium, reagents yielded coordinated P,y-unsaturated ketones viu allenyl, CO and nucleophile coupling.359 Furthermore nucleophilic on [Fe2(Co)6(p-PPh2)(pq1:q2-HCCCH2)Jwas reported. Attack at the a and f3 carbons of the allenyl ligand was observed by P(0Me)R; selectivity for the site of attack was described.”’ A related study of nucleophilic attack by alcohols was described during which a coupling reaction with a ligated C O took place.361 In an analogous diruthenium allenyl complex treatment with dppm led to allenyl migration to CO: a different reactivity pattern was observed for Treatment of [Cp2Ru2(p-CH2)(p-CO)(CO)(NCMe)] with diazoalkanes { N2C( R)R’)afforded the coupled products [ C P ~ R{U p-q ~ ’:q2-CHC(R)R’j(pH)(CO)2] which contain a bridging alkenyl Diphenylacetylene inserts into the Ru-N bond in [RU~(~-H)(~~-NCP~~)(CO)~~] to ultimately give 48 which has been structurally characterised. 364 The interaction between C8 ring systems and [ R u ~ ( C O ) Ihas ~ ] been reported. For cot, cluster degradation results and the isolation of [Ru2(C0)5(p-q4:q4-CsHg)l;and for cyclooctene, cluster build up and

5: Hydrocarbon Transition Metal II- Compkses other thun tpC,H5 und q- Arcnr Ctmple.ues 247

ligand dehydrogenation gave [Ru&(C0)1&3-q ':q ':q2-CgH12)].365The biologically active molecule (+)-calichemicione has been prepared from a [Co2(CO),] alkyne protected enedi~ne.~,,Methods for the rapid decomplexation of enediynes coordinated via the akyne moiety to [co2(co)6] , which are indefinitely stable, have been investigated. The importance of these molecules is in their biological activity; however they are unstable, t112 = 8 - 24h, when d e ~ o m p l e x e d The .~~~ complexes of type 49 were prepared and shown to undergo intramolecular

48

49

0

51

Pauson Khand reactions.368Tandum cyclisation of a complex propargyl unit on [co2(co)6] has been used in the synthesis of i n g e n 0 1 . ~The ~ ~ Pauson Khand reaction on eneyne functionalised complexes has been carried out with functionalised Fischer carbene complexes affording the expected c y c l o a d d u ~ t s .The ~~~ preparation of some [co,(co)6] complexed alkynyl aldehydes and their reactivity towards y-alkoxyallylboranes was reported. Some 3,4-dioxy- 1,5-eneynes were A series of chiral prepared in good yield with reasonable enantio~electivity.~~' mesyl oxylacetyl functionalised alkynes complexed to [Co2(CO),] underwent 1,2shifts of the complexed alkyne when treated with organoaluminium reagents.372 Compound 50 was prepared and shown to convert to 51 on heating.373Treatment of 52 with H[BF4] led to the formation of 53 by a SET mechanism. Some competition for hydride transfer was noted."' Treatment of [co2(co)8] with alkynyl tin reagents yielded alkynyl complexation to [Co2(CO),] moieties.375 Nucleophilic attack by lithium acetylides on 2,6-disubstituted pyrrilium salts afforded unstable y-substituted pyrans. These compounds could be stabilised by forming the [CO,(CO)~]complex. The reactivity of these complexes was investigated.376 A collection of C( 10) alkynyl substituted anthrone complexes of [Co2(CO),] and [ C ~ M O C O ( C Owere ) ~ ] reported. Protonation with H[BF4] yielded a carbonium centre at C( 10) and the charge was shown to redistribute over the cluster.377 The complex [(CO)2Rh(j.~-Cl)~Rh(q~-cod)] was prepared and characterised by ab initio powder diffraction. The results showed noticeable deviation from planarity of the Rh2CI2core.378The phosphinoalkynes Ph2PC2R (R = H ,

Orgunometullic Chemistry

248

52

53

54

Me, CF3, But, Ph and PPh2) behave as tertiary phosphines towards [Cp2Rh(pCO)(p-q2:q2-CF3C2CF3)]; however, if they were oxidised prior to complexation they coordinated through the triple bond. Treatment of the phosphine complexes with 0 2 sources afforded phosphaeneone complexes not the q2-alkyne phosphine with alkynes oxide complexes.379The reaction of [Ir2H(CO)2(p-H)2(dppm)2][BF4] gave complexes of the type [Ir2H(CO)2(p-H)(p-RC2R)(dppm)2][BF4](R = C02Me, H, CF3) where the alkyne coordinates parallel to the Ir-Ir bond axis. For PhC2Ph hydrogenation to cis-stilbene was observed.380 Reduction of [Cp*Ir(q'L)] (L = Cp, Cp*, indenyl) afforded the dimeric products exemplified by 54.381A collection of Ni(0) and Pt(0) complexes containing n-bound vinyl silanes was reported.382 Treatment of the complex [Ni2Br~(PMe3)3(pz-q':q3-CH2-OC6H4)] with Lipz (pz = pyrazol-1 -yl) afforded [Ni2Br(PMe3)(pz-q1:q3-CH2-OC6H4)(p2Pz)] which was studied by X-ray diffraction and shown to have a Ni-Ni distance of 2.7 I O(2)A indicating weak interaction between the metal centres.383 Deuteromethanolysis of the cis and trans 0-acetoxycyclohexyl allyl Pd containing complexes was investigated under mildly acidic conditions; a theoretical study using density functional theory was also carried A collection of bimetallic Pd allyl containing complexes with ruthenocene containing ancillary ligands were used in asymmetric allylation reactions affording good enantio~electivty.~~~ Trans-6,7-dihydroimachalene(1 R ,2R,7 R)- tetrameth ylbicyclo[5.4.0ldeca-8-ene was readily cyclopalladated and the resulting complex was structurally charact e r i ~ e d . ~Comproportionation '~ of [Pt(PMe3)4] and [Pt(qfacac)2] afforded the unusual complex 55.387 A series of dimeric [Cu(p-Cl)(q2-cycloheptyne)] com-

55

56

57

5: Hydrocarbon Trunsition Metul7c-Complexes o

h r

tlzrrn q-CsHJand q- Arme Complexes 249

plexes were prepared where the CH2 moiety in the cycloheptyl ring was replaced by S and SiMe2 groups.3ssThe reaction between Au(1) and Au(I1I) species with alkynyl titanocenes was investigated. In some cases some trigonal planar gold complexes were synthesised. The bonding in these complexes was also discussed.389Deprotonated alkoxy and amino Fischer carbene complexes have been used to nucleophilically attack cationic cyclohexadienyl iron complexes affording neutral diene species and cationic arene manganese complexes to give neutral hexadienyl compounds.390 The cyclotrimerisation of dimethylacetylenedicarboxylic acid by Zr~ns-[Cr(CO)~(p-q~:q~-Me,Ind)Rh(CO)~] was investigated. After all the monomer was consumed two organometallic species were isolated: trans[Cr(CO),( p-q!( q3- Me7Ind)Rh(CO)(fade)] (fade = fumaric acid dimethylester) and the precatalyst. The formation of 'fade' was proposed to occur through C-H activation of the cyclohexane solvent.391The reaction between [Cr(CO)3(q5SC4H3Li)] and some platinum precursors afforded a series of heterobimetallic complexes.392The complex 56 was prepared and shown to exist as a tautomeric mixture.393EPR data for compound 57 showed the odd electron resides o n Cr and that there is only weak interaction between the metal centres.394A collection of sesquifulvalene complexes containing Mn and Cr centres was rep~rted.~" [Cr(C0)3(q6-C6HsNH2)] was shown to nucleophilically attack cyclohexadienyl Fe and Ru complexes to form an amino bridged heterobimetallic species.396The [M(CO)S] (M = Mo, W) stabilised phosphabutadiene compounds [M(CO)s{(TMS)2CPC(OEt)C(H)Ph}] form diene complexes on reaction with [Fe(CO)S] in which the diene adopts the s-~is-conformation.~~~ Reaction of the complex [W12(CO){q2-Ph2P(CH2)2PPh(CH2)2PPh2)(q2-RC2R)] with either [M(CO)S(NCMe)] or [M(C0)4(piperidine)2] afforded a collection of bi- or trimetallic species.398 The reactivity of [WReCp(0)(CO)4(p-H)(o-CCPh)] towards alkynes has been investigated. When the alkyne was 4-Me-PhC2Ph-4-Me a bridging (T-R metallocyclopentadienyl moiety was observed.399The anionic complex [NEt4][W(C0),(o-C2But)]has been used as a nucleophile in reactions with cycloheptatrienyl molybdenum, cyclohexadienyl iron and arene manganese carbony1complexes. At the end of the reaction the tungsten acetylide is modified to a vinylidene l i g a ~ ~ d . ~ Nucleophilic " attack by aryl lithium reagents on 58 eventually afforded alkoxycarbene specie^.^" The anions [Re(CO)s]-, [ c ~ F e ( C 0 ) ~ ] and - , [0s(CO),l2- nucleophilically attack a variety of n-bound organic fragments complexed to Ru affording hydrocarbon bridged polymetallics.402Compound 59 was prepared from the reaction between [ { 1'3-q- 1-MeOun~i-2,3-bis(methoxycarbonyl)prop-2-en-l -ylidene}Fe(C0)3] and [Ru(CO)3(q4cod)]. The reactivity of this complex was reported.403A collection of compounds

58

59

250

Orgunometuliic Chemistry

of the type [M2(p-S-S)2(q4-cod)2](M = Rh, Ir; S-S bidentate sulfur ligands) were prepared and their reactivity in~estigated.~'~ Addition of Ag[C104] to trans-[Pt(oC2R)2(PMe2Ph)2]yielded cyclic dimers when R = But (C104 independent unit) and linear polymers when R = H (C104 coordinated to Ag).405

8.2 Multimetallic Complexes - The clusters [ C ~ M O ~ R U ( ~ ~ - C ~ H R on )(CO)~] treatment with PMePh2 underwent carbonyl at ruthenium substitution whereas, on reaction with Ph2PH more complex reactivity was observed including the formation of p-phosphido species.406A collection of compounds of type 60 were

CP*

?P*

Re(CO), 60

reported and the various resonance forms discussed.407The reaction of methanol stabilised [Fe3(C0)12]with 1-phenylprop-2-yn-l-ol yielding a variety of OH '~ of [Ru~(CO)IZ]with 1 functionalised C3, C5 x-bound l i g a n d ~ . ~Treatment methylpyrrole gave [Ru3(p-H)(p3-q3-C4H3NMe)(C0)9] where metallation had occurred at the 3 position. Two isomers were observed to be in dynamic ~*~ was preequilibrium by VT NMR s p e c t r o ~ c o p y .[Ku3(C0)9(p3-q2:q2:q2-C~~~)] pared on treatment of [ R u ~ ( C O ) ~with ~ ] C70.410The reactions between [ R u R ( C O ) ~and ~ ] the diynes hexa-2,4-diyne- 1,6-diol, and 174-diphenylbuta-1,3diyne were reported. The diynediol furnished a [Ru3(p3-q2-alkyne)] containing cluster; whereas, for diphenyldiyne a ruthenacyclopentadiene was i ~ o l a t e d . ~The ' reactions of PhC2Ph with [Ru3(p-H)(p3-CMeCHCMe)(C0)9]and [Ru3(p-H)(p3C I 2H 1 5)( CO)9] were reported .4 2, 41 Thermolysis of [ { Ru3(pdppm)(C0)9}n(Ph2PC2H)](n = 1, 2) afforded the compound [ R u ~ ( P ~ PPhCH 2PPh2)(p3-q :q 2-PC2PPh2)(p-P Ph2)(Ph)(CO),].4 The react ion between [ R ~ ~ ( p - d p p m ) ( C O and ) ~ ~ ] 1,4-diphenylbuta-I ,3-diyne was investigated and shown to give a cluster containing ruthenacyclopentadiene and p-alkyne interac(CO)~) was reported to t i o n ~ .Thermolysis ~'~ of [ { R u ~ ( ~ - H ) ( ~ - C ~ B U ' ) 2(p-C2PPh2)] yield two multinuclear complexes in which coupling of the acetylide and bridging phosphinoalkyne had taken place.416 Treatment of [ R u ~ H ( ~ - H ) ( C O I] )with I acetylene at low temperature afforded [Ru3(CO)I I(q2-HC2H)]which on warming transformed to [Ru~(CO)~(~-CO)(~~-~~-HC~H)].~'~ 61 was prepared on treatment of [ {Cp*Ru)3(p-H)3(p3-H)2]with cyclohexa- 1,3-diene. Two le oxidations afforded a p3-q3:q3-diallylic coordination of the organic moiety.418The reaction between the clusters [Ru3(C0)9{p3-q2-CH2CHCNCH2CH3] (p-H)] and [M2(C0)9{p3-q2-CN(CH3)2J](M = Ru, 0s) with alkynes was reported. A collection of p-alkyne containing compounds were c h a r a c t e r i ~ e d .The ~ ' ~ compound [ R U H ( C O ) & ~ -':q2:q2-Cl ~ 2H9)] has been structurally ~haracterised.~~'

'

'

'

5: Hydrocurbon Transition Metal n-Complexes other than q-C5H5and g-Arene Complexes 25 1

62

63

The compound [ R u ~ ( C O ) ~ ( ~{ p3-NS(0)MePh)] -H) was reacted with internal and terminal alkynes affording a variety of p-alkyne and m-vinyl containing clust e r ~ ; however ~~' treatment of [RuJ(CO)g(p-H) { p3-NS(0)MePh)] with p-NO2diphenylacetylene afforded two complexes where the alkyne moieties had coupled and the resulting ligands were best considered as a p3-q3-5e butenynyl PhC2C=CHPh or a butatrienyl ligand PhC=C=C=CHPh .422 A collection of R u ~ clusters containing C8 rings bonded in an allenylic or acetylinic mode were reported.423 Treatment of [ R u ~ ( C O ) ~with ~ ] cyclohexene or cyclooctatetraene afforded a series of clusters. For each alkene one of the products contained an organic moiety where ring contraction had occurred.424The thermal reaction between [Ru3(CO)12] and styrene and substituted styrenes was reported to give a selection of Ru4 and Rug clusters.425The compounds [M3(CO)l2] (M = Ru, 0 s ) were reacted with vinyl phosphines. For 0 s simple CO substitution was reported; whereas, for Ru a P-vinyl group oxidatively adds to the Ru core.42662 has been prepared and structurally c h a r a c t e r i ~ e d .Treatment ~~~ of [Os3(CO)l2] with Et2PCHCHOBu" gave [OS~(~-H)(~~-BU"OCCCHPE~~)(CO)~]. This compound was shown to catalyse the silylation of terminal a l k e n e ~ Regioselective .~~~ addition of an alkyne to the CO and CNR functional groups in [Os3(CO)Io(CNPr)(NCMe)]was reported.429Electrochemical studies were carried out on [Os3(CO),I ( ~ ~ - Cand ~ ~[Os3(CO)lo(PPh3)(q2-C60)] )] and there was evidence of C60 mediated electron transfer.430 The molecular structure of [Os3(C0),(PPh,){p3-o-q2-C(Ph)C(Ph)P(Ph)O)]was rep0rted.4~'A series of tri- and tetranuclear CoCp p-alkyne containing clusters were prepared by C-H activation of cycloalkenes induced by the CpCo fragment.432Compound 63 was prepared on thermolysis of [Cp3C03(p3-CO)(p3-HOCH2C2CH20H)].The furyne was shown to display propeller like rotation and the compound was shown to undergo reversible chemical and electrochemical one electron oxidations.433 Reaction of [ ( C P * M ) ~ ( ~ ~ -(M S )= ~ ]Rh, Ir) with [{Rh(p-C1)(q4-cod)}2]yielded the cationic triangular clusters [(Cp*M)2Rh(p3-S)Z(q4-cod)].434The butadienyl complex 64 is said to be stabilised by becoming z ~ i t t e r i o n i c Treatment .~~~ of [Pt(o-CzBu')2(q4-cod)] with HC2Bu' in the presence of NaOEt afforded 65.43h Compound 66 was prepared and shown to act as a double tweezer to HgC12.437 Treatment of [Cp2M(q2-TMSC2TMS).thfl (M = Ti, Zr) with l,%bistrimethylsilylocta-l,3,5,7-tetrayneafforded 67.438The complex [Cp2Mo2Ir2(C0)10] was reacted with a wide range of alkynes affording compounds of the type [Cp2M021r2(p4-q2-RC2R)(p-CO)4(CO)4]. From cryst allographic studies it was

Orgonometallic. Clzemistry

252

64

cpp-l-Ms

- t i

“”Y I ILcp,

Mcp2

TMS

67

66

apparent that the alkynes inserted into a formal Mo-Mo bond.439Treatment of [CpW(O)z(o-C2Ph)] with [Os,(CO) I I(NCMe)] afforded acetylide transfer to the 0 s cluster and the remaining W fragment was incorporated via (p-0) linkagesw An inorganiclorganometallic host composed of a [W404] core with six polyoxo supported [Ir(q4-cod)] in an octahedral arrangement was shown t o have an octahedral cavity which formed a guest compound with NCMe.441A series of pentanuclear clusters of the type [Fe3MC(C0)12M’L](M = Co, M’ = Pt, Rh, L = q3-CSHS, q3-P-pinenyl) were reported.442 Thermolysis of [Fe2(C0)&PPh2)(pIq I:q2-C2Ph)] affords [Fe4(CO)&-PPh2)(p4-q ‘:q I:q2:q2-C2Ph)2] which reacts with C O to give [Fe3(C0)8{p-Ph2C(CPh)C(CPh)PPh2}] resulting from C-C The molecular structure of [ { Fe(C0)3}3{ p3-CC) Fe(C0)2Cp(CCF3)] was determined.444 Compound 68 was structurally characterised and shown to have a close C-C contact of 1.610A through the plane defined by the Fe atoms.445 afforded 69 and Treatment of [Fe2(CO),{p-SeC(H)C(Ph)Se}] with [RuJ(CO)I~] 70. 446 [Os3(CO)lo(NCMe)2] was reacted with a series of methyl and dimethyl ,Ph

68

69

70

substituted cyclohexadienes and shown t o afford the acetonitrile substituted products.447 Treatment of [ R u ~ ( C O ) ~ ~with ] cycloheptatriene yielded [Ku4(C0)7(p-C7H7)2] in which the ruthenium core was edge bridged by two parallel organic rings.448The complex [Ru2(CO)&PPh2)(p-q1:q2-C2C2R)] (R =

5: Hydrocarbon Transirion Metal n-Complexes other than g-CsHs und g-Arenne Complexes 253

Bu', Ph) reacted with [Pt(PPh3)2(q2-C2H4)],[Pt(dppb)(q2-C2H4)],[Ni(q4-cod)2] or [Ni(C0)4] to give a series of heterometallic corn pound^.^^ Treatment of [Cp*Ru(p-CH2)(p-Cl)Ru(SiMe3)Cp*] with ethyne afforded 71 and 72 and the reaction of propadiene with [ (Cp*RuCl(p-C1)}2] gave 73.450 Treatment of [Ru3(C0),2] with 1-iodonaphthalene and 9-iodophenanthrolene yields the noniodine containing compounds [Ru4(p4-q2-L)(C0),,1(L = 1,2-naphthyne, 9,lOphenanthryne) which is in contrast to iodobenzene and 4-iodotoluene which afford the expected oxidative addition products.451Compound 74 was prepared

Cp* 71

72

Me

73

74

on treatment of [Os3(p-H)(p3-C2Me)(CO),2] with [ R u ~ ( C O ) I ~Theoretical ].~~~ aspects of the bonding of the C2 fragment in organometallic clusters of the type [L,MnC2] (n 3 5) was investigated.The bonding interactionsfollowed the classical Dewar-Chatt-Duncanson Treatment of [(q5-C5H4TMS)2TiC12]with 2 mole equivalents of LiC2C2Li or LiCzSi(Me)2C2Li afforded the a-diynyl complexes [ ( T ~ ~ - C ~ H ~ T M Swhich ) ~ T ~went L ~ ] on to form multimetallic species on .~~~ reaction with [CO(CO)~], [Ni(CO)] and [M(PR&] (M = Pd, Pt) ~ y n t h o n s A collection of alkynyl and aryl silanes were complex to [Co2(CO)6] and [CpMo(CO)2] moieties and then polymerised. Molecular weights upto 1 55000 were reported.455Reaction of [Cp*WRu2(CCR)(C0)8] with [CpWH(C0)3] af) ( C O )R~ ]= But, which was in contrast to forded [ C P * ~ W ~ R U ~ ( ~ ~ - C C B U 'where [ C ~ * ~ W ~ R U ~ ( ~ ~ - C P ~ ) ( ~when ~ - CR) (=CPh.456 O ) ~A ] collection of multimetallic species have been built up from rhenium acetylide starting precursors.457Treatment of [Fe2(CO)6(p-SeCHC(C2R)Se}]with [Cp2Mo2(C0)4], [co2(co)8], [Ru3(CO)lo(NCMe)2], [ O S ~ ( C O ) ~ ~ ( N C M afforded ~ ) ~ ] clusters where the alkyne u~ cores bridged either two or three metal centres.458A collection of A u ~ R cluster have been prepared that contain bridging acetylide l i g a n d ~ Condensation .~~~ of [Ru4(CO)]3(p3-PPh2)]with [Cp*W(0)2(C2Ph)]afforded cluster compounds containing bridging acetylide and 0x0 ligand~.~"The cluster [RuS(CO)1 &C2PPh2)(p-PPh2)]was thermolysed in the presence of Me2S ultimately affording

254

Orgunometullic Chemistry

clusters with bridging C2 fragments.461Carbonylation of [Ru5(p-C2)(p-SMe)& PPh2)2(C0)111 at 30 atm afforded [Ru5(p4-C2)(p-SMe)2(p-PPh2)2(CO)13]and [ R ~ ~ ( p - C ~ ) ( v ~ - sJM I - eP)P~~(~ ) ~ ( C O ) The carbido cluster [Ru5(p-C)(CO)15] reacted with [Cp*W(C0)3(C2Ph)] in the presence of Me3NO to yield [Cp*W Ru5(p-C) (C2Ph)(CO)15]and [Cp*W Ru5(p-C) (C2Ph)(CO),3]. The former readily converts to the latter on warming and the reactions of these compounds with H2 were investigated.463 Reaction of [ R u ~ C ( C O ) I ~or] [Ru&(CO)I~]with c60 followed by PR3, the compounds [Ru5C(CO)]1(PPh3)(~3-11~:11~:r~-C60)1 and [R~~C(CO)~~(dppm)(p~-q~:q~:q~-c~~] were isolated and structurally charact e r i ~ e dThe . ~ ~reactivity ~ of [ R u ~ C ( C O ) towards ~~] alkynes and arenes have been reported.465467 The dynamic behaviour of SO2 and NO ligands in a [RU&(p-?l3allyl)] cluster were investigated by VT NMR spectroscopy, the possibility of the fluxionality being due to the ally1 ligand was discounted on the grounds that the barrier would be high.468Treatment of [N(PP~~)~][OS~(~-H)(CO)I 11 with [ {Rh(pCl)(q4-nbd))21 in the presence of Ag[BF4] afforded [ O S ~ R ~ ~ ( P ~ - H ) ( P ~ CO)(CO)l,].469 Compounds of the general type 75 were prepared and where n = 1 it was characterised by a single crystal X-ray diffraction The reaction between RhC13.3H20 and Bu'OH at 70 "Cgave Based on crystal structure data the supramolecular assembly of prop-2-yn-1-01 and alkyne diol complexes of Ni and Pt have been examined. The hydrogen bonding motif was shown to take up a variety of shapes.472The reactivity of some alkynyl platinum complexes has been investigated and multimetallic complexes have been built up by the formation of alkynyl bridges one example includes 77.473475 The synthesis and conductivity of some Ag(1) polymers with q2-pyrene and perylene ligands were reported .476

P 75

5: Hyclrocurbun Trunsition Metal n-Complexesother thun g-CJHT unclq-Arene Complexes 255

8.3 Ferrocenyl Containing Complexes - Treatment of [Mo(C2Fc)(dppe)(q7C7H7)] with [FeCp2][PF6] affords the cation [Mo(CzFc)(dppe)(q7-C7H7)][PF6] and ESR spectroscopy suggested that the odd electron is resident on the cycloheptatrienyl ring.477 A collection of oligonuclear complexes based upon bifunctional (ferrocenylpyrazol- 1-yl)borates have been prepared and include Mo 7c-ally1 complexes.478A ferrocenyl substituted acetylide has been added to a 1alkoxy substituted cyclohexadienyl iron complex which after treatment with H[BF4] regenerated a cyclohexadienyl complex that displayed significant SHG.479 Reactions of the complex [M3H(C,Fc)(CO),] (M = Ru, 0s) with [ R u ~ ( C O ) I ~ ] afforded tetranuclear clusters [RuM3H(p4-C2Fc)(CO)121 in which the fluxional nature of the p-acetylide was studied by VT NMR spectroscopy.480Some Rh(1) diene complexes with chirai oxazolinylferrocene ligands have been prepared and spectroscopically ~ h a r a c t e r i s e d . ~ ~Treatment ' of the complex [ { Rh(pCl)(PPri3)2)21 with ethynylferrocene gave the vinylidene ferrocene-containing complex [RhCI(PPr'3)2{ CC(H)Fc}] which on treatment with Grignard reagents afforded 78 and 79.482A series of alkene and allyl complexes have been prepared

78

79

that contain chiral aminophosphinoferrocene ancillary ligands. The fluxionality of the alkene and allyl ligands have been studied by VT NMR spectroscopy.483 Treatment of the (SiMe2) ansa-bridged ferrocene with [Pt(q4-cod)2] affords a [2]platinasilaferrocenophaneand its ability to catalyse ROMP of the starting silamsa- bridged ferrocene was investigated .484

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5: Hyclrocurbun Transition Metal n-Complexes other thun q-C5H5und q-Arene Complexes 259 119. 120. 121. 122. 123. 124. 125. 126. 127. 128. 129. 130. 131.

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181.

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5: Hydrocarbon Transition Metul n-Complexes other than q-C5H5and q- Arene Complexes 26 I

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223. 224. 225. 226. 227. 228. 229. 230. 231. 232. 233. 234. 235. 236. 237. 238. 239. 240. 241. 242. 243. 244. 245. 246. 247. 248. 249. 250. 251. 252. 253. 254. 255.

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412.

41 3.

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420.

H. Nagashima, A. Suzuki, M. Nobata, K. Aoki, K. Hoh, Bull. Cliem. Soc. Jpn., I997,70,223 1. V. Ferrand, K. Merzweiler, G. Rheinwald, H. Stoeckli-Evans, G. Suss-Fink, J. Orgunomet. Chem., 1997,549,263. V. Ferrand, C. Gambs, N. Derrien, C. Boltn, H. Stoeckli-Evans, G. Suss-Fink, J. Orgunornet. Chem., 1997,549,275. D. Braga, F. Grepioni, D.B. Brown, B.F.G. Johnson, J. Chem. Sue., Dalton Truns., 1997,547. D.B. Brown, P.J. Dyson, B.F.G. Johnson, C.M. Martin, D.G. Parker, S. Parsons, J. Cliem. Soc., Dulton Truns., 1997, 1909. B.F.G. Johnson, J.M. Matters, P.E. Gade, S.L. Ingham, N. Choi, M. McPartlin, M.A. Pearsall, J. Chem. Soc., Dalton Truns., 1997, 3251. R. Giordiano, E. Sappa, G. Predieri, A. Tiripiccho, J. Orgunomet. Ciiem., 1997,547, 49. J.V. Kohler, J. Lewis, P.R. Raithby, M.A. Rennie, Orgunometullics, 1997, 16 3851. A-Z. Voshoboymkov, M.A. Osina, A.K. Shestakova, M.A. Kazankova, I.G. Trostyanskaya, I.P. Beletskaya, F.M. Dolgushin, A.I. Yanovsky, Y.T. Struchkov, J. Orgunomet. G e m . , 1997,545-546, 7 1. J-Y. Huang, K-J. Lin, K.M. Chi, K-L. Lu, J. Chem. Soc., Dalton Truns., 1997, 15. J.T. Park, J-J. Cho, H. Song, C-S. Jun, J. Kwak, Inorg. Chem., 1997,36,2698. M.V. Capparalli, Y. de Sanctis, A.J. Arce, E. Spodine, Actu Cryst., 1997, (33,302. H. Wadepohl, T. Borchert, H. Pritzow, Chem. Ber., 1997,130,593. W.D. King, C. Barnes, J.A. Orvis, Orgunometullics, 1997, 16, 2 152. Z. Tang, Y. Nomura, Y. Ishii, Y. Mizobe, M. Hidai, Orgunometullics, 1997, 16, 151. T. Murahashi, H. Kurosawa, N. Kanehisa, Y. Kai, J. Orgunomet. Chem., 1997,530, 187. L.R. Falvello, S. Fernandez, J. Formies, E. Lalinde, F. Martinez, M.T. Moreno, Orgunometullics, 1997, 16, 1 326. D. Zhang, D.B. McConville, C.A. Tessier, W.J. Youngs, Orgunometullics, 1997, 16 824. P-M. Pellny, N. Peuleche, V.V. Burlakov, A. Tillack, W. Baumann, a. Spannenberg, R. Kempe, U. Rosenthal, Angew. Chem. Int. Ed. Engl., 1997,36,2615. N.T. Lucus, M.G. Humphrey, P.C. Healy, M.L. Williams, J. Orgunornet. Chem., 1997,545-546,5 I 9. C-W. Shiu, Y. Chi, A.J. Carty, S.M. Peng, G-H. Lee, Orgunometullics, 1997, 16, 5368. Y. Hayashi, F. Muller, Y. Lin, S.M. Miller, O.P. Anderson, R.G. Finke, J. Am. Cliem.Soc., 1997, 119, 11401. S.P. Gubin, T.V. Galuzina, I.F. Gogovaneva, A.P. Klyagina, L.A. Polyakova, O.A. Belyakova, Y.A.V. Zubavichus, Y.L Slovokhotov, J. Orgunomet. Chem., 1997,549, 55. A.J. Carty, G. Hogarth, G. Enright, G. Frapper, Chem. Commun., 1997, 1883. K.W. Muir, L. Manojlovic-Muir, F. Morrice, K. Guennon, F. Petillon, R. Rumin, Actu Cryst.. 1997, C53,219. J.E. Davis, M.J. Mays, P.R. Raithby, K. Sarveswaran, Angeiv. Chem. Int. Ed. Engl., 1997,36,2669. P. Mathur, S. Ghosh, M.M. Hossain, C.V.V. Satyanarayana, A.L. Rheingold, G.P.A. Yap, J. Orgunornet. Chem., 1997,538,57. S.L. Ingham, B.F.G. Johnson, 1.H. Sadler, J.G.M. Nairn, J. Orgunomet. Cliem., 1997,531,237.

421. 422. 423. 424. 425. 426. 427. 428.

429. 430. 431. 432. 433. 434. 435. 436. 437. 438. 439. 440. 441.

442.

443. 444. 445. 446.

447.

5: Hydrocarbon Transition Metul n-Complexes other thun q-CSHS and q- Arene Complexes 269

D. Braga, P.J. Dyson, F. Grepioni, B.F.G. Johnson, C.M. Martin, L. Saccianoce, A. Steiner, Chem. Commun., 1997, 1259. 449. P. Blenkiron, G.D. Enright, A.J. Carty, Chem. Commun., 1997,483. 450. W. Lin, S.R. Wilson, G.S. Girolami, Orgunometullics, 1997, 16, 2356. 451. A.J. Deeming, D.M. Speel, Orgunometullics, 1997, 16, 289. 452. A.A. Koridze, A.M. Sheloumov, F.M. Dolgoushin, A.I. Yanovsky, Y.T. Struchkov, P.V. Pertrovskii, J. Orgunomet. Chem., 1997, 536537,381. 453. G. Frapper, J-F. Halet, M.I. Bruce, Organometullics, 1997, 16,2590. 454. H. Lang, I-Y. Wu, S. Weinmann, C. Weber, B. Nuber, J. Organomet. Chem., 1997, 541, 157. 455. T. Kuhnen, M. Stradiotto, R. Ruffolo, D. Ulbrich, M.J. McGlinchey, M.A. Brook, Organometallics, 1997, 16, 5048. 456. P.C. Su, Y. Chi, C-J. Su, S.M. Peng, G.H. Lee, Organometullics, 1997,16, 1870. 457. S . Mikan, T. Weidmann, V. Weinrich, D. Fenske, W. Beck, J. Orgunomet. Chem., 1997,541,423. 458. P. Mathur, A.K. Dash, M.M. Hossain, C.V.V. Satanatayana, A.L. Rheingold, L.M. Liable-Sands, G.P.A. Yap, J. Orgunomet. Chem., 1997,532, 189. 459. M.I. Bruce, P.A. Humphrey, B.W. Skelton, A.H. White, J. Orgunomet. Chem., 1997, 545-546,207. 460. P. Blenkiron, A.J. Carty, S-M. Peng, G-H. Lee, C-J. Su, C-W. Shiu, Y. Chi, Organometullics, 1997, 16, 5 1 9. 461. C.J. Adams, M.I. Bruce, B.W. Skelton, A.H. White, J. Ciiem. Soc., Dulton Truns., 1997,2937. 462. C.J. Adams, M.I. Bruce, R.W. Skelton, A.H. White, G. Frapper, J.F. Halet, J. Chem. Soc., Dulton Truns., 1997,371. 463. W-J. Chao, Y. Chi, C-J. Way, I.J. Mavunkal, S-L. Wang, F-L. Liao, L.J. Farrugia, Orgunometullics, 1997, 16, 3523. 464. K. Lee, H-F. Hsu, J.R. Shaply, Organometallics, 1997, 16,3876. 465. R.L. Mallors, A.J. Blake, P.J. Dyson, B.F.G. Johnson, S. Parsons, Org~inometullics, 1997,16,1668. 466. A.J. Blake, J.L. Haggett, B.F.G. Johnson, S. Parsons, J. Chem. Soc., Dulton Trcms., 1997,991. 467. P.L. Mallors, A.J. Blake, S. Parsons, B.F.G. Johnson, P.J. Dyson, D. Braga, F. Grepioni, E. Parisini, J. Orgunomet. Chem., 1997,532, 133. 468. T. Chihara, A. Jesorka, H. Ihezawa, Y. Wakatsula, J. Chem. Soc., Dulton Truns., 1997,443. 469. S . Hung, W-T. Wong, Chem. Commun., 1997,2099. 470. M. Altman, J. Friedrich, F. Beer, R. Denter. V. Eskelmann, U.H.F. Bunz, J. Am. Chem. SOC.,1997, 119, 1472. 471. L. Pandolf, G.A. Rizzi, G. Paiaro. Inorg. Chim. Actu, 1997,254, 173. 472. D. Braga, F. Grepioni, D. Walter, K. Henbach, A. Schmidt, W. Imhof, H. Gorls, T. Klet tle, Orgunometallics, I 997, I6,49 10. 473. I. Ara, L.R. Falvello, S. Fernandez, J. Formies, E. Lalinde, A. Martin, M.T. Morino, Orgunometallics, 1997. 16,5923. 474. I. Ara, J.R. Berengner, J. Fornies, E. Lalinde, Inorg. Chim. Acta, 1997, 264, 199. 475. I. Ara, J.R.Berengner, J. Fornies, E. Lalinde, Orgunomefullics, 1997, 16, 3921. 476. M.Munahata, L.P. Wu, T. Kuroda-Sowa, M. Maekawa, Y. Suenagu, K. Sugimoto, Inorg. Chem., 1997,36,4903. 477. Z . I. Hussain, M, Whiteley, E.J.L. Mclnnes, J. Orgunomet. Chem., 1997,543,237.

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270 478. 479. 480. 481. 482. 483. 484.

Orgunometullic Chemistry

F.F. de Biani, F. Jihle, M. Spiegler. M. Wagner, P. Zanello, Inorg. C k m . , 1997,36, 2103. E. Hendrickx, A. Persoons, S. Samson, G.R. Stephenson, J. Organomet. Chem., 1997,542,295. A.A. Koridze, V.I. Zdanovich, A.M. Skeloumor, V.Y. Lagunov, P.V. Peregudov, F.M. Dolgushin, A.I. Yanovsky, Orgunometullics, 1997, 16,2285. Y . Nishibayashi, K . Segawa, Y. Arikawa, K. Oke, M. Hidai, S. Vemura, J. Orgunomet. Clzem., 1997,545-546, 38 1. R.Weidermann, R. Fleisher, D. Stalke, H. Werner, Orgunometullics, 1997,16, 866. R.F. Galan, F.A. Jaton, B.R. Manzano, J.R. de la Fuente, M.Vrahami, B. Jedlicka, W. Weissensteiner, G. Jog], Orgcmometullics, 1997, 16, 3758. J.B. Sheridan, K. Temple, A.J. Lough, I. Manners, J. Chem. Soc.., Dalton Truns., 1997,711.

6 q-C5H5and q-Arene Substituted Transition Metal Complexes BY I.R. BUTLER

1

Introduction and Main Group Cyclopentadienyl Ligands*

The review has been changed slightly in format in that more emphasis is given to articles where the cyclopentadienyl and arene ligands are non-spectators, thus the number of references has been reduced dramatically in comparison with previous years. The general format however follows that used in previous issues.’ Overall the use of cyclopentadienyl ligands as both stabilising and functionalisable groups continues to be a fruitful area of research. The synthesis, structure and bonding in [ ( ~ l ~ - C ~ M e ~ ) A l - F e ( Chas 0 ) ~been 1 described. The compound is obtained on reaction of [{Cp*AIC12)2]with an excess of [K2Fe(C0)4]in toluene. The product was obtained as colourless cubes in relatively low yields (10-2O‘Yo) and attempts to increase the yields by the use of stabilising solvents were unsuccessfuL2 A general review has dealt with the synthesis of the types of complexes which may be obtained from bis-(dimethylsily1)dicyclopentadiene ligands e.g. the use of the salt 1 in ~ynthesis.~ An extremely useful review article entitled ‘From Organotransition-Metal Chemistry Towards Molecular Electrons:’ has been published in which the redox chemistry of biferrocenes, triscyclopentadienyldiiron complexes and bis(arenecyclopentadieny1 complexes) has been discussed in detaiL4 Other general reviews are as follows: ‘Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemi~try’,~ and the coordination chemistry of pentahalocyclopentadienes.6 Amidoarsenic-substitutedcyclopentadienyl ligands have been prepared in the second paper in the series of cyclopentadienyl arsenic derivative^.^ Meanwhile a theoretical study has been carried out on the geometry of coordinatively UnSdtUrdted two-legged piano stool complexes which contain 16-valence electrons.* A useful study has been carried out on the fluxionality of tricyclopentadienylaluminium compounds and the data obtained has been compared with solid state X-ray crystallographic information.’ The use of anstr-calcocenes in the reductive coupling of fulvenes has been * Throughout this review the abbreviations Cp, Cp, Cp*, Cp’, Bz, hmb, and Fp explicitly denote (q5-C5H5),$q5-C5H4Me),(q5-C5Me5),(unspecified cyclopentadienyl), (q5-C,H,), (q5-C6Me6)and [(q -C5H5)Fe(C0)2],respectively. Other abbreviations are as listed in the abbreviations list.

Organometallic Chemistry, Volume 27 0The Royal Society of Chemistry, 1999

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Orgunometullic Chemistry

272

+$$ Li+

Me 1

explored" and the synthesis and characterisation of a series of alkali metal(+)neomenthylcyclopentadienyl complexes has been described: their structures are intriguing multidecker polymeric zigzag chairs. I A range of novel ligand precursors pofyelement substituted cyclopentadienyl and indenyl boranes and arsanes containing Me& and Me3Sn- have been obtained. l 2 Lastly vibrational studies of (qs-Cp) metal complexes have been carried out.13 ~

2

Monocyclopentadienyls

Lanthanides and Actinides - The synthesis of [Cp*$3mH] has been reported in a very elegant paper which also deals with the reaction of [Cp*$m] with ethylene to give Cp* insertion products (insertion proceeds into the Cp* ring via the 0-bond Cp*). l 4 The complexes [(C4Me4P)2Yb(C2Me2(NiPr)*C)] and [(C4Me4P)Y b(C2Mez(NMezC))] have been prepared from [(C4Me4P)Yb]," and the synthesis and structure of [(t-C4H9CsH4)2Yb(THF)2][BPh4]has been reported together with its catalytic activity with respect to styrene polymerisation.I6 A binuclear substituted cyclopentadienyl complex has been obtained on reaction of Lac13 with excess NaCp, followed by the reaction with (S)-(+)-(1-phenylethyl)salicylideneamine.l7 The synthesis and characterisation of a range of cyclopentadienyl-lanthanide iodides has been carried out. Variable temperature N MR studies have been performed on the products and these compounds have been shown to exhibit fluxional properties. All of the products obtained also showed catatytic activity towards Diels-Alder reactions. Is A diastereomericalfy pure organolanthanide hydride complex, as shown in 2 has been isolated and it has 2.1

been demonstrated to be the active species in a number of asymmetric catalytic reactions." The gas phase reactions of metal cations and their monoxides with Cp*H to form cyclopentadienyl cationic products has been reported,20 and an interesting general paper has described the formation of anti-aromatic cyclopentadienyl cations.2' The reactions of [Cp2*Se] with transition metal carbonyls have been documented 22 together with the structures of [CpSn{Zrz(OPr')g}] and related complexes.23A thorium bis-(q8-pentalene) complex has been obtained in

6: q-C5H5 and q-Arene Substituted Transition Metul Complexes

273

the reaction of 2 equivalents of K2[C8H4(SiiPr3-I ,5)2] with ThC14. The product is .~~ structural obtained as a mixture of staggered and eclipsed g e o m e t r i e ~ Finally, studies have been carried out on [q'-(C5Ph5)SnC13]and the related radical [C5Ph5*].25 2.2

Titanium, Zirconium and Hafnium

-

The crystal structure of

[Zr-{q5-C5H4(SiMe2CH2Ph)}(CH2Ph)3] has been reported.26 Microwave synthesis has been applied to the preparation of optically active cyclopentadienyl ligands - the condensation of the optically active ( - )-pinane-3-carboxylic methyl ester with vinylic lithium reagents gave alcohols which were dehydrated to chiral cy~lopentadienes.~~ The synthesis of benzyl-substituted cyclopentadienyltitanium complexes28and a one pot synthesis of a bifunctional cyclopentadienyl ligand attached to a phenolic group using the metal(tetra-benzylate)complex precursors have been described.29 Again the preparation and characterisation of [(C5Me4Ph)TiCl3Jand [(C5Me4Ph)TiC12]2(p-O)30have both been reported and a simple and effective synthetic route to the complexes [(q5:q1C5H4(CH2),NR)TiR2], R = C1, alkyl, has been de~eloped.~' The syntheses of a range of mono-cyclopentadienyltitanium complexes such as [Cp*Ti(Me)(E)(p-Me)B(C;f5)3],32 and also the series of half sandwich diene and dienyl complexes, both for use as olefin polymerisation catalysts, have been developed The first monofluorenylzirconiumtrichloride complex [(q5:q'-C1~H~CH2CH20Me)ZrCI2(p-C1)]2 has been obtained in the reaction of ZrCl4 with fluorenyl lithium. The weak fluorenyl-zirconium bond is stabilized by coordination of the pendant ether chain on the ligand thus rationalizing its isolation.34Finally the synthesis and characterisation of [q5-C5Me4"Pr]MF3,M = Ti, Zr, Hf,35and the formation of [Hf-(q5:q':q 1-C5Me4SiMe2N(CH2)2(OMe)nBu2)]have both been reported.36 A range of cyclopentadienyl indenyl and bis cyclopentadienyl titanium-imido complexes have been prepared; a significant number of compounds are reported in this paper together with mechanistic details of for example pyridine exchange.37 Finally in a paper entitled 'Synthesis, characterisation, crystal structure, reactivity and bonding in titanium complexes 2,3,4,5-tetramethylpyrrolyl' the reactions of [Li(NC4Me4)] with titanium chlorides are discussed.38

2.3 Vanadium, Niobium and Tantalum -- The reaction of Li[C5HSBNMe2]with [(tribenzylidenemethane)TaMe2Cl]affords the complex (TBM)[C5H5BNMe2]TaMe2 which has been structurally ~haracterised.~'Lithiation of trovocene followed by a quench with C 0 2 afforded the complex (q7-C7H7)V(q5-C5H4C02H) after hydrolysis. The EPR spectra of the product complex together with its anhydride and acid chloride derivatives were then described and inter~reted.~' The molecular structures of [(q5-C5H4C02R)M(C0)4],M = Nb, Ta, R = CH3; M = Nb, R = Ph 41 and the insertion of isocyanides in the tantalum carborane complexes [(Et2C2B4H4)CpTaR2],R = Me, Ph,42 have been reported while a comparison of [Cp*(q4-C4H6)NbMe2] with dimethyltitan~cene~~ has been made. A simple and effective synthesis of [Cp*V(O)C12] has been reported: this utilises Cp*VC12 and molecular oxygen as the source materials.44The cluster

214

Orgunornetullic Chemistry

complex [Cp*V(p-C1)2]3 has been obtained in the reaction of VCl,(thf), with Bu",SnC5Me5.It was subsequently oxidized to CpVC12(0)(see also ref. 44.)45An electrocatalytic reduction process of [Nb[q5-C5H4(SiMe3)12(CI)(NHPh)]BF4has appeared. This complex is protonated on nitrogen to give the corresponding cationic complex, which subsequently undergoes an amido group elimination, which is electrochemically induced.46Further arm-q-cyclopentadienylimide derivatives of niobium47and a related reference have appeared.48

2.4 Chromium, Molybdenum and Tungsten - The three different reaction types exhibited by [Cp*Mo(NO)(CH2SiMe3)2]with various lithium reagents (lithium amide reagents, lithium trimethylsilazine, LDA and ally1 lithium) have been described to give deprotonation products such as [Cp*Mo(NO)(CH2SiMe3) (=CHSiMe3)]2 [Li2(thf)3Ir and [(q5;q'-C5Me4CH2)Mo(NO)-(CH2SiMe3)2][Li(thf)3].49A communication has examined the effect of electron pairing as a stabilising factor in open-shell organometallics in the case of 15-e CpMClz(PH3) complexes, M = Cr, Mo.~*The reaction of bis(pdipheny1phosphino)dicyclopentadienyldimolybdenum complexes with electron withdrawing sub~tituents~' has been described in detail as have the substitution reactions in the dinuclear p-SR)2][BF4] induced by molybdenum(I I I) thiolato complexes [Cp12M02(C0)4( isocyanato l i g a n d ~ I.t~has ~ been observed that the structure of the 17-electron complex [Cp*MoCl2(dppe)]adopts the unusual truns geometry in the solid state in contrast to the cis geometry previously reported for the related [CpMoBr2(dppe)].53 The reactions of the clusters [Cp(q5-RC5H4)MoNiFeS(CO)5]and [(CpMoNiFe(S(C0)5)2(q5-C5H4C(0)CH2)2] with Fez(C0)g give rise to isolobal addition/ displacement products.54 The reactions of the metal acetylenes [Cp(NO)(CO)WC=CR]- with alkyl halides give rise to q7-alkyl derivative^.^^ The kinetics of the reaction of a range of thiols with [Cp12M02C02S3(C0)4]have been investigated and have been found to be first order in thiol and in the cluster.56 The interesting arsino-carbene complexes [CpW(CO)2(=C(R)}-AsPh2][PF6-], R = aryl, have been prepared from the carbyne complexes [CP(CO)~W = CRI5' The reaction of the anion [Cp(CO)3W]- with CH212 in CH3CN gives [cp2(co)6w2(pC = C)] while in MeOH the dinuclear ketene complex [Cp2(CO)5W2(p,q',q2CH2CO)I is obtained under identical condition^.^^ A key paper has described the trapping of the intermediate [Cp*W(NO)(q2PhCECH)] formed in the C-H bond activation of alkanes by [Cp*W(NO)(CH2siMe3)(CPh=CH~)l.~~ The preparation of [Cp2W2(CO)4(p4-L2)]L = dppm in the direct reaction of [Cp2W2(CO)4]with the phosphine has also been reported.@The unusual reactivity of the Co-Sn bond in [Cp[(q2-C2H4)(Co-Sn)CHSi(CH3)3]2]in the reactions with chalcogens is the subject of a communication reporting the first Co-Sn-chaicogen bond.6' A cyclic anhydride complex is obtained viu a lactone (~ with carbon moncomplex in the reaction of [ C P W ( C O ) ~I-CH=C(COMe)N)] oxide.62 Further reactivity studies of q5-Cp, q5-Ind and their substituted analogues with M2C12(NMez)4 have been carried out and the crystal structures of [Mo(q5-1nd)(NMe2)4]and [W2Cp'2(NMe2)4]have been described.63The reaction

6: 4-C5H5und q-Arenc. Substituted Trunsition Metal Complexes

275

of [CpMo(NMe2)3] with aryl or alkyl alcohols proceeds to yield a range of amidooxomolybdenum complexes.64 Other general references in this section which are reported in a summarised Fashion are as follows: amidine and guanidine complexes;65the synthesis of linked cyclopentadienyl-amide complexes;66the synthesis of pentamethylcyclopentadienyltungsten imido, hydrazido and amino acid derived N - 0 chelate l i g a n d ~ the ; ~ ~deprotonation of [Mo(COR)(C0)2(PPh2H)Cp], R = Me, Et;68 a study in the reactivity of [CpCr(N0)2(H20)]' in historical context of cyclopentadienylchromiumdinitrosyl chemistry;69 metallation of the phosphido ligand [Cp2M2(C0)4(p-PH2)]-, M = Mo, W;70the synthesis and spectroscopic (NMR, PES and gas phase diffraction) characterisation of [CpMo(N the synthesis and fluxional properties in indenylmethylmolybdenum and tungsten complexes;72the air oxidation and carbonyl substitution in [Cp*2Mo2(CO)4(pRCCR')] with trimethy lamine-N -oxide or nit rosonium tet rafluoroborate;73 an investigation of the reaction of FpMe and [CPM(CO)~M~], M = Mo, W with B(C6F5)3;74the synthesis and characterisation of [Cp3Mo(C0)3]complexes, Cpf = 1, ~ , ~ - ( C ~ H J ) Cthe ~ Hsynthesis ~ ; ' ~ of [Cp'MoC14(PH2R)]; R = 2,4,6-Pri3C6H2, c y ~ l o h e x y land ~ ~ trans-[Cp2MoO2(p-O)(p-Te)] and cis-[Cp2M0202(p-O)(p-S)] from [ C P ~ M O ~ F ~ ~ ( C O ) ~ ( ~ ~ and - S ) ( 02;77 ~ ~ - T the ~ ) I synthesis of K[(q5C5H4MeMnH(C0)2]78and [ { C5H4(CH2)2NMe2) M o ( ~ - S ) ~ S ~ - C H protona~];~~ tion studies in [Cp*MH3(dppe)],M = Mo, W;80 the synthesis and structure of [Cp2M021r2(p3-Co)(p-Co)5(C0)4]8'; the decarbonylation of [MoW(Cp)2(C0)4( p - d ~ p e ) ]the ; ~ ~synthesis and structures of cis- and trans-dimolybdenum nitrosyl derivatives bearing silyl substituted cyclopentdienyl ligand~;~' the nucleophilic and electrophilic reactions of C5 cyclo-polyenes bound to [CpMoL2]"+ (L = phosphine, CO) fragments;84the directed synthesis of chromium and molyb; ~ ~phosphine denum metallaborane clusters (e.g. (Cp*Cr)ZBSH9 e t ~ . ) the substitution reaction of [CpW2(C0)7(p-PPh2)];86a detailed study of the reactions of [CPCO(L)~] with diyne~;'~ and other general references on molybFinally a route to the extremely strong donor denum cycl~pentadienyls.~~*~~~~~ fragment [Cp*W(NO)(PPh3)] which involves the ligand induced reductive elimination (of the CJ bonded ligand) in [Cp*W(N0)(H)(q2-Ph2PC,H4)] has been discussed.9 1

2.5 Manganese, Rhenium and Technetium - The synthesis and properties of the heterobimetallic sesquifulvalene complex [(CO),Mn(p-q5:q7-C5H4C7H6)Cr(C0)3]Br4-has been examined,92and a time resolved infra-red spectroscopic study has been carried out on [CpRe(C0)3] in both conventional and supercritical fluid solutions. Interestingly the complexes [CpRe(CO)zXe] and [CpRe(CO)2Kr]have been shown to have 'significant' stability.93The oxidation of the rhenium carbonyl complex [(q5-C5H4(CH&N(CH3))Re(C0)2] with MCPBA affords an q2-C02complex.94The synthesis and reaction chemistry of [CptRe(NO)(PPh3)CN(Ph3P)(ON)Re(Cp*)]+TfO-, Cps = Cp, Cp* have been explored.95 A high yielding synthesis of chiral rhenium complexes, formed by the nucleophilic addition of either alcohols, thiols, allylsilane or triphenylphosphine to rhenium allylic alcohols has been described.96Meanwhile the synthesis of the

276

Orgunometullic Chemistry

complex [p-(q5-C5H4(CH2)2N(H)CH,)Re(C0)2] which was obtained from sodium cyclopentadienide has been described. 97 Other significant references are as follows: the structure and reactivity of [ReBr2(q4-C4Ph4)(Cp)] and [Re(=C(Ph))-q3-C(R)CCHCHC6H4PPh2-o)C P ] [ B F ~ ] ;the ~ ~ photoexcitation of iron-ally1 complexes of the type [(q5:q1C5H4CH2CH2PPh2)Fe(CO)(q I-CH2CR=CH2)], R = H, CH3;99 the reaction of [Mn(Co),CCp[(q6-C6H4)Mn(co)3]}] with aryllithium reagents;"" the synthesis of the 2: 1 adduct of complex [CpRe(NO)(PPh3)NH3]+ and 18-crown-6 using vapou r diffusion; the synthesis of [Cp*Re(q3-C3H 5)(CO)CI] from [Cp*Re(C0)3] and ally1 chloride and its reaction chemistry with LiBEt3H to give the corresponding hydride; Io2 the preparation and characterisation of cyclopentadienylrhenium-silyl ethers of the type [Cp*(CO)(NO)ReC(0)OSiR3],R = Me2Ph, Et3;Io3the reactions of [Cp*(CO)Re=Re(CO)Cp*] with terminal alkynesto4and finally the synthesis of C02-bridged Re-Sn compounds, e.g. [Sn(02C)Re(NO)(Cp*)(CO)]Me2].105

2.6 Iron, Ruthenium and Osmium - Two new types of ruthenium complexes, Ph)=CPh] and [(q5-Ph4C4COH)(CO)2RuCnamely [(q5-Ph4C4CO)(C0)2RuC( (CO;!Me)=CHCO2Me] have been obtained on reaction of [(q5-Ph4C4COHOCC4Ph4-q5)(p-H)(C0)4Ru2] with alkynes. It was observed that the first of these complexes acts as a catalyst poison due to its stability, however the second is able to itself act as a catalyst in the hydrogenation of alkynes.Io6 The unusual rearrangement reaction (shown as 344) occurs on thermolysis of the binuclear precursor complex 3 in heptanel" and the thermal rearrangements in disilyl-

A

oc'~'-si co

4

bridged bis(tetramethyl)cyclopentadienyltetracarbonyl diiron have been reported by the same authors.'" A number of butadiynyl complexes with terminal (CP*F~(CS)~) and/or (Cp*Fe(PPh2(CH2)2PPh2))groups have been prepared. Io9 The synthesis of novel inorganic cage structures based on AuS and cyclopentadienylruthenium ligands,' l o and the use of [CpRu(chiraphos)]+ as a chiral auxiliary in the synthesis of (R)-sulforaphane and its (S)-sulforphane epimer' I have been described. The metallophosphaalkenes [Cp*(C0)2FeP=C(NMe2)2] react with sydnones 3-aryl-NNOC(O)CH, aryl = Ph, 4X-CsH4, X = F, U , Br, to afford ferriophosphaalkenes, [Cp*(CO),FeP=CHN(R)N=C(N Me2)2]. l 2 The reaction of hydrosilanes with the methoxycarbonyl complexes [Cp(L)(CO)MC02Me],M = Fe, Ru, and related cobalt and manganese complexes carried out with and without catalysis have been investigated.' l 3 The compounds FpMe (Fp = CpFe(COh-) and Cp'Fe(C0)zMe were prepared as a, p and y-

'

6: q-C5H5 and q-Arene Substituted Transition Metul Complexes

277

cyclodextrin inclusion compounds and their ligand substitutional properties with phosphines were examined under inclusion conditions, which were exemplified by the lack of CO insertion products usually observed.Il4 The hydration of a terminal-vinylidene containing ruthenium complex gave rise to the formation of a carbonyl complex and a ketone. I l 5 The ruthenium(I1) allenylidene complex [(q5ind)Ru=C=C=C(R)Ph(L)2]PF6, L2 = 2PPh3, dppe, dppm has been reacted with a number of nucleophiles and attack on the a- or y-carbon is observed dependent on the reaction steric requirements. The three-electron reduction product of [(q5C5Ph4)(2,5-benzoquinolyl)Ru(C0)2Br]has been shown to be best represented in an 18-&metalate anion with a semi-quinolyl substituent of the form shown in 5.’17 The reactions of hydrosilanes with the complexes [Cpf(PR3)20sCH2SiMe3], c p t =

Cp, -~ Cp*, R = Ph, Me have been used to prepare a range of osmium I1 and IV silyl complexes. I The reaction of Na[Fp]O.Sthf with [(r16-C,H,)Cr(Co)2(CH,CN)] give the new heteronuclear anions [Cp(Co)Fe(~-Co)2Cr(co)(116-C6Hs)l- Naf which was subsequently alkylated. l 9 A structural comparison of the isoelectronic cyclopentadienyl, indenyl and hydride (3,5-dimethylpyrazolyl)borate complexes of osmium (VI) has been made.I2’ The reaction of [Cp*Ru(OMe)]* with carvone gives rise to a range of Cp*Ru-enyl and ally1 complexes. As an example the reaction of dihydrocarvone leads to clean dehydrogenation of the cyclohexenone core to give planar chiral [Cp*Ru(carvacrole)J.12’ The thermolysis of [Cp(PPh3)Ru{SiMe2-O(OMe)-SiMe2}] with phosphine ligands produces o-metallated triphenyl phosphine products of the form [Cp(L)RuSiMe2(o-C6H4PPh2)].12* The reaction of [Cp*Ru(CI)(PPh3)=C=CHPh] with Et3N affords a product [Cp*Ru(PPh3)(C = CPh)] which can be further reacted in ether with a range of small molecules such as CO, Hz, PhC=CPh and C02 to give a range of stable products.12’ The cleavage of the dimeric [Cp*Ru(acac)]2 by a range of CT- and n-donor ligands has been carried out and a Ru-L bond strength has been established for a range of ligands, from phosphines to a 1 k ~ n e s . INumber ~~ 33 in the series ‘Transition-Metal-Substituted Acyl Phosphanes and Phosphaalkenes’ is on the subject of the reactivity of metallodisilylphosphanes and arsanes [Cp*(C0)2MI(SiMe3)2], M = Fe, Ru, E = P, As, with CS2. 125 The facile nucleophilic addition of thioethers to the complexes [Cp*Ru(q4-CH2CHCHCH2)Br2]CF3S03 has been demonstrated.j2‘ The neutral fragments ‘CpFeC5H4=O’, ‘CpFeC5H4CH2’and ‘CpFeC5H4’have been generated in gas phase tandem mass spectrometry.’27

278

Orgunometullic Chemistry

The synthesis of [(q5-C5Me4CF3)M(p-CO)(CO)]2,M = Fe, Ru, complexes has been achieved.'28 The interesting stereospecific thermal rearrangement 6-7 essentially a cis to

0 6

7

trcins-isomerisation, occurs in an intramolecular reaction. 129 The potassium salt of [CpFe(CN)2(CO)]- has been used as a model compound for an examination into the Fe-site in nitrogenase. The similarities to the site as well as the critical differences have been e v a 1 ~ a t e d . A I ~ comparison ~ of the reactivity of phosphenium complexes of the type [q5-CpFe(CO)(ER,)(P(OMe)(NCH2)2)] has been E carried out. The reaction of [Cp(CO)(EMe3)F;e(PN(Me)CH2CH2NMe(OMe)f, = Si, Ge and Sn, with the Lewis acid BF3.0Et2 has been the focus of much work.13' Meyer's complex [OsH2C12(P1Pr3)2]has been used as a synthon towards cyclopentadienyl osmium derivatives. I 32 An update of the work describing Fp*-(C = C)2-Fp* oligomers has been reported with the full paper on the synthesis of these linear conjugated polyvinyl materials. 1 3 3 The metallocarboxylates FpC02- and RpC02- have been generated at -78°C in T H F by treatment of the metal salts with C02. The carboxylates were then systematically trapped using MeRSiC1. A whole range of spectroscopic techniques have been carried out to examine these interesting rcaction intermediates. 134 The new metalloarsine [Fe(AsPh,)(dppe)Cp].2thf has been structurally characterised: the complex was prepared by metathesis of Fe-I with K(AsPh2).2thf. 3s The interesting ring contractions of a cyclohexene, which results in the formation of a coordinated methylcyclopentadienyl ligand, has been found to occur in the thermal reaction of [ R u ~ ( C O ) I with ~] c y c l ~ h e x e n e .A '~~ range of cationic [(2-aminoethenyl)carbene]iron complexes have been obtained in the reactions of primary amines with [Cp(C0)2Fe(C(OMe)CH=CR(OMe))][PFG-] which in turn were obtained in the reaction of methanol with alkynyl methoxy carbenes [Cp(C0)2Fe(C(OMe)C= CR)+][PFh-]. '37 Some other interesting articles presented in list form are as follows: the ring methyl activation in Cp*M- complexes of the [Ru(q2:qsCsH&H20(CH2),,CH=CHR2)(CO)12]+ BF4- with n ~ c l e o p han ~assess~ ~ ~ ~ ment of the aromaticity of Group 14 metalloles; ' 3 9 the synthesis of [CpRu(=C=C=CR2)(PPh3)3]PF6 complexes; the use of [CpRu(CH3CN)$ as a precursor to carbonyl cluster synthesis;'41 the synthesis and characterisation of [Cp*2Fe(p-SEt)2(CO)2]2[tcnq]; 142 and the preparations and reactions of [CPOS(A N) 3]+.'43 2.7 Cobalt, Rhodium and Iridium - The complex [Cp*IrCl2PPh3]was unexpectwith PPh3. This reaction edly formed in the reaction of [Cp*Ir(q5-C6€i50)][BF4]

6: q-C5H5 und V-Airene Substituted Trunsition Metul Comp1c.rc.s

279

involves C-CI solvent bond activation. '44 The structural effects in the reductive activation of [(indenyl)Rh(L)] complexes specifically the reduction of [Rh(q5C9H7)(q4-COD)] have been described which deals with the formation of the radical ion intermediate and then the d i a n i ~ n . 'The ~ ~ reaction between [Cp*RhC1]2 and disodium maleonitriledithiolate ( Na2mnt) in dichloromethane afforded the complex [Cp*Rh(mnt)].In solution the complex is monomeric but a reinvestigation of the solid state structure has revealed a dimeric entity.'46 The reactions between cyclopentadienyl ligands bearing bulky substituents with cobalt atoms using metal vapour synthesis has been explored and a significant number of new cluster complexes have been obtained and characterised. 147 The reactions of the iminoacylcobalt complexes [CpCo(C(CH3)NCH3)(PMe2Ph)] with propargylic esters afford half sandwich compounds of the type [CpCo{C(CH~)=NHCH3}(C=CC02R)(PMe2Ph)l.l4* The first molecule containing [q5-NC4H4]- and an organic C-NC4H4 group has been r e ~ 0 r t e d . The I ~ ~ mechanism of C-fluorine activation by [Cp*Rh(PMe3)H2] has been studied it has been found that the reaction is autocatalytic with the fluoride responsible for the catalytic effect.'50 In the series of papers on borole derivatives the iodine degradation of the triple-decker sandwich complexes [(pC4H,BR){RR(C4H4BR)}2], R = Ph, Me to afford [ R ~ ( P ~ - I ) ( C ~ H ~ B and R)]~ bis(boro1e)rhodium complexes has been described. 15' The results of molecular mechanics calculations on transition-metal inserted thiophene complexes have indicated that the best metallocyclic geometries result from steric rather than electronic The reaction of [Cp*IrC12]2 with the lithium amidinate RN(CCH3)NRH results in the formation of an iridium(I1) complex [Cp*IrX(CH3C(NR)2)], R = t-Bu, cyclohexyl, X = Br. A range of alkyl complexes were subsequently obtained by metathesis of the halide 1iga11d.I~~ The isomerisation of an alkylidene moiety [CpCo(S2C2(COOMe)2)(C(COOMe)*)] by metal carbon bond cleavage has been investigated; the radical anion of one of the bridged isomers undergoes irreversible isomerisation to the ylide anion.'54 The complex [Cp*Rh(PMe3)PhH] reacts with selenophane at 60 "C to give the C-Se insertion product [Cp*Rh(PMe3)(SeCH=CHCH=CH)] which has been spectroscopically ~ h a r a c t e r i z e d . ' ~The ~ reactions of [LRu(PPh3)2CI], L = CpCo(P(O)(OEt2))3 with PhC= CH and 3-butyn-1-01 give rise to a range of vinylidene complexes and cyclic carbenes.'56 In an interesting mechanistic paper the addition of ethylene to an Ir-OH bar in the complex [Cp*Ir(PMe3)(Ph(OH))] in benzene at 20 "C has been studied. The reactions, although superficially simple, actually involves the participation of two metal centres to form the ultimate The reaction of triflic acid with [Cp*Ir(PO'Pr)3(CH3)2] affords the ally1 complex [Cp*Ir(q3-C3H5)(P(OH)(0'Pr)lOTf and methane. 15* A mechanistic study has provided direct evidence for a dissociative mechanism in the C-H activation process by a cationic iridium complex [CPIr(PMe3)CH3J.'59Either the mononuclear [Ir(q4-HC4R,R')(q3C9H7)] or the dinuclear [(q5-C9H7)21r(CO)(p-C2R2)] are obtained from the with C2R2.I6' reaction of [(q2-CgHl4)(q5-C9H7)(C0)Ir] The vicinal C-H bonds in the cycloalkenes CnH2n-2 (n = 5-8) have been observed to be activated in the presence of CpCo- fragments. For example using

280

Orgunometullic Chemistry

[CpCo(C2H&] the trinuclear cluster complexes of the form [H2{CpCo}3-p3C2(CH2),-2}] are obtained whereas the use of the 'more active' [Cp2Co]/K leads to the formation of tetranuclear clusters containing P ~ - C ~ ( C H Z2) ~ fragments.16' The electrochemical formation of the complexes [(q5-RC5H4)Co(C4H2Ph4)],R = H, Et, 'Pr, Bn has been achieved using a cobalt anode in the simultaneous electrolysis of the substituted cyclopentadiene with diphenylacetylene in acetonitrile. On addition of iodine the tetrabutadiene ligand is eliminated with the formation of the diiodide dimers [ ( ~ ' - R C ~ H ~ ) C O I ~ ] ~ . ' ~ ~ Other general references presented in list form are as follows: the synthesis of [CpCo{K ~ (C,s)-C(=CH2)N(R)C(=S)}(PMe2Ph)];163 the crystal structures of [Cp*Ir{q3-(SPPh2)3C-S,S',S'f}]BF4;la the crystal structures of mixed Mo/Ir cyclopentadienylcarbonyl and phosphine clusters; 165 the synthesis of 7,7'[Cp*Co(2,3-Et2C2B4H3)]2and related cyclopentadienylcobalt carboranes;'66 the synthesis of [ I I - R ~ ~ ( ~ - H ) ~ ( C O ) ~ (167 ~ ~the - C synthesis ~ H ~ ) ] ; of cyclopentadienyl containing Co, Rh and Ir silaborate complexes;I6' the reactions of [Ir3(p-CO)(q5CgH7)3] with Cu', Ag+, Au' or Hg2+fragments to form an array of new cluster complexes; 169 phosphinoalkyne additions to [Cp2Rh2(p-CO)(p-q2:):; CF3C2CF3)];' 70 the characterisation of [Cp*IrC2(tert-butylphosphirane)]; chiral cobalt amidophosphonate complexes; 172 the simple effective synthesis of the rhodocenium complexes containing 1,2,3-tri-tertiary butylcyclopentadienyl ligands; 173 and rhodium cluster complexes. '74

2.8 Nickel, Palladium and Platinum The trimethylene methane palladium(1I ) intermediate which arises from the loss of chloride ion from [CpPd(q3CH2C(CH2CI)CH2)] in polar solvent undergoes an intermolecular reaction to 175 The complex afford the alkyl complex [Pd{q3-CH2C(CH2C5H5)CH2}C1],. [CpNi(p-CO)(p-PMe2)CpW(Me)(PMe3)] was obtained in 58% yield on treatment of [CpNi(p-CO)(p-H)WCp] with four equivalents of PMe3 in thf.'76 A series of copolymerisation studies have been carried out on the use of metallocene catalysts to probe the nature of active sites. This study concludes that the ligand environment influences the degree of pairing and ethylene reactivity ratios may be varied by a Factor of 50 for the metallocenes used in the The reaction chemistry of [ { CpNi(PEt3)}2] with [ {CH(SiMe3)2}2AICI],InCl and TICI, Ga and Hg has been explored towards the simple effective preparation of mixed main grouphickel complexes. A range of complexes have been obtained, e.g. [CpNi(PEt&]+ [ { CH(SiMe3)2}2AIC12] - .I7' The activation of C-H bonds in olefins by cyclopentadienylnickel species has been described. The alkylindylnickel cluster compounds [(N iCp)&(C H2)'CH 31, [( N iCp)3CCH3] and [(N ~ C P ) ~2]Hwere isolated in the reaction of nickelocene with phenyllithium in the presence of 1decene. Related clusters were obtained in the similar reactions with 1-hexene. In addition, in the former reaction a range of organic products were obtained including phenyl-coupled products. Other general references are as follows: the synthesis and characterisation of [( 1-methylindenyl)NiLL'], L, L' = tertiary phosphines ;'" the synthesis of P,O bonded ligands and the preparation of the complex [q5-(C5Ph5)Ni-0,P-(Ph2PCH2C(0)C=PPh3)]+;'" and the reaction of 5(CH2)2S-6[((CH3)2Si)2C=CH]-BIoH I with [CpNiC0]2.182 ~

6: q-C5H5und 9-Arene Substituted Trunsition Metul Complexes

3

28 I

Bis-cyclopentadienyl Compounds

3.1 Main Group, Lanthanides and Actinides - The reaction of calcium amalgam with the fulvalene 8 affords the rac-unsu-caicocene complex 9.183A wide range of ansa-metallocenes (Y, Sm, Ho, Er and Lu) have been obtained in the reactions of Me2Si (C5HMe4)(C5H4(CH2)2NMe2)following deprotonation, with a range of

8

9

metal halides. The metathesis reaction between [ C P * ~ C ~ and ] [ L n ( c ~ ) in ~] toluene gives rise to a mixed cyclopentadienyl-ring compound [LnCp*Cp] while only one ring is exchanged between [Cp*Ca thf,] and [Ln(C~)~thf,].Similar exchanges are observed with lead and tin dicyclopentadienyl complexes. 185 The ‘paddle wheel’ anions [Cp3E]-, E = Sn, Pb are obtained on nucleophilic addition to Cp2Sn and C ~ 2 P b . lFurther ~~ investigations of the structures of MCp, M = Li, Na and K have been carried out and all three compounds form polymeric multidecker structures. 187 The insertion of phenylisocyanate into the Ln-N CJ bond in [C~’2Ln(i-Pr)~(thf)], Ln = Y, Er and Yb resulted in the isolation of - NPh]] complexes. 188 [C~’Ln(thf)[o-CN(i-Pr)~ The reaction of [Cp*,U(N Me2)(0C4H8)][BPh4]with amines gives a heterocyclic metallocyclic product while its reaction with ‘BuNC results in the isocyanide replacement of the thf, and with COZ, CO and CH3CN insertion products (into U-N) are obtained. The reactions of [Cp*2Sm(thf),] with one equivalent of ArOH or [Sm(OAr)2(thf)3]in toluene give rise to the heteroleptic Sm(I1) dimers [Cp*Sm(pOAr)]2, Ar = C6H2‘Bu2-2,6-R-4; R = H, Me, ‘Bu, which on further reaction with Cp*K give polymer complex products. I9O The synthesis and structural characterisation of bis-[q5-I ,3-bis(trimethylethyI)cyclopentadienyl]lanthanide and yttrium iodides’” and anciliary ligand effects on organo-lanthanide ansa-metall~cenes’~~ have both been reported while the reactions of dimeric lanthanide and yttrium hydrides with silane give rise to hydride transfer products rather than Ln-Si addition products. 193 Finally the cyclopentadienyl-ring metathesis between [Cp*2Ca] and [LaCp3] in toluene has been used to obtain compounds such as [ C P * ~ L ~ C ~ ] . ’ ~ ~ 3.2 Titanium, Zirconium and Hafnium - A preliminary communication has described the synthesis of [Cp* {C5Me4CH2B(C6F5)3}ZrPh],which is a Zwitterionic one-component alkene polymerisation catalyst: the complex is formed on reaction of the complex [Cp*(7r-q5:0-qi-tetramethylfulvene)ZrPh] with

282

Orgunometullic Cliemistry

B(ChF5)3.195A new synthetic route to 1,l'-alkylthioferrocenes and zirconocene difluorides has been described beginning directly with the alkylthiocyclopentadienyl sodium salt.'96 The first example of a stable unbridged homogeneous metallocene-betaine Ziegler catalyst system [Cp*2Zr ( ~ - C ~ H ~ ) B ( C ~has F Sbeen )~] reported. 197 The zirconocene-aluminohydrides [Cp2ZrH(p-H)2AIH2( L)], L = quinuclidine, NMe2, have been prepared from [Cp2ZrC12] on reaction with LiAlHj and then [H3GaL] or directly on reaction of [Cp2ZrHa] with the gallium reagent. 19* Doubly-bridged bis(indeny1)titanium and zirconium dichlorides have been synthesised from 1,Sdimethyl-1,5-~pclooctadieneviu a double Nazarov cyclization methodology. 199 A useful synthesis of the polymerisation catalyst M = Ti, Zr from M(CH2Ph)4 precursors [M~~S~(T~'-M~~C~)(~-B~N)M(CH~P~)~], has also been reported.200 The formation of aromatic amines from the complexes [Cp2TiAr]2N2has been described: a treatment of these complexes with a mixture of PhLi and Li results in the formation of the corresponding aromatic amine and ammonia. Interestingly in the absence of either PhLi (NH3 only formed) or Li (no amines) no amino products are obtained.20' The synthesis and crystal structures of dimethylsilylenebridged ansa-permethyltitanocenes [Ti(II), (11 I) (IV)] have been described.202An cmsa-metallocene with the shortest bridge namely [ 1 , l '-isopropylydene-3,3'-di-tBu-bis(Cp)]Ti and Zr dichlorides have been obtained using a conventional synthetic methodology.203 The cyclopentadienyl-silyl ether complexes of (CsH40SiR3) and hydroxycyclopentadiene have been prepared using conventional synthetic methods.204The regioselective dimerisation of terminal alkynes to afford 2,4-disubstituted 1-buten-3-ynes are catalysed by the hafnium dicarbolI 1)Hf(Cp)Me2].~*~ The lide complexes [Cp*(q5-C2B4HI I)Hf(p-q2:~,3-C2B9H complex products arising from the activation of the trimethylsilyltetramethylcyclopentadienyl ligand in [ { CSMe4(SiMe3)f2TiCl2]/Mg system have been characterised. The molecular structure of two products 10 and 11 have been described in detail. 206

11

The use of very large counterions in cationic metallocene polymerisation activity has been e~plored.~"' A zirconium( I I I) ally1 species has been identified in the Negishi [Cp2ZrC12.2LiBu] catalyst system using ESR spectroscopy.208 Bis(propyny1)zirconocene reacts with half an equivalent of butyltetraphenylborate to give [Cp, ZrCrCCH3'] which in turn reacts with the starting

6: q-CsH5 und q-Arene Substituted Trunsition Metal Complexes

283

zirconocene complex to give the complex salt [ ( p C = CCH3)(pCH3C ZE CC = C C H ~ ) ( Z ~ C P ~ ) ~ + ] [.209 B PA ~ ~study ] - has described the stabilizing effect of the [(CH2)2N'Pr2]on the cyclopentadienyl ligand in the use of titanocene polymerisation catalysts.210 Transmetallation has been used in the effective synthesis of ansa-metallocenes beginning with the more usual lithium salts.2' In a communication [ T ~ C P ~ ( C O )has ~ ] ~reportedly + been obtained under extremely simple conditions: either the oxidation of [Cp2Ti(C0)2] with [FeCp2][13Ph4]or the double protonation of [Cp4Ti] with [N("Bu)~H][BP~~] under COa2I2The synthesis of compounds of the type [21-{(SiMe3)2(q~-C5H3)2)Cl(q~-C(~Pr)N(2,6Me2C6H3)}] has been achieved in a paper which describes the insertion of isocyanides into zirconium-alkyl bonds in di-ansa-zirconocene complexes. The paper contains a considerable volume of synthetic work including the preparation of [zr((SiMe2)2(1l~-C~H~)~) Me(q3-CMeNR)], R = 2,6-Me$bH3, 'Bu, and its subsequent reaction with water to give p o x 0 dimeric Further Group 4 ansa-metallocenes [trans- 1,2-cycIoalkylene-bridgedbis(indenyl)MC12], M = Ti, Zr, Hf, with bridging hydrocarbyl moieties ranging between four and eight membered rings, have been prepared and used as Ziegler catalysts. The new catalysts were used in propane polymerisation. The m e d i k e diastereomers obtained during the synthesis were less active than the isomeric racemic-like systems a result which has been explained in terms of the relative shielding effects of the metal centres based on X-ray single crystal The reaction of [ C P ~ M ( P M ~complexes, ~)~] M = Ti, Zr, with N-(p-to1)-diphenylketamine [(ptol)N=C=CPhz] in a 1:l molar ratio affords the metallocene complexes [Cp2M(q2-(C,N)-(p-tol)N=C=CPh2)(PMe3)4].215 The mixed arsenic-sulfinyl metallacyclic complexes [Cp2 M(-SCH3 AsSCH3AsS-)], M = Ti, Zr, Hf, and [Cp2Zr(-SCH3ASS-)], have been obtained in the reaction of cyclo-(CH3AsS)3,4in thf with metallocene dichlorides.2'6 The synthesis, structure and reactivity of [Cp2Ti(HBcat)(PMe,)], a cr-mono-borane complex, has been propounded.217The synthesis of the papramagnetic complex [Cp2Ti(SiH2Ph)(PHCy2)] has been achieved in the reaction of [Cp2TiMe2] with [PhSiH3] in the presence of dicyclohexylphosphine.218Liquid crystalline titanocene complexes have been prepared and used as catalysts. Essentially the synthetic procedure involves the addition of a liquid crystalline group to the cyclopentadienyl ring in the t i t a n ~ c e n e Other . ~ ~ ~ useful references presented in list form are as follows: the structure of [Cp3Zr(CH3CN)]f;220model titanocene enolate cations in solution;221 the synthesis and polymerisation behaviour of chiral mixed fluorenyll indenyl zirconocene dichlorides;222the use of titanocene thiolato complexes in the preparation of new sulphur-containing heterocycles;223the synthesis of a range of bridged half-sandwich n i o b ~ c e n e sthe ; ~ ~use ~ of metallocenes [Cp2M-], M = Ti, Zr in reductive coupling of Cl,C=PR; 225 the reactions of [Cpx2MC12J,Cp' = q5C~H~B with U [(CO),M'PPh2]- to give new binuclear complexes;226the synthesis of zirconocyclopentanes by insertion of ethylene into a 7t-alkenylzirconocene complex;227the use of dimethylzirconium dichloride in the synthesis of ansazirconocenes;228 a dynamic NMR study of the complexes [M( 1,3-'Bu2-q5C S H ~ ) ( ~ ~ - C ~ H , ) ( C HM~ )=] +Zr, , Hf;229the structural characterisation of [q3C5Me4SCH2CH2CH3]2TiC12;230hydrozirconation of CH2=CHCH2SiHMe2 to

'

284

Orgunometullic Chemistry

give [Cp2Zr(CH2CH2CH2SiHMe2)CI];23' the synthesis of hafnoceneboracyclopentane complexes;232the generation and reactivity of the vinylidene intermediate [(Cp*(N))(Cp*)Ti=C=CH2], Cp*N = q 5-C5Me4(CH2)2NMe2;233propylene polymerization with chiral and achiral unbridged 2-arylindenezir~onocenes;~~~ further cmscr-~irconocene;~~~ the synthesis of chiral and achiral mono-Cp-amido Ti and Zr complexes;236 studies in the formation and decomposition pathways for cationic zirconocene hydride silyl complexes;237the synthesis of ctnsu-zirconocene binaphtholate stereoisomers;238an examination of the Cp2ZrC12/BuLimixture to characterise key solution species;239 cationic metallocene complexes which contain tetrakis(pentafluoropheny1)borate and its derivative^;^^' and the synthesis of ethylene bridged a n s ~ - z i r c o n ~ c e n e s . ~ ~ ~

3.3 Vanadium, Niobium and Tantalum - The addition of 1-(Bu3Sn)C9H7to a dichloromethane suspension of TaC15 resulted in the formation of the complex [(q 5-C9H7)2TaC12][TaC16],a rare example of a Ta(V) indenylmetal halide.242The synthesis and spectroscopic properties of dihydrogen isocyanide niobocene complexes of the type [Nb(q5-C5H4SiMe3)2(q2-H2)(CNR)]+have been described in a key paper.243The olefin-hydride niobocenes [Cp'2Nb(H)(q2-R(H)C=CH2)]have been prepared and their reactions with CO and C02 which give alkyl-carbonyl and a range of carbon dioxide complexes, have been studied.244The insertion of ClSbPh2 into a nobium-hydride bond in [CpzNbH3] gives the product [Cp2NbH2SbPh3] after d e p r o t o n a t i ~ nThe . ~ ~ rather ~ complex ligands [C5R4SiMe2N(CH2)2X], R4 = Me4, H3'Bu, X = OMe, NMe2, have been used in heterobimetallic yttrium and lutetium complexes which have been used in caprolactone po~ymerisa t ion.246 Trimethyllead niobocene dihydride has been obtained in the reaction of trimethyllead chloride with niobocene trihydride in the presence of triethylamine.247An interesting paper has described the reactions of the carbene-like insertion in the reaction of chlorophosphine with CpzNbH2. The synthesis of the complexes [(q-C5H4R)Nb(q-C5H4R')CI(NNMe)],R' = H, Me.248 The reaction of chlorophosphines is found to occur either by direct insertion of the chlorophosphine into the Nb-H bond and electron and/or hydride transfer dependent on the bulk of the c h l o r ~ p h o s p h i n eOther . ~ ~ ~ useful references are as follows: the preparation of [Nb(q-C5H4-CMe2-q-C~H4)(q2-BH4)]and [Nb(qC5H4-CMe2-q-C5H4)(H)PMe3];250 the crystal structure of CpZTa(H)(p-H)(pPMe2)Cr(C0)4;25'the synthesis of [(q-C5Me4R)2V2(p-Br)4]complexes, R = Me, Et;252and a useful preparation of unsa-bis(cyclopentadieny1)imido derivatives of Group 5 and Group 6 transition metals.253 3.4 Chromium, Molybdenum and Tungsten - The carbido-alkylidyne cluster [ C P * ~ H ~ R U ~ ( ~ ~ - C ) ( ~ ~ - Ctogether P~)(CO with ) ~ ]three other products were obtained in the reaction of [Cp*WRu2(CCPh)(CO)g]with excess [Cp*W(C0)3H].254 The synthesis of a wide range of unsa molybdocenes and tungstenocenes and an examination of intramolecular H-D exchange in some methyl and ethyl derivatives have been reported.255 Octamethyl-1, 1 -diphosphachromocene has been prepared and its spin distribution and oxidation properties have been compared

285

6: q-C5H5und q-Arene Substituted Trunsition Mrtul Complexes

with the parent c h r ~ m o c e n eThe . ~ ~synthesis ~ of bi- and tri-metallic complexes of bis(q5-Cp)W have been described - essentially the methodology makes use of the reactions of dichlorotungstenocene with lithium salts of metal complexes.257The ring-bridged chromocene carbonyl complex [Me2Si(C5Me4)]2Cr(CO)has been obtained from the reaction of [Me2Si(CSMe4)]2 Li2 with CrC12.thf in the presence of carbon monoxide. A dicarbonyl product is obtained on further treatment with CO, a consequence of a hydrogen atom shift within the initial Finally, octaisopropylchromocene has been shown to exist in a low spin state at low temperature, but it undergoes a spin transition on warming and 4 unpaired electrons are apparent in the complex at 300 K in the solid state.259 3.5 Iron, Ruthenium and Osmium - Without doubt the most interesting paper of the year was the report by Tilley on the ring opening polymerization of ethylene-bridged ferrocene. Although in the previous year there had been a reported synthesis of the same compound, the simplicity of this work makes it deserving of the accolade.260Some interesting gold complexes of N,N-dimethylaminoethylferrocene have been described. The synthesis makes use of the lithium salt of the N-dimethylated ferrocenethylamine on reaction with chloro(tripheny1phosphane)gold(I). One example is shown as the di-ligand gold complex shown as 12.26’ A range of ferrocenylhydrazones of the type [CpFe{(q5-C5H4)-

&CH2-NMe2 Au

A

Me2N-CH2

u

p Fe

C(CH3)=N-NHR)] R = C6H4-4R’, R’ = NO2, Cl, C6H4-2-CH3, etc., have been described which react with Naz(PdCl4) and sodium acetate to yield di-p-chlorocyclopalladated products.262 Further chiral ferrocenyl oxazolines have been prepared: these include the addition of thioether units into the o x a ~ o l i n eand ,~~~ enantiomerically pure phosphaferrocenes (2-formyl-3,4-dimethylphosphaferrocene) with planar chirality have been prepared using column chromatographic separation as resolution.2a A further paper has described the synthesis and structures of oxazolinylferrocenes - Rh(I) complexes of these complexes are reported and structurally ~ h a r a c t e r i z e dA. ~useful ~ ~ bisferrocene bearing tetrapyrazoline-linkages has been obtained in a synthesis which utilises ferrocenylpyrazoles as key intermediates.266 The synthesis and crystal structures of the tetrathiofulvalene complexes of ferrocene, TTF-CMe(0H)Fc and TTF-CMe(0Me)Fc have been described - these complexes were essentially prepared by reaction of the lithium salt of TTF with acetylferrocene. Interestingly, attempts to make the octamethyl has TTF ferrocene by the direct route using tetramethylcyclopentenone failed.267 An interesting C2-syrnmet1-i~ferrocenophane has been prepared using compound 13 as a precursor; the final ferrocenophane obtained is 14 following a

286

Orgunometullic Chemistry

four-step synthesis.268 An extremely useful synthesis of a phenylnaphthylphosphinoferrocene 15 has been described. The synthetic method utilizes the borohydride adducts of the phenyl(naphthy1)methoxyphosphine as key precursors.269 The synthesis and structures of E-Z isomerism in I ,2-dimethyldiruthenocenylethylene270have been described in some detail.

Ph

13

Ph

LC02H

14

15

As has become normal a significant number of references deal with complexes of dppf. The preparation and electrochemical characterisation of a further range of dppf complexes have been worked out. For example the complexes [(d~pf)Fe(NO)~],[(dppf)Co(NO)2][SbF6] as well as the well known [(dppf)Fe(C0)3] were investigated with the cobalt complex subjected to a single crystal diffraction A series of complexes of the type [(dppf)Pd(Ar)(Nt ~ l y l ~have ) ~ ] been prepared by the action of KN-tolyl on the haloprecursors [ ( d ~ p f ) P d ( A r ) I ]A. ~novel ~ ~ octa-substituted iridium carbonyl complex containing dppf has been described in a preliminary communication with the structure of the complex [H41r4(C0)4(Fe(C5H3PPh2)(C5H4P(Ph)C6H4)}]discussed in The photolysis reactions of 1,I’-diacetylferrocene in the presence of 1 , l O phenanthrolene to gave the stable trisphenanthrolene iron(I1) complex and the free cyclopentadienyl-based ions ( C S H ~ C O C H ~in) the ~ , structurally characterised The use of phenylcyclopentadiene and diphenylcyclopentadiene in the synthesis of ferrocenes and their q6-arene metal complexed derivatives275has also been reported. The stereochemical rigidity in the trimetallic complex trans[Pd{CpFe[(q5-CSH4)-CH=N-N(CH,W)2C12]276has been noted and a range of ferrocenylsilatranes (5-aza-2,8,9-trioxy-l-silabicyclo-[3.3.3]undecanes) have been the subject of synthetic, structured and theoretical investigations. These compounds are prepared from (triethoxysily1)ferrocene by reaction with triethanolamine. The silatranes are more easily oxidised than the corresponding triethoxysilanyl derivatives.277The reaction of FcPC12 with NaCo(C0)4 at room temperature unexpectedly afforded the complex [ C O ~ ( C O ) ~ ( ~ L ~ - P F C ) ( ~ ~ - P F C which has been crystallographically ~ h a r a c t e r i s e dA. ~useful, ~ ~ albeit low yielding,

6: v-CSHsund q-Arene Substituted Trunsition Metal Complexes

287

synthesis of alkyl ferrocenes has been described from lithioferrocenes. Although this procedure has been well known amongst ferrocene chemistry for several years no yield quantification was previously available.279 Interesting a-(nonamethyImetal1ocenyI)-a-hydroxycarbocations have been isolated by protonation of formylnonamethyl metallocenes with HBF4 or CF3C02H. The iron salt products have open fulvenoid structures with interionic hydrogen bonds.280In an interesting paper the reaction chemistry of trans- 1-(4-pyridyl)-ethylene ferrocene is described. Of interest are the complexes [R~(2,2'-bipy)~L,Cl,](PFs),,n = 2, m = 0, o = 2, n = 1, m = 1, o = 1, which exhibit luminescence generally by energy transfer.281 The electronic spectrum of [Fe"'(C5H4PPh2)2Re(C0)3C1]+has been examined and optical metal-to-metal charge transfer has been observed.282A range of heterobimetallic ferrocene containing complexes derived from ferrocenyle t h y l a m i n e ~and ~ ~ ~the synthesis of nitrido Tc(V) and Re(V) complexes with ferrocenedithiocarboxylate ligands has been described.284 The bonding and hyperfine interactions in neutral ferrocenyl allylic and cumulenic compounds have been described.285A useful paper has described the synthesis, structure and electrochemistry of functionalised pentamethylferrocenes: for example under normal conditions with CpFeCp* the pentamethyl group is able to function as a protecting group and the unsubstituted cyclopentadienyl ring is amenable to the normal reactions of ferrocene. In this respect a whole range of suitable functionalised ferrocenes have been obtained.286 Further palladium complexes of ferrocenyl Schiff oximes have been prepared, which result in the cyclometallation of the ferrocene in most cases.287 A facile route to ferrocifen, the ferrocenyl analogue of tamoxifen, has been described. The synthetic methodology makes use of the McMurray coupling of ferrocenyl ethyl ketone.288The condensation reactions of thiophene-2-carbaldehyde with ferrocenylamine leads to the formation of heterocyclic imine ligands with a ferrocenyl group as the substituent at the amino nitrogen.289The oxidation of ferrocenyl ketones using selenium(1V) oxide have been described with the production of f e r r o c e n y l d i ~ n e sThe . ~ ~ ~selective electrochemical recognition of bidentate anionic guests in different solvents using novel ferrocenyl thiourea and guanidinium receptors has been observed for the first time.29' Ferrocenylamines are selectively cyclometallated in the presence of mercuric acetate to afford the appropriately substituted chloromercuryferrocenes.292 There are a number of papers which continue the interest in molecular wires derived from ferrocenylacetylenes. For example, coupling of iodoferrocene in the presence of arylacetylenes affords the synthetically important precursors such as 16, which have been incorporated into a number of palladium and ruthenium complexes.293Related to this are the reactions of ferrocenylacetylenes with ruthenium complexes of the type 17. 294,295 The reductive coupling induced by remote site oxidation may be used as a novel route to molecular wires with metallocenes at both ends.296Two papers have also described the use of an octamethylferrocenes as units in peripheral groups in molecular wires as a means of s o l ~ b i l i s a t i o n . 2~(~2 -~ . ~ ~ ~ Pyridy1)phosphaferrocenes and their analogues have also been prepared as ligands with new planar chiral features.299 Probably one of the most intriguing structures of the year is the ferrocene

288

Orgunometallic Chemistry PnP

A

16,17 R = Fe, P P = Ph2PCH2PPh2

macrocycle which contains no less than seven ferrocene units in the cycle, shown as 18, which has been obtained in the polymerisation reactions of doubly silylbridged bis-cyclopen tadienyl ligands (TTDSi)2- with ferrous chloride. The

sit3

1

B3.F

18

product was extracted with hexane from the reaction mixture and was characterised using a range of techniques including mass spectrometry and X-ray ~ r y s t a l l o g r a p h y The . ~ ~ mechanism and solvent catalysis of the 1,12-metallations of [ 1. l]ferrocenophenyIIithiumhas been studied using NMR spectroscopy. In thf rapid proton transfer reactions occur between the 1,12 sites. It was concluded that the degenerate rearrangement of the mono-anion does not go by a pseudorotation mechanism but occurs by the direct syn-syn conformer conversion. The primary isotope effect of the 1,12-hydrogen transfer was measured at -7.4 at 320 K. This study answers many questions which have existed for several years in ferrocene ~hemistry.”~Further ferrocenyl dendrimers, for example 19, have been prepared using the reaction of ferrocenyllithium with vinylmethyldichlorosilene at - 20 ‘C. The product is further extended by the platinum catalysed hydrosilylation using phenylchlorosilene to give the dendron ClSiPh(CHzCH2SiMeFc2)2

6: t p C ~ H 5ant1 q- Arene Substituted Transition Metul Complexes

e

20

289

290

Orgunometullic Chemistry

which contains the reactive chlorosilane which can be further reacted with a l k e n e ~ . ~Again '~ yet more redox active ferrocenyl dendrimers have been obtained, for example 20; these complement those reported in this review last year303 and again some of these ferrocene dendrimers have been prepared as a class of super-molecular sensors in the recognition of small inorganic anions.304 One of the most interesting papers of the year is certainly the paper dealing with self-assembled monolayers which incorporate ferrocenyl thiols and porphyrins . ~ ~ ~new alkenyl complexes with the ultimte goal of artificial p h o t o s y n t h e ~ i sSome of the ferrocene ligands PPFA and PTFA have been characterised and an NMR study has been carried out to observe the alkene rotation.306The chiral recognition of P-hydroxyphosphines and the discrimination of rut.-bis(diphenylph0sphino)- 1,l '-binaphthyl is achieved by the well known cyclopalladated derivative of cr-N,N'-dirnethylamin~ethylferrocene.~~~ An interesting range of PPFA derivatives with the amino function replaced by a o-cyclopentadienyl group have been reacted to afford Ru and Rh complexes which themselves undergo interesting reactions with a l k y n e ~ . ~Polymeric, '~ redox-active ligand with switchable bonding affinities for transition metals have been reported: these are based on pferrocenylphenylacrylate polymers interacting with [Cp*Ru]+ fragments.309 A reinvestigation has been carried out into the Rosenburg synthesis of silyleneferrocenylene polymers: it has been observed that the addition of R2SiCI2 to 1 ,l'-dilithioferrocene at 0 "C leads to the formation of the [I]-silyleneferrocenophane regardless of solvent but at reflux in thf the polymer is obtained exclusively.310Phosphaferrocenes with phosphorus or nitrogen substituents have been used as new ligands for the preparation of c h i d Ru and Pd complexes for use in asymmetric ~ynthesis.~"Further work has been carried out on the substitutional effects on the rate of intramolecular electron transfer in biferrocenium t r i i o d i d e ~ . ~ ' ~ It has been observed hat decaphenylferrocenes exist in two isomeric forms: the blue [Fe(q6-C6H5C5Ph2)(q5-CsPh5)] and the unstable form [Fe(qS-C5Phs)2].313 A fluorescence and time resolved flash photolytic study on covalently linked ferrocene-fullerene donor-bridge-acceptor compounds has elucidated alternate quenching mechanisms of the excited states.314The synthesis of dehydroannulenes which contain ferrocene or (cyclopentadienylcoba1t)cyclobutadiene has A useful reaction of trimethylsilylferbeen achieved from 1,2-diynylpre~ursors.~~~ rocenes with BC13 at low temperature affords the products [(C5H4BCI2)2Fc] cleanly. Interestingly the reaction is less effective in the case of Group 4 m e t a l l ~ c e n e s . ~The ' ~ reactions of ethynylferrocenes with [RhC1(PiPr3)2] complexes give rise to a series of oxidative addition reaction^.^" Further triple decker complexes have been combined with the synthesis of the first complex with a bridging phosphoyl l i g a r ~ d . The ~ ' ~ crystal and molecular structures of 4-aminobenzoyl-4-hydroxybenzyl- and 1,1'-bis-(4-hydroxybenzoyl)ferrocenes have been reported together with an improved synthetic method to these compound^.^'^ A ferrocene-appended porphyrin has been proposed as a model for selective halide, nitrate and hydrogen sulphate anion r e ~ o g n i t i o n . ~A~ ' method of controlling the molecular architecture in the ferrocenylsilane polymers has been developed - in essence control of the end group in polymers (Cp-SiEt,,

6: q-CJHJund q-Arene Substituted Trunsition Metul Complexes

29 1

SiH) has been used to obtain graft polymers by reaction with ~ i l o x a n e s . The ~~' Manners group have also been able to isolate the product of insertion of [Pt(COD)2] with (1,l '-ferrocenediy1)dimethylsilane. The product complex functions as a key precatalyst in the ROMP polymerisation so fully explored by the same group in previous years.322 Poly(ferrocenylmethylhydrosi1ane) [Fe(qC5H4)2SiMeH] has been hydrosilylated with 1-hexene and ethylacrylate using Karstedt's catalyst to yield the functionalised polymers with pendant alkyl groups. The same methodology has then been used to attach mesogenic groups to the silylferrocenyl polymeric backbone with the formation of two new calamitic thermotropic side chain liquid crystalline polymers.323 Further ferrocenophanes which contain boron-phosphorus bridges have been prepared, which complements the work published last year in this particular area.324 An extremely useful novel soluble conducting polymer 21 has been obtained by treatment of [CpFe(q1-NC4H4)(C0)2] with N(Bu)&Og in the . ~ ~ ~ purple charge transfer presence of DBSA, after solution t h e r m ~ l y s i s Deep compounds, e.g. 22, are produced in the reaction of 2,2'-dipyridine with a range of borylated ferrocenes. A full electrochemical characterisation is reported. In the

21

22

case of the tetraboroyl tetrabipyridyl complex the complex acts as a 9-electron sponge.326 A key reference is one which allows a facile synthesis of mixed ferrocenes, i.e. unsymmetrically substituted ferrocenes. The method utilizes a well-known but normally poorly yielding procedure, of the use of an arene exchange reaction. In this case the complex [(fluorene)FeCp]PF6 in its deprotonated form is used to obtain the mixed ferrocenes FeCpCpi where Cpf is derived from a traditional cyclopentadienyl anion.327Another useful reference involves the stepwise synthesis and further derivatisation of the key compound octamethylferrocene- l , l '-dicarbaldehyde. The synthesis makes use of l ,2,3,4-tetramethyl-5-(methoxycarbonyl)cyclopentadiene as the basic starting compound.328 One other excellent paper is a study of the mechanism of ferrocene mercuriation - this paper seeks to address the age-old problem of whether the electrophilic attack occurs at the metal centre or on the cyclopentadienyl ring. The conclusion reached is that the mercuriation occurs on the cyclopentadienyl ring and it does not give rise to intramolecular interannular proton transfer reactions. In combination with the previous work by the same author, an overall view of ferrocene electrophilic substitution is presented.329A range of 1 ,l'-substituted pyridinothiaferrocenes have been prepared and the NMR spectra and electrochemical properties of these new ligands has been discussed.330 Gokel's group have further developed the systematic synthesis of diferrocenes with interesting spacers for use in sensors - these molecules are generally of the form shown as 23.331The

Organometallic Chemistry

292

‘ & - C 0 2 H

23

&CO2H

molecular structure of complexes of ruthenocene hgands dppr, such as [M(dppr)Cl2], M = Pd, Pt, Ni, have been discussed. Although these complexes have been used for a considerable time this is the first comparative paper of the structures. 332 A further complex of 1,l ’-bis(diphenylthiophosphory1)ferrocene and its selenium analogue have been obtained: a crystal structure of [Cu(dptpt)]PF4 has been described.333 A useful ambient temperature ligand exchange (arene/cyclopentadienyl) has been carried out in chloroaluminate(II1) ionic liquids - this synthesis complements the traditional AIC13 catalysed synthThe coordination chemistry of octamethyl-5,5’-di(2-pyridyl)(ferrocene towards palladium, platinum and copper has been investigated: on coordination with copper(1) an extremely high anodic shift was observed.335A further study by Grossel’s group on the alkali-metal bonding properties of ferrocenyl and ruthenocenyl substituted aza-crown ethers shows an interesting dual bonding mode which involves bonding of the outside four of the cyclopentadienyl ring in some of these complexes.336 Two tungsten carbonyl complexes of multiply substituted thiomethylferrocenes have been described.3371,2-FerrocenemethyIenediyldiamino tetraacetate (1,2-FDTA), which may be considered as a redox active version of EDTA, has been obtained in the reaction of bis(l,2-chloromethy1)ferrocene with [HN(CHZ(COOMe)*)] in the presence of base. This useful ligand has been shown to have high Ca2+/Mg2+and Ca2+/Sr2+selectivity in aqueous solution.338 The synthesis of donor/acceptor paracyclophanes with ferrocene NLO-phores has been developed. Essentially the synthesis makes use of tetrabromocyclophanes to which vinylferrocenes are coupled in the presence of palladium acetate, in the last step of a lengthy procedure. Both the absorption and electrochemical properties of the compounds are described. An example of one of the compounds prepared is shown as 24.”’ 57FeMossbauer spectra and X-ray structural analysis

6: q-C5H5and V-Arene Substituted Trunsition Metal Complexes

293

of the iodide salts of [l’,l”-bis(a- and ~-naphthylmethyl)-l,l”-biferrocenes].340 The rhodium complexes of chiral ferrocenylphosphines containing pyrazole units have been reported in which an in-depth account of the bonding and structural geometries of the complexes is reported.341 A series of new chiral tridentate ligands of the type 25 have been prepared by the Togni group in a continuation towards the preparation of new chiral ligands - ruthenium complexes have been used in the asymmetric transfer hydrogenation of a c e t ~ p h e n o n e . ~ ~ ~

I

PPh2

25 X = PCy, S

Finally two interesting medicinal papers are of general interest: the synthesis and anti-malarial activity, in vivo and in vitro, of a new ferrocene-chloroquinine analogue has been tested against a strain of Plasmodium falciparin and it has been found that one of the ferrocene derivatives tested shows high anti-malarial activity.343The use of platinum(I1) complexes of ferrocenylphoshine against leukemia has also been further explored.344 Other significant references in the area are highlighted as follows: the reaction the of ruthenocenylacetylene with [RuCIL2Cp*], L2 = (PPh3)2 or synthesis of [Fc{CH2P(CH20H)2)];346 the synthesis of ferrocene-containing bipyridines, terpyridines and bi~(pyridy1)pyrididazines;~~~ osmium carbonyl clusters of dppf;348the synthesis of mixed ruthenium dppf/bipyridyl complexes;349the X-ray structure of [Fe(f~lvene)~] and the synthesis of 1,l’-bis(benzhydry1)ferrocene and related compounds;350the synthesis of the alkynyl-bridged heterobimetallic complexes of the type [Mo(C = CFc)(dppe)(q7-C7H7)In,n = 0, l;351 the synthesis and full characterisation of [CpFe(q5-C4HMe2P)]2 and [CpFe(C4HMe2PhP)(C0)]2;352further ferrocenylcryptates for use as molecular switches for alkali and alkaline earth metals ;353 intervalence transfer in diferrocenylaryl corn pound^;^^ the synthesis of ferrocenyl bis(y1ene)phosphoranes beginning with either FcPC12 or F c P L ~dppf ~ ; ~as~a ~bridging ligand between ruthenium(I1) or Rh(II1) centres;356the coordination complexes N,N’-dimethylaminoethylferrocene with trimeth~laminealane;.~~~ the structure of E- and 2-bromo- I-ferrocenyl1-phenylcy~lopropanes;~~~ the synthesis of ferrocenylalkynyl substituted cyclohexadienyl iron complexes for N LO studies;359and ferrocene-substituted amidinate derivatives.360

3.6 Cobalt, Rhodium, Iridium and Platinum - Cobaltocene has been absorbed under vacuum at lOOK onto pyrolysed graphite and its electronic spectra have been studied using UPS and XPS: partial oxidation is observed.361Cobaltocene has been used in the reduction of [(styrene)(Mn)(CO)$ complexes to new

294

Organometallic Chemistry

bimetallic complexes which have been structurally ~haracterised~‘~ and the preparation and characterisation of ([C~H~(iPr)~l2Co), n, m = 2, 3; 1, 4, complexes which show exceptional air stability has been achieved.363The synthhas esis of the complex [Mn( q 5-HL’)(CO)3][Rh(q5-HL’)(q-C5Me5)]+[SbF6 been reported as has the crystal structure of [ P ~ C P * ~ bimetallic ]~+ complexes which have been structurally characterised. 365 Finally the carbon nanotubes have been obtained by pyrolysis of a range of metallocenes including c ~ b a l t o c e n e . ~ ~ ~

4

Arenes

4.1 Main Group - The lead arene complex [Pb(q6-xylene)2(A1C14)2Jhas been prepared and structurally c h a r a c t e r i ~ e d .A~ ~range ~ of coordination modes of naphthalene have been described in pentamethylcyclopentadienyllutechium naphthalene complexes.368 4.2 General - in paper 26 in the ‘borobenzene derivative’ series the synthesis of 1methylboratobenzene complexes of titanium, zirconium and hafnium has been reported.369 The titanium-arene complex [Ti(q2-l,3,5-C6H3’Pr)2] reacts with FeCp2[BArI4derivatives to afford a range of Ti(i) complexes of the type [Ti(q6l,3,5-C6HiPr3)2][BAr4].370 Polymeric zirconium tetrachloride dissolves in halogenated solvents in the presence of aromatic hydrocarbons to give q6-ane comp l e ~ e s . The ~ ~ ’ tantalurn(II1) arene complexes [(q6-C6Me6)Ta(OAr)2C1], Ar = 2,6C6H3iPr2, and [(q6-C6Me6)Ta(OAr)C12]have been alkylated by halide metathA range of new heterometallocycloptaneshave been prepared by incorporation of germanium into the periphery of [V(BZ)~] and [Bz2Cr],Bz = ~ l ~ - b e n z e n e . ~ ~ ~ 4.3 Chromium Arenes - The synthesis and structure of [q6-pC6H4(CH2P03H*)2]Cr(C0)3have been described.374A range of q6-bisfluorene complexes have been prepared using metal vapour synthesis - it has been observed that the reactivity of fluorene differs from that of cyclopentadiene and indene.375A range of q6-metal arene complexes have been obtained from trindane (the trimer condensation product of cyclopentanone) including the Cr(C0)2 complex.376Bis-naphthalene vanadium, chromium and molybdenum have been obtained by non-vapour (i.e. non-metal atoms) methods.377Thienyl-linked arenecyclopentadienyl complexes have been formed,378 together with allenyl-substit u ted (q6- benzene(t r icar bony1))ch rom ium complexes. 79 0t her general chromium arene references are as follows: the benzylic functionalisation of (q6-alky1arene)chromium tricarbonyl complexes;380the study of the solid state structure of [(q6arene)Cr(CO),] complexes by NMR;38’ and two other general references;382the synthesis and structure of [ {q,q’, q6-(C6H5)P(C2F5)2)Cr(C0)2]2383 and the stereoselective synthesis of [p-(Bz)Cr(CO),] complexes of podocarpic

4.4 Manganese Arenes - The reaction of a-halogenoester cations with cationic [(q6-arene)- tricarbonyl manganese] complexes,385and the synthesis and reachave both been reported. tivity of [(q6-biphenylene)Mn(C0)3]+386

6: t p C ~ H 3and q-Arene Substituted Trcmsition Metul Complexes

295

Iron Arenes -. Dendri tic cyclopentadienylarene iron complexes have been prepared for the activation of 0 2 for molecular engineering in an intriguing synthetic The synthesis of a range of (q-arene)(q-cyclopentadieny1)iron(I1) salts containing amino acid side chains.388The effect of pressure on the Mossbauer spectra of three cyclopentadienyl arene iron salts has been examined the dynamic reorientation normally observed at room temperature may be stopped under pressure.389The synthesis of iron centred hexapolypyridine star complexes and their hexaruthenium complexes has been described and the same group has subsequently reported the synthesis of polycationic dendrimers with [FeCp(arene)] One of these papers also reports the synthesis of dendrimers in cobaltoceneium termini. An q6-arene complex is formed in the reaction of a ruthenium acetate complex to the chiral biaryl ligand bis(3,5-di-tertbuty1phenyl)phosphino M e O - B i p h e ~ An . ~ ~aryl ~ group in the PPh3 ligand in [Ru~C(CO),~PP is ~converted ~] to an p-q6-arene ligand on solution thermol y ~ i s . ~The ’ ~ synthesis of ruthenium(I1) arene complexes containing K~ and K*poly(pyrazoly1)borates together with the crystal structures of [BzRu{K ~ HB(pz),)Cl] and [BzRu { ~~-Hc-(dmpz)~}Cl][PF~], dnpz = 3,5-dimethylpyra~ 0 1 ~ have 1 , ~been ~ ~ described. Enaritiomerically pure (triazoliny1idene)ruthenium(I1) and rhodium(II1) chelates containing (q6-cymene) and Cp* respectively have been prepared395 as have bis(arene)ruthenium(II) complexes of the type [(q6-cyrnene)Ru(q6-aa)][CF3SO3ln, aa = amino acid.3” The following papers are presented in list form: the reactions of chiral Schiff bases derived from pyridine-2carboxaldehyde with arene ruthenium complexes;397the hydrogenation of organoruthenium chlorides in aqueous solution;398 and a range of piano-stool rhodium bisphosphinic, q6-arenes have been prepared and factors which give rise to the stabilization of the Rh(I1) oxidation state noted.399

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281. 282. 283. 284. 285. 286. 287.

6: q-CJHjund q-Arene Substituted Trunsition Metul Complexes

288. 289. 290. 291. 292. 293. 294. 295. 296. 297. 298. 299. 300. 301. 302. 303. 304. 305. 306.

307. 308. 309. 310. 31 1 . 312. 313.

314. 315. 316.

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333. 334.

335.

336.

337. 338. 339. 340. 341. 342. 343.

344. 345. 346. 347.

Orgunomet ul1ic Cliemistry

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6: q- C5Hs uncl q-A rene Substituted Trunsition Metal Comp1c.xc.s

348. 349. 350. 351. 352. 353. 354. 355. 356. 357. 358. 359. 360. 361. 362. 363. 364. 365. 366. 367. 368. 369. 370. 371. 372. 373. 374. 375. 376. 377. 378. 379.

307

J. W.-S. Hui and W.-T. Wong, J. Chem. Soo., Dalton Trans., 1997, 2445. V.W.-W. Yam, V. W.-M. Lee and K.-K. Cheung, J. Chcm. SOL'.,Dulton Truns., 1997,2335. R. Teuber, R. Koppe, G . Linti and M. Tacke, J. Orgunornet. Chem., 1997,545, 105. Z .I. Hussain, M.W. Whitely, E. J. L. McInnes, J. Orgunornet. Chem., 1997, 543, 237. A. Dupuis, M . Gouygou, J.-C. Daran and G. A. Balavoine, Bull. Cliem. Soc. Fr., 1997, 134,375. H. Plenio and C. Aberle, Orgunometullics. 1997, 16. 5950. C. Patoux, C. Coudret, J.-P. Launay, C. Joachim and A. Gourdon, Inorg. Chern., 1997,36,5037. R. Pietschnig, M. Rieger, E. Niecke and K. Airola, J, Orgunornet. Chem., 1997,541, 237. J.-F. Ma and Y. Yamamoto, J. Orgunomet. Chem., 1997,545, 577. S . Nlate, E. Herdweck, J. Blomel and R.A. Fischer, J. Orgunornet. Cltem., 1997,545, 543. E. I . Klimova, B.T. Klimova, L.R. Ramirez, G. M . Martinez, T. C. Alvarez, P. G. Esprinosa and R. A. Toscans, J. Organomet. Chem., 1997,545, 191. E. Hendrickx, A, Persouns, S. Samson and G . R . Stephenson, J.Orgunornet. Chem., 1997,542,295. J. R. Hagadorn and J. Arnold, Inorg. Chem., I997,36, 132. 0.Henrion, and W. Jaegerman, Surfuce Science, 1997,387, LI 073. S. U. Son, S. S. Lee and Y . K. Chung, J. Am. Chem. Soe., 1997, 119,771 1. D. J. Burkey, M. L. Hays, R. E. Duderstadt and T. P. Hanusa, Orgunornetullics, 1997,16,1465. S. Barlow, D. R. Cary, M. J. Drew and D. O'Hare, J. Chem. Soc., Dalton Truns., 1997,3867. Y. T. Struchkov, M. Y. Antipin, K. A. Lysenko. 0. V. Gusev, T. A. Peganova and N. A. Ustynyuk, J. Orgunornet. Chem., 1997,536,281. R. Sen, A. Govindaraj and C.N.R. Rao, Chem. Phys. Lett., 1997,267,276. W. Frank and F.-G. Wittmer, Chem. Ber. Recueil, 1997, 130, 1731. A.V. Protchenko, 0. G. Almazova, L.N. Zakharov, G.K. Fukin, Y.T. Struchkov and M.N. Bochkarev, J. Orgunornet. Chem., 1997,536,457. G. E. Herberich, U. Englert and A. Schmitz, Organornetullics, 1997, 16, 3751. F. Calderazzo, I. Ferri, G. Pampalmi, U. Englert and M. L. H. Green, Orgunornetullics, 1997, 16, 3100. F. Musso, E. Solari, C. Floriani and K. Schenk, Orgunornetullics,1997, 16,4889 D. S. J. Arney, P. A. Fox, M. A, Bruck and D. E. Wigley, Orgunometullics, 1997, 16, 3421. C. Elschenbroich, E. Schmidt, R. Gondrum, B. Metz, 0. Burghaus, W. Massa and S. Wocadlo, Orgunometullics, 1997, 16,4589. R. W. Deemie, J. C. Fettinger and D. A. Knight, J. Organomet. Chem., 1997, 538, 257. F. G . N. Cloke, A. R.Dias, A. M. Galvao and J. L. d a Silva, J. Orgunomet. Chem., 1997,548, 177. H. K. Gupta, P. E. Lock and M. J. McGlinsky, Orgunornetallics, 1997, 16, 3628. M.K. Pomitje, C. J. Kurth, J. E. Ellis and M. V. Barijbin, Orgunornetullics, 1997, 16, 3582. D. D. Graf and K. R. Mann, Inorg. Chern., 1997,36, 141. T. J. J. Miiller and M. Ansorge, Chem. Ber. Recueil, 1997, 130, 1 135.

308 380. 381. 382. 383.

384. 385. 386. 387. 388. 389. 390. 391. 392. 393. 394. 395. 396. 397. 398. 399.

Orgunometullic Chemistry V. N. Kalinin, I. A. Cherepanov and S. K. Moiseev, J. Orgunomet. Chem., 1997, 536,437. P.J. Barrie, C.A. Mitsopolou, M. Motevalli and E.W. Randall, J. Chem. Sue., Dulton Truns., 1997, 353. M. C. Amenodola, K . E. Stockman, D. A. Hoic, W. M. Daus and G. C. Fu, Angew. Chem. Int. Ed. Engl., 1997,36, 267. R. G. Peters, B. L. Bennett, R. C. Schnabel and D. M. Roddick, Inorg. Chem., 1997, 36, 5962. G. R. Clark, B . Kuipers, M.. Metzler, M. H. Ngugen and P. D. Woodgate, J. Orgunomet. Chem., 1997,545, 225. F. Balssa, V. Gagliardini, C. Le Corre-Susanne, F. Rose-Munch, E. Rose and J. Vaisserman, Bull. Chem. Sue. Fr., 1997, 134,537. C. A. Dullaghan, G. B. Carpenter and D. A. Sweigart, Chem. Eur. J.,1997,3,75. S. Rigaut, M.-H. Delville and D. Astruc, J. Am. Chem. Soc., 1997, 119, 1 1 132. R. M. G. Roberts and E. Johnsen, J. Orgunomet. Chem., 1997,544, 197. J. Silver, J. R. Miller, D. A. Davies and C. A. McCammon, Inorg. Chem., 1997, 36, 4017. V. Mavaud, D. Astruc, E. Leize, A.V. Dorsselaer, J. Gurttard and J.-C. Blais, New. J. Chcm., 1997,21, 1309. E. Alonso, C. Valerio, J. Ruiz and D. Astruc, New. J. Chem., 1997,21, I139 N. Feiken, P.S. Pregosin and G. Trabesinger, Organometuffics, 1997, 16, 3733. H.-F. Hsu, S. R. Wilson and J.R. Shapley, Orgunometullies, 1997, 16,4937. S. Bhambri and D. A. Tocher, J. Chem. Soc., Dulton Truns., 1997,3367. D. Enders, H. Gielen, G. Raabe, J. Runsink and J.H. Teles, Chem. Ber. Recueil, 1997, 130, 1253. J. M. Wolff and W. S. Sheldrick, Chem. Ber. Recueil, 1997, 130,98I . D. L. Davies, J. Fawcett, R. Krafczk and D. R. Russell, J. Orgunomel. Chem., 1997, 545, 581. G. Suss-Fink, G. Meister, S. Haak, G. Rheinwald and H. Stoeckli-Evans, New J. Chem., 1997,21, 785. F. Singewald, C. S. Stone, C. L. Stern, C. A. Mirkin, G. P. A. Yap, L. M. LiableSands and A. L. Rheingold, J. Am. Chem. Soc., 1997, 119, 3048.

7 Organic Aspects of Organometallic Chemistry BY LOUISE TONKS AND JONATHAN M. J. WILLIAMS

1

Introduction

There can be no doubt that modern organic synthetic chemistry relies heavily on many aspects of organometallic chemistry. In particular, transition metal mediated reactions have demonstrated their utility in terms of selectivity and reactivity. Each year there are many thousands of papers published where organometallic chemistry has been exploited with an organic synthesis goal in mind. This chapter therefore needs some focus, and the authors have chosen to concentrate on organic reactions catalysed by metal complexes. The last section of the chapter considers the recently emerging area of fluorous phase chemistry applicd to organic reactions catalysed by metal complexes.

2

Coupling Reactions: C-C Bond Formation

Fundamental to organic synthesis is the formation of new carbon-carbon bonds. Typical of the reactions which can be achieved is the reaction of the functionalised organozinc iodide l with an aryl donor 2 to provide the coupled product 3.' A very short synthesis of the anti-cancer drug (2)-Tamoxifen 4 has been

0 1

5 molo/o Pd(PPh&

+

THF, 8 h at 20 "C then 23 h at 65 "C 70%

3 2

Organometallic Chemistry, Volume 27 0The Royal Society of Chemistry, 1999 309

Orgunomc~tullicChemistry

310

5

4 mot% Pd(dba)2

+

THF, 55 "C,10 h Then HCI

16 mol% Ph3P c

75%

I

4

(Z):(E)>99:1

Et

Ph

6

reported by Stiidemann and Knochel.* Coupling of the organozinc bromide 5 with (2)-vinyl iodide 6 affords, after salt formation, (Z)-Tamoxifen 4 with preservation of the double bond geometry. A recent development in metal-catalysed coupling chemistry involves the

+

vph

7.5 mol% Pd(dba)2 grnoi%~~P~

0 8

7

2.2 eq. KN(SiMe3)2 * THF, reflux, 45 min 84%

0^aPh 9

DTPF = 1 , l '-bis(di-cztoly1phosphino)ferrocene

a-arylation of ketones, independently reported by the research groups of Buchwald' and H a r t ~ i g In . ~ a typical example, acetophenone 7 and bromobenzene 8 underwent coupling to afford product 9. A palladium catalysed intermolecular ctarylation of ketones has also been r e p ~ r t e d . ~ The Suzuki cross-coupling reaction involves the use of organoboron compounds as the 'nucleophilic' coupling partner. One advantage of this method is that the organoboron compound can be prepared in situ by hydroboration of an alkene. Thus, alkene 10 undergoes hydroboration and subsequent coupling with aryl bromide 11, which affords a protected form of a trisaccharide mimic 12.6 The related Stille cross-coupling reaction employed an organotin reagent, and sees considerable use in organic synthesis, for example, Nicolaou and co-workers have coupled the vinyl phosphate 13 (derived from the corresponding lactone) with tributylvinyltin 14 to give the diene 15.'

3

Coupling Reactions: C-XBond Formation

Coupling reactions involving the formation of carbon-heteroatom bonds has seen a lot of recent development, especially the amination of aryl halides. Wolfe and Buchwald have now reported that amination of aryl iodides is

7: Orgunic Aspects of Orgunometullic Chemistry

31 I

OMOM

6CH3 10

i ) 9-BEN-H, THF, reflux

i) PdCh(dpp0,K3P04 (aq) DMF, r.t

+

-

OBn OBn

BnO"" OCH3

Br

11

13

5 mol% Pd(PPh3),

+

3 eq. Licl THF, reflux, 2 h 82%

c

o-.*

PhV"'

H 15

possible at room temperature.' For example, p-iodotoluene 16 and piperidine 17 are converted into the aniline 18 in good yield. Hartwig and co-workers have employed the aromatic amination reaction in the synthesis of dendrimers. Using lithium diphenylamide 19 with tribromide 20 afforded the first generation dendrimer 21.9 Larger dendrimers were also prepared. The use of aryl chlorides as the 'electrophilic' partner in amination reactions has been reported using either palladium'*.' o r nickeli2catalysts. Despite the many developments in the aromatic amination procedures, no simple means for the formation of primary amines has been reported. However, Buchwald and co-workers have demonstrated the use of benzophenone imine 22 as an ammonia equivalent in these reactions.13Thus aryl bromide 23 is converted into the imine 24, which undergoes reductive cleavage to give the primary aniline 25. BuchwaldI4 and Hartwig" have also reported how aryl halides can be converted into aryl ethers using alcohols and palladium catalysed coupling. The conversion of aryl halides into into aryl boronates is of considerable interest, because the products can subsequently be used in Suzuki coupling reactions.

312

Orgunometullic Chemistry 0.5 rnoPh Pd2(dba)3 1.5 rnd%(i) BINAP

-

16

Li

17

6

,

Br 19

Bu'

1.4 eq.NaO'Bu 1.4 eq. 18-Crown-6 THF, r.1. 6 h 85%

2 mol% Pd(P-etOryl),), 2 mol% P(etolyl), D

toluene, 110 "C 84% Br

20

nBr 23

.t

18

Ph

"

-

HC02NH4 c

cat. PdIC MeOH, 60 "C 84%

1.4 eq.NaO'Bu toluene, 80 "C, 13 h

90%

Ph

~

0.25 d%PdZ(dba)s 0.75 molX (k) BINAP

24

25

H/N 22

Masuda and co-workers have developed a simple procedure, exemplified by the conversion of aryl iodide 26 with pinacolborane 27 into the aryl boronate 28.16 The same group has reported that carbon-silicon bonds can be formed from aryl halides. Thus, aryl iodide 29 and triethoxysilane 30 afford the aryl silane 31 under simple coupling conditions.'7 Aryl halides can also be converted into aryl phosphines using a nickel-catalysed coupling procedure.

4

Reactions Involving Carbon Monoxide

Many coupling reactions performed in the presence of carbon monoxide will produce carbonylated products. One of the classic reactions of this type is the hydrofarmy lation of alkenes. Leighton and O'Neil have reported the highly diastereoselective hydroformylation of enol ethers, including the conversion of enol ether 32 into the aldehyde 33.19

313

7: Orgunis Aspects c+f Urgunometullis Chemistry

28

29

1.5 mol% Pd2(dba),CHC1, 6 mot% P(etol), w

+

3 eq. 'Pr2NEt NMP, r.t, 1 h

H-Si(OEtk

77%

w 31

30 (1.5 eq.)

An unusual arylation reaction takes place on substrate 34, where the amide group directs the reaction to give a unsaturated ketone 35 as the Beller and co-workers have shown that aldehydes can be carbonylated in the presence of amides and bromide.22 In the best example, aldehyde 36 is converted into the amino acid derivative 37,via an equilibrium concentration of the amido bromide 38. The Pauson-Khand reaction is generally conducted using stoichiometric amounts of C02(C0)8, although other metal carbonyls are also effective. Two groups have independently reported ruthenium catalysed variants of this reaction.23924All of the examples were for intramolecular Pauson-Khand reactions, such as the conversion of enyne 39 into the cyclopentenone 40. The multiple insertion of carbon monoxide into organic substrates can be achieved. Grigg and Pratt have demonstrated a palladium catalysed 'pentamolecular queuing cascade', where the starter species 41 reacts with two molecules of carbon monoxide and then allene, and is terminated with morpholine 42, to give the product 43 in good yield.25

5

Allylic Substitution Reactions

Palhdium catalysed allylic substitution reactions have been receiving considerable attention in terms of the stereoselectivity which they can afford. Trost and co-

Organometallic Chemistry

314 'BU

o n 0 Me

A 32

'BU

1 mol% Rh(acac)(CO), 4 mol% PPh3

0

800 psi H2/C0 (1:l)

THF, 75 "C,8 h 72%

Me

33 > 5o:l diastereoselectivify 13:1 regioselectivily

Me

g>

Me 4 mol% Rh4(C0),2

*

toluene, H2C=CH, CO (15 atm), 1 6 0 'C, 20 h 89%

PhAO 34

35

0.25 mol% (PPh3)*PdBr, 1 mol% H2S04

36

35 md% LiBr CO (60 atm) NMP, 120 "C, 12 h 99%

37

0

38

workers have made significant progress on the problem of how to control enantioselectivity when prochiral nucleophiles are used.26The reaction between pketo-ester 44 and methallyl acetate 45 using a palladium catalyst in the presence of ligand 46 provides the substitution product 47 with remarkable enantioselectivity. Mortreux and co-workers have shown that malonate can function as a leaving group in the allylic substitution reaction, which will ultimately lead to an erosion of enantioselectivity, as shown by the racemisation of compound 48.27 Although palladium is the traditional choice for allylic substitution reactions, other metals catalyse the reaction, and can afford differences in regioselectivity. Thus, with an iridium catalysed reaction, ally1 acetate 49 affords the substitution product 50 where the nucleophile has attacked at the more sterically hindered terminus.**

315

7: Orgunic Aspecls of Orgunornetullic Clwmistry Et02C

2 mol% R u ~ ( C O ) , ~ CO (15 atm)

Et02C+-

39

41

+ H

"1 0

Et02C

Me2NCOMe 140 "C. 8 h 8490

40

10 mol% P ~ ( O A C ) ~ 20 mol% PPh3 L

H2C=C=CH2(1 atm) CO (1 atm) 4 eq. K2CO3 1 ea. ELNCl toluene, 11% "C, 18 h 67%

43

42

Janssen and Helmchen have reported an enantioselective variant of the iridium-catalysed allylic substitution reaction.29

6

Alkene Metathesis Reactions

The ring closing metathesis reaction of dienes is a reaction of considerable synthetic utility.30 During the period of this review, there were many examples of ring-closing metathesis applied to synthesis, and only a few can be described here. During the efficient synthesis of ( - )-gloeosporone, Fiirstner and Langemann effected the ring-closing metathesis of diene 51 to give the macrocycle 52, using a ruthenium catalyst. Two research groups have independently reported the use of ring-closing metathesis in the preparation of fused o x a ~ y c l e s .For ~~~~~ example, diem 53 is converted into the bicycle 54 using a molybdenum catalyst . As well as the many examples of diene ring-closing metathesis, there have been synthetically useful reports of cross m e t a t h e ~ i senyne ,~~ and a metathesis cascade.36 Gibson and co-workers have obtained the cross metathesis product 57 in reasonable yield from the amino acid derivative 55 and styrene 56. The self-metathesis product was also isolated in 40% yield. Treatment of enyne 58 under metathesis conditions affords the cyclised diene 59, whereas the triyne 60 undergoes a remarkable metathesis cascade to provide the arene 61.

316

Orgunometullic Chemistry

0.4 mol% [q3C3H,PdCI], 0.9 mol% 46

44

+

1.2 eq. (Mt N),C=NH

toluene, 0 6 . 3 h 81% 47 95% e.e.

45 0

NH

PPh,

46

MeO& Ph

C02Me Ph

MeO&

5 mol% Pd(dppb), 2 eq. NaCH(C02Me), THF, 100 “C,165 h

*

C0,Me

PhdPh 48

48

5% e.e.

87% e.e

2 mol% [Ir(cod)CI], 8 mol% P(OPh), c

OAc

2 eq. NaCH(C02Et)2 THF. r.t, 2 h

49

7

80%

CH(CO2Et), 50

Reactions Involving Carbenes

Organometallic carbene complexes have a rich history in organic synthesis. Hegedus and Reed have continued their research into the synthetic utility of chromium carbenes by demonstrating the photochemical cycloaddition of carbene complex 62 with vinyl oxazolidinone 63 to provide the cyclobutanone 64 with very high diastereo~electivity.”~ Ledford and Carreira have reported an interesting alternative to the Horner

7: Orgunic Aspects of Orgunometullic Chemistry

317

3 mol% PhCH=RuCI,(PCy,),

52

51

(E):(Z) 3.6:l

benzene (0.008M)

H 54

53

CHMe2

Me2HC

Mo catalyst =

h

Ph

Emmons reaction, which effects the conversion of aldehydes 65 into a$unsaturated esters 66 on treatment with ethyl diazoacetate and a rhenium catalyst.38 The mild reaction conditions are a useful characteristic of this process. However, most synthetic organic reactions involving carbenoid intermediates use rhodium(I1) catalysis. Sheehan and Padwa have reacted the diazo compound 67 with methyl acrylate 68 to provide the product 69 in a remarkable cascade sequence initiated by the catalytic formation of a rhodium carbenoid species.39 There are now several effective asymmetric rhodium (I I) catalysts. The Davies research group has demonstrated enantioselective C-H4* and Si-H4' insertion reactions using catalyst 72. Diazoester 70 inserts into cyclopentane to give the product 71 with good control of enantioselectivity. Generally, metal carbenoids do not react with electron deficient alkenes. This problem has been overcome by Aggarwal and co-workers who add sulfides to the reaction, which then mediate the reaction by the formation of sulfur ylides (which are known to cyclopropanate electron deficient alkene~).~* Thus chalcone 73 reacts with the ylide formed by the rhodium catalysed reaction of phenyldiazomethane 74 and sulfide 75. The product 76 is formed with excellent enantiomeric excess.

Orgunometullic Chemistry

318 C02Me

BocHN

55

\\

BocHN

* \

5 mol% PhCH=RuCI,(PCy,), CICH,CH2CI, r.t, 30 h N2 stream 52%

Ph

C0,Me

57

Ph

56

(2eq.1

MQ

59

58

0.5 mol% PhCH=RuCI,(PCy,),

-0 CH2C12,r.t, 2 h 88% 60

61

EtofiQ Ph

CO (80 psi) CH&, -35O C , 24 h

EtO V O B n Cr(C0)5

62

+

" K O0

hv (carbazoWDMFfilter) 79%

0 64

63

> 97% d.0

1 molo/oReOCI3(PPh3)* R l "

65

1 eq. (Et0)3P 1 eq. N2CH2C02Et THF, 23 "C 65-95%

b

R AOEt

66 (E):(2) 3:l to >20:1

319

7: Organic Aspects of Orgunometullic Chemistry

0

67 86Yo

+

69

@C02Me 68

Cat. 72

71 87% 8.8.

70

Rh (11) complex =

Ar = C6H4(PC12H25) 72

Ph

Ph

73

+ 74 PhCHN,

(added by syringe pump)

1 mol% RhdOAcL -. ~.

toluene, r.t, 12 h 60%

+

-

Pha

bPh

Ph

76

97%8.8 4:l trans:cis

75

8

Hydrogenation and Related Reactions

Transition metal catalysed hydrogenation reactions undoubtedly have made a major contribution to the organic synthetic repertoire. More recently, transfer hydrogenation catalysts have shown considerable utility for the asymmetric reduction of ketones. Noyori and co-workers have shown that, using their catalysts, carbonyl reduction of a,P-acetylenic ketones occurs both chemose-

320

Orgunometallic Chemistry

0 0.5 mol% 79

Ph2

.

9

'PrOH, 28 "C,20 h > 99%

77

PhA

M

e

78

79

lectively and regio~electively.~~ Thus ketone 77 is reduced to propargylic alcohol 78 using the ruthenium catalyst 79 and isopropanol as the hydride donor. Alternative ligands have been employed in related reactions, also providing high levels of e n a n t i o s e l e ~ t i v i t y . ~ , ~ ~

9

Oxidation Reactions

Transition metal catalysed oxidation reactions enable the highly selective functionalisation of alkenes. Epoxidation, dihydroxylation, and more recently aminohydroxylation are of particular importance from a synthetic standpoint. The Sharpless group at Scripps has commanded a leading position in this research. One of their latest results involves the epoxidation of alkenes with hydrogen peroxide using catalytic amounts of methyltriox~rhenium.~~ Significantly, the addition of pyridine accelerates these reactions. Oxidation of oct-4-ene 80 affords the epoxide 81 with complete selectivity. The Sharpless group has reported further developments in the recently described asymmetric aminohydroxylation reaction.47 Using N-bromoacetamide 82 as the nitrogen source, it was possible to convert cinnamate 83 into the functionalised product 84 with superb enantiocontrol. The asymmetric aminohydroxylation reaction was being used by other groups within one year of the first reports from the Sharpless

I0

Miscellaneous Reactions

There have been significant developments in diverse areas of organic synthesis which although they belong in this chapter, do not fit comfortably in the previous sections. They follow in the next sub-sections.

32 1

7: Orgunic Aspects of Orgunometullic Chemistry 0.5 moPh MeRe03 12 md% pyridine 1.5 e ~ H202 . (30%) CH2CI r.t, 6 h 99%

80

-7 0

81 > 99% cis

0 MeKNH

4 mol% K2[0sO2(0H),] 5 mot% ligand 85

0

c

1 q.LOH-HZO

OH

H20hUOH(3:2) 81%

84 99% 8.8

83

X

ligand 85 (DHQ),PHAL

X X=DHQ

DHQ

2 mot% Cu(OTf), 4 mol% ligand 86 1.1 eq. Etgn toluene, -30 OC, 3 h

94%

-6 EtN'

88 > 90% 8.8

87

ligand 86 =

10.1 Conjugate Addition Reactions - Asymmetric conjugate addition reactions which are truly catalytic have been set a new very high standard to match. Feringd and co-workers have reported remarkably selective reactions using copper(l1) catalysts in the presence of ligand 86.49Cyclohexenone 87 undergoes

322

Orgunometallic Chemisty

selectivity = 20

7: Orgunic Aspects of Organometollic Chemisrry

323

copper-catalysed conjugate addition of diethylzinc to give 3-ethylcyclohexanone 88 with excellent enantioselectivity.

10.2 Ring-opening Reactions of Epoxides - Epoxides are useful synthetic intermediates because they undergo ring-opening reactions with a range of nucleophiles. Jacobsen and co-workers have developed a very efficient ring-opening of epoxides with water which involves a kinetic re~olution.~'Hydrolysis of propylene oxide 89 on a lmol scale catalysed by cobalt complex 90 affords recovered epoxide and propylene glycol 91 with excellent enantioselectivity. This is a useful and practical kinetic resolution process. The same group has also reported the enantioselective catalytic ring opening of epoxides using carboxylic acids as the incoming n~cleophile.~' 10.3 Planar Chirat n-Complexes as Asymmetric Catalysts - Fu and co-workers at MIT have been investigating the use of the planar chiral n-complexes in catalysis. Achiral complex 92 has been used to catalyse the ring-opening of e p ~ x i d e s , ~and * complex 93 has been used to catalyse the addition of diethylzinc to aryl a l d e y d e ~ The . ~ ~ most exciting example is the use of complex 94 as a non.~~ enzymatic catalyst for acytation of racemic alcohols with kinetic r e s o l ~ t i o nFor example, alcohol 95 undergoes catalysed acetylation with acetic anhydride, and unreacted alcohol is recovered with high enantiomeric excess.

10.4 Higher-order Cycbaddition Reactions - Rigby's group at Wayne State University has developed the chemistry of higher order cycloaddition reactions of tricarbonylchromium complexes of cycloheptatriene. They have now reported a catalytic variant of this reaction.55 In the best example, cycloheptatriene 97 and diene 98 undergo a 671 + 4n cycloaddition reaction catalysed by a suitable chromium complex to give product 99. Me 98 10 mol% ( ~f-naphthaIene)Cr(CO)~

+

m

C4H9CN,Mg powder, 140 "C 80% 99 97

OSiMe3

100

0

DMF, 4A molecular sieves 2 eq. H20 then 'Pr2NH(0.5 mol%) 50 "C,18 h 83%

101 79% 8.8

324

Orgunometullic Chemistry

10.5 Catalytic Protonation - The hydrolysis of a silyl enol ether to a ketone provides an opportunity for an asymmetric reaction. Sugiura and Nakai have shown that palladium complexes can catalyse the reaction, presumably via an intermediate palladium en01ate.~~ Silyl enol ether 100 undergoes a palladium catalysed conversion into ketone 101 with reasonable control of enantioselectivity . 10.6 Electrochemically Driven Metal Catalysed Reactions - Many organic reactions only require stoichiometric qualities of an organometallic reagent because of a change of oxidation state of the metal. In principle if the metal can be recycled by the addition or removal of electrons, a stoichiometric process can be converted into a catalytic one. 0 +

Ph-I

PhKH

103 (1.2 eq.)

102

0.1 mot% P ~ ( O A C ) ~ 0.4 mol% PPh3 10 mot% CrCI2

OH

P

D

A

0 . l M LiC104 in DMF "electrons" 66%

10 mol% PdC12(PPh3), C02 (1 atm) DMF, r.t, 'electrons" 80%

105

104

D

But+

C02H

106

Grigg and co-workers have achieved an electrochemically driven version of the Nozaki-Hiyama-Kishi reaction which is catalytic in chromium.57 Thus iodobenzene 102 and benzaldehyde 103 are coupled to give benzhydrol 104 in acceptable yield. A palladium catalysed electrocarboxylation of vinyl triflates has been described by Jutand and N e g ~ - i Vinyl . ~ ~ triflate 105 is converted into the a$unsaturated acid under the electrocarboxylation conditions.

11

Fluorous Phase Organornetallic Chemistry

Highly fluorinated hydrocarbons are usually immiscible with water and with many common organic solvents. Such fluorinated compounds can therefore establish a separate 'fluorous phase'. Compounds with a very high fluorine content will selectively partition into the fluorous phase rather than a conventional organic phase. Although this has been known for a long time, there have been several organometallic reactions reported recently which use fluorous reagents or ligands, and hence the final section of this chapter is devoted to this topic. There seems little doubt that fluorous phase catalysis will gain popularity over the next few years.59

7: Orgunic Aspects of Orgunometullic Chemistry

325

Using a fluorous Stille reagent 107, coupling with aryl iodide 108 took place in a conventional organic solvent under microwave irradiation in just two minutes to give biaryl 109.60 Three phase extraction (aqueous, dichloromethane and perfluoroheptanes) facilitated work up and removal of tin residue 110. Betzemeier and Knochel have reported cross-coupling reactions using fluorous phase catalysts.6' Coupling between phenylzinc bromide 111 and aryl iodide 112 is performed in a two-phase system of toluene and fluorous solvent (l-bromoper-

-Ph

(C,F13CH2CH2),Sn

107 (1.2eq. )

+

108

-

2 mol% PdCI,(PPh3), 3 eq. LiCl microwaves (6OW)

Me0

0

Ph

lo9

+

DMF, 2 min Then three phase extraction

(C6F13CH2CH2)3Sn1

77%

110

112

5 moPh catalyst 116

114

1.5-2.0eq. 'PrCHO 0, (1 atm) toluene / CBF1+r 50 "C, 12 h 85%

116

-

oo 115

OrgunometullicChemistry

326

0.1 md% P[CH2CH2(CF2),CF3l3 0.1 md% (Rh(cod)CI],

118

+

&

toluene / C F&F, 40 "C, 6 h

-

0

90% 119

117

fluorooctane) where the ligand/metal complex resides in the fluorous phase. At 60 OC, the reaction mixture is a single phase, but o n cooling a two-phase system is re-established allowing easy work up of the product 113 and re-cycling of catalyst. Knochel and co-workers have also developed perfluorinated acac analogues for use in transition metal catalysed oxidations using two phase organic/fluorous systems.62 Nickel catalysed oxidations of aldehydes to acids and of sulfides to sulfoxides, as well as ruthenium catalysed epoxidation reactions were all described, including the conversion of cyclooctene 114, into cyclooctene oxide 115 using catalyst 116. Rhodium catalysed hydroboration has also been reported using fluorous phase chemistry.63 Norbornene 117 undergoes hydroboration with catecholborane 118, to give, initially, the alkylboronate 119. Upon cooling, the product is in the organic phase and can then be oxidised to the corresponding alcohol. The fluorous phase contains the rhodium catalyst, with attached fluorous ligand, and can be recycled without removal of solvent or purification. Acknowledgement manuscript.

-

The authors wish to thank Mrs Jo Curtis For typing the

References 1.

2 3. 4. 5. 6. 7.

8. 9. to. 11.

12.

R. Rossi, F. Bellina and D. Ciucci, J. Orgunumet. Chem.,1997,542, 13-120. T. Studemann and P. Knochei, Angew. Chem. Int. Ed. Engl., 1997,36,93-95. M. Palucki and S.L. Buchwald, J. Am. Chem. Soc., 1997, 119, 1 1108-1 1109. B.C. Hamann and J.F. Hartwig. J. Am. Chem. Sue., 1997,119, 12382-12383. H. Muratake and M. Natsurne, Tetruheclrun Lett., 1997,38, 7581-7582. C.R. Johnson and B.A. Johns, Synlett, 1997, 1406-1408. K.C. Nicolaou, G.-Q. $hi, J.L. Gunzner, P. Gartner and Z. Yang, J. Am. Chem. Suc., 1997,119,5467-5468. J.P. Wolfe and S.L. Buchwald, J. Org. Chem., 1997,62,606&6068. J. Louie, J.F. Hartwig and A.J. Fry, J. Am. Chem. Suc., 1997, 119, 11695-1 1696. N.P. Reddy and M. Tanaka, Tetruheclrun Lett.. 1997,38,4807-48 10. M. Beller, T.H. Riermeier, C.-P. Reisinger and W.A. Herrmann, Tetrahedron Lett., 1997,38,2073-2074. J.P. Wolfe and S.L. Buchwald, J. Am. Chem. Sue., 1997, I 19,60546058.

7: Orgunic Aspects of Organometullic Chemistry 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43.

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J.P. Wolfe, J. Ahman, J.P. Sadighi, R.A. Singer and S.L. Buchwald, Tetrahedron Lett., 1997,38,6367-6370. M. Palucki, J. P. Wolfe and S. L. Buchwald, J. Am. Chem. Soc., 1997, 119, 3395-3396. G. Mann and J.F. Hartwig, J. Org. Chem., 1997,62,5413-5418. M. Murata, S. Watanabe and Y . Masuda, J. Org. Chem., 1997, 62, 6458-6459. M. Murata, K. Suzuki, S. Watanabe and Y. Masuda, J. Org. Chem., 1997, 62, 8569-857 1. D.J. Ager, M.B. East, A. Eisenstadt and S.A. Laneman, J. Chem. Suc.,Chem. Cummun., 1997,2359-2360. J.L. Leighton and D.N. O’Neil, J. Am. Chem. Sue., 1997,119,11118-1 11 19. Y. Ishii, N. Chatani, F. Kakiuchi and S. Murai, Tetrahedron Lett., 1997, 38, 7565-7568. Y. Ishii, N. Chatani, F. Kakiuchi and S. Murai, Orgunumetullics, 1997, 16, 36 15-3622. M. Beller, M. Eckert, F. Vollmiiller, S. Bogdanovic and H. Geissler, Angew. Chem. Int. Ed. Engl., 1997,36, 1494-1496. T. Morimoto, N. Chatani, Y. Fukumoto and S. Murai, J. Org. Chem., 1997, 62, 3762-3765. T. Kondo, N. Suzuki, T. Okada and T.-A. Mitsudo, J. Am. Chem. Sue., 1997,119, 6 187-6 188. R. Grigg and R. Pratt, Tetrahedrun Lett., 1997,38,4489-4492. B. M. Trost, R. Radinov and E.M. Grenzer, J. Am. Chem. Sue., 1997, 119, 7879-7890. H. Bricout, J.-F. Carpentier and A. Mortreux, Tetrahedrun Lett., 1997, 38, 1053-1 056. R. Takeuchi and M. Kashio, Angetv. Chem. Int. Ed. Engl., 1997,36,263-265. J.P. Janssen and G. Helmchen, Tetruhecirun Lett., 1997,38,8025-8026. T.A. Kirkland and R.H. Grubbs, J. Org. Chem., 1997,62,7310-7318. A. Furstner and K. Langemann, J. Am. Chem. Sue., 1997,119,9 130-9136. J.S. Clark and J.G. Kettle, Tetrahedrun Lett., 1997,38, 127-130. M. Delgado and J.D. Martn, Tetrahedron Lett., 1997,38,6299%6300. S.E. Gibson, V.C. Gibson and S.P. Keen, J. Chem. Suc.,Chem. Cummun.,1997, 1107-1 108. A.G.M. Barrett, S.P.D. Baugh, D.C. Braddock, K. Flack, V.C. Gibson and P.A. Procopiou, J. Chem. Suc., Chem. Cummun., 1997,1375-1 376. J-U. Peters and S. Blechert, J. Chem. Soc.,Chem. Cummun., 1997,1983-1984. A.D. Reed and L.S. Hegedus, Organumetullics, 1997, 16,2313-231 7. B.E. Ledford and E.M. Carreira, Tetrahedron Lett., 1997,38,8 125-81 28. S.M. Sheehan and A. Padwa, J. Org. Chem., 1997,62,438-439. H.M.L. Davies and T. Hansen, J. Am. Chem. Soc., 1997,119,9075-9076. H.M.L. Davies, T. Hansen, J. Rutberg and P.R. Bruzinski, Tetruhedrun Lett., 1997, 38,1741-1744. V.K. Aggarwal, H.W. Smith, R.V.H. Jones and R. Fieldhouse, J. Chem. Suc.,Chem. Cummun., 1997, 1785-1786. K. Matsumura, S. Hashiguchi, T. Ikariya and R.Noyori, J. Am. Chem. Sue., 1997, 119,8738-8739. T. Sammakia and E.L. Strangeland, J. Org. Chem., 1997,62,6104-6105. M. Palmer, T. Walsgrove and M. Wills, J. Org. Chem., 1997,62, 5226-5228.

328

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46.

J. Rudolph, K.L. Reddy, J.P. Chiang, and K.B. Sharpless, J. Am. Chem. Soc., 1997, 119,6l89-6190. M. Bruncko, G. Schlingloff and K.B. Sharpless, Angew. Chem. Int. Ed. Engl., 1997, 36, 1483--1485. R. Angelaud, Y. Landais and K. Schenk, Tetrahedron Lett., 1997,38, 1407-1410. B.L. Feringa, M. Pineschi, L.A. Arnold, R. Imbos and A.H.M. de Vries, Angew. Chem. Int. Ed. Engl., 1997,362620--2623. M . Tokunaga, J.F. Larrow, F. Kakiuchi and E.N. Jacobsen, Science, 1997, 277, 936-938. E.N. Jacobsen, F. Kakiuchi, R.G. Konsler, J.F. Larrow and M. Tokunaga, Tetroheclron Lett., 1997,38, 773-776. C.E. Garrett and G.C. Fu, J. Org. Chem., 1997,62,4534-4535. P.I. Dosa, J.C. Ruble and G.C. Fu, J. Org. Chem., 1997,62,444-445. J. C. Ruble, H. A. LathamandG. C. Fu, J. Am. Chem. Soc., 1997,119, 1492-1493. J.H. Rigby and C. Fiedler, J. Org. Chem., 1997,62, 6106-6107. M . Sugiura and T. Nakai, Angew. Chem. Int. Eel. Engl., 1997,36,236&2367. R. Grigg, B. Putnikovic and C.J. Urch, Tetruheclron Lett., 1997,38, 63074308. A. Jutand and S Negri, Synlett., 1997,719-721. B. Cornils, Angew. Chem. Int. Ed. Engl., 1997,36,2057. M. Larhed, M. Hoshino, S. Hadida, D.P. Curran and A. Hallberg, J. Org. Chem., 1997,62,5583-5587. B. Betzemeier and P. Knochel, Angecv. Chern. Int. Ed Engl., 1997,36,2623-2624. 1. Klement, H. Lutjens and P. Knochel, Angew. Chem. Int. Ed. Engl., 1997, 36, 1454-1456. J.J.J. Juliette, I.T. Horvath and J.A. Gladysz, Angew. Chem. Inl. Eel. Engl., 1997,36, I61&1612.

47. 48. 49. 50.

51.

52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63.

8 Scandium, Yttrium and the Lanthanides JOHN

1

G. BRENNAN AND ANDREA SELLA

Introduction

This review covers all organometallic complexes of Sc, Y and the lanthanides reported in the year 1997 and their reactions. Endohedral fullerene complexes of the lanthanides are however excluded.

2

New Compounds and Complexes

2.1 Cp Compounds - The Cp ligand (C5H5) continues to find applications in organolanthanide syntheses, although the trend toward increasingly more complicated Cp derivatives continues to evolve. There were two notable achievements in Cp-Ln chemistry. Crystals of NaCp3Yb and Cp2Yb were obtained at 400°C under vacuum and shown to be polymeric by X-ray diffraction.’ A series of metathetical reactions of LnCp3 with either K(C5Me5) or [Ca(C5Me5)2]to give Ln compounds with both Cp and C5Me5 ligands were outlined: and the syntheses and mass spectral characterizations of [Cp2Ln(phthalimido)]2 dimers were r e p ~ r t e d . The ~ reactivity of [CpLu(anthracenide)(THF)2] and related systems is discussed in Section 2.8. 2.2 Substituted Cp Ligands - The monosubstituted Cp ligand classification can be separated into simple alkyl or silyl derivatives and compounds with functional substituents. The Me3SiC5H4 (TMSCp) and Me3CC5H4 (Bu‘Cp) ligands were used most notably to study synthesis, structure, and reactivity of [(Cp’)~LnMe]z (Ln = Y,Tb, Yb, Lu; Cp’ = Bu‘Cp, TMSCp) with compounds containing Si-H or Ge-H bonds. In contrast with the Cp* chemistry described last year, these compounds transfer hydride to the electropositive metals to give [(Cp’)zLnH]z, rather than eliminate H2 and form direct Ln-Si, Ge, or Sn bonds. The intermediate asymmetrically bridged [ ( C P ’ ) ~ L ~ p-Me)(p-H) ]~( was also successfully isolated. More acidic (i.e. alkoxysilane) proton sources react with the dimethyl compounds to eliminate methane and form [(Cp’)2LnOR]2,and the intermediate [(Cp’)2LnIz(p-Me)(p-OR)can also be isolated. The dimethyl compounds were also found to react with Si(OMe)4 to give the asymmetric [(Cp’)2Lu]z(p-Me)(pOMe), which contains equivalent Lu-C bonds and inequivalent Lu-0 (2.20(2)A, with NaHBEt3 2.21(2)A) bonds! Along similar lines, reaction of [(B~‘Cp)~SrnCll

Organometallic Chemistry, Volume 27 The Royal Society of Chemistry, 1999 329

330

Organometullic Chemistry

gave either the monomeric [(BuCp)2SmHBEt3(THF)] or [(ButCp)2SrnH]2; the latter could also be obtained by hydrogenolysis of the [(Bu'Cp)zSmR] (R = CH2SiMe3, CH(SiMe3)2)and is unstable with respect to ligand redistribution and the formation of [Srn(B~'Cp)~l. In the presence of PMe3 the monomeric coordination corhplex [ ( B U ' C ~ ) ~ S ~ H ( P forms. M ~ ~ )Hydrogenolysis ] of the related methyl dimer [(ButCp)2SmMel2 gave an asymmetrically bridged (p-H, p-Me) dimer. With additional (Bu'Cp)zSmCl present, the related (p-H, p-Cl) compound was prepared, and the chloride can also be replaced with a l k ~ x i d eThe . ~ structure of [(TMSCp)2NdI(pyridine)] was described,6 and the ability of lanthanide complexes with TMSCp and 3-(2,6-dimethoxyphenylallyl)ligands to polymerize ethylene and methylmethacrylate was r e p ~ r t e d . ~ Lanthanide Cp compounds with NR3, OR2, and PR3 functional groups on the C p ligand were approached by a number of synthetic strategies, and in one case the compounds were shown to have useful applications. Transmetallation of Tl(C5H4PPh2) with Ln (Ln = Sm, Eu) in either T H F or DME gave Ln(I1) compounds, and further oxidation of the Sm compound in toluene gave [(C5H4PPh2)3Sm]. For the redox inactive metals, syntheses of trivalent compounds were often intractable, but crystalline [(C5H4PPh2)3Ln(OPPh3)]were successfully isolated (Ln = La, Pr, Nd, Sm, Er, Y). In Sm(I1) and Yb(I1) chemistry, substitution of the ether donors with OPPh3 proceeded to give (C5H4PPh2)2Ln(OPPh3)2.8 The chemistry of Cp ligands incorporating classically 'hard' Lewis acids received more attention. Chelating amido-Cp ligands were used to prepare La and Y compounds. Two equivalents of Li2(C5R4SiMe2NCH2CH2X) (X = OMe, NMe2) react with LnC13 to give heterometallic Li/ Ln compounds; the structure of the Y compound revealed tetrahedral Li, pseudotetrahedral Y, and pyramidal amido N geometries.' In this paper, a tethered C=C functional group was also found to coordinate to Y but was displaced by THF. A related series of heterometallic Li/Lu and LirY compounds incorporating C5H$iMe2NCH2CH2R2 (R = OMe, NMe2) hgands were shown to give high molecular weight poly-s-caprolactone with a moderate polydispersity (the C5Me4R and C5Me3Bu'R compounds were also examined). lo Similarly, utility of Y complexes containing dibenzopyrrolyl-substituted Cp ligands as polymerization catalysts for ethylene and 1-octene was patented.' The chiral substituted Cp' ligand S-C5H4CH2CHMeOCH2Ph formed stable complexes of the formula Cpt2LnI and Cp'Ln12-THF, (Ln = La, Sm), and the structure of CpJ2Smcomplex revealed both 0 atoms were coordinated to the Sm(II1) ion. The mono-Cp' compounds were active Diels-Alder catalysts. l 2 A chiral Cp ligand was generated by the reaction of NdC13 with an excess of NaCp, followed by subsequent treatment with (,!j')-(+)-N-( 1-phenylethyl)salicylideneamine to give a dimeric structure via C-C bond formation and H transfer between one of the Cp rings and the C=N bond of the Schiff base 1igand.l3 Donor substituted Cp chemistry was also applied to a-olefin polymerization. l4 There was also a description of lanthanide compounds in which a donor phosphorus atom was built into the Cp group: divalent [(q5-PC4Me4)2Yb]forms coordination complexes with carbenes and, while not stable in THF, the phosphorus lone pairs do react with [RuHq(PPh3)3] to give heterometallic

8: Scunciium, Yttrium anci the Lunthunicles

33 1

[RuH2(PPh3)2(p:qS-PC4Me4)2Yb(carbene)] (1). This reactivity depends heavily on the steric properties of the carbene,I5 and ligand exchange to give monometallic products is an alternative reaction pathway.

1

The effects of metal size on alkylation chemistry were examined in the reactions of (BuLCp)2LnC1-LiCl(Ln = Sm, Yb) with LiCH2(CH2)PPh2.The Sm reaction gave the anionic metal-containing product [Me2PPh2][(BuLCp)3SmC1],while the Yb reaction gave the neutral lanthanide ylide ( B u ' C ~ ) ~ Y ~ C ~ ( C H ~ P ( M ~ ) P ~ presumably because ligand redistribution processes are less favorable with the smaller metal. When diphenylamido ligands were substituted for Bu'Cp, ligand redistribution gave [Ln(NPh)2]4- as the only isolable metal containing product (Ln = Er, Yb).I6 The tendency of Bu'Cp to form stable Cp2Yb fragments was also noted in the oxidation of (BuLCp)2Yb(THF)2with AgBPh4, which gave [(Bu'Cp)zYb(THF)2]BPh4, a compound that polymerizes ethylene. l 7 Polymerization activity was also noted with ( B U ' C ~ ) ~ Y M (prepared ~ by reacting the monochloride with MeLi at 4OOC). In this case, a series of methacrylates were studied, and the activity was found to increase in the order I > Et > Bu methacry late. * The use of smaller alkyl substituted C p ligands continues to decline, but there were still two reports describing complexes of MeC5H4- (MeCp). Again, because the smaller Ln show less of a tendency to redistribute ligands, [ ( M ~ C P ) ~ L ~ ( N Pri2)(THF)] (Ln = Y, Er, Yb) could be isolated by metathesis of the chloride with LiNPr'z. These monoamide compounds react cleanly with one equivalent of PhN=C=O to give the insertion products [(MeCp)zLn(OC(NPr12)NPh)].Both the amides and the insertion products polymerize PhNCO. l 9 Another MeCp study focused on the reactions of (MeCp)3Ln (Ln = Nd, Gd, Dy) with 3,5-dimethylpyrazole (Hpz), in which proton transfer to the Cp ring gives [(MeCp)Ln(Pz)2] at room temperature. These compounds react further with dimethylsilicones to give [(q5-MeCp)Ln(q2-pz)(p:q ':q2-OSiMe2pz)]2 for which the Dy complex was structurally characterized.20The structure of (MeCp)3Pr has also been determined.2'

'

2.3 Disubstituted Cp Ligands - The sterically demanding Cp ligands (TMS2Cp) and (BuL2Cp)provided a synthetic entry to a number of interesting compounds. A highly unusual compound with the non-classical ion La2+was detected by EPR

332

Orgonome iallic Chemistry

spectroscopy in the reaction of [(TMS2Cp),La] with K in dimethoxyethane (DME). The ultimate reaction products were lanthanum methoxides, which presumably originated by the reductive cleavage of the solvent C-0 bond. In the La study, the intermediates were tentatively assigned as K(DME),La(TMS2Cp), and La(TMS2Cp)2(DME) The reduction potential of [(TMS2Cp)3La] was also determined to be -2.8 V. 25 Neutral alane complexes of Yb(I1) have also been described. (Bu'2Cp)Yb forms coordination complexes with AIH3L, (L = NEt,, THF, Et,O), presumed to be dimeric with bridging A12H6L2units, which were moderately active for polymerizing polystyrene. Linear olefins were not incorporated into the polymerization process, which suggested some evidence for a heterometallic mechanism.23 The synthesis and molecular structures of (TMS2Cpj2Lul(THF),24 Na(TMS2C P ) ~ Y ~[ I( B , ~u ~' ~ C P ) ~ Y ~ (TMS2Cp)3Ln C ~ ] ~ , ~ ~ (Ln = La, Nd, Sm, Gd, Dy) and [(TMS2Cp)*LnC1]2(Ln = Gd, Dy, Y, Er or Yb)27have also been reported. Cp* Complexes - Pentamethyl Cp (Cp*) and pentaalkyl substituted Cp ligands continue to provide a source of steric saturation at Ln centers, particularly with respect to the stabilization of Ln-H bonds. With Y(III), the hydride dimer Cp*2YH reacts at low temperature with 3,3-dimethyl- 1,4-pentadiene to give the pentadienyl chelate [YCp*2(q',q2-CH2CH2CMe2CH=CH2)] (2), which was characterized by multidimensional NMR techniques and shown to exist in solution in both chair and boat conformations. Addition of T H F displaced the alkene donor. The hydride dimer also reacted with 1,4-pentadiene or methylenechelate [YCp*2(q ',q2cyclobutadiene to form the pentenyl CH2CH2CH2CH=CH2)]. 2.4

2

Deuteration studies confirmed that intramolecular alkene insertion is occurring.28 The reaction of [ c ~ * ~ L n C(Ln l ] = Ce, Pr, Nd, Sm) with 2-(dimethylaminomethy1)lithioferrocene (LiFc) displaced a Cp* ligand to produce Cp*Ln(FcN)CI. In the same work, a series of heterometallic ferrocenyl cerium halide complexes were obtained by metathesis reactions with Ce(IVj starting materials.29 Metathesis with [CaCp'2] and KCp' was also used in the preparation of heteroleptic Cp3M (Cp' = Cp*, C5H5, C,H,; M = La, Nd)2 and Cp*/ naphthalenide complexes (see Section 2.8).54 Unsolvated heteroleptic dimers with

8: Scundium,Yttrium unct the Luntlzunittes

333

bridging OAr ligands were prepared by the comproportionation of [Cp*2Sm(THF)] with Sm(OAr)2(TH F)3. The bridging alkoxide ligand can be displaced with HMPA to give monomeric [Cp*Sm(OAr)(HMPA)], which oxidizes in air and redistributes Cp* to give trivalent [Cp*2Sm(OAr)]. The Sm(II1) coordination environment is saturated by agostic interactions. The heteroleptic compounds also react with KCp* to give polymeric heterometallic structures that can again be disrupted with HMPA.30 The recently described Cp*3Sm has been shown to polymerize ethylene, most probably via a transient structure with an ql-Cp* ligand, since the reaction of Cp*3Sm with H2 to give [Cp*2SmH]2 would be consistent with such an intermediate.31 Similarly, the mixed oxidation state [ C P * ~ S ~ was ] ~ Rused to prepare link functionalized poly-s-caprolactone and methyl m e t h a ~ r y l a t e . ~ ~ A comprehensive study of scope, selectivity, and mechanism of Ln catalysed imine hydrogenation included the identification of interesting by-products. Both C P * ~ L ~and R the ansa-metallocene Me2Si(C5Me4)2LnRsystems (Ln= La, Sm, Lu; R = H, CH2SiMe3) were studied. The stoichiometric reaction of C P * ~ S ~ R with N-benzylidene(methy1)amine gives an orthometallated product that is either hydrogenated or undergoes insertion of a second substrate to yield a Cp*2Sm-imine-amido complex with a chelating seven-membered ring. With 2-methyl- I -pyrroline two substrate molecules couple to give a six-membered chelate (3), and with benzylidene(trimethyIsilyl)amine a desilylated [Cp*2Sm(NSiMe3)(CPh)N=CHPh] chelate is produced. Additional heating of this product under H2 gives a hexametallic product with an 18-membered (Sm-C-N)6 ring (4).33

.'.

\

3

4

2.5 Linked Cp Ligands - Covalently linked pairs of C p ligands (ansa-metallocenes) continue to evolve both in complexity and in utility. The synthesis and reactivity of ansu-metallocenes based on the RMeSi(CSMe& system, in which R is an OMe unit connected through a variable number of methylenes, was investigated. The organometallic complexes [RMeSi(C5Me4)2Ln(CH(SiMe3)2] (Ln = Y, Sm) were isolated, and their catalytic properties examined. Catalytic reactions involving initial coordination of a weak donor (i. e. olefin hydrogenation) were inhibited by the presence of the OMe group, presumably because of competition between C=C and OMe for a metal binding site. In contrast, where a

334

Orgunometullic Chemistry

strong donor is the substrate (i.e. amino-alkene hydroamination/cyclization), catalytic activity was enhanced at no expense t o dia~tereoselectivity.~~ Enantiomcrically pure { Me2Si(B~'Cp)[(+)-nen-Men-Cp]]~reacts with LnC13 to give metallocene dichloride products (R,S)-Me2Si(BuLCp)[(+)-neo-MenCp]Ln(pCI)2Li(OEt)2 (Ln = Y , Lu). Alkylation of the (R,S) chloride epimers with MCH(SiMe3)2 (M = Li, Na) proceeded with retention of configuration at the Ln center, and further reaction with H2 gave the diastereomerically pure hydride dimer, which appears to be an excellent catalyst for asymmetric olefin hydr~genation.~~ The donor-substituted chiral unsa metallocenes [(C5Me4)SiMe2(C5H3CH2CH2NMe2)LnC1] (Ln = Y, Sm, Ho, Er) were prepared, and metathetical replacement of the chloride with Me was successful (Ln = Y , Ho, L u ) . A ~ ~linked indenyl complex Me2Si(q5-CgHS-2-Me)2Y(N(SiHMe2)2) was prepared via the amine elimination reaction of the linked indenyl ligand with Y(N(SiHMe2)3).37 The structure of [ S m ( ( q ' - C ~ M e ~ S i M e ~ )N-q5-C5H4SiMe2NMe2)] ~0)( was also reported. 38

2.6 Lanthanide Carbaboranes - Closo and exo-nido carbaborane complexes of Ln( 11) and Ln(II1) were prepared by salt elimination reactions. Trivalent Lac13 reacts with one equivalent of Na2-R2-niclo-7,8-R2C2B9Hg(R = H, CH2Ph) to give the heterome tallic [(T H F)2N a][La(q5- R2C2B9H9)2(THF)2], a simple anionic metallocene analogue. The reaction of Sml2 with Na2(PhCH2)2-nido-7,8-C2BgHg in THF, followed by addition of DME, gave dimeric [(PhCH2)2-nido-7,8C2B9HgSm(DME)2]2, in which the dicarbollide ligands bridge the two Sm atoms. 39340

2.7 Neutral Hydrocarbon Donors - Neutral arenes coordinating t o Ln were examined in the gas phase, in solution, and in the solid state. Clusters of Sc,(benzene), were prepared in layer vaporization experiments. The compounds were identified by mass spectroscopy and characterized by measuring ionization energies. In contrast to the later transition metals, Sc formed only layered structures (y = x + 1) and there was no evidence for the formation of compounds with M-M bond^.^' A more stable example of this arene sandwich structure is found in the structurally characterized [Ho(2,4,6-But3-C5H2P)2],the first lanthanide his-he teroelemen t-arene compound (5) .42 Stable, structurally characterized

* HO

5

6

8: Scandium, Yltrium unci the Ldanthunitic.s

335

arene compounds were isolated from the thermal decomposition of L2YCH2SiMe3 (L = PhP(CH2SiMe2NSiMe2CH2)2PPh) in benzene (6). Such arene compounds could also be isolated from the reaction of the L2YCI with LiR.43The structure of [(q6-C7Hg)Nd(AlC14)3]was also determined.4 2.8 Extended Aromatic Anions - The tris(indeny1) adducts [(C9H7)3Ln.THF], (Ln = La, Pr, Nd, Sm) were isolated and characterized by 'H NMR and X-ray crystallography. The C5-fragments of the C9H7 ligands were essentially q5 coordinated to the Ln, with two or three C9H7 ligands adopting paddle-wheellike orientations. Solution H/'39La NMR and MCD spectroscopies indicate the presence of three rapidly equilibrating, indistinguishable C9H7 l i g a n d ~ The .~~ OPPh3, or Ph2SO T H F ligand can be replaced by (R)-(+)-methyl-p-tolylsulfoxide, to give the analogous coordination complexes, all of which have equivalent indenyl resonances in the 'H NMR spectrum. The chiral donor produced significant diastereotopic splitting.46 Tris-indenyl compounds react with 2-tetrahydrofurfuryl methanol in T H F to form binuclear [(C9H7)2Ln(p,q2OCH2CHCH2CH2CH20)I (Ln = Pr, Nd), in which the indenyl ligands are all q5 and the alkoxide both bridges and chelates the metal ions.47 The structures of [(C9H7)2PrCI(THF)]and [(C9H7)3La(THF)]were also de~cribed.~' The utility of anthracenide type ligands as leaving groups continued to attract attention. The reaction of the cyclopentadienyllutetium anthracenide, [(C5H5)Lu(C14HIO)(THF)~], with PhN=NPh yielded bimetallic [C5H5(THF)Lu(p:q2:q2-PhN-NPh)J2 (7),which was structurally characterized.

'

/

a

7

/m

\

v 9

336

Organomc~tallii~ Chemistry

The solution dynamics of this product were also i n ~ e s t i g a t e d .A~ ~layered naphthalenide structure, [ { (q2-CloH8)Tm(DME)2}2(p-q2:q2-C~0H8)](8) was prepared by the redox reaction of Tm12 with Li2(CIOH8)in DME.” This reaction will be the first of many to capitalize on the recently described synthesis and isolation of TmIf in DME.” A related multimetallic naphthalenide complex with several Ln-C bonding modes was isolated from the reaction of [Cp*2LuCI] with sodium naph t halenide in TH F, which gave [(Cp* Lu)3(C1oHg)(CI OH7)(H )][Na(THF)3].(CIOH8) (9), as well as [Cp*LuH(THF)I3(CIOH7), and Cp*Lu(CIoH&Na(THF),. In DME, [Cp*Lu(CloHg)(DME)]was isolated in 48% yield.’2 2.9 Cyclooctatetraene - The cyclooctatet raene (COT) ligand continued to find applications in the stabilization of lanthanide compounds. An interesting difference in reactivity was noted in the reduction of COT/RN=CRCR=NR (DAD) mixtures with elemental Sm and Yb to give [(COT)Ln(DAD)]. The more strongly reducing Sm formed a trivalent complex with a DAD radical anion, whereas Yb formed a divalent complex (as judged by ‘ H and I7’Yb NMR) with a neutral DAD fragment coordinated to the metal.’3 A second Sm(1II) COT complex, [(H MPA)3(COT)Sm][Sm(COT)2] was prepared by the direct reduction of COT with elemental Sm in hexamethylphosphoramide (HMPA). This structure is an excellent example of how strongly HMPA binds to Ln(II1) ions.54 The syntheses of a number of substituted trimethylsilyl-COT compounds were reported. Mixed Cp/COT complexes of Pr, Sm, and T b were prepared in a one-pot reaction of LnC13 with Li[Cp(SiMe3)2]/Li2[C8H7(SiMe3)],5sand both disubstituted [ 1,4(Me$i)2CsH6] and trisubstituted [ 1 ,3,6-(Me3Si)3C8H5]COT ligands were used in the metathetical syntheses of Ln(COT)*- compounds (Ln = Ce, Pr, Nd, Sm, Tb,

Y)? 2.10 Nitrogen-based Supporting Ligands There were a variety of nitrogen based anionic ligands used to support organolanthanide chemistry. A survey of the utility of PzB ligands in the stabilization of lanthanide borohydrides, amides, and alkyls has appeared.57 PzB ligands have also been used in Sc chemistry in the synthesis of metal dialkyl complexes. Lithium salts of methyl and butyl substituted pyrazolyborates (RPzB) react with ScC13 in T H F to give octahedral ( RPzB)ScCI2(THF), but further metathesis reactions with LiR (R = CH2SiMe3, CH(SiMe&) gave LiRPzB almost exclusively. The exception was ( M ~ P z B ) S C ( C H Z S ~ M ~ ~ ) ~ ( which T H F ) ,was isolated with approximately 10% Li impurity. A salt-free alkane elimination approach to this compound involved the proton transfer reaction of in situ generated Sc(CH2SiMe3)3(THF)2 with the protonated pyrazolyborate gave the desired dialkyl product in 67% yield. The THF-free product could also be isolated in 87% yield.58 Simple silylamides were used in the synthesis of Y carbene coordination complexes. Just as isocyanides have been shown to coordinate to the larger Ln(N(SiMe3)2)3, so too will isocyanides coordinate t o the smaller electropositive metals if the size of the silylamide is reduced: Y ( N ( S ~ H M ~ Z ) ~ ( T reacts H F ) ~ with carbenes t o form mono and bis-carbene corn pound^.^^ The asymmetric chelating amido

8: Scunciium. Yttrium and the Lonthunicles

337

[Me2Si(NCMe3)(OCMe3)]- (NSiC) forms disubstituted (NSiC)2YCl compounds from the reaction of YC13 with 2 Li(NSiC) in THF. Salt elimination reactions with LiBH4, LiOAr, NaN(SiMe3)2, and LiCH(SiMe3)2 gave the anticipated (NSiC)2Y-X substitution products. ‘The alkyl compound reacts with H2 in T H F to give a hydride dimer that disproportionates at room temperature to give (NSi(&Y. The alkyl compound also reacts with HCCR to give tris acetylido compounds Y(CCR)3 (R = SiMe3, But) or polyacetylene (R = Ph). Theoretical calculations o n the (NSiC)2YR model indicate that the NSiC ligand resembles benzamidate rather than a C p ligand. The Y-N bond is highly ionic and the ether functionality coordinates weakly. The ionicity of the Y-N bond results in little tendency of these compounds to undergo a-bond metathesis reactions or polymeric insertions. Instead, the ligands function as strong Brsnsted bases. The alkyl compound reacts with common organic solvents such as MeCN, which undergoes metalation of the Me group and proton transfer to give CH2SiMe3. Insertion of another MeCN into the new Y-C bond and a 1,3 H shift gives [(NSiC)2Y(p(N,N’)-NHCMe=CHCN)2],60 while reaction with the a-H atoms of pyridine, or allyl-substituted pyridines gave the corresponding q2-(C,N) pyridyl complexes.6’ The related P-diketiminato hgands were also investigated. The reaction of NaN(SiMe3)C(Ph)CHC(Ph)N(SiMe3) (N-N) with LnC13 (Ln = Ce, Pr, Nd, Sm, Yb) gave (N-N)2LnCl. The Ce compound was reacted further with LiCHR2 in EtZO to give [(N-N)Ce(CHR&]. Divalent (N-N) complexes of Sm and Yb were also obtained from metathetical reactions with Ln12 starting materials.62Several Ln(I1) and Ln(II1) aza-ally1 complexes (i.e. Ln(LL’)2X(THF), (LL’ = q3Me3SiN=C(But)CHSiMe3, X = CI. I), Sm(LL’)z(THF) and Yb(LL’)2 were prepared from LnX, starting materials. The Yb(I1) complex reduces Ag(OS02CF3) to give Yb(LL’)*(OSO*CF3)and 12 to give Yb(LL‘)2I as well as a ligand coupling product [Me3SiN=C(BuL)CH(SiMe3)]2. Y b(LL’)2 reacts with PhCN to give the previously known P-diketiminate Yb(L‘L’)2 [L”” = N(SiMe3)C(Ph)C( H)C( Bu‘)N SiMe3].63 Neutral 1,4,7-trimethyI-1,4,7-triazacyclononane (Cn) was used to saturate Ln coordination spheres. Cn reacts with (THF)3LnC13 (Ln = Sc, Y) to give (Cn)LnCI3. Methylation with LiMe gives the trimethyl complexes that are unreactive toward unsubstituted alkenes or alkynes. 2-Butyne does react with (Cn)Y(Me), by C-H bond activation to give (Cn)Y(Me)2(qt-C(Me)CCH2) and (Cn)Y(Meh(q ‘-CH2CCMe) as the major and minor products, respectively. The analogous Sc compound is less reactive but can be activated by B(C6F5)3 to give active olefin polymerization catalysts.@ Similarly, the deprotonated aza- 18crown-6 ligand (MAC) was used to support dialkyls. (MAC)Y(CH2SiMe3)2 was isolated and characterized by X-ray diffraction. The compound is stable with respect to ligand redistribution, inserts CO to form a bis-enolate, and reacts with B(CbF5)3 to form cationic [(MAC)Y(CH2SiMe3)]+.65

2.1 1 Organolanthanides without Ancillary Ligands - The coordination chemistry of dimeric [La(q3-C3H5)3(C4Hg02)1 was applied to diene polymerization chemistry. The glyme ligand is displaced by chelating ligands such as diglyme,

Orgunometullic Chemistry

338

TMEDA, and HMPA to form stable coordination complexes that were characterized spectroscopically (the TM EDA compound was structurally characterized). The complexes catalyse polymerization of butadiene in toluene at 50 "C with high 1,4-trcmsselectivity. Catalytic activity was inversely proportional to the bond strength of the neutral donor ligands. Addition of methylaluminoxane increased catalytic activity.66 The activation of the complex Nd(q3C3H5)3.dioxane with alkyl aluminoxanes (methyl or hexaisobutyl) results in highly selective living catalysts for the 1,4-cis-polymerization of butadiene (cisselectivity > 80'~)). 67 Heterometallic Cu/Ln acetylide compounds were isolated and structurally characterized. The compounds [(PhCC)&u][Eu(py)(TH F)& and [(PhCC)&h][Yb(THF)2]2 (10) were prepared either by reduction of CuCCR with elemental Ln (Ln = Eu, Yb) or by reacting CuCCR with Ln(CCR)2 in THF. Both heterometallic products have similar centrosymmetric structures in which the two Ln ions are connected by two bridging (PhCC)$u fragments. In both molecules all three alkynyl C, atoms bridge to form 4-membered Ln(p-C)2Ln rings and 4-membered L n ( ~ - c ) ~ C rings6* u Ph

\

Ph/-

Ph

10

2.12 Halide Compounds - The diphenylbutadiene (DPBD) dianion bridges Gd ions in [GdC12(THF),]&-DPBD), isolated from the reaction of GdC13 with K2(DPBD). The bridging DPBD ligand is q4-bonded to both of the distorted octahedral Gd ions. In the two 11:-bonded GdC4H4 fragments one of the Gd-C q4-distances is longer (by ca. 0.20 A) than the other three. Curiously, the expected short-long-short distribution of the C-C bonds in the diene fragment was not observed.69 Treatment of Nd(BH4)3(THF)* with K[C7H9] gave bimetallic [(THF)(BH4)2Nd(p-q7:q7-C7H7)Nd(BH4)(THF)2], the first lanthanide cycloheptatrienyl compound. The formation of the cycloheptatrienyl ligand resulted from the disproportionation reaction in which three C7H9- give C7H73- and two C7H10.70 Reactions of LiCH2Ph with LnBr3 were found to give both metathesis and redox products. The reaction of (PhCHz)Li(tmeda) with YBr3 gives [(tmeda)Y(PhCH2)2(p-Br)2Li(tmeda)]. Redox active metals are more complicated: [(PhCH2)Li(tmeda)]reduced SmBrRin toluenehmeda to give [(tmeda)2SmBr(p-

8: Scunciium, Yttrium unnd the Lanthanides

3 39

Br)2Li(tmeda)J which reacts further with DME to yield Li-free [(dme)2SmBr(pBr)]2.71

3

Polymerization Catalysis

Several polymerization systems have been covered in the sections describing new compounds. 3.1 Ethylene and Other Simple Olefins - A robust heterogeneous catalyst for the polymerization of ethylene has been prepared by treating finely divided MgC12 with [Nd(C5Me5)2CH(SiMe3)2]and butylethylmagnesium chloride.72 A patent has been filed for the polymerization of a-olefins, aromatic vinyls and acrylates using LnR,L, and Ln(NR2),Ly (Ln = S, Y, and lanthanides; R = alkyl The ' same systems efficiently or silylsubtituted alkyl; L = neutral donor h g a n d ~ ) . ~ ring open caprolactone to give p o l y l a ~ t o n e s A . ~ ~range of metallocene systems based on Nd and Sm have been used to polymerize butadiene, isoprene, and styrene. The addition of methylaluminoxane (MAO) as cocatalyst considerably increased the activities of the catalysts and cis content of the p o l y b ~ t a d i e n e . ~ ~ A system based on divalent samarium complexes such as C P S ~ ( O A ~ ) ( H M P A ) ~ (Ar = 2,6-Bu'-4-MeC6H2) (see Section 2.4) for the polymerization of methyl methacrylate has been patented.76 Complexes of the type (ArO)SmI(THF)3 were also found to be active for MMA p ~ l y m e r i z a t i o nas~ ~well as for hydroboration and copolymerization of styrene and ethylene. 78 [Y(BuLCp)2CH3J2showed good catalytic activity for polymerization of methyl methacrylate. The activity was progressively reduced for ethyl and butyl rnetha~rylates.~~ [Y~(M~CP)~NPri2(THF)]was found to exhibit high catalytic activity for the polymerization of MMA at low temperature." The ring opening polymerization of &-caprolactone by [Nd(ButCp)2CH3] has been studied and found to involve initial formation of an alkoxide by insertion in to the Nd-C bond.81 A patent for the preparation of biodegradable polyesters from such monomers as c-caprolactone, lactides, diglycolides, etc. using rare earth catalysts such as YPh3 has been described.82 Cationic thiolate complexes such as [Ln(SPy)2(hmpa)3]I were also found to give narrow molecular weight poly~actones.83

4

Lanthanide Organometallics in Organic Synthesis

The synthesis of alkoxycerium and amidocerium compounds was reported. For example, the addition of cerium triisopropoxide to trans-3-ethenyl-2-methylcyctopentanone gave (1 ol72.a,3P)-3-ethenyI-l,2-dimethylcyclopentanol as the major diastereomer in 86% diastereomeric excess and in 93'!4 overall yield.84 Organocerium reagents (RCeCI,; R = Ph, Me, Et, Pr, Bu, Bus) added selectively to the cdrbonyl C of R'3SiCH=C=0 to generate enolate anions, which react with N H4CI or alkyl halides to give a - s i l y l k e t ~ n e sDiallylcerium .~~ chloride/

340

Orgunometullir Chemistry

A1(0-2,6-Ph2C6H3)3has been found to be a very effective amphiphilic conjugate allylation reagent for a,P-unsaturated aldehydes.86The reductive dehalogenation of aryl halides by nanometric sodium hydride is catalysed efficiently by lathanide halides.87 Evidence for the formation of chelates by binding of the exo oxygen atom to the metal in the reaction of sydnones with MeYbI was obtained by FTIR.88 [Y(q5-C5MeS)CH3.THF]is an effective precatalyst for the selective sequential cyclization/silylation of I ,6- and 1,7-enynes. The catalyst's ability to insert the alkyne in preference to the alkene in a regioselective manner, combined with the high diastereoselectivity of the insertion process, yields a product with only one stereochemistry about the exocyclic olefin. The reaction proceeds under extremely mild conditions with short reaction times.89 A new acylation method using an oxime ester and isopropenyl acetate as the acylating agent and Cp*2Sm(THF)2 as the catalyst has been developed. Thus, a variety of alcohols could be acylated under mild conditions to give the corresponding esters in good yield^.^',^^ Catalytic methods for the preparation of carboxamides and carboxylates based on divalent samarium have been patented."

5

Theoretical and Spectroscopic Studies

5.1 Hypothetical and Labile Species - Density functional studies on LaC2+, LaCZ2', LaC3, and LaC3- clusters suggest that cyclic structures with lanthanum to carbon single bonds are favoured over alternative multiply bonded species.93 The ionization potentials and electron affinities of lanthanum carbon clusters Lac, (n = 1-6) have been calculated by density-functional methods within LDA and gradient corrections for the exchange-correlation potential. The results obtained are in good agreement with the experimental data: odd-even alternating IPS, and no alternations for the E A s . ~ Theoretical ~ studies of monolanthanum carbides, Lac, (n = 2-6), predict that fan structures obtain as ground states in most cases studied. The calculated enthalpies of formation of Lac, and atomization energies of these species are close to the corresponding experimental data.9s Ab initio density functional methods have been used to explore the relative stabilities of isomers of LaC12' and LaC13'. In the most stable isomer of Lac,*' the La atom is inserted into the carbon ring, whereas for LaC13+ the La atom lies inside the ring in the most stable structure.96 The electronic structure of ScC2 has been studied by ub initio methods giving results for the enthalpy of formation and dissociation energy in close agreement with available experimental data.97The yttrium dicarbide, YC2, was identified in the reactions of laser-ablated Y atoms with methane and other small hydrocarbons under supersonic jet-cooled expansion conditions. Analysis of vibrational structure of the fluorescence spectra suggests a side-bound C2 group on an yttrium atom with a high barrier to the internal rotation of the C2 unit.98A FTIR matrix isolation study of gaseous yttrium carbides in equilibrium with the corresponding metal and graphite has been carried out. The most abundant species YC2 was identified and their structures discussed with the help of I3C isotopic s ~ b s t i t u t i o n . ~ ~

8: Scunciium, Yttrium und the Lunthunicks

34 I

Ab initio studies of the reaction of Sc' with methane to give ScCH2 + H2 suggest that the 3Dground state is less reactive that the ID excited state primarily due to the electronic multiplicity change required in the insertion reaction. loo Reactions of Y2' with CI-Cb alkanes have been studied by Fourier transform mass spectrometry. Although methane showed no reaction, the predominant product from the reactions with ethane, propane and butane was found to be YC2Hz+. Since Y2+is a d' system oxidative addition to form two covalent bonds to the metal center is not possible, and alternative multicentred mechanisms were proposed including charge-transfer, hydride-transfer, carbanion-transfer, dehydrogenation and alkane-loss. ' O ' DFT calculations show that the insertion of Sc' into C02 to give Sc=O' + CO is exothermic due to the strength of the Sc=O bond. C02 coordinates to Sc' in end-on fashion because of strong electrostatic interaction^.'^^"^^ Ab initio calculations on ScCO predict a linear geometry, consistent with recent density functional results.lo4 The dissociation energy and vibrational frequency of CO bound to La, Gd and Lu atoms has been studies by relativistic DFT for three different binding geometries: Ln-CO (I), Ln-OC (II), and Ln-(q2-CO) (111). The vibrational frequency for Gd-CO is in good agreement with experiment. The dissociation energy is found to decrease in the order La > Gd > Lu essentially as a result of relativistic effects on the 6s and 5d orbitals while the dissociation energy varies of in the order (I) > (111) > (11) for the same metal. lo' The terminal monoacetylide of ytterbium, YbCCH, has been characterized spectroscopically for the first time. Resonance-enhanced two-photon ionization, laser-induced fluorescence (LIF), and photoionization efficiency spectroscopy together with density functional calculations have allowed detailed characterization of the ground and excited vibrational electronic states. Io6 5.2 Molecular Complexes - A series of divalent ytterbocene derivatives have been studied by I7'Yb CPMAS NMR spectroscopy. Spinning sideband analysis allowed the derivation of the chemical shift tensors which are discussed in terms of the molecular structures.107 The isotropic NMR shifts of paramagnetic compounds [LnCp3.L] (L = neutral donor) have been interpreted, using the singular value decomposition method, in terms of dipolar and contact shifts.Io8 Elastic neutron scattering and SQUID magnetometry measurements on the dimeric complex [Dy(C5D5)2(p-Br)]2revealed a rare example of intramolecular anti-ferromagnetic coupling (K ca. - 0.15 cm- I ) between the metal centres but no long range order. The single crystal X-ray structure of the complex was also determined. Io9 Single crystal magnetic and optical studies of [Ln(CH(SiMe3)2)3] (Ln = Pr, Nd, Sm) have been carried out at 150 K. The spectra are similar to those found for the corresponding bis-trimethylsilylamide and tris-alkoxo complexes but the crystal field splittings are smaller while the nephelauxetic effects are more significant. l o The absorption, MCD and luminescence spectra of monomeric pseudo-trigonal planar [ P r ( ~ l ~ - M e ~ s i Chave ~ H ~been ) ~ ] measured at room and at low temperatures. Cystal field splitting patterns, assuming D3h symmetry, were fitted and the crystal field parameters obtained. I I Similar measurements made on [(q8-C8H8)Nd(HB(3,5-Me2pz)3)] (pz = pyrazol- I -yl) allowed estimation of the crystal field strength of the cyclooctatetraenyl ligand.' I 2

342

Organometullic Chemistry

Large-scale state-averaged multiconfiguration SCF, multireference CI, and averaged coupled-pair functional calculations, including relativistic effects, were carried out for the ground and low-lying excited states of the complexes M(CgH& (M = Nd, Tb, Yb, U). The ground state configurations for the lanthanocenes are 4Y7t3,while for the actinocenes they are 5f”- In4.The special characteristics of the U 5f’ orbitals in uranocene are described. The calculations on uranocene confirm the assignment of the ground state and first excited state of uranocene made previously by other authors and are in excellent agreement with experimental data. However, a different ordering was obtained for the higher states. I Nonrelativistic and relativistic discrete variational-)
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Ma, W.-W.; Wu, Z.-Z.; Cai. R.-F.; Huang, Z.-E.; Sun, J. Polyheclron, 1997, 16, 3723-3728. Shen,Q.; Qi, M.; S o n g s . ; Zhang, L.; Lin, Y. J. Orgunomet. Chem., 1997,549,95-100. Roitershtein, D. M.; Lyssenko, K. A.; Belyakov, P. A.; Antipin, M. Yu.; Petrov, E. S. Russ. Chc.m. Bull., 1997,46, 1590-1594. Bochkarev, M. N.; Fedushkin, I. L.; Fagin, A. A.; Schumann, H.; Dentschuk, J. Chem. Commun., 1997, 1 783- 1 784. Bochkarev, M.N.; Fedushkin, 1. L.; Fagin, A.A.; Petrovskaya, T.V.; Ziller, J.W.; Broomhall Dillard, R. N . R.; Evans, W. J. Angew. Clzem., Intl. Edn. Engl., 1997, 36, 133. Protchenko, A. V.; Almazova, 0. G.; Zakharov, L. N.; Fukin, G. K.; Struchkov, Y. T.; Bochkarev, M. N. J. Orgunomet. Chem.. 1997,5361537,457463. Poremba, P.; Edelmann, F. T. J. Orgunomet. Chem., 1997,549, 101-104. Mashima, K.; Fukumoto, H.; Oshiki, T.; Tani, K.; Nakayama, Y.; Nakamura, A. Kirlorui, 1997, 30, 96--97. Poremba, P. Edelmann, F. T. Polyhedron, 1997, 16, 2067-2071. Poremba, P.; Reissmann, U.; Noltemeyer, M.; Schmidt, H.-G.; Brueser, W; T. Edelmann, F. J. Orgunomet. Chem., 1997,544, 1-7. Takats, J . J. Alloys Compd, 1997, 249, 52-55. Blackwell, J.; Lehr, C.; Sun, Y.; Piers, W. E.; Pearce-Batchilder, S. D.; Zaworotko, M. J.; Young, Victor G., Jr. Cun. J. Chem., 1997,75, 702-71 1 . Herrmann, W. A.; Munck, F. C.; Artus, G. R. J.; Runte, 0.; Anwander, R. Orgunometullics, 1997, 16,682 688. Duchateau, R.; Tuinstra, T.; Brussee, E. A. C.; Meetsma, A.; van Duijnen, P. T.; Teuben, J. H. Orgunometullics, 1997, 16, 351 1-3522. Duchateau, R.; Brussee, E. A. C.; Meetsma, A.; Teuben, J. H. Orgunometullics. 1 997, 16,5506-55 16. Hitchcock, P. B.; Lappert, M. F.; Tian, S. J. Chem. Soc., Dalton Truns., 1997, 19451952. Hitchcock, P. B.; Lappert, M. F.; Tian. S. J. Orgunomet. Chem., 1997,549, 1-12. Hajela, S.; Schaefer, W. P.; Bercaw, J. E. J. Orgunomet. Chem., 1997,532,45-53. Lee, L.; Berg, D. J.; Einstein, F. W.; Batchelor, R. J. Orgunometullics, 1997, 16, 18 19- 182 1. Taube. R.; Windisch, H.; Weissenborn, H.; Hemling, H.; Schumann, H. J. Orgunomet. Chem., 1997,548,229-236. Maiwald, S.; Weissenborn, H.; Windisch, H.; Sommer, C.; Muller,G.; Taube, R . Mucromol.Chem. Phys., 1997, 198, 3305-331 5. Bochkarev, L. N.; Druzhkova, 0. N.; Zhiltsov, S. F.; Zakharov, L. N.; Fukin, G . K.; Khorshev, S. Ya.; Yanovsky, A. 1.; Struchkov, Y.T. Orgunometullics, 1997, 16, 500 502. Emelyanova, N. S.; Trifonov, A. A.; Zakharov, L. N.; Shestakov, A. F.; Struchkov, Y. T.; Bochkarev, M . N. J. 0rgunornc.f.Chem., 1997,540, 1-6. Arliguie, T.; Lance, M.; Nierlich, M.; Ephritikhine, M. J. Chem. Sue., Dalton Truns., 1997,2501 -2504. Mandel, A.; Magull, J. Z . Anorg. Allg. Chem., 1997,623, 1542-1546. Soga, K.; Yamamoto, S.; Inematsu, K. Jpn. Kokui Tokkyo Koho JP 09272710 Yasuda, H.; Ihara, E.; Hayakawa, T. Jpn.Kokui Tokkyo Koho J P 09241314. Yasuda, €1.; Ihara, E.; Hayakawa, T. Jpn.Kokui Tokkyo Koho JPO9241358. Cui, L.; Jin, Yi.; Sun, J.; Li, K.; Ba, X.; Teng, H. Hecheng Xiungjiuo Gongye, 1997, 20.79-82.

48. 49. 50. 51.

52.

53. 54.

55. 56. 57. 58.

59. 60. 61. 62. 63. 64. 65. 66. 67. 68.

69. 70.

71. 72. 73. 74. 75.

8: Scundium, Yttrium uncl the Lanthunicies

76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. 99. 100. 101. 102. 103. 104. 105.

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KO, S.; W., Yasuo; Yoshimura, H. Jpn. Kokui Tokkyo Koho JP 09309888. KO, S.; W., Yasuo; Yoshimura, H. Jpn. Kokui Tukkyo Koho J P 09309887. Hou, Z.; Zhang, Y.; Wakatsuki, Y. Kiclorui, 1997,30,4041. FIu, J.; Ren, J.; Shen, Q. Yingyong Huuxue, 1997, 14, 86-88. Mao, L. S.; Xue, M. Q.; Shen, Q. Chin. Chem. Lett., 1997,8,637-638. Luo, Y.; Yao, Y.; Shen, Q. Guofenzi Xuebuo, 1997,734-737. Deng, X.; Yuan, M. Fuming Zhutmli Shenqing Gongkcii Shuomingshu C N 1146466 A. Shibahara, T.; Nakayama, Y.; Mashima. K.; Nakamura, A. Kiclorui. 1997, 30, 302-303. Alcaraz, C.; Groth, U. Angew. Chem., Int. Ed Engl., 1997,36, 2480-2482. Akai, S.; Kitagaki, S.; Matsuda, S.; Tsuzuki, Y.; Naka,T.; Kita, Y. Chem. fhurm. Bull., 1997,45, 1135-1 139. Ooi, T.; Miura, T.; Kondo, Y.; Maruoka, K. Tetruheclron Lett., 1997, 38, 3947--3950. Zhang,Y.; Liao, S.; Xu,Y.; Yu, D.; Shen, Q. Synth. Commun., 1997,27,4327 4334. Ezernitskaya, M. G.; Lokshin, B. V.; Kazimirchuk, E. I.; Khandozhko, V. N.; Kalinin, V. N. Mikrochim. Actu, Suppl., 1997, 14,381-382. Molander, G. A.; Retsch, W. €1. J. Am. Chem. Sue., 1997, 119,8817-8825. Tashiro, D.; Nishiyama, Y .; Sakaguchi, S.; Ishii, Y. Kiclorui, 1997,30,296-297. Tashiro, D.; Kawasaki, Y.; Sakaguchi, S.; Ishii, Y. f. Org. Chem., 1997, 62, 8 14 I --8144. Ishii, Y .; Nakano, T. Jpn. Kokui Tokkyo Koho JP 09239270. Wu, Z. J.; Meng, Q. B.; Zhang, Si Y.Chin. Chem. Lett., 1997,8,919-922. Ayuela, A.; Seifert, G.; Schmidt, R. 2. fhys. D: At., Mol. Clusters, 1997,41, 69-72. Roszak, S.; Balasubramanian, K. J. Chem. Phys., 1997, 106, 158.- 164. Roszak, S.; Balasubramanian, K. Chem. fhys. Lett., 1997, 264,SO-84. Roszak, S.; Balasubramanian, K. J. fhys. Chem. A, 1997, 101,26662669. Steimle, T. C.; Marr, A. J.; Xin, J.; Merer, A. J.; Athanassenas, K.; Gillett, D. J. Chem. Phys., 1997,106,2060-2066. Balducci, G.; De Maria, G.; Nunziante, C. S. Proc.Electrochem. So(*., 1997, 97-39, 7 I 2-7 17. Ye, S.; Shi, N.; Huang, J.; Dai, S. Int. J. Quuntum Chem., 1997,62, 23-27. Hill, Y. D.; Huang, Y.; Ast, T.; Freiser, B. S. Rupid Commun. Muss Spectrom., 1997, 11, 148-154. Sodupe, M.; Branchadell, V.; Rosi, M.; Rauschlicher, C. W., Jr. J. Phys. Chem. A , 1997,101,7854-7859. Sodupe, M.; Branchadell, V.; Oliva, A.; Bertran, J. Int. J. Quutztum Chem., 1997, 63, 523 528. Jeung, G.-H.; Haettel, S. Znt. J. Quuntum Chem., 1997,61, 547-550. Hong, G.; Lin, X.; Li, L.; Xu, G. J. Phys. Chem. A, 1997, 109,9314-9317. Loock, H.-P.; Berces, A.; Simard, B.; Linton, C. J. Chem. fhys., 1997, 107, 272S2727. Keates, J. M.; Lawless, G. A. Orgunometullics, 1997, 16, 2842-2846. Reddmann, H. Mugn. Reson. Chem., 1997,35,403409. Wehausen, P.; Borgmeier, 0.; Furrer, A.; Fischer, P.; Allenspach, P.; Henggeler, W.; Schilder, H.; Lueken, H. J. Alloys Compcl., 1997,246, 139-146. Guttenberger, C.; Amberger, H.-D. J. Orgcmomer. Chem., 1997,545-546,601-606. Unrecht, B.; Jank, S.; Reddmann, H.; Amberger, H.-D. J. Alloys Comprl., 1997,250, 387-390.

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1 12.

Unrecht, B.; Jank, S.; Reddmann, H.; Amberger, H.-D.; Edelmann, F. T.; Edelstein,

113.

N. M. J. Alloys Compd, 1997, 250, 383 -386. Liu, W.; Dolg, M.; Fulde, P. J. Clzem. Plzys., 1997, 107, 3584-3591. Kaltsoyannis, N.; Bursten, B. E. J. Orgunornet. Cliem., 1997,528, 19-33.

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9 Organometallic Chemistry of Group 15 Elements BY CAMERON JONES

1

Phosphorus

Due to space restrictions a comprehensive review of organophosphorus chemistry cannot be included here. Instead emphasis has been placed on developments in low coordination phosphorus chemistry. In this area reviews have appeared on a number of topics which include the transition metal assisted oligomerisation of phosphaalkenes and phosphaalkynes,' and the chemistry of phosphaalkyne tetramers.2 In addition, trigonal planar phosphorus cation^,^ the use of cationic low coordination phosphorus compounds as ligands? the chemistry of three coordinate pentavalent phosphorus compounds5 and transition metal functionalised phosphorus heterocycles' have all been reviewed. Various reports dealing with phosphaalkynes have appeared which include the synthesis of the first 0-phosphaalkyne complex of ruthenium, [Ru(q'P = c M e ~ * ) ( C o ) ~ ( P P h ~Mes* ) l , = C6H2But3-2,4,6,which was characterised by a range of spectroscopic techniques7 The q2-ligated phosphaalkyne in [Pt(dppe)(q2-P = CBu')], dppe = Ph2P(CH2)2PPh2,readily undergoes hydrozirconation with [ZrHClCp2] to give [Pt(dppe)(q2-Bu'CH=PZrC1Cp2)],the further chemistry of which was examined.* An unusual series of reactions involving the 4-electron q2-phosphaalkyne complex, [WF(C6H4CH2NMeCH2CH2NMe2)(CO)(q2-PCBu')] have been described.' Treatment of P=CR, R = But, adamantyl (Ad), with (PhSe)zXeF2 effects vicinal selenenylation of the phosphaalkyne affording R(Ph)SeC=PSePh. The 1,2-addition of PhSeX, X = C1, Br to phosphaalkynes was also investigated. l o The reaction of excess P 3 CBu' with [Ru3(pdppm)(CO)101, dppm = Ph2PCH2PPh2, yields a bis-ketenylphosphinidene ruthenium complex, [ R ~ ~ ( p - d p p m ) ( C Op3-PC(=C=O)BuL} )~{ 21 (X-ray).' Related compounds, e.g. [Ru~(CO)I 2(p3-PPh)(p3-PC(C0)But}](X-ray) have been prepared and studied.I2 The reaction of [Fe2(CO),(p-Se2)]with P = CBu' affords the tetrairon cluster [Fe4Se2(p-SezPCBu')(CO), I ] (X-ray) which displays non-linear optical proper tie^.'^ Stepwise addition of two equivalents of (Mes)zSi:, Mes = C6H2Me3-2,4,6, to P r C A d yields firstly - ( M ~ S ) ~ viu a [2+1] cycloaddition, and secondly fi=C(Ad)Si(Me~)~Si( M ~ S(X-ray) ) ~ viu a silylene insertion r e a ~ t i 0 n . lA ~ range of organometallic cage compounds, e.g. 1, have been prepared by reaction of aluminium alkyls with P=CR.l5*l6 Formal [2+2] cycloaddition reactions have been shown to occur between F2C=PCF3 and Organometallic Chemistry, Volume 27 The Royal Society of Chemistry, 1999 347

348

Orgunometullic Cltemistry

P = CR to give a series of 1,2-dihydro-l,3-diphosphetes, R-CF3, R = N Me2 ( X - ~ a y ) . Theoretical '~ studies of the [3+2] cycloaddition reactions of P = CH with diazomethane have suggested that an aromatic diazaphosphole would be produced." The phosphaalkyne, P = CBu', thermally tetramerises in the presence of tropane at 95 "C to give a tetraphosphasemibullvalene, (PCBU')~, the valence isomerisations of which were investigated. I' A considerable number of reports dealing with the chemistry of species

1

2

containing cr2/h3-phosphorus centres, e.g. phosphaalkenes, have come forward. At room temperature (E)- or (Z)-Mes*P=C(Br)Li eliminates LiBr to form a reactive intermediate, [Mes*P=C:], which undergoes an intramolecular insertion reaction to give the dihydrophosphanaphthalene 2.20 The reaction of [k(Mes)CZH,N(Mes)dPPh], 3, with an excess of BH3(THF) yielded [3(BH3)2] (X-ray) with both BH3 units coordinated to the P-centre in 3. This result suggested that 3 can be considered as a carbene-phosphinidene complex rather than a phosphaalkene.21Flash vacuum thermolysis of (Me2Si-PR)z or 3 yielded the unhindered silaphosphaalkenes, Me2Si=PR, 4, R = Ph, But. Photoelectron spectroscopic studies show that the first ionisations arise from the 7csiZpbonds of 4.22A series of phosphaalkenes, e.g. (TMP)P=CC13, T M P = NC5H6Me4-2,2',6,6', have been reacted with [MCpz], M = Zr, Ti, to give dihydrophosphetes, e.g. {(TMP)PCCI), 5, via dechlorination reactions. The X-ray crystal structure of 5 shows it to have a long P-P bond which has been ascribed to negative hyperconjugative effects.23 A variety of new phosphaalkenes have been accessed viu palhdium(0) mediated coupling reactions of bromophosphaalkenes, e.g. (Z)Mes*P=C(H)Br, with Grignard reagents.24Similarly, phosphaalkenes containing furan or thiophene substituents have been prepared and their electrochemistry studied.*' Ah initio calculations on fluorinated phosphaalkenes, e.g. F,C=PF, have shown that fluorination at the P-centre strongly stabilises such species.26 The metallophosphaalkene [Ru(P=CHBwL)Cl(CO)(PPh3)216 reacts with either Me1 or [AuCI(PPh3)] affording [Ru(RP=CHBu')CI(X)(CO)(PPh3)21,R = Me, X = 1(X-ra~);~ R' = Au(PPh3), X = CI (X-ray)28via insertion of the Ru-P bond of 6 into the R-X bond of the other reactants. The reactivity of another metallophosphaalkene, [( q'-C5Me5)(C0)2Fe-P=C(N has also been i n ~ e s t i g a t e d . ~ ~ Two 2-phosphabutadiene complexes, [M(C0)5{ q '-(SiMe&C=PC(OEt)=CHPh)l 7, M = W, Cr (X-ray), have been synthesised and one thermally rearranged to a 2,3-dihydrophosphete complex, [W(CO)5 { q 1-P=C(OEt)C(H)(Ph)&(SiMe3)2)].30 Complex 7 can also act as an q4-ligand to the Fe(CO)3 fragment in [Fe(C0),(q4-

9: Orgunometullic Chemistry of Group 15 Elements

349

7)] (X-ray) via its reaction with [Fe2(CO),l.3' The preparations of several other 2R = Bu', Ad, have phosphabutadienes, Bu1(Me3SiO)C=PC(SiMe3)=C(R)OSiPr'3, appeared.32 The synthesis of a number of compounds containing a P-C double bond in which the phosphorus centre is in the +5 oxidation state, e.g. phosphorus ylides, have been reported. Treatment of the iminophosphane (Me3Si)&P=NMes* with Me2S=CH2 yields (Me3Si)3CP(=CHZ)=NMes* (X-ray) which rapidly rearranges in refluxing toluene.33 The closely related compounds, Mes*P(=E)=CH2, E = C(SiMe3)2, NMes*, have been lithiated in THF to yield Mes*P(=E)=C(H)Li(THF)3 (X-ray) which have been used as transfer reagents in reaction with HgC12.34A number of ylidyl substituted phosphane systems have been prepared, e.g. { Ph3P=C(SiMe3)P(SiMe3)}2(X-ray) via reaction of Ph3P=C(R)C12 with P(SiMe3)3.35 Similarly, the 2,4,-diphosphoranediyl-1,3-diphosphetanes {Ph3P=CPX}2,X = CI, Br, have been synthesised and their chemistry investigated.36A series of bis(ylide) substituted phosphenium and phosphonium halides have also been in~estigated.~~ The known diphosphene Mes*P=PMes*, has been prepared via the [Pd(PPh&] catalysed decarbonylation of Mes*PCO. The related stoichiometric reactions of Mes*PCO with 'ML2', M = Pd, Pt; L = chelating diphosphine, yields a range of complexes, [L2MP(Mes*)C(=O)PMes*],which can be considered as intermediates in diphosphene f~rmation.~' The diphosphene complex [ { W(C0)5)3(q',q',q2-PhP=PPh)] undergoes [2+2] cycloaddition reactions with several alkynes to give 1,2-dihydro-1,2-diphosphete complexes, e.g. [ { W(CO)s}2 { q ,q '-Phk(Ph)=C(Ph)PPh}].39 Many reports concerning heterocycles containing low coordinate phosphorus centres have appeared. Dechlorination of the 1-chloro-1H-phosphirene Clk(Ph)=dBu' with Ag(OS02CF3) followed by treatment with B(OS02CF3)3/S02 yields a delocalisd phosphirenylium cation [PC(P~)CBU']'.~ A related 1 H-diphosphirene, ;=C(NPri2)P(NPri2), has been prepared and utilised as a ligand in the formation of a W(CO)5 c ~ m p l e x . ~Treatment ' of the diphosphacyclopropenium cation [bP(NPri2)2C(NPri)]+with lithium metal yields the first room temperature stable 1,3-diphosphaallyl radical [(Pri2N)k(NPri2)P(NPri2)]*which has been examined by EPR spectroscopy, both in solution and the solid state.42 A synthetic route into a range of a-functionalised phospholide ions has been developed whereby P-substituted phospholes, e.g. PhPC(H)=C(Me)C(Me)=CH, are heated in the presence of a base which causes a 1,5-sigmatropicshift of the Psubstituent and accompanying aromatisation to give phospholide ions, e.g. [#'C(H)C(Me)C(Me)kPh]-.43The tetramethylphospholyl ligand has been used in the preparation of several triple decker complexes in which it adopts a bridging Fe(q5-C5Me4CH2C6H11))(RuCp*)][CF3S03], Cp* role, e.g. [(p-q5,q5-C4Me4P){ = C5Mes, (X-ray).& The same ionic ligand when reacted with CrC12 leads to the chromocene, [Cr(qS-C4Me4P)2] (X-ray), which has been oxidised electrochemically and chemically to give [Cr(q5-C4Me4P)]' which was studied by EPR spectro~copy.~~ Structural elucidation of a related ferrocene, [Fe(qs-C4Ph4P)2],

'

-

I

350

Orgunometullic Chemistry

shows it to contain eclipsed heterocycle^.^^ Electrochemical investigations on a series of polyphosphaferrocenes, e.g. [FeCp*(q5-1 ,2,4-P3C2But2)],and their metal carbonyl complexes have been carried out and coriclusions about the o-donor, xacceptor properties of the complexes inferred.47Several other polyphosphaferrocenes have been reported.48 The complex [Ni(q'-P3C2Bu'2){ q2-P3C2Bu12CH(SiMe3)2Me)]has been synthesised; its X-ray crystal structure shows it to possess an q5-coordinated triphospholyl ligand and an q2-coordinated cyclic 2-phosphaallylic ligand which is, remarkably, coordinated to the nickel centre solely through its saturated P - ~ e n t r e sThe . ~ ~first triphosphole complexes, [M(CO)3{q5P3C2BuL2CH(SiMe3)2)],M = Cr, Mo, W (X-ray), have been prepared, the ligands of which are q'-coordinated and partially aroma ti^.'^ A series of phosphonio substituted phospholes, e.g. [Ph,P=&PC(=PPh2)Nfi], have also been investigated," as has a triphospholyl phosphane, [P(PC4Me4)3](X-ray).52 The [4+2] cycloaddition products between two molecules of the diphosphacyclopentadienes P2C3Bu'3H, or one molecule of P3C2Buf2H and one of P2C3But3H, yield P4C6BU16H2and PsCSBu'5H2 (X-ray) r e s ~ e c t i v e l y . ~ ~ The phosphabenzene, PC5H2Bu13-2,4,6, has been reacted with holmium vapour, viu metal vapour synthesis (MVS), to prepare the first zero valent heteroarene-lanthanide complex, [Ho(PC5H2But3-2,4,6)2] (X-ray), the magnetic moment of which has been determined.54 The same heterocycle has been used in the preparation of [Ti(PC5H2Bu'3-2,4,6)2]8, again by MVS. Reaction of 8 with potassium yields K[8].s5A range of 2-phosphanyl substituted phosphinines have been used as bridging ligands in the formation of dinuclear transition metal carbonyl complexes, e.g. [ { Cp2Mo2(C0)4) { PC~H2Me2-4,5-P(OEt2)-2}]( X - r a ~ ) . ~ ' Thermolysis of several 2-phosphinyl substituted zirconocenes, e.g. [(C5H4Me)2ZrMe(2-PC5H2Me2-3,4)], initiates methane extrusion reactions and the formation of q2-phosphabenzyne complexes, e.g. [(C5H4Me)2Zr(q2PC5HMe2-3,4)] (X-ray), the reactivity of which has been e ~ p l o r e d . 'The ~ formation of a 1,3-diphosphinine in which both phosphorus centres are in the +5 oxidation state has been reported.58 It has been shown that the 1,3,5-triphospha7-hafnanorbornadiene, 9, rearranges to its 1,2,4-isomer, 10, upon heating to 70 "C.Treatment of 10 with C2C16 generates the uncoordinated 1,2,4-triphosphade-war benzene, ll.s9 The 1,3,5-isomer of 11 has been reacted with electron deficient alkynes in a series of homo-diels alder reactions.60 Several interesting phosphinidene complexes have been reported. For example, the reaction of AgCl with PPr"3 and PhP(SiMe3)2 gives several remarkable

,SiMe3

11

9: Orgunometullic Chemistry of Group I5 Elements

35 1

phosphinidene bridged silver clusters, e.g. [Ag50(PhP)20C17(PPrn3)I 31 (X-ray) via ClSiMe3 elimination.61 Similarly, the phosphinidene bridged mercury complex [{ ( H ~ P B u ' )3] ~ }(X-ray) has been synthesised by a related route.62 The transient affording phosphinidene complex [W(PMe)(C0)5] reacts with [ O S ~ ( ~ - H ) ~ (101 CO ) [Os(p-H)(p-PHMe)(CO)lo] and subsequently [0s3(p-H)2(p-PMe)(C0)9] via hydrogen migration reactions.63 2

Arsenic, Antimony and Bismuth

Reviews have appeared on the syntheses and structural aspects of terminal arsinidene and phosphinidene complexes of both transition and main group metals.64 In addition, complexes containing terminal pnictinido ligands (P, As and Sb) have been reviewed.65 Surveys of organoantimony compounds containing Sb-Group 14, 15 or 16 bonds,66 and the biological and medicinal chemistry of some organobismuth compounds have been published.67 A number of reports have appeared describing low coordination organoGroup 15 compounds. The bonding of a triplet carbene, FI* = 2,7-di-tertbutylfluorenylidene, to arsinidene or phosphinidene fragments, EMes*, E = P, As, yields the novel arsa- and phospha-alkenes, Mes*E=Fl* (X-ray).68 By contrast the coordination of a singlet imidazol-2-ylidene carbene, :kN(Mes)CzHzd(Mes) 12, to arsinidene and phosphinidene fragments, ER, E = P, As; R = Ph, C6F5, gave complexes of the type 12+--ER which X-ray crystallography shows to have little double bonding ~ h a r a c t e r .An ~ ~ unstable stibaalkene, R-Sb=C(SiMe3)(2-C5H4N) 13, R = { C(SiMe3)2(2-C5H4N)f, is thought to result from the reaction of two equivalents of [Li(tmeda)(R)] with SbC13. The carbometallation reaction of in-situ generated 13 with AIMe3 affords [RSb(Me)C(SiMe3)(A1Me2)(2-C5H4N)] (X-ray).70 Treatment of [M]-As(SiMe&, [MI = -MCp*(C0)2, M = Fe, Ru, with CS2 yielded the metalloarsaalkenes [MIAs=C(SSiMe3)2, which were treated with a source of the Cr(CO)5 fragment to produce the first q '-arsaalkene complexes, [Cr(CO), { q -[M]-As=C(SSiMe3)2}] ( X - r a ~ ) . ~ ' Employment of a sterically demanding aryl ligand, C6H2{CH(SiMe3)2}3-2,4,6TBT, has allowed the preparation of the first dibismuthene, [trans-(TBT)Bi=Bi(TBT)] (X-ray) via a novel deselenation reaction between [ { (TBT)BiSe) 3] and P(NMe2)3.72Cationic arsinidene and phosphinidene complexes, [(N3N)W=EMe]'[CF3S03]- 14, E = As, P, N3N = [(Me3SiNCH2CH2)3NI3-, were prepared by reaction of methyl triflate with the phosphido and arsenido complexes [(N3N)W = El. The crystal structure of 14, E = As, displays a linear W=As-Me arsinidene fragment.73 Various reports detailing the chemistry of heterocyclic species containing low coordination group 15 centres have come forward. In particular, the first diphosphastibolyl anion, [ 1,4,2-P2SbC2But2]- 15 (X-ray) has been described.74 This has been used in the preparation of a variety of polyheteroferrocenes and ruthenocenes, e.g. [Ru(q5-15)2] (X-ray), which can display inter-ring Sb...Sb interactions in solution and the solid state.75 In addition, Several half sandwich complexes, e.g. [Rh(q5-15)(q4-1,5-C8H ,2)] (X-ray) and [CoCp*(q4-

352

Orgunometullic Chemistry

P2SbCBu'CHBu')l (X-ray) derived from 15, have been synthesised. The latter is diamagnetic and most likely arises from solvent proton abstraction by a reactive paramagnetic intermediate, [C0Cp*(q~-l5)].~~ Oxidative coupling of IS with FeC13 affords the novel organoantimony cage [P4Sb2C4But4]16 (X-ray).77The further reactivity of 16 and formation of other organoantimony cages, e.g. [cisPt(PEt3)2(q2-P4Sb2C4But4)]17 (X-ray) are described in another paper.78 The first complex in which 15 acts solely as an ql-ligand, [PtCl(PEt3)2(q1-15)], (X-ray) is also reported. A range of 1,3,2-diaza-phosphinines and -arsinines, e.g. ASNC(BU~)C(H)C(BU~)& 18, have been prepared. Interestingly, 18 reacts with alkynes to give arsinines, e.g. AsC(SiMe3)C3(H)&!SiMe3, viu a cycloadditioncycloreversion reaction sequence.79 Bu'

B"' 16

There have been several accounts detailing the chemistry of heterocyclic or polycyclic systems containing saturated arsenic or antimony centres. The fused bi- and tri-cyclic stibacycles 19-218078',82result from exchange reactions between the corresponding zirconacycles 22-24 and PhSbCI2. Treatment of 21 with sulfur leads to oxidation at the P-centre only. The tungstaarsirenes [ C o ( C 0 ) 2 ~ s P h 2 ] [ P F 6R] = Me, Ph (X-ray), result from the reaction of [Cp(CO)2W= CR] with Ph2AsCl in the presence of TlpF6.83 The previously described reaction of RSbC12, R = -CH(SiMe&, with Mg has given a new product, SbgR4 25 (X-ray), which consists of three edge sharing Sb5R2 mono-

M=SbPh 19 M=ZrCp.L22

20

23

25 R = CH(SiMe&

21 24

9: Orgonometallic Chemistry of Group 15 Elemenls

353

cycles.84 Similarly, when the known monocycle (AsBu')~ is treated with [co2(co)8] and the mixture heated in toluene, the bicyclic species AsgBu'6 26 (Xray) is obtained in good yield.85 A comparable reaction between ( S ~ B U ' and )~ [Cp*Mo(C0)3] yields two tetrahedral products, [{Cp*(C0)2Mo)2(p-Sb2)] and [Cp*(CO)2Mo(q3-Sb3)] (X-ray), the latter of which contains a three membered Sb3 ring capped with a [Cp*(C0)2Mo] fragment.86 A series of cyclic amido derivatives of arsenic cyclopentadienyls, [(Cp'AsNR),], n = 2 or 4, Cp' = substituted cyclopentadienyl, have been prepared and structurally characterised. In each there is a primary o-As-Cp' bond and a secondary q2-interaction between the Cp' ligand and the As centres.87 Many reports have come forward concerning the synthesis and chemistry of compounds of the type R3-,,EXn or R5-,EX,, R = alkyl or aryl, X = other ligand, E = As, Sb, Bi. These include the preparation and crystal structures of RAs(S2CNEt2)2, R = Me, Ph (X-ray), which have pyramidal geometries.88 Oxidative addition of Sb(Biph)Ph, Biph = 2,2'-biphenyl, with halide sources gave Sb(Biph)(Ph)X2, X = CI, Br, F, which have square pyramidal geometries and are dimeric through weak Sb-X...Sb bridges in the solid state.89 A number of organoarsenic and antimony dimesylamides, e.g. PhE[N(S02Me)2]CI, E = As, Sb, have been prepared." The polar reactions of bis(perfluoroalkyl)cadmium compounds with EC13, E = As, Sb, yields E(Rr)3, Rr = C2F5, C4F9, C6FI3,several of which have been oxidised to the corresponding dihalides, e.g. E(C2F5)3X2, X = F, C L ~ 'Triphenyl antimony reacts with [PdX*(COD)] X = CI, Br, to give [PdXPh(SbPh&] (X-ray) via a Sb-C bond cleavage reaction.92 A new two step synthetic route to triaryl Group 15 compounds has been developed which involves the reactions of Group 15 element oxide with 2,6-(Me0)2C6H3SH.93 Dicarboxylic acids react with SbPhS to give a range of products which include antimonium salts.94 The first dendritic Bi(III),-bismuthanes, n = 4 or 10, have been prepared via directed ortholithiation of triarylbismuthane~.~~ The sterically hindered bismuthane [Bi(C6H2Ph3-2,4,6)CI2](X-ray) has been prepared and found to be dimeric through chloride bridges.96The crystal structure of MeBiI2 shows it to be a one dimensional polymer possessing square pyramidal Bi centres with methyl groups in the apical sites, [runs- to stereochemically active lone pairs. The compound decomposes at 185°C to yield Me1 and BL9' Metathesis reactions between BiX3 and BiMes3 yield BiMesX2, X = CI, Br (X-ray).98 Aryl bismuth(V) carboxylates and sulfonates, e.g. Ph3Bi[OC(0)CF3]2,are readily prepared by the reaction of Ph3Bi(OAc)* with strong carboxylic or sulfonic acids.99 Similar complexes, e.g. Ph3Bi[OC(O)C3H60H]2 (X-ray), can be formed by treatment of Ph3BiC12 with silver salts, e.g. Ag[OC(0)C3H60H].loo Oxidising Bi(CbH3F2-2,6)3 with XeF2 or Cl2 yields Bi(CbH3F*-2,6)X2,X = F, CI. The former compound has also been used in transmetallation reactions. Iol Various cationic organoarsenic and antimony systems have been investigated. A range of arsonium and stibonium triiodides, e.g. [SbMe4][13] (X-ray), were synthesised by the general reaction of R4EI, E = As, Sb, with I2.lo2Several other arsonium salts have been described elsewhere.'03 Cationic Sb(II1) and Bi( 111) compounds, e.g. [EAr2][PF6](X-ray), E = Sb, Bi, Ar = ~ - M ~ z N C H ~ ( Chave ~H~),

Orgunometullic Chemistry

354

been stabilised by intramolecular coordination from both amine arms of the aryl ligands. The related complex [SbPh2{0P(NMe2)3)][PF6] (X-ray) was also reported. '04 Two stibocenium complexes, [Cp'2Sb][AlC14], Cp' = C5MeS or C5H2But3-I ,2,4, the cations of which are isoelectronic to stanocene, have been prepared and structurally characterised. lo' Tertiary pnictanes have been used as ligands in the formation of a number of complexes. The distibinomethanes, R2SbCH2SbR2, R = Me, Ph form complexes with Co, Ni and Mn carbonyls, e.g. [Fe(C0)4(Ph2SbCH2SbPh2)], in which the ligand can act in an 11'-, chelating or bridging mode as determined by X-ray crystallography.'06 The crystal structures of [M(CO)5(BiPh3)],M = Cr, Mo or W, have been reported.'07 It has been shown by X-ray crystallography and stopped flow spectrophotometry that SbPh3 has a greater trans-effect than PPh3 in the substitution of the trans-iodide ligand in [NBu4][PtI,(EPh3)], E = Sb or P.lo8 The complexes [trans-RuX2L4], X = Cl, Br, I; L = AsMe2Ph, SbMe2Ph, (X-ray) have been synthesised by several routes and their Ru(1I)-Ru(II1) oxidations probed by cyclic voltametry. '09 The triphenylarsane adducts [GaI3(AsPh3)] (X-ray), and cocrystallised [In13(AsPh3)J and [In13(A~Ph3)2] (X-ray) have been prepared and structurally characterised.' l o When Sb(SiMe3)J is reacted with GaBu'3 or GaBu'zCI, [GaBu13{Sb(SiMe3)3)](X-ray) and dimeric [ {But2GaSb(SiMe&)2] 27 (X-ray) are produced respectively. Thermolysis of 27 at 400 "C produced nanocrystalline GaSb. Several pnictide complexes of transition metals have been reported. The arsanes, AsR2Br (R = Me, Et) insert into an Nb-H bond of [Cp2NbH3] to give [Cp2NbH2(HAsR2)]Br, the deprotonation of' which yields the arsenido complexes [Cp2NbH2(AsR2)].'l 2 Similarly, treatment of [Cp2NbH3] with SbPhzCl in the presence of a base has given the first niobium antimonide, [Cp2NbH2(SbPh2)](Xray).'13 Reaction of K[As(M~s)~] with Sm12 yielded [Sm(As(Mes)2}2(THF)4] (Xray) which contains the first structurally authenticated Sm-As bond.' l 4 The preparation of a monomeric arsenide [FeCp(AsPh2)(dppe)].2THF has also been reported.' l 5 A series of complexes containing bridging stibinido ligands, [ N ~ I O ( S ~ R ~ ) ( C O ) ~ ~ ] R[ N=M Me, ~ ~ ] ~Et, , Pr' (X-ray), were prepared by the ~ ] ~ SbR2Br.' l6 treatment of [ N ~ ~ ( C O ) Iwith Several 0x0-bridged organoantimony complexes have featured in the literature. For example, [ { Sb(p-tolyl)3Br}20] (X-ray) possesses a linear Sb-0-Sb bridge. l7 In addition, a variety of multiply 0x0-bridged species, e.g. [(SbPh&(p0)2(p02A~Me2)2] (X-ray)' Is, [{ (2-PhOC6H4)O(C6H4)2Sb} 2p-02] (X-ray)' l 9 and a p4peroxo-antimony complex [(o-tolyl2Sb0)4(0~)2](X-ray),I2O have been prepared by a variety of routes. An oxygen bridged organoarsenic compound, Me2As(S)(pO)(S)AsMe2, has also been prepared and structurally characterised. 12'

'' '

References 1.

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9: Organometullic Chemistry of Group IS Elements

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10 Carbaboranes, Including Their Metal Complexes BY CATHERINE E. HOUSECROFT

1

Introduction

'

This review covers the 1997 literature of carbaboranes and metallacarbaboranes, with sections arranged according to carbaborane composition; metal complexes are included in the appropriate C,yB,,-section. Papers dealing with theory and spectroscopic studies are considered in Section 2, rings and ring-stacking in Section 3, and BNCT (selected papers) in Section 11. Current Contents and the Cambridge Structural Data Base have been used to search the literature; several references from the tail end of 1996, and missed from last year's review, are included. All structures excepting (l),(2), (ll),(13) and (14) were redrawn using coordinates taken from the Cambridge Structural Data Base, implemented through the ETH, Zurich.2 Page restrictions for the review have meant that it has been necessary to curtail detailed discussion of individual papers. A general review has dealt with analytical methods for the determination of boron concentration and isotopic composition in sample^.^ Hosmane and coworkers have produced a review detailing recent advances in main group heterocarborane cluster^.^

2

Theoretical and Spectroscopic Studies

Molecular modelling is becoming a routine addition to many experimental studies, and parameters have been developed within the MM3 force field giving access to conformational calculations on 12-vertex carbaboranes, boranes and their derivative^.^ Density functional calculations have been carried out for the anions and radicals of monocarbon carbaboranes of formula CB,H,+I (n=4, 9 and 11). Ionization potentials for the monoanions have been determined to be 2.88, 4.36 and 5.19 eV respectively.6 Ab initio calculations have been carried out to investigate isomers of the clusters X2B10H10(X = CH, SiH, N, P and Sb), and the results indicate that these derivatives (with the exceptions of X = N or Sb) follow similar trends in relative stabilities in the ordering 1,12 > 1,7 > 1,2-is0mer.~Two related studies have been concerned with investigations of the vibrational Organometallic Chemistry, Volume 27 The Royal Society of Chemistry, 1999 359

360

Orgunometullic Chemistry

frequencies of CZBIOH12, NBIIH12, C2BloCI and (C2BioHI 1)2 using either Gaussian 92 (at the 6-31G level) o r Gaussian 94 (STO-3G and 6-31G basis sets) program^.^.^ Oscillator strength spectra in the region of B 1s and C 1s excitation of 1,2-, 1,7- and 1,12-C2BlOH12 have been derived using HEELS; spectroscopic features have been assigned by comparing the data with those predicted from ab initio and extended Hiickel M O calculations."

3

Rings and Ring Stacking

The reaction of Li[C5H5BMe] with [ c ~ * F e ( N c M e ) ~ ]leads ' to the formation (in excellent yield) of Cp*Fe(C5H5BMe). Stacking from this building block has given rise to the products [Cp*Fe(C5H5BMe)FeCp*]+, [Cp*Fe(C5H5BMe)RuCp*]+ and [Cp*Fe(CSH5BMe)MCp*I2' (M = Rh or Ir). The [C5H5BMe]- ligand has also been incorporated into the complex [(COD)Rh(C5H5BMe)Rh(COD)]+,the structure of which has been determined (as the CF3S03- salt) along with that of [Cp*Fe(C5H5BMe)FeCp*][PF6]."With the electrophiles Me3ECl (E = Si, Ge, Sn, Pb), Li[C5H5BMe] reacts t o form [2-(Me3E)C5H5BMe] and the structure of the tin complex has been elucidated. In solution, the products are stereochemically non-rigid, exhibiting [ 1,3] sigmatropic migrations of the Me3E group from atom C(2) to C(6). Detailed investigations of the fluxional processes are presented, as well as reactivity studies.12 The complexes [(C5H5BMe)TiC13], [(C5H5BMe)ZrC13],,, [(C5H5BMe)HfC13],, [(C5H5BMe)2ZrC12]and [(C5H5BMe)2 HfC121 have been prepared by treating MC14 (M =Ti, Zr, Hf) with Li[C5H5BMe], [2-(Me3Si)C~H5BMel o r [2-(Me3Sn)C5H5BMe]. In similar fashion, [CpMCl2 (C5H5BMe)] (M =Ti, Zr) and [Cp*MCI2(C5H5BMe)] (M = Zr, Hf) have been made. Structural and electrochemical data for the new sandwiches have been reported. I

I

Rh

Rh

1 The reaction of compound 1 (R = Me, Ph) with 12 has led to the isolation of the cubane complexes [Rh(p3-I)(C4H4BR)I4 and the sandwiches [RhI(C4H4BR)2].

10: Curbuborunrs, Including Their Metul Complexes

36 1

Exchange of RhI(C4H4BR)-fragments takes place rapidly on the N M R spectroscopic timescale; these and isomerization processes involving [Rh I(C4H4BR)2] have been studied in detail, and the results complemented by X-ray diffraction data.I4 The cubane [Rh(p3-1)(C4H4BMe)l4reacts with Lewis bases, e.g. py, bpy, MeCN, CO, dppf (1,l '-bis(dipheny1phosphino)ferrocene) and dppm, to give mononuclear products such as [ R ~ I ( P Y ) ~ ( C ~ H ~ and B M ~dinuclear )] species including [(C4H4BMe)2Rh2(p-1)2(pL'dppm)]. Structural and N MR spectroscopic data are presented. Single clusters containing the C2B4-unitwill be considered in Section 6, but relevant to stacks is the preparation of the linked clusters [Cp*Co(2,3The latter can be Et2C2B4H3)I2MeCHand cis-[Cp*Co(2,3-Et2C2B4H3)I2C2H2. partially converted to the trcms-isomer by irradiation with UV light. Related species have also been prepared, and all products have been fully characterized.16 The synthesis of the triple-decker sandwich [Cp*Co(E ~ ~ C ~ B ~ H ~ ) R U is H C ~ * ] described in Section 6.

4

Composition C4B,and C3B,

From the reaction of Et2BH with Et2B-C= C-BEt2, it has been possible to isolate C4H4B4Et4. On treatment with Fe3(C0),2, the diiron derivative 6,9-(Fe(C0)3)21,2,3,4-Et4-5,7,8,10-C4B4H4. An X-ray diffraction study of this compound confirms a nido-structure, related to that of B I ~ H ~Displacement ~.'~ of the bromo group in pentaalkyl derivatives of type 2 (X=Br) has given routes to 2 with X = SnMe3 and SnPh3.These substituents can, in turn, be displaced by SnCI3and SnBr3 groups. The results of a range of reactivity studies have been presented, and all products have been characterized by 'H, I3C, "B and '19Sn NMR spectroscopies.

R

R

R 2

X = Br, SnMe3, SnPh3, SnC13, SnBr3

Several carbaboranes with C3B7 and C3Bg skeletons have been reported. I I-Vertex cages are by no means as well exemplified in the literature as other classes of carbaborane cages, and this year Sneddon and coworkers have made valuable contributions to this area. Reactions of [CpFe(CO)*I] with [arachno6-R-5,6,7-C3B,HI 11- (R = H, NCCH2, MeOC(0)CHz) lead to the formation of [closo-CpFeRC3B7H9]. Crystallographic data on several derivatives have

362

Orgunometullic Chemistry

confirmed the presence of closo-octadecahedral cages with carbon atoms in the 2,3,4-positions. Further members of this family of clusters, including the novel compound [(pCH2)(closo- 1-CpFe-2,3 ,4-C3B7H9)(urachno-5’-( N CCH2)have been prepared and characterized. l 9 The clusters 5’,7’,9,12, I 1’-C4NB7H [7,8,9-C3BgHI I]-, 7,8,9-C3B8HI2and 8-Me-7,8,9-C3B8HII have been prepared lo; further derivatives have also been starting from 7-(Me3N)-nido-7,8,9-C3B8H 10 and [7,8,9made and characterized. Heating 7-(Me3N)-nido-7,8,9-C3B8H C&HI at 350 “C resulted in isomerization to 10-(Me3N)-ni~o-7,8,10-C3B~Hro and [7,8,10-C3B8H1,]- respectively. The structure of the former has been determined by X-ray diffraction, and structures of several of the other clusters have been optimized using ab initio studies. Agreement between experimental B NMR spectroscopic data and the results of IGLO/NMR calculations has provided support for the proposed structures.20 Improved yields of nido-5,6-C2B8HI2 have been obtained by modification of the PleSek reaction. In a series of reactions, acidic aqueous [Fe(H20)6]C13is used derivatives (R,R’ = H,H; H,Me; Me,H; to oxidize [7,8-R,R’-nido-5,6-C2B9HI0]Me,Me; H,Ph; Ph,H; Ph,Ph) and extrusion of a boron vertex (one which is adjacent to carbon and in the open face) occurs. The products have been characterized by multinuclear NMR spectroscopy and mass spectrometry.21

5

Composition C2B3

A low temperature (120 K) X-ray diffraction study of 1,5-C2B3Et5 has been carried out; a crystal of suitable quality was grown in situ using an IR-laser beam producing a molten zone in a Lindeman capillary. Average B-B and B-C bond distances were 187.6 and 157.1 pm respectively, and the through-cage C . . C separation was 227.7 pm. Deformation electron density maps indicated that charge accumulates within the B-C bonding regions and this appears to give rise to ‘bent bonds’. There was no evidence for charge accumulation between adjacent boron atoms, and this has been taken to indicate the absence of direct B-B bonding interactions.22 The anion [Cp*Co(Et2C2B3H4)]- is discussed in Section 6.

6

Composition CB4 and C2B4

In the gas phase reaction of B4Hlo with allene, two isomers of CB4Me2H7 are formed. Their structures, and those of CB4HI0 and [B5HI0]-, have been investigated by means of the ab initiolIGLOINMR technique; exchange mechanisms have also been probed. CB4Me2H7is the smallest aruchno-carbaborane to be isolated to date, and exists as a rapidly interconverting mixture of the isomers l,3-Me2-I-CB4Hg and 1,2-Me2-1-CB4H8.23 The pathway of the thermal conversion of 1,2-(Me3Si)z-l,2-C2B4H4 to 1,6(Me3Si)2-1,6-C2B4H4 has been investigated using I B N MR spectroscopy, and the structures of the two isomers optimized at the ab initio HFl6-31 G*level. These

10: Curhuborunes, Including Their Metal Complexes

363

structural results compare well with data obtained from electron diffraction and low temperature X-ray diffraction.24 Two intermediates from the rearrangement pathway of arachno-[C2Et2(BEt2)B4Et4H3] to cfoso-[1 ,5-C2B3Et5] have been isolated. The structure of Na[CaB4EtbH] has been determined by X-ray diffraction; it exists as a dimer (3)in the solid state.25

Each B atom carries an ethyl group; these are omittedfor clarity

3

Treatment of [ C P * ~ R U ~ Cwith I ~ ] [Et2C2B4H5]- in T H F leads to the formation of [Cp*RuH(Et2C2B4H4)] which has been characterized by spectroscopic, mass spectrometric and crystallographic methods. The H ligand is terminal (Ru-H = 155(8) pm) and can readily be removed by base ('BuLi); the conjugate base reacts with methyl triflate to give the unexpected product [Cp*Ru" H( Et2C2B4H3-5-Me)] which was characterized by spectroscopic and mass spectrometric techniques. The studies have been extended to include the reaction of [ C P * ~ R U ~ Cwith I ~ ] [Cp*Co(Et2CzB3H4)]- which yields [ C P * C O ( E ~ ~ C ~ B ~ H ~ ) R u H C ~ * ]The . ~ ~insertion of nitriles and isonitriles into [ C P T ~ R ~ ( E ~ ~ C ~ B ~ H occur under conditions of UV-radiation (R = Me) or thermal promotion (R = Ph). Crystal structure determinations have been carried out for the insertion products [(Et2C2B4H4)CpTaMe(q2-C,N-C{=N'Bu) Me)] (two isomers) and [(Et2C2B4H4)CpTaMe(q2-C,N-C { =N(2,6-Me2C6H3) 1Ph)]. The photochemical isomerization of the latter compound, followed by reaction with an extra equivalent of isocyanide, has also been reported; X-ray diffraction has confirmed the nature of the product. The study gives valuable insight into behaviour of tantalum cdrbaborane complexes as compared to their metallocene analogues.27 The reactions between CpzTiCl;! and [cfoso-em-Li- I -Li-2-R-3-SiMe3-2,3C2B4H4](R = SiMe3, Me, H) have yielded the Ti( I I I) compounds [commo-1-Cp- 1Ti-2-R-3-SiMe3-2,3-C2B4H&. Oxidation of these new clusters by TiCI4 in T H F gave Ti(1V) species with the metal centre bearing coordinated THF. Treatment of [closo-exo-Li-l-Li-2,3-(SiMe3)2-2,3-C2B4H4] with TiC13 in the presence of TMEDA gave [Li(TMEDA)2][I-Cl-1 ,l'-Ti-(2,3-(SiMe3)2-2,3-C2B4H4)2]; replacing

364

Orgunometullic Chemistry

the bulky SiMe3 group by, e.g., Me resulted in the formation of a dimeric product. Replacing the unsolvated carbaborane starting material with a TMEDA-solvated analogue resulted in the reaction being swung in favour of a monomeric half-sandwich complex. The synthetic work has been complemented by ESR spectroscopic, electrochemical, magnetic susceptibility and X-ray diffraction studies.28 The anion [C2(SiMe&B4H4j2- reacts with [Cp*ZrC13] to give the bent sandwich complex [Cp*ZrClz(C2(SiMe&B4H4)]- isolated as the [Li(THF)3]+ salt. The structure has been confirmed by X-ray diffraction; pertinent parameters are L CI-Zr-CI = 94.6", L C2B3 centroid-Zr-Cp* centroid = 131 .3".29

7

Composition CZBB

The crystal structure of 6-chloro- 1 , l -bis(trimethylphosphine)- 1-endo-H-2,3dicarba- 1-irida-isonidu-undecaborane(12), cluster 4, has been

4

8

Composition CBg, CBlo and CBll

Monocarbon carbaboranes with large cage-size remain a relatively small group of compounds in relation to dicarbon counterparts. It has been shown by "B NMR spectroscopy that in dichloromethane solution, [ C P F ~ ( C O ) ~ ( C B ~ Hexists as a mixture of two isomers in a 3:l ratio. The major isomer has C4, symmetry, with the iron centre coordinated viu the antipodal, B(10), B-H bond. In the minor species, coordination is through an equatorial boron, B(6), B-H bond (adjacent boron to the antipodal position). Reactions of the [CBgHloI- anion with a range of electrophiles have been investigated. The salts Cs[CBgHgX] (X = F, C1, Br, I) have been isolated; substitution was at the B(6) position. Dihalogenation gave 6 3 - (with some 6,7- and 6,lO-) substitution. Deuteration of [CBgHlol- was found

10: Curbuborunes, Including Their Metul Complexes

365

to occur both at the B(10) and adjacent equatorial sites giving [6,7,8,9,10C B ~ H ~ D S IThe - . crystal structure of a silver(1) salt of [6,8-F2CB9H8]- has been determined. The cation is of interest: Ag+ is coordinated by two q2-C6H6ligands with Ag-H interactions to two em-hydrogens of the a n i ~ n . ~ ' The synthesis of Na[Pt(PEt3)2CBloHI I] has been described. Protonation of the 1]- with anion occurs at the metal centre. Treatment of [Pt(PEt3)2CBIOHI [Ph3PAuCI], [ ( P ~ ~ P C U Cor ~ ) [PhHgCl] ~] yields [PtM(PEt3)2(PPh3)CB10H1I] (M = Au, Cu) or [HgPhPt(PEt3)2CBloH1 1]respectively. A related compound also reported is [PtCo(PPh3)CBloH1 11. Crystallographic results have been presented for all the new compounds.32The reaction of the nido-cluster [BloH12CNMe3] with [Rh(PPh3)3Cl] in alkaline solution gives rise to [closo-2,2-(PPh3)2-2-H-lMe3N-2,1-RhCBloHlo].In solution at low temperature, two isomers of this complex have been observed. Treatment of the cluster with chlorine-containing reagents yields [cfoso-2-(PPh3)-2-CI-1-Me3N-2, 1-RhCBloHlo], the structure of which has been confirmed by X-ray diffraction. Related reactions have also been reported.33 The structure of nido-7-NH~Bu-7-CBloH12 has been elucidated by X-ray diffraction and these data are in accord with conclusions drawn from multinuclear NMR spectroscopic studies. The prediction from MO calculations that deprotonation should occur at nitrogen was upheld by experiment and confirmed cry~tallographically.~~ The reaction of nido-7-NMe3-7-CBIoH12 with anhydrous HCI in the presence of AIC13 results in the formation of nido-7-NMe3-9-C1-7CBloH 1 1 , with smaller amounts of nido-7-NMe3-6,9-C12-7-CBloH10. These products have been characterized by elemental analysis, and spectroscopic and mass spectrometric techniques. Deuteration studies have also been carried Treatment of nido-7-NMe3-7-CBloH1 2 with [OS~(CO)~,] in bromobenzene at elevated temperature yields the novel complex [Os3(C0)8(7-NMe3-7-CBloHlo)], the structure of which has been determined by X-ray d i f f r a ~ t i o nThe . ~ ~ reaction of nido-8-Me2S-7-CBloH 12 with dppf (1,l '-bis(dipheny1phosphino)ferrocene) has been shown to give nido-8-dppf-7-CBloH12; this forms part of a wider study, discussed in Section 9.37 As part of a study concerning chlorination of CB1 I-cages, the crystal structure of the salt [Me3NH][Me-l-CBl lClll] has been determined.38

9

Composition CzBg

As in previous years, the chemistry of C2B9 and C2BI0carbaboranes and their metal complexes dominates the carbaborane literature. The former compounds are dealt with in this section. A number of nido-C2B9cages bearing S- or P-donor atoms have featured this year, for example, cluster 5a, the structure of which has been determined by X-ray d i f f r a ~ t i o n .The ~ ~ anion [7,8-p-SCH2C(O)S-7,8C ~ B ~ Hhas ~ Obeen ] prepared; in its reaction with [RhCI(PPh3)3], it is proposed that the carbaborane anion, L-, acts as a didentate ligand forming [RhL(PPh3)2]. However, when treated with [PdCI2(PPh3)2], L- is transformed to 173-8lo]2- and at the same time coordinates to the SCH2C(0)OCH2CH3-7,8-C2B9H

Orgunometullic Chemistry

366

5a

Only the ipso-C atoms of Ph groups are shown.

5b

Pd(I1) centre. The crystal structure of this latter complex has been determined, thereby confirming the ligand tran~formation.~"The coordination of [7,8(PPh2)2-7,8-C2BgH101- to gold( 111) is exemplified in complex 5b, the crystal structure of which has been r e p ~ r t e d . The ~ ' same ligand has been incorporated into two silver(1) complexes; the ligand reacts with [Ag(OC103)(PR3)] (PR3 = PPh3, PMePh2) to yield [Ag(7,8-(PPh2)2-7,8-C2B9H I~)(PR3)]and, for the PPh3 derivative, it has been shown that the Ag(1) centre is in a trigonal planar environment. Interestingly, boron vertex extrusion occurs when [Ag(OCI03) { 1,2(PPh2)2-1. ~ - C ~ B I O His~treated ~ } ] with, for example, 1,lO-phenanthroline, thereby giving complexes containing the [7,8-(PPh2)2-7,8-C2B9H - l i g a ~ ~As d . part ~ ~ of a wider study (see Section lo), the complex [ A u { ( P P ~ ~ ) ~ C ~ B ~ H ~ O } ( ~ - S C2B 1oH10)2] has been prepared and ~ h a r a c t e r i z e d .The ~ ~ same bis(phosphine) hgand has been incorporated into the tetragold cluster complex

10: Curbuborunes, Incluciing Their Metul Complexes

367

[ A u ~ ( ( P P ~ ~ ) ~10)C2(AsPh3)2], ~ B ~ H the synthesis and structural characterization of which have been reported.& Three rhodium(1) complexes containing the ligands [7-PPh2-8-R-7,8-C2B9HI0](R = H or Me) have been shown to be active for the cyclopropanation of alkenes with d i a ~ o a c e t a t e s . ~ ~ Sneddon and coworkers have carried out a detailed investigation of the reactions of 1,l ‘-bis(dipheny1phosphino)ferrocene(dppf) with a range of boranes, carbaboranes and thiaboranes. The reaction of [nido-9-Me2S-7,8-C2BgHI 11 with dppf gave rise to methyl transfer yielding the salt [dppf-Me][nida-9-MeS-7,8C2B9HI The reaction between the potassium salt of [nido-7-Ph-7,8-C2BgH1 I] and dmso in sulfuric acid leads to the formation of [nido-7-Ph-9-Me2S-7,8C2B9H and [nido-7-Ph-1 1-Me2S-7,8-C2B9H and [nido-7,8-Ph2-9-Me$3-7,8C2B9H9] may be similarly prepared. These products have been characterized by multinuclear N MR spectroscopy, and the structure of [nido-7-Ph-1 1-Me2S-7,8C2B9H10]has been confirmed by X-ray diffraction. The conjugate base of [ d o - 7 Ph-9-Me2S-7,8-C2B9H reacts with [Rh2C12(CO),] to give [ 1-Ph-3,3-(C0)2-7Me2S-3,1,2-RhC2B9H9].46 Studies of isomerizations of icosahedral cages (in particular C2B 10) have received, and continue to receive, much attention over the years. Experimental results have shown that severe overcrowding can lower the temperature at which isomerization may occur, and steric effects within carbaborane dusters continue to be explored by the Welch group. Pertinent to this review is the isomerization of the icosahedral MoC2B9-cage.The reaction between Na2[7-Ph-7,8-C2BgH 101 with [ M O ( N C M ~ ) ~ B ~ ( ~ ~ - C , H , ) ( leads C O ) ~to ] the formation of anion 6. However, introducing a second phenyl substituent into the starting d o - a n i o n results in the formation (after reaction with [Mo(NCMe)2Br(q3-C3H5)(C0)2]) of 7. Anion 7 was found to be the kinetic rather than thermodynamic product, and heating 7 in THF at reflux caused isomerization to 8. Salts of each of these anions have been fully characterized, with X-ray diffraction data confirming all three structure^.^^ Successive oxidation of [ M o ( C O ) ~ ( S P ~ ) ~ ( C ~ B ~ H using Ph2S2 and iodosyl-

6

Orgunometullic Chemistry

368

8 benzene has resulted in

the formation of

the novel cluster anion

[ { (CzB9H1I)Mo(SPh)2)2J2-which exhibits four bridging thiolate ligdnds. Struc-

tural and NMR spectroscopic studies are detailed, and reveal CdrbdbOrdne C-C cleavage and r e f ~ r m a t i o n . ~ ~ The cluster [Ru(THF)(CO)*(C*B9HI I)]reacts with [Cp(C0)2M( =CCbH4Me-4)] (M = Mo, W) to yield the compounds [CpMRu(pL-CC6H4Me-4)(CO)4(C2B9H1 I)] which undergo isomerization. The structure of the isomerized molybdenum product has been determined by X-ray diffraction. When M = W, a minor

10: Curbuborunes, Including Their Metal Complexes

369

product of the reaction was an 0x0 derivative. Reactivity studies of the major products have been carried out, and all products have been characterized with structures being confirmed by representative crystallographic studies.49 Treatment of [nido-7,8-Me2-7,8-C2BgH1 I] with [Ru3(CO),2] leads to the formation of [ R u ( C O ) ~ ( ~ , ~ - M ~ ~and - ~[Ru3(C0)8(7,8-Me2-7,8-C2B9H9]. ,~-C~B~H~] The latter compound reacts with tertiary phosphines to yield either diruthena- or triruthena-carbaboranes. The reaction of [Ru3(CO)8(7,8-Me2-7,8-C2BgHglwith Me2NCH2NMe2 has also been studied, and the products characterized; the results of X-ray diffraction analysis has confirmed that in [Ru2(7,8-Me2-10CH2N Me2-7,8-C2B9H8)(C0)5], the carbaborane ligand coordinates in an $-manner to one Ru centre while the second Ru bears four CO ligands and is also coordinated by the terminal N-donor of the carbaborane amino substituent. Full NMR spectroscopic data are reported for the new products, as well as additional structural data.50 The reaction between potassium pyrrolide, anhydrous CoC12 and [nido-7,8Ph2-7,8-C2BgH 101- has been investigated. Yieids are improved if the starting the reaction then proceeding with carbaborane is [closo-1,2-Ph2-1,2-C2BloH boron extrusion. The crystal structure of [clusu-3-(q-C4H4N)-1,1 1-Ph2-3,1,llC O C ~ B ~ has H ~ been ] determined, and the reason for the preference of the 1,llrather than 1,2-isomer (i.e. in respect of the C positions) has been rationalized as a consequence of the electron withdrawing and steric requirements of the phenyl sub~tituents.~'Related work deals with the reactions of [nido-7-R-8-C4H4N (CH2)3-7,8-C2B9H10]-(R = Me, Ph) with K['BuO] and CoCl2. Again, comparisons have been made with the use of a suitable C2BIo-precursor rather than direct use of the C2Bgcage. Crystallographic data are presented for the complexes [(q-CqH4N)Co(7-Me-8-Bu-7,8-C2B9Hg)] and [(q-C4H4N)Co(7-Ph-8-C3H5-7,8c 2B9H9)l.52 The crystal structure of the rhodacarbaborane 9 has been reported,53 and an investigation of the interactions of nucleophiles with [3,3-(q4-C8H12)-1 -CH23,1,2-RhC2BgHIo]- has been detailed.54 The reactions of [nidu-7,8C2B9H12-,,Fn]- (n= 1, 2 or 4) with [RhCl(PPh3)3] or [RhCl(PMePh&] have yielded a series of fluoro-substituted rhodacarbaboranes in which a terminal Rh-H bond is present. This hydride can be exchanged for chlorine. The crystal structures of [3,3-(PPh3)2-3-H-3,1 ,2-RhC2B9H7F4] and [3,3-(PMePh2)2-3-C13,1,2-RhC2B9H9F2] have been determined, and the catalytic properties of the rhodacarboranes with respect to hydrosilation (by PhMe2SiH) of styrene and phenylacetylene have been assessed.55A survey of the chemistry and structures of rhodium, ruthenium and osmium derivatives of [C2B9H12]- has been p r e ~ e n t e d , ~ ~ and the theme of platinum group metals continues with an interesting report of (R = H, Me) with [PdCl*(PMe2Ph)2]. the reactions of T12[7-C4H2RS-7,8-C2B9Hlo] 1,2-PdC2BgHlo], The major products are [1-C4H2RS-3,3-(PMe2Ph)2-8-PMe2Ph-3, and the compounds [ 1-C4H2RS-3,3-(PMe2Ph)2-8-PMe2Ph-3,1,2-PdC2BgHg] [ C ~ H Z R S C ~ 12] B ~are H formed in smaller amounts. Crystallographic data for the main (R = Me) and minor (R = H) products confirm the presence of icosahedral PdC2B9-cagesin both cases.57 When [Cp*2(C2B9HI 1)2Hf2Me2] is treated with H2. the hydrido complex

Organomet a l k Chemistry

370

W

Only the ipso-C atoms of Ph groups are shown.

9 [Cp*(q5-C2B9Hl)Hf(p-q5:q‘-C2B9Hlo)HfCp*(H)]results. This compound catalyses the hydrogenation of internal alkynes to (2)-alkenes, and it is proposed that the active species is [Cp*(q5-C2B9H11)HfH].58 In a later paper, this work is extended to studies of [Cp*(q5-C2B9H1 I)Hf(p-q2:q3-C2BgH11)HfCp*Me2]which acts as a catalyst in the regioselectivedimerization of terminal a l k y n e ~ . ~ ~ Lanthanum(II1) chloride reacts with Na2[7,8-R2-7,8-C2BgH9] in THF (R = H, PhCH2) to yield ~~O~O-[(THF)~N~][(R~C~B~H~)~L~(THF)~]. This has been characterized by IR and multinuclear NMR spectroscopy, and for R = H , an X-ray diffraction study has shown that the coordination sphere of the La(II1) centre is distorted tetrahedral (taking each carbaborane ligand as occupying one site). The reaction of Sm12 with Na2[7,8-(PhCH2)2-7,8-C2B9H9] in THF with the addition of DME leads to the formation of [em-nido-{(PhCH2)2C2B9H9)Sm(DME)2]2 which has been fully characterized; the crystal structure reveals the presence of a centrosymmetricdimer in the solid state,60 The complex 10, isolated as the tetraphenylphosphonium salt, has been the subject of a crystallographic study.61Related to this is the anion [8,8’-pOSO20( 1,2-C2B9H10)2-3-C0]-, the preparation and structure of which have been reported. This work also includes syntheses, NMR spectroscopic and structural details of the sandwich complexes [(8-Ph-1,2-C*BgHl~)-3-Co-( 1’,2’-C2BgH1 I)]and [(8-(dioxane)-1,2-C2B9H10)-3-Co-(1’,2’-C2BgHI In related work, two examples of R2P-bridged Venus fly trap compounds have been reported; these are the Zwitterions [8,8’-pMe2P-(1,2-C2BgH10)2-3-C0] and [6,6‘-pMezP-(1,7C2BgH 10)2-2-C0]which have been fully characterized. Closely related to the latter are the two sandwich compounds [8-Me3P-(1,2-C2BgHl0)-3-C0-( 1,2-C2BgHI I)] and [6-Me3P-(1,7-C2B9Hlo)-3-Co-(1,2-C2BgHI I)] which have been prepared and characterized by mass spectrometry and multinuclear N MR spectroscopy; the crystal structure of [6-Me3P-(1,7-C2B9H,0)-3-Co-(I ,2-C2B9H1I)] has confirmed the anticipated structural features.63The reaction of [Co(1,2-C2BgH11)2]- with

10: Curbaborunes, Including Their Metal Complexes

371

10 naphthalene in the presence of AlC13 gives the unusual compound [8,8’-pCH&H6-( 1,2-C2BgH10)2-3-Co]- with the bridging unit arising after rearrangement of the naphthalene ring system. The unexpected nature of this bridge has been confirmed by the results of an X-ray diffraction study.64 The structure of the ‘semipseudodoso’ cluster [ 1-(PhCC)-2-Ph-3-(4-cymene)3,l , ~ - R u C ~ B is~ discussed H~] towards the end of the next section.

10

Composition CzBlo

In previous reviews in this series, we have mentioned a series of macrocyclic complexes reported by Hawthorne and coworkers, and these have now been presented in review form.65 A number of examples of boron extrusion leading to CZBIO to C2B9 cage transformations have already been mentioned. The Wade group has studied in detail the use of tetrabutylammonium fluoride hydrate as a decapping reagent. The reactions of 1-(4-FC&)-I ,2-C2BloHI I and 1-(4-FC6H4)-1, ~ - C ~ B I1Owith H~ [Bu4N]F hydrate in T H F or MeCN have been followed by 19Fand IlB NMR spectroscopies; no carbaborane intermediates could be detected. The boron atom removed from the cage forms [B(OH)HF*]-, and it has been shown that the hydrogen atom attached directly to boron originates from the carbaborane (R = R’ = Me; R = Ph, precursor.66 The reactions of [1,7-R,R’- 1,7-C2BloH R’ = Me; R = R‘= Ph; R = R‘ = 4-FC6H4) with tetrabutylammonium fluoride hydrate in T H F have also been studied; as well as deboronation to give the corresponding nido-cluster anions, B-fluorinated products have been obtained and a detailed investigation for R = R’ = 4-FC6H4 has revealed that [lo-F-7,9(4-FC6H4)2-7,9-C2BloHg]forms initially and that isomerization to the 3-F derivative follows s p o n t a n e ~ u s l y . ~ ~

372

Orgunometullic Chemistry

The insertion of acetylenes (propargyl bromide, but-2-yne- 1,4-diacetate and non-1-yne) into BloH12L2 (L=various R2S) has been the subject of a kinetic study. For a particular alkyne, the rate constants decrease with both an increase in the electronegativity and/or an increase in steric bulk of R. It has also been observed that the yields of carbaborane increase as the size and/or basicity of R2S increases. As is to be expected, the literature contains a number of reports dealing with organic derivatives of 1 ,2-C2BloH12. The 1 ,2-C2BloHI I-substituent has been used as a protecting group for aldehydes and ketones.69 The preparations of 1-dialkylaminomethyl-derivatives of 1,2- and 1,7-C2BloH12 containing mercapto-groups and carboxy-groups have been described .70 1,2-Carboranylmethylthiopyridines have been obtained in high yields by the reactions of pyridine-2( 1 H)-thiones with bromomethyl- 1,2-carborane; the products have been characterized by spectroscopic method^.^' The hydroboration of 1-alkenyl-l,2carboranes using various hydroborating agents having a range of steric requirements has been i n ~ e s t i g a t e d The . ~ ~ reactions between 1 -Me3Si-l ,2-C2B10H11 and various conjugated carbonyl compounds results in [3+2] a n n e l a t i ~ n . ~ ~ [2,2]-Paracyclophane derivatives of 1,2- and 1,7-C2BloH12 in which the [2,2]paracyclophane is separated from the cage by one or two carbon centres have been prepared.74 In an investigation of the salts [O2C(CBl0Hl~C)CO~M],, (M = Cu(II), Mg, Ca, Zn, Cd), a relationship has been shown to exist between their thermal and electrophysical properties. Heat treatment at 500 "C results in a significant increase in the electrical conductivity of the salts; after pyrolysis at 9OO0C, the conductivity increases by 6-1 1 orders of magnitude. The changes have been shown to persist with storage over a period of three years.75The acylation of 1,2(OH)2-1,2-C2BloH10 is highly efficient under conditions of general base catalysis, and ' H NMR spectroscopy has been used to illustrate the formation of a complex between 1 ,2-(0H)2-1,2-C2B10HI0and Et3N during the reaction. The mechanistic implications of this observation have been addressed, leading to the development of efficient methods of preparing oligomers of carborane carbonate

met ha cry late^.^^ In 1997, reports of polymer formation and studies aimed towards polymers have included the preparation of (cyclobutadiene)(c yclopentadien yl)cobal t derivatives of the ~ Y P ~ ( C ~ R ~ ) C O in ( Cwhich ~ R ' ~R ) is a rigid arm capable of linear coupling through the para-position. Relevant to this review is the reaction between 4-IC6H4CzCC6H41-4and l-H-12-Cu-l,12-C2BIOHIO in the presence of [PdC12(PPh3)2]and N-methyl-2-pyrolidinone. Compound 1l a was the major product, with l l b being formed in smaller amounts. Treatment of l l a with [CpCo(CO)2] in xylene resulted in cyclo-dimerization of the alkyne and formation of (C4R4)CoCpwhere RCCR = lla.77As part of a wider study, the condensation reaction of 1,4-diIithiobutadiyne and 1,7-bis(tetramethylchlorodisiloxane)-1,7CzBloHlo has given rise to a linear polymer which has been characterized by IR and NMR spectroscopies, and DSC and TGA analyses. All the polymers in this study were soluble in common organic solvents and were viscous liquids or low melting solids at 298 K.78 Linear polyetherketones, in which both aromatic rings

10: Curbuborunes, Including Their Metul Complexes

373

and C2Blo-cages are present in the polymer chain, have been prepared by superacid-promoted polycondensation between bis(6phenoxyphenyl) derivatives of 1,2- and 1,7-carborane and aromatic or aliphatic dicarboxylic acids. Polymers with molecular weights greater than 150000 can readily be obtained. The polymers are soluble in organic solvents and from these solutions it is possible to cast strong, transparent films. The advantages of these materials have been discussed.79 This work has been extended to included polymer materials derived from the polycondensation of bis(4-phenoxypheny1)-1,12-dicarbadodecacarborane with aromatic and aliphatic dicarboxylic acids in trimethanesulfonic acid."

Each unmarked vertex = BH

l l a R = 1,12-C$l&ll llb R=H Langmuir-Blodgett films of stearic acid on graphite have been used as a matrix to disperse carborane derivatives; STM studies reveal a regular dispersion and the technique seems a promising approach to single electron devices.81 Two supramolecular assemblies involving I ,2-C2BloH1 2 have been reported by Raston and coworkers. The first is a bis(cyclotriveratry1ene) clathrate complex, and crystallographic data reveal that only one of the two macrocycles interacts with a carbaborane cage in the solid state lattice. This host-guest arrangement is shown in structure 12.82In the second report,83 host-guest complex formation of 1,2-C2B10Hl2 and azacrown ethers 13 and 14 has been explored. Slow evaporation of toluene solutions of 1:1 carbaborane:macrocycle yielded complexes, the crystal structures of which were determined. These data revealed that 1,2C2B10H12 forms hydrogen bonds with macrocycle 13 (CH.e.0 and BH...N), while with 14, an infinite structure of alternating layers of carbaborane cages and crown ethers resulted. The derivatization of 1,2-C2BIOH12 with groups suitable for donation to metal centres has been a focus of attention for Teixidor, Vifias and coworkers. The preparation of mixed S,P-donors of type 1-PPh2-2-SR-1,2-C2BloH10 can be achieved as follows, exemplified for R = Et. Treatment of 1-SH- 1,2-C2BloHl1 with KOH followed by EtBr yields the 1-SEt-derivative which reacts with BuLi and PPh2Cl to give 1-PPh2-2-SEt-1,2-C2BloHlo.This closo-cage can be deboronated by treatment with C ~ HI IN in EtOH. The structures of 1-PPh2-2S'Pr- 1,2-C2B,OH 10 and [7-PPh2-8-S'Pr-7,8-C2B9Hhave been confirmed by X-ray d i f f r a c t i ~ nThe . ~ ~ crystal structure of 1-PPh2-2-Ph-1,2-C2BloH10 has been determined; the unit cell contains two crystallographically independent molecules.

Organometullic Chemistry

374

12

NH

X

13 X = N H 14 x = o The average carborane-cage C-C distance is 174.4(8) pm, which is significantly longer than the norm in such cages; another manifestation of steric crowding is the tilting away of the PPh2 group from the expected radial ~ r i e n t a t i o nSteric .~~ effects are critically important in dictating the observed cage-structure of [1-(PhCC)-2-Ph-3-(4-cymenej-3,1 , ~ - R u C ~ B ~which H ~ ] has been described as possessing a ‘semipseudoclosu’ skeleton. This compound is formed by complex formation with ruthenium after the facile decapping of [l-(PhCCj-2-Ph-l,2C2B lOH I 01.86 The syntheses and characterizations of the gold(1) complexes [Au( 1-S-2-Me1,2-C2BloHlo)L] (L = PPh3, AsPh3, PMePh2) have been described. Treatment of [Au( 1-S-2-Me-I ,2-C2BloHIOj(PPh3)]with [Au(03SCF3)(PPh3j]led to the formation of [ A u ~l (-S-2-Me- l ,2-C2BloH i0)(PPh3j2][O3SCF3].The reaction between [ 1-SH-2-Me-1,2-C2BloH101 and [AuzCl2(pdppe)] (2: I molar ratio) yields [ A u ~1-( S-2-Me-I ,2-C2BloHl&(pdppe)]. By reacting [AuC12]- with [ l-SH-2-Me-l,2C~BIOHIO], the complexes [Au( 1-S-2-Me-1,2-C2BloHlo)C1]-or [Au( 1 -S-2-Me- 1,2C ~ B ~ O H were obtained, depending on the reaction s t o i ~ h i o m e t r y .In ~ ~a

10: Curbaborunes, Including Their Metal Complexes

375

related study, the derivative [ 1 ,2-(SH)2-1,2-C2BloH was treated, under basic conditions, with [AuC14] - or [AuC13(tht)](tht = tetrahydrothiophene) and, with appropriate cations present, these reactions yielded salts of the anion [Au( I-S-2-Me-l,2-C2BloH I&]-. Cage degradation occurred when this ion was subjected to hydrazine or phenylhydrazine. Structural studies complement the synthetic work reported.87 The preparations of [Au2(p-S2C2BI0HIo)L2](L = PPh3, PMePh2, PPh2(C6H4-4-Me), SPPh3) have also been reported. The reaction of [ A u ~ ( ~ - S ~ C ~ BlO)(PPh&] IOH with [Au(OTf)(PPh,)] yields a trigold species. A range of related species have also been reported, and representative structural data are presented; e.g. complex The first organometallic goId(1) derivatives of 1,7-C2BIOH12have been claimed; reaction of 1 ,7-C2BloH12with BuLi and then [R3PAuCI] (various R) results in the formation of [Au2(p-1, ~ - C ~ B ~ O H ~ O ) ( P R & ] , the crystal structure of which has been dete~mined.~’

R

W

Only the ipso-C atoms of Ph groups are shown.

15

11

Studies Relating Specifically to BNCT

In this final section, selected papers dealing with carbaboranes in the context of BNCT are described. Several general articles should also be mentioned. A review entitled ‘Imaging of boron in tissue at the cellular level for boron neutron capture therapy’,’’ a paper describing the development of a technique to measure the photons emitted during therapy in order to measure boron c~ncentration,~’ and a general overview of BNCT and boron-containing compounds that may be useful92have appeared. The preparations of 1,7-bis(carboxyalkylcarbamoyl)-1,7-carbordnes have been detailed; interest in these compounds stems from their use as intermediates for

376

Orgunometullic Chemistry

the synthesis of water-soluble compounds for BNCT.93The compound 1-amino3-[2-( 1 ,7-dicarbadodecaboran- 1 -yl)ethyl]cyclobu tanecarboxy l ic acid has been synthesized; this is an unnatural amino acid and may have applications in BNCT.94 The 1 ,2-C2B10H12 cage has been functionalized with (bromoalky1)phthalimides or propargylphthalimide, and these compounds have been converted into isocyanate-substituted derivatives. The reactivity of these species towards amino- and alcohol-containing species has been studied. The work is motivated by the need to find suitable precursors for drugs in BNCT; the new compounds have been fully characterized, and the report includes the results of two crystallographic studies.95 Internal and terminal N-substituted carboranyl spermidines and spermines have been prepared for use as agents in BNCT?6

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76.

77. 78. 79. 80.

10: Curbuborunes, Including Their Metul Complexes

81. 82. 83.

84. 85.

86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96.

379

S.A. Iakovenko, A.S. Trifonov, E.S. Soldatov, V.V. Khanin, S.P. Gubin and G.B. Khomutov, Thin Solid Films, 1996,285, 873. R.J. Blanch, M. Williams, G.D. Fallon, M.G. Gardiner, R. Kaddour and C.L. Raston, Angew. Chem. Inf. Ed., Engl., 1997,36, 504. P.D. Godfrey, W.J. Grigsby, P.J. Nichols and C.L. Raston, J. Am. Chem. Soc., 1997, 119,9283. F. Teixidor, C. Viiias, R. Benakki, R. Kivekas and R. Sillanpaa, Inorg. Chern., 1997, 36, 1719. M.A. McWhannell, G.M. Rosair, A.J. Welch, F. Teixidor and C. W a s , Actu Crystullogr, Sect. C , 1996,52, 3 135. R.L. Thomas and A.J. Welch, J. Chem. Soc., Dalton Truns., 1997,63 1. 0.Crespo, M.C. Gimeno, P.G. Jones and A. Laguna, J. Chem. Soc., Dulton Trans., 1997, 1099. 0 . Crespo, M.C. Gimeno, P.G. Jones, B. Ahrens and A. Laguna, Inorg. Chern., 1997,36,495. 0.Crespo, M.C. Gimeno, P.G. Jones and A. Laguna, J. Orgunometul. Chern. 1997, 531,87. H.F. Arlinghaus, M.T. Spaar, R.C. Switzer and G.W. Kabalka, And. Chern., 1997, 69, 3169. W.F.A.R. Verbakel and F. Stecher-Rasmussen, Nucl. Instrum. Meth. Plzys. Rex A, 1997,394, 163. D. Gabel, Chem. Unserer Zeit, 1997,31,235. V.A. Sergeev, N.I. Bekasova, E.A. Baryshnikova, M.A. Surikova and N.M. Mishina, Russ. Chem. Bull., 1996, 45,2661. R.R. Srivastava, R.R. Singhaus and G.W. Kabalka, J. Org. Chem., 1997,62,4476. Y. Wu, P.J. Carroll, S.O. Kang and W. Quintana, Inorg. Chem., 1997,36,4753. J.P. Cai and A.H. Soloway, Tetruhedron Lett., 1996,37,9283.

11 Group 13: Boron, Aluminium, Gallium, Indium and Thallium BY M. J. ALMOND

1

Boron

1.1 General - A number of papers report the use of organoboron reagents in synthetic organic chemistry. These are largely beyond the scope of this review. However, one or two examples may briefly be referred to here. The enantiometric synthesis of homoally lamines has been achieved by nucleophilic addition of chirally modified allylboron reagents to imines. I A new and practical synthesis of a-amino acids from alkenyl boronic acids is also described.2 The interest here is to find a concise approach to the unnatural a forms of the amino acids which may have use as building blocks in pharmaceutical synthesis. These first two examples lie clearly in the domain of organic synthesis. Rather different is the report of a cationic metallocene polymerisation catalyst based on tetrakis(pentafluoropheny1)borate and its derivative^.^ This organoboron anion is selected for use because of its strong non-coordinating properties. Gas phase electron diffraction has been used to determine the structure of the 7 symmetrical tetra-tert-b~tyltetraboratetrahedrane.~ The structure is given in 1.

1

Organometallic Chemistry, Volume 27 @,: The Royal Society of Chemistry, I999 380

I I : Group 13: Boron. Aluminium, Gallium, Indium und Thallium

38 I

The structure consists of a B4 tetrahedron with a B-B distance of 170.4(4) pm, while the B-C distances are determined to be 158.0(6) pm. There is overall agreement between the gas and solid phase structures for this compound. The tris(9-borabicyclo[3.3.l]nonyl)silylium,which has not yet been unambiguously shown to exist in solution, has been investigated by ab initio quantum chemical r n e t h o d ~ In . ~ particular the coordination ability of this cation with benzene was studied - the resulting 'complex' is among the weakest solvent-silylium cation complexes ever investigated. 1.2 Compounds Containing Nitrogen, Oxygen or Phosphorus - The reaction of 1-chloro- 1-boracyclohexa-2,5-dienewith (3-(dimethylamino)propyl)magnesium chloride followed by reaction with tert-butyllithium in ether affords lithium 1-(3-(dimethylamino)propyl)boratabenzene (2).6 The reaction of 2 with Mn(C0)3(CH3CN)3PF6 affords tricarbonyl[ 1-(3-(dimethy1amino)propyl)boratabenzenelmanganese(1) (3). The crystal structure of 3 shows that it exists in the intramolecularly B-N-coordinated form with a B-N bond distance of 1.716(5) A. However, in toluene-& solution 3 is in mobile equilibrium with a ring open isomer.

3 The synthesis and crystal structure of borabenzene-4-phenylpyridineis reported (4).7 The compound, which incorporates a pyridine, a benzene and a borabenzene

ring is the first hetero-p-terphenyl analogue to be structurally characterised.

382

Organometullic Chemistry

4

A range of novel [2+2] cycloaddition reactions of (dimethylamino)bis(trifluoromethy1)borane with N-sulfinylsulfonamides, aminoiminophosphines, carbodiimides and a keteneimine are reported.* These examples all demonstrate the remarkable reactivity of the B=N linkage in the starting compound (CF3)2BNMe2. The current work looks at the reactivity of this molecule with compounds containing N=S or N = P double bonds. In general the products are four-membered heterocycles although a number of rearrangement reactions are seen. Amongst the products is the four-membered heterocycle 5. A crystallographic study has been made of P-B and N-B rc-bonding.' Structural studies are reported on the 18-crown-6 complexes of the potassium salts of diphenylphosphido- and diphenylamidoboratabenzerie (6, 7). It appears that the phosphorus lone pair engages in little, if any, n-bonding with the boron atom, whereas the nitrogen atom adopts a geometry that permits such an interaction.

5

A

This point is empha$sed by a P-B bond distance of 1.968(7) and an N-B distance of 1.510(10) A in the two homologues. This is the first time that a crystallographic comparison of P-B versus N-B rc-bonding has been made in two molecules that differ only in the Group 15 atom. An I'B NMR study has been made on the kinetics of methylboronic acid methylboronate interchange in aqueous solution." A dimeric transition state is suggested for the path similar to that proposed for the interchange between boric acid and borate. The fact that the rate constants depend on the hydroxide ion concentration indicate an associative route for the interchange, The controlled hydrolysis of (diorgany1amino)dihalo- 1,3-diboroxanes gives bis(diorgany1amino)-

I I: Group 13: Boron, Aluminium, Gullium, Indium and Thallium

383

7

6

’

dihalo- 1,3-diboroxanes (8) alongside cyclic species (9). Dehalogenation with sodium-potassium alloy yields compounds containing a B4O2 ring (10). A range of other reactions on these compounds are also reported in this paper.

8

9

10

1.3 Compounds Containing a Metal Atom - A number of novel metalloboroxides bearing boron-bound mesityl and fluoromesityl substituents have been synthesised and structurally characterised.I2The starting point for these syntheses is the dimer [Li(thf)OB(fme~)~]~ (fmes = 2,4,6-(CF3)&H2) which is made by treatment of the new boronous acid HOB(fmes)2 with n-butyllithium. Reaction of the dimer with [Mo2(NMe&] and CuBr2 yields Mo2(NMe2)4[0B(fmes)2]2,while treatment of CuBr2 with LiOB(mes):! (mes = 2,4,6-Me3CbH2)followed by work-up and addition of pyridine yields the first metallaboroxane complex to be structurally characterised. This complex -- { CU[O~B~(~~S)~]~[L~(CH,CN)(C~H~N) (11) contains the new ligand mesB(O)OB(O)mes formed by loss of mesitylene and formation of a B-0-B bond. There has been a report of the diboration of alkenes with bis(pinaco1ato)diboron catalysed by a platinum(0) complex,I 3 The first EPR characterisation of the structures and reactivities of 01- and P-boryl radicals derived from boronic esters is r e p ~ r t e d .The ’ ~ carbocyclisation of diynes and an enyne compound using a borylstannane in the presence of a palladium catalyst has been performed.I5The process leads to high regio- and stereo selectivity.

Orgunometullic Chemistry

384

6

11

12

The reaction of Li(C5HSBMe) with the electrophiles Me3ECI (E = Si, Ge, Sn or Pb) produces the 1,2-dihydroborinines 2-(Me3E)C5H5BMe.l 6 The stFcture of the Sn compound (12) shows a lengthened Sn-C(ring) bond of 2.287(2) A. The silicon compound can be deprotonated to give Li[2-(Me&)CSH4BMe] which may be silylated or stannylated. Silylation affords (Me3Si)2C5H4BMewhich exists as a slowly interconverting mixture of 2,2- and 2,6-isomers whereas stannylation gives the fluxional derivative (Me3Si)(Me3Sn)C5H4BMe. The cyclopentadienyl, indenyl- and fluorenyl-bis(pentafluoropheny1)boranes have been synthesised and used as ligands in titanium and zirconiuni half-sandwich compounds. l7 The crystal structures are reported for the compounds C ~ ~ H ~ B ( C ~ F ~ ) ~ . ~ - B U N ) ~further } T ~ C range ~ ~ . of boraC,3H8SiMe3B(C6F5)2and { T ~ ’ - C ~ H ~ B ( C ~ F ~ A benzene derivatives is described elsewhere.l 8 Here the complexes TiC13(C6H5BMe),[MC13(C5H5BMe)],and MC12(C5H5BMe)2(M = Zr or Hf) are obtained from the corresponding tetrachlorides in excellent yields. The complexes TiClzCp(C5H5BMe) (13), MC12Cp(C5H5BMe) and MC12Cp*(C5H5BMe)(14, M = Zr) are made similarly from the corresponding cyclopentadienyl precursors MC13Cp or MC13Cp*. The compounds 13 and 14 show typical bent sandwich structures. The syntheses and X-ray crystal structures of the boron-bridged ansametallocene complexes [ { Ph(Me2S)B(q5-C5H&}:C12].C6Db (15) and [ {Ph(Me3P)B(q5-C5H4)2}ZrC12]have been reported. 15 is obtained as the product of a double dehalodesilylation reaction between PhB(C5H4SiMe3)2and ZrCI4(SMe2)2.The dimethyl sulfide moiety of the adduct is readily replaced by trimethylphosphine. There is some interest in these and other boratabenzene complexes of zirconium because of their possible role as olefin polymerisation catalysts. It is hoped that the reactivity of the catalyst may be carefully ‘tuned’ by small changes in the molecular structure. The reaction of two equivalents of lithium 1-phenylboratabenzene with ZrCI4 in diethyl ether affords bis( 1-phenylborata-

I I : Group 13: Boron, Aluminium, Gallium, Indium and Thallium

385

c1

C14

c19

14

13

R

+

0

2 Li

Y

16

A = H. Y = N(iPrk R = H, Y = Ph R = CM%. Y I: Ph

benzene)zirconium dichloride (16).20 The reaction of 16 and methylaluminoxane with C2H4 (1 atm at 25 "C) gives ethylene oligomers with dimers of 1alkenes as the major product and minor amounts of 1- and 2-alkenes. Of course the use of boratabenzene derivatives aIlows substituents to be added at the boron atom. Thus complexes such as 17 may be made where the B atom is attached to two N(i-Pr)z groups.2' It is found that an analogue of 17 where the N(i-Pr)z groups are replaced by Ph, undergoes an unprecedented ring annulation with ethyne to form a complex containing a novel boratanaphthalene ligand.

Orgunometallic Chemistry

386

C26

c22

17

Zirconocene reacts with tris(pentafluoropheny1)borane to yield the carboncarbon coupled C P ~ M ( ~ - R C ~ R ) B ( (M C ~=FZr, ~ ) ~R = Me). A variety of differently substituted analogues was also prepared (M = Zr, R = n-butyl, phenyl; M =Ti, R = Me; M = Hf, R = Me, Ph, SiMe3).*' These complexes are chiral and the activation barriers to enantiomerisation were estimated by dynamic 'H NMR spectroscopy; AG values ranging from 13 to 16 kcal mol-' were obtained. The methyl-substituted zirconium complex reacts with 2,6-dimethylphenylisocyanide to yield the methylenecyclopropene (18) which was characterised by X-ray diffraction.

cj

18

A novel diaminoborate ligand system has been explored.23 l,%diaminonaphthalene reacts selectively with one equivalent of 9-BBN to form a bridging

I I: Group 13: Boron, Aluminium, Gullium, Indium und Thullium

387

amine-aminoborane and with two equivalents of 9-BBN to form a non-bridging bis(aminoborane). These aminoboranes give rise to a novel four electron ligand system, with a 1- charge, by reactions with the dimethylamides of titanium and zirconium. There has also been a report of the synthesis and structures of zirconocene and hafnocene boracyclopentane derivative^.'^ These have been made by organodiborate ring transformations promoted by zirconocene and hafnocene dichlorides. A range of molybdenum tricarbonyl complexes of 1-substituted borepins have been ~ y n t h e s i s e dThe . ~ ~ borepins which were the subjects of this study are the compounds C6H6BX where X = Me, Ph or C1. Upon reaction with Py3Mo(CO)3 and BF3.0Et2the corresponding borepin molybdenum tricarbonyl complexes are formed;similar reaction of 1-methoxyborepin gives (C6H6BF)Mo(C0)3 however. (19) are shown schematically below. The The reactions of (C6&$Cl)Mo(C0)3

19

1

vii

products are the boron-substituted complexes (C6H6BX)MO(C0)3, where X = H, OMe, OH, 0 4 , N(iPr)z, N(CH& N(c-C6H11)2 and NBnMe. The complexes have been studied-by 'H, "B and 13C NMR spectroscopies and some have been structurally characterised by X-ray diffraction. The structures of the cyclo-C6H1 1 (20), chloro (21) and N ( ~ P I -(22) ) ~ derivatives show that in the first two examples

38 8

Orgunometaliic Chemistry

the molybdenum atom is coordinated to the six carbons and to the boron atom, whereas in 22 there is q6-coordination of Mo to the six ring carbons but not to B. Cl?

CII

20

21

QB""

22

A study has been made of q3-q5 interconversion in a series of structurally related Mo(I1) IT-ally1complexes with a conjugated double bond appended to the ally1 group.26 The interest in this work is that weak interactions such as C-H-Mo or B-H-Mo appear to prevent the change in hapticity. Ferrocenophanes are unusually strained organometallic compounds which have attracted attention because of their structure and reactivity, in particular their propensity to undergo ring-opening polymerisation reactions which provide access to high molecular weight poly(ferrocenes). Thus it is of interest to note the preparation and structural characterisation of a boron-bridged [ Ilferrocenophane (23).27This has a B-N bond length of 1.399(2) A which is typical for a B=N double bond, while the Fe and B atoms do not seem to show any significant interaction. The molecule is highly strained with a tilt angle between the two rings of 32.4(2)",the highest observed for a [n)metallocenophane. A number of ferrocenophanes with interannular boron-phosphorus bridges have also been made.** These compounds include 24, where a continuous breaking and reforming of the interannular B2P2 ring is detected by NMR

I I : Group 13: Boron, Aluminium, Gallium, Indium and Thallium

389

C

23 spectroscopy even at ambient temperature, and 25, where a rigid molecular geometry is found. The aim of the work described in the current paper was to make a systematic study of the influence of the R substituents in 24 at boron on the strength of the interannular B-P bonds and to investigate the reactivity of these derivatives towards selected Lewis bases.

.R

R

24

25

Multistep redox processes and intramolecular charge transfer in ferrocenebased 2,2'-bipyridylboronium salts have been studied.29The synthesis, characterisation and structure of a number of novel borane- and borate-containing ruthenocenes is rep~rted.~'The complex Cp*RuCpC(Me2)C6H4Br undergoes bromine-lithium exchange with BuLi, and the resulting lithiate can be trapped with Ph2BOMe to give the neutral boron-containing ruthenocene Cp*RuCpC(Me2)C6H4BPhzPy or with BPh3 to give the anionic borate-containing ruthenowhich ~ B Pcan ~ ~be L ~isolated , either base-free, as a cene C ~ * R U C ~ C ( M ~ ~ ) C ~ H diethyl etherate or as a tetrahydrofuranate. An X-ray structure of the tetrahydrofuranate indicates that the anionic ruthenocene adopts a slightly bent, partially staggered conformation with the borate directed away from the metal centre. The staggered conformation appears to be due to the intermolecular interactions within the crystal packing and not intramolecular interactions between sterically-demanding Cp ligands. A study has been made on the reactivity of a range of 1-alkynylplatinum(I1) complexes towards trialkylborane~.~' The alkynylplatinum complexes selected for

390

Orgunumetullic Chemistry

study were of the type cis-[(dppe)Pt(CCR)2] where R = Me, t-Bu, C(Me)=CH2, Ph or SiMe3. The main reaction route with trialkylboranes is 1,l-organoboration involving cleavage of a Pt-C bond and formation of an alkynylborate-like intermediate in which a positively charged platinum fragment is coordinated to the CC triple bond. In most cases these complexes are not stable and the next products are either q2-alkyne platinum(0) o r q3-borylaIkene platinum(0) complexes. The proposed structures of all of these complexes are based upon multinuclear NMR spectroscopy. A recent paper extends the large amount of work which has been carried out on borole derivative^.^^ In this study the reversible carbonylation and Lewis base degradation of the heterocubane [Rh(p3I)C4H4BPh)J4 and of the bis(boro1e) RhI(C4H4BPh)2 are investigated. The synthesis and structure of the dinuclear complex Cp*Rh(p-I)3Rh(C4H4BPh) is also reported.

2

Aluminium

2.1 Compounds Containing Nitrogen - Cationic aluminium alkyl complexes incorporating amidinate ligands are proposed as transition-metal free ethylene polymerisation catalysts.33 Addition of three equivalents of AIMe3 to a heptadentate Schiff-base ligand made from salicylaldehyde and bis(2-aminoethy1)ethylenediamines (H3L') results in an unusual alkylalumination of one of the imine bonds. Addition of two equivalents of B(OMe)3 or AIMe3 to one of these ligands leads to the formation of bimetallic derivatives (26 and 27 respectively) containing four-coordinate boron or five-coordinate aluminium. Addition of three equiva-

R

R

~

2 B(OMe)a

R' -2 MeOH (A = R' = Bu')

2 Alma

-3 MeH (A

. R'

-

I

R'= H)

3 AIMe3 -3 MeH

(R = Cl. A' H) . I

k

R

~

-Ny -N-N- -

HO OMe

O

I

lv Ml e O e . i ,~ p R

OMe

R'

39 1

11: Group 13: Boron, Aluminium, Gallium, Indium and Thullium

lents of AlMe3 to one of these ligands leads to a trimetallic derivative (28) containing two five-coordinate and one four-coordinate aluminium centres.34 The first Si-Al-NH cage compound (29) has been synthesised from a stable triaminosilane and A1Me3.35 It had previously been found that AlMe3 and RSi(NH& (R = i-Pr2C6H3NSiMe3) react to give a product which is almost insoluble in all common organic solvents and is therefore difficult to characterise. The strategy employed in this work therefore was to make the corresponding trichlorosilane and to convert this to the triamine (30) by ammonolysis. The reaction of 30 with AlMe3 then yields 29.

P

29 0

6 30

392

Orgunometallic Chemistry

A number of dimeric dialkylaluminium p-dialkylamido compounds have been synthesised and their structures determined by X-ray d i f f r a ~ t i o nThese . ~ ~ compounds, of general formula (R'2AlNR22)2 ( R ' = M e , Et, i-Pr, i-Bu or t-Bu; R2 = Me, Et, i-Pr, i-Bu or Ph) were made by alkane or arene elimination from the corresponding adduct of formula R13Al.NHR22.The general trends identified in this series of compounds suggest that the environments around aluminium and nitrogen are affected primarily by their closest alkyl groups, i.e. R' and R2 respectively, but that loss of a centre of symmetry depends only on R2. Mass spectrometric data suggest that dimers are also present in the gas phase but that monomers are also present and that these monomers in turn fragment to the more stable species [R'A1NR2,]+. Preliminary experiments have been performed to assess the suitability of these species as precursors to thin films of aluminium nitride. An X-ray crystallographic study of the aluminium-nitrogen compound C52H78A14Li2N4shows it to possess a ladder-shaped (AlNk core The mesityl ligands of the inner nitrogen atoms are each metallated by one of their neighbouring aluminium atoms, while on the outer nitrogen atoms the negative charge is localised. This structure represents the first report of a tetrameric anionic Al-N compound. The compound may also be thought of as an intermediate en route from an aminoalane to an iminoalane.

-Q,

31 The aminodimethylalanes R1R2NAlMe2 (R' = 2,6-i-Pr&6H3, 2,6-Me2C6H3; R2 = SiMe3, Si(i-Pr)Me*, Si(t-Bu)Me2 or Si(2,4,6-Me3C6H2)Me2)are prepared in high yield via reaction of the respective amine R'R2NH with AlMe3 in nh e ~ a n e .Further ~~ reaction of (2,6-i-Pr&H3)N(SiMe3)A1Me2 (32) with two equivalents of trimethyltin fluoride in toluene affords the aminoalane difluoride (2,6-i-Pr2C6H3)N(SiMe3)AlF2 (33). 32 is dimeric with bridging methyl and

I I : Group 13: Boron, Aluminium, Gullium, Indium und Thallium

393

terminal amino groups. 33 is trimeric with a six-membered alternating aluminium-fluorine ring. Terminal fluorine atoms are located above and below the ring. Reaction of the aminoalanes R'R2NAlMe2 with two equivalents of trimethyltin fluoride in T H F gives the monomeric T H F adducts R R2NAlF2.THF.

'

32

33 The synthesis and structure of a number of mono- and bi(amidinate) complexes of aluminium have been described.39 The starting point for these syntheses is the reaction of AlMe3 with one equivalent of carbodiimide, RN=C=NR (R = i-Pr or cyclohexyl) which gives { MeC(NR)2}AlMe2. The novel dimeric, tetrameric and hexameric amino- and imino-metallanes (MeAINR,-), (Rf = 4-C6H,F; n = 4 (34)

394

Organometallic Chemistry

or 6 (35)), (Me2GaNHRf)2, (MeGaNRr)b, (Me21nNHRf)2 and (MeIn(THF)NRf)4 have been prepared in high yield by the reaction of A1Me3, GaMe3 or InMe3 (as appropriate) with 4-fluoroaniline. For the degree of oligomerisation of 34 and 35 a solvent- and temperature-dependent influence is found. (MeGaNRf)6 is the first hexameric iminogallane and (MeIn(THF)NRf)4 the second iminoindane to be described in the 1iteratu1-e.~' 14 51

Fl2l

34

2.2 Compounds Containing Oxygen or Sulfur - Dimethylaluminium and dimethylgallium alkoxides of the type Me2MOR (M =A1 or Ga, R = CHMeCH2NMe2; M = Al, R = CHMeCH2NH2) were synthesised by the reaction of Me3M with the corresponding amino alcohol. The resulting compounds have been characterised by 'H, 13C and 27AlNMR spectroscopy and the

1 I : Group 13: Boron, Aluminium, Gullium, Indium und Thullium

395

crystal structures determined by X-ray diffra~tion.~' The compounds (e.g. 36) are dimeric with A1202 cores and five-membered heterocyclic rings. Base effects on the formation of four- and five-coordinate cationic aluminium complexes have been investigated as part of a continuing effort to determine the factors that affect cation formation for organometallic aluminium complexes.42In the current study the interactions of R2AlX ( R = M e , i-Bu, t-Bu; X=C1, Br, I) with the monodentdte bases THF, pyridine, NEt3, NH(i-Pr)z, H2N(i-Bu), HzN(t-Bu) and O=PPh3 are examined to determine the role of the base in cation formation. The reactions result in the formation of both neutral adducts of the general form R2AlX.base as well as the cationic complexes [RzAl(base)z]X.

d N1

36 It has been found that novel trinuclear metal complexes of formula (MeM)(CH2[C(Me)NNC(S)(NR)]2j(MMe2)2 (M = A1 or Ga, R = Me, Et or Ph) result when the ligands 2,4-bis(4-N-alkylthiosemicarbazono)pentaneare mixed with Me3Al or Me3Ga. The structure of the methyl-aluminium product is shown in 37.

The synthesis and chardcterisation of the dinuclear Group 13 heterocyclic carboxaldehyde thiosemicarbazone complexes (Me2M)[NC5H4CMeNN C(S)

396

Orgunometallic Chemistry

NR](MMez) (M = Al or Ga; R = Me, i-Pr or Ph) and the acetophenone thiosemicarbazone complexes (MezM)(MeRCNNC(S)NR’)(MMe2)(M = Al or Ga; R and R ’ = M e or Ph) have been described.& The carboxaldehyde complexes were prepared by the reaction of MMe3 with 2-acetylpyridine-4-alkylthiosemicarbazone in toluene while the acetophenone complexes were prepared using MMe3 in toluene with acetophenone-4-alkylthiosemicarbazoneunder anaerobic conditions. Two of the products have been studied by single crystal X-ray diffraction methods and they are both shown to be dinuclear although the metal atoms may vary between a coordination number of four and five. A new synthetic route to the organoalumoxanes (RAlO), is described.45 The synthesis of ( m e ~ * A l Ois) ~given and the reactions of this compound with AIR3 are discussed.45The structure of (mes*A10)4with its A1404 ring is given (38). The product of the reaction of 38 with Et3AI is 39 which has an intriguing ladder structure.

38 There has been an interest in alumoxanes and galloxanes with general formulae (RMO), or (R2MOMR2), since the 1960s because of their possible role as polymerisation catalysts. It is therefore of interest to note the recent report of a novel approach for the stabilisation and structural characterisation of Group 13 organometallic hydroxide^.^^ Thus (mes3M.OHLi).3THF (M = Al or Ga) have been synthesised by the reaction of LiOH with mes3M. In a second series of syntheses the hydroxides (R2MOH), (R=mes, Ph or Me) resulting from the reaction of R3M and water were deprotonated with RLi to give (mes2GaOLi),.4THF, (rne~2AlOLi)~.4THF, (Ph2A10Li)3.6THF and (MezAIOLi)4.7THF.LiCl. Reaction of Al(t-Bu), with between one and two equivalents of HOCH2CH2NMe2 allows for the isolation of a Lewis base complex (40) which is stabilised by intramolecular hydrogen bonding.47 The A1-0 bond distance in 40 is similar to that found in bridging alkoxide compounds suggesting that the Al-

11: Group 13: Boron, Aluminium, Gullium, Indium and Thllium

397

39

0...H unit may be considered analogous to a bridging alkoxide unit. 40 under45 "C to yield [(t-Bu)2AI(p goes alkane elimination above O C H ~ C H ~ C H ~ N M a~ ~compound )]Z, which is also formed directly when two equivalents of Al(t-Bu), react with one equivalent of HOCH2CH2CH2NMe2. The kinetics of alkane loss from 40 have been studied. A large activation energy and a positive deuterium isotope effect are consistent with the breaking of the hydrogen bond during the transition state.

Two novel blue luminescent organoaluminium complexes AI4Me&3-0)2(dpa)2 p3-0) (dpa = deprotonated di-2-pyridylaand A13(7-azain)4(0CH(CF3)2)2(Me)( mine, 7-azain = deprotonated 7-azaindole) have been synthesised and characterised s t r ~ c t u r a l l yThe . ~ ~ unusual stability of these compounds is attributed to the presence of the triply-bridging 0x0 ligand. The first organoaluminium derivative of a hydroxy carboxylic acid - the tetranuclear species [Et2AI]4[(p02C)C6H4-2-p-O]2(41) - has been prepared and structurally ~ h a r a c t e r i s e d The . ~ ~ molecule is a centrosymmetric cluster with a

398

Organometullic Chemistry

skeleton framework consisting of three fused heterocycle rings, one 12- and two 6-membered. The carboxylate groups display bidentate coordination.

41

The reaction of Al(t-Bu), with the carboxylic acids RC02H yields the dimeric di-tert-butylaluminium carboxylates [ ( ~ - B u ) ~ A I ( ~ - ~ ~(RC=Rt-Bu, ) ] ~ CC13, Ph, Bz, CHPh2, CPh3, C(H)=C(H)Ph, CH20CH3, CH20CH2CH20CH3 or CH2(0CH2CH2)20CH3).50 In these compounds the carboxylate groups are bidentate giving rise to AI2O4C2cores. These cores are either planar or puckered and the extent of the puckering is found to be dependent on the steric bulk of the carboxylate groups. The reaction of [t-BuAI(p3-0)]6 with two equivalents of (R,S)-P-butyrolactone results in the formation of the alumoxane, (R, S)-[Al6t-Bu6(p3-0)4{p3-OCCH2C(H)( Me)O)2] with a molecular structure consisting of two ring-opened lactone moieties inserted into and bridging the edge of the Also6 alumoxane. The role of this alumoxane in the latent Lewis acid catalysed ringopening polymerisation of P-butyrolactone is d i s c ~ s s e d . A ~ ' number of lithium trialkyloxo[tris(trimethylsilyl)aiuminates] have been synthesised and the crystal structures of [Li(THF),)][AlR(OEt)3] and { Li[AlR(Oi-Pr)2](OH)]>2 (R = (Me3Si),C) are reported.52 The interest in these compounds is that they are analogues of the intermediates presumed to be present in the reduction of carbonyl compounds by LiAIH4. The monomeric species is found to have a planar Li02AI ring while the dimeric species has an Li2A1206 framework comprising two adjacent face-sharing cubes with missing atoms at diametrically opposite corners. The phenylarsenates [t-BuAI(p-O3AsPh)]4 and [t-BuzGa(p202AsPh)I20 have been synthesised and structurally ~ h a r a c t e r i s e d .These ~~ compounds are of interest because of the lack of information regarding aluminoand galloarsenates when compared with the corresponding alumino- and gallo phosphates. The reaction of AIMe3 with an equimolar amount of ethyl rac-lactate (Helac) The adduct (42) is formed in a highly stereoaffords ruc-[Me2AI{(S*)-ela~)]2.~~ selective manner which is non-rigid in solution. A structural investigation has also been made of a range of dimethylaluminium

11: Group 13: Boron, Aluminium, Gullium, Indium and Thallium

399

42

43

-gallium and -indium O,U-chelate complexes in solution and in the solid state.55 These complexes are formed by reaction of MMe3 (M = Al, Ga or In) with an equimolar amount of methyl salicylate, 2-(HO)C6H4C02Me (Hmesal), to give [MezM(mesal)],. All three compounds are dimeric in the solid state with fivecoordinate metal centres; the structure of the aluminium derivative is given in 43. In solution the aluminium and gallium compounds are monomeric, four-coordinate chelate complexes, whereas the indium compound retains its dimeric structure. The following sequence of Group I3 metal centre Lewis acidity in fourcoordinate diorgdnometak 0,U-chelate complexes is proposed: In>AbGd. In a further related study structural investigations of dialkylaluminium chelate derivatives of a-and P-hydroxy carbonyl compounds are discussed.56The interest here is to investigate electronic factors which may determine the rearrangement of dimeric five- to monomeric four-coordinate complexes on dissolution. The study was performed on the complexes [R2A1(0,U)], (where 0,U is the deprotonated form of 2-acetyl-4-chlorophenyl and R = Me; 0,O is the deproto-

400

Orgunomet ullic Chemistry

nated form of a-tropolone and R = Et; 0, O i s the deprotonated form of ethyl roclactate and R = Me). The first and second compounds rearrange to monomeric four-coordinate complexes on dissolution whereas the third compound retains its dimeric structure. The reactions of resorcinvl or hydroquinone with AIMe3 give compounds which dissolve in pyridine to yield the adducts (1,4-(Me*AlO)&H4)(Py)2 and ( 1,3-( Me2A10)2C6H4)-(Py)2.57 A recent work gives the synthesis and first structural characterisation of complexes possessing a single Al-0-Si linkage.58 These compounds are of the formula LAIOSiPh3 (where L = W e n (t-Bu), Salpen(t-Bu), Salophen(t-Bu) or Salomphen(t-Bu)). The structures of the Salen(t-Bu) and Salomphen(t-Bu) derivatives are given (44,45). There is also considerable interest in the cage molecules, with adamantane like structures, which are made by reaction of an alumazene with a stable silanetriol and a triaminosilarie since they may be thought of as molecular aminoaluminosilicates.

(R = Me,Et, ‘Bu)

(Salcn(‘BuP

44

45

2.3 Compounds Containing Another Metal Atom - A number of insertion products (including 46 to 49) have been synthesised using polynuclear aluminium-magnesium compounds and various heteroannulenes such as isothiocyanates, isocyanates and carbon disulfide.hO The reactions are summarised schematically below. The reaction of AIMe3 with the proposed stibene intermediate (-Sb=C) formed R

R

S $C-

CH3

R = I-PK

S R-

R

47

I I : Group 13: Boron, Aluminium, Gullium, Indium and Thallium R.

R

R

R

40 I R’

48

R=EI;

in the reaction of [(2-pyr)(SiMe3)2CLi(tmeda)]with SbCI3 gives the carboahminium product containing a gm-Al/Sb C centre as part of a six-membered ring The Ti-F bonds in [(CP*T~OF)~] and [ { (C5H4Et)TiOF}4] may be activated by AIMe3.62Products are formed by bonding between the fluorine atoms of Ti-F units in the starting compounds with the Al atom of AIMe3. An X-ray diffraction study reveals that such coordination, as expected, lengthens the Ti-F bonds. The synthesis is reported of the compound [Cp*AIFe(C0)4] (51).63 The synthesis is achieved by reaction of [(Cp*AlC12)2]with two equivalents of the potassium salt of [Fe(C0),l2-.

50

Organumetallic Chemistry

402

H 0 20

51

3

Gallium

General - The synthesis of the first gallyne - a compound with a Ga-Ga triple bond is reported.64 This is the species Na2[Mes*2C6H3GaGaC6H3Mes*2] (Mes*= 2,4,6-i-k3C6H2) (52). The Ga-Ga bond forms part of a. near-planar Ga2NaZ four-membered ring. The Ga-Ga bond distance is 2.3 19(3) A whichomay be compared with the Ga-Ga single bond distances of 2.688 A in [Ga4(C(SiMe,)),] and 2.541( 1) in [(Me3Si)2HC]2Ga-Ga[CH(SiMe3)2]2. The Ga-Ga bond in 52 is the shortest Ga-Ga bond on record. The crystal structure of [GaCp*] has recently been ~btained.~' This structure completes the series [MCp*] (where M = Al, Ga, In, TI). The crystals were obtained by cooling a molten sample and the structure is found to be hexameric (53). Solid [GaCp*] is isomorphous with [InCp*] and may be contrasted with the tetrameric [AI&p*4] which contains a tetrahedron of aluminium atoms. An allylgallation reaction of C-C triple bonds with allylsilanes and GaC13 has been described.66 In the most

3.1

A

52

53

11:Group 13: Boron, Aluminium, Gullium, Indium und Thallium

403

recent of a continuing series of papers on the chemistry of C-substituted heterocarboranes a number of half- and full-sandwich gallocarboranes of the 2,3and 2,4-C2B4 carborane ligand systems have been reported.67 A number of 2,6-dimesitylphenyl-based sterically demanding gallium aryls have been synthesised (54-57); these syntheses are summarised schematically.68 One point of note is the rare T-shaped coordination about the gallium centre in 56 in which the C-Ga-C bond angle is 153.5(2)c.

54

55

Ga

I

Br

57

56

3.2 Compounds Containing a Group 15 Element - A series of aminogallanes of general formula [Me2GaRI2 (R = NMe2, NEt2, N(n-Pr)z, N(n-Bu)z, N(i-Bu)2, N ( c - C ~ H I ~ )NC4H8, ~, N C S H ~ NC6HI2 ~, and N(CHzCH&NMe) have been synthesised from Me3Ga and the corresponding amine in toluene at 110 "C by elimination of CH4. Syntheses of [Me2GaN(iPr)2]2, [Me2GaN(s-Bu)& and [Me2GaN(CH2Ph)2I2were achieved by reaction of MezGaCl with the respective lithium amide.69 X-ray crystal structures were determined for [Me2GaN(CH2Ph)2]2,which has a slightly puckered four-membered Ga2N2 core, and [ M ~ ~ G ~ N ( C H Z C H ~ ) ~which N M ~has ] ~ ,a planar core. The reaction of Ga(CH2Ph)3 with CsN3 in T H F gives the metallate [Cs(toluene)o.s ((PhCH2)3GaN3}](S),whereas the corresponding reaction of In(CHZPh), with CsN3 in toluene gives the solvent-free salt Cs[(PhCH2)3InN3](59)." Both 58 and 59 may be considered as coordination polymers in the solid state. In 58 the monomers are connected by Cs.. .N3 and Cs. -aryl contacts to form polymeric sheets. In 59 the monomers are connectep by Cs- . -phenyl contacts. In addition weak In..-N3interactions of 2.901(5) A are observed leading to a strongly distorted trigonal bipyramidal coordination sphere of the indium centre.

404

Orgunometallic Chemistry

58

N3

59

A study has been made of the relative Lewis acidities of the series of triorganogallium compounds GaR3 (R = Me, Et, CH2CMe3, CH2SiMe3, CH2CMe2Ph and CbH2Me3) towards the common Lewis base HPPh2 and of the relative Lewis basicities of the series of organophosphines HPRR' (PRR' = PPh2, P(C6Hl1)2, PEt2 and P(H)(CbHI I ) ) towards the common Lewis acid Ga(cH~CMe3)3.~' The equilibrium constant for the dissociation of the adducts was measured using cryoscopic molecular weight techniques backed up by 3 1P N MR spectral data. A number of gallium-phosphorus, gallium-arsenic and indium-phosphorus compounds with chromophoric substituents have been made.72These compounds are of the general type [R2ME(t-Bu)2I2(M = G a or In; E = P or As; R contains a chromophoric group, r.g. vinyl, ally1 or benzyl). The aim of this work is t o produce precursors which are suitable for use in photoassisted MOCVD reactions to yield thin layers of 111-V semiconductors. It is found that the vinyl compounds absorb with cut-offs around 300 nm while the

I I :Group 13: Boron, Aluminium, Gullium, Indium und Thallium

405

ally1 and benzyl compounds have cut-offs around 330 nm. Structural studies show that these compounds have planar M2E2 cores. Examples of two of the benzyl compounds are given in 60 and 61.

61

60

Two compounds with novel connectivities, (Et20)2Li[pi-E(SiMe3)2]2GaH2 (E = P or As (62)) have been ~ y n t h e s i s e dThese . ~ ~ compounds, formally pnictidogallates, were formed by the reactions between LiGaH4 and E(SiMe3)3 in diethyl ether viu trimethylsilane elimination. N o reaction took place if E = N under similar conditions. The phosphorus and arsenic (62) compounds are isomorphous in the solid state with planar four-membered rings of the (Li[p-E]2Ga) core.

62

The compound (Me3CCH2)2Ga(C5H5)reacts at room temperature in pentane solution with HPEt2 and H2P(C6H11) to eliminate C5H6 and form [(Me3CCH2)2GaPEt212 and [(Me3CCH2)*GaP(H)(C6HI 1)]2.74 In addition the compound [(Me3CCH2)2GaP(C6H1 1)2]2 was prepared from Ga(CH2CMe3)2C1 and LiP(c6H11)2 by a metathetical reaction in diethyl ether. The Et2 and (C6H I 1)2

406

Orgunomerallic Chemistry

compounds were characterised structurally and were shown to contain butterfly Ga2P2 rings. The compounds [(n-B~)~MP(SiMe3)2]2 (M = Ga or In) have been prepared and subject to t h e r m ~ l y s i sThermolysis .~~ of the gallium compound at 400 "C under nitrogen gives GaP and BuSiMe3. Similar thermolysis of the indium analogue gives butene, butane and butyltrimethylsilane alongside a grey solid which is shown by powder X-ray diffraction to consist of InP and metallic indium. The results suggest that while the gallium compound may be a useful precursor to GaP the indium compound appears to have a more facile pelimination pathway which makes it a less suitable precursor for the production of pure InP. The reaction of t-Bu3Ga and Sb(SiMe3)3 in a 1:1 molar ratio in hexane gives the expected adduct t-Bu~Ga.Sb(SiMe&.~~ The reaction of tBu2GaCl and Sb(SiMe& in a 1:l molar ratio gives the dimer [t-BuzGaSb(SiMe3)2]2 (63) while the corresponding reaction of the same reagents in a 2:l molar ratio gives 64 which contains a GaSbGaCl four-membered ring.

63 3.3 Compounds Containing a Group 16 Element - The thermolysis of (Mes2GaOH)2.THF in toluene or 1,4-dioxane at 100°C results in the formation of ( M e ~ G a o ) This ~ . ~ ~compound represents the first galloxane comparable to catalytically active aluminium compounds. The structure, which has been determined by X-ray diffraction consists of two six-membered (MesGa0)3 rings connected by three p2-(MesGaO) units. A number of syntheses have been performed which involve selenium insertion into the M-C bond (M = Ga or In). The preparations have been carried out by reaction of elemental selenium with a number of organometallic reagents, namely InNp3 (Np = CH2CMe3), Ga(CH2-

I I : Group 13: Boron, Aluminium, Gullium, Indium untl Thallium

407

SiMe3)3 and Ga(Mes)3. The following products have been structurally characterised by X-ray diffraction:- [NpzIn(p-SeNp)]2, [(Me3SiCH2)2Ga(p-SeCH2SiMe3)]2, [(Mes)C6H7N.Ga-p-SeI2(65) and [(Me~)~C~H~N.GaseMes](66).

Cl8

18)

1141

3.4 Compounds Containing Another Metal Atom - A number of reactions have been carried out between transition metal carbonyl dianions and organogallium chlorides, the products being anionic gallium complexes of chromium, iron and manganese.79The structure of one of these complexes, namely [PPN}z { [(y0)4FeGa(CH3)-Fe(CO)4]>is reported. The reaction of Naz[Fe(CO)4] with (Mes )GaC12 (Mes* = 2,4,6-(i-Pr)3C6H2) gives rise to !he compound 67.** This compound shows a short Fe-Ga bond of 2.2248(7) A which provides strong evidence for a triple bond. 67 may therefore be thought of as the first ferrogallyne.

Urgunometallic Chemistry

408

66

co Ga-,F%-

I

CO

oc ‘co

67

4

Indium

Vibrational spectra are reported for trimethylindium and trimethylthallium. The data for trimethylthallium (Raman spectra of the melt and crystal; IR spectra of vapour and matrix-isolated samples) represent the first report of vibrational spectra of this compound.*’ The data on trimethylindium were obtained for comparison. It is possible that Me3TI has a distorted planar TIC3 skeleton in the condensed phases, possibly as a result of a pseudo-Jahn-Teller effect. A variety of penta-2,4-dienyl- and pent-2-en-4-ynylindium reagents have been prepared in situ from the reaction of the corresponding allylic bromides with indium metal, and their reactions with carbonyl compounds have been examined. The reaction with aldehydes gives the corresponding homoallyl alcohols in high yields and the coupling occurs regioselectively at the gamma posi tion.82 An intramolecularly coordinated diindacycle: 9,1O-dihydro-9,1O-bis[2,6-bis((dimethylamino)methyl)phenyl]-9,lO-diindaanthracene(68),has been prepared from 68 is the first structurally characterised intramolecuo-phenylenemagne~ium.~~ lady coordinated diindacycle. Adducts of formula Me31n.C3H6N3R3 ( R = M e , i-Pr or t-Bu) have been synthesised. Bonding in these adducts is viu three lone pairs (69); the adduct bonding of these three lone pairs is shown to be only slightly stronger than a standard lone-pair adduct bond at about 85 to 90 kJ mol-’.84 A number of

I I: Group 13: Boron, Aluminiitm, Gullium. Indium und Tltullium

409

68

69

organoindium azides are reported as new precursors to indium nitride.85 The synthesis, properties and molecular structures of the following compounds are given: triazido(tripyridino)indium(I), the mixed coordination polymer ((CF3S03)In[(CH2)3NMe2]2(p-N3)In[(CH2)3NMe2]2),and the polymeric monoazide {(N3)In[(CH2)3NMe2]>,,.The chemistry of these preparative routes and formation of indium nitride is summarised below (70). The trinuclear complex (( M~;!I~)~[NCSH~CM~NNC(S)NC~H~]~)(I~ (71) has been prepared. X-ray analysis reveals that the two indium moieties are coordinated to the three nitrogen atoms in the ligand and the one indium moiety is attached to the two nitrogen and two sulfur atoms of the two ligands.86 The indium centres thus show a rather unusual distorted-squarepyramidal coordination geometry. A number of organic-soluble neutral and ionic indium siloxane cages have been produced.87 The preparative chemistry is summarised in 72. These compounds are potential precursor to indium-containing silicates. The compound In4S[C(SiMe3)3]4 (73) has been synthesised by the reaction of In4[C(SiMe3)3I4 with propylene sulfide.88 73 contains an 1114s core which is isoelectronic to the unknown compounds pentahydro-cfosopentaborate(2 - ) [B5H5J2- and thia-cfoso-pentaborane(4) B4H4S as well as to the well-characterised 1,5-dicarba-cfoso-pentaborane(~)B3C2HS. The average InIn distance to the axial indium atom in 73 is 2.838 A which lies in the range of

Orgunometullic Chemistry

410

Toluene Pyridine +NaN3

+AgTfl -AgBr

-NaCI

b3

ToluenelRT

+!-

Toluene

OMCVD

70

A

In-In single bonds in organoindium derivatives but is 0.16 shorter than the average In-In distance in the tetraindane starting material In4[C(SiMe3)&. The solid-state structure of di-tert-butylindium chloride, [(t-B~)~In(p-Cl)]~ (74) has been determined by X-ray diffraction.89 It consists of polymeric [-In-CI-1, chains arranged in an unusual saw-tooth pattern. The indium atom is in a severely distorted coordination environment approximated as a capped trigonal planar geometry .

The reaction of indium( I) bromide with a,o-alkanediylbis(bromomercury) complexes (alkane = butane, pentane or hexane) results in the formation of the corresponding a,o-alkanediylbis(dibromoindium)complexes which were isolated as THF adducts.gOThe structures of the butane and hexane derivatives are given ( 75 and 76).

11: Group 13: Boron, Aluminium, Gullium, Indium und Thallium

2 : 4,lnMej c *

6 CH4

-

4 : 4, InMe3

- 12 CH4

THF

RSi(OH)3

+ MejSi,

R=

N-

I . 4. Li[tnMe4] ’

12 CH4

A/

Ar

=

0

I

3.Na(InMe4]

- 2 SiMe30H - 8 CH4

72

41 1

Orgunometullic Chemistry

41 2

533

73

74

75

76

As mentioned previously in this report several organoindium syntheses start with the tetrahedral cluster I I I ~ [ C ( S ~ M ~It~ )is~proposed ]~. that upon heating the monomer InC(SiMe3)3 is formed and it may be noted that this monomer is isolobal with CO. Thus it is of interest to note that In4[C(SiMe3)3]4 reacts with Fe3(CO)12 and Fe2(C0)9 in hexane to yield. by substitution of bridging CO, three novel iron indium compounds Fe3(CO)lo(p-InR)2,Fe2(CO)&-InR) and F~~(CO)&I-IIIR (R) ~= C(SiMe&) which were characterised by crystal structure determinations.” In all of these complexes the Fe-In bond lengths are in the range 2.559 to 2.605 while the Fe-Fe distances are all much elongated with

A,

1 I : Group 13: Boron, Aluminium, Gullium, Indium and Thullium

413

respect to the starting carbonyl complexes. The dimeric products [(tBu)2InNEt2]2 and [(t-Bu)2InN(n-Bu)& have been made by the photoinduced e~ and reactions of (t-Bu)3In with Et2NSnMe3 and ( n - B ~ ) ~ N s n Mrespectively the preparations have been i n ~ e s t i g a t e d .One ~ ~ point of interest is that a number of by-products are observed which suggests that the reactions do not proceed by simple alkyltrimethyltin elimination. A possible radical mechanism for the formation of the by-products has been suggested. A novel bifunctional Lewis acid: @,a’-rn-xylenediylbis(indiumdichloride) (77) has been ~ynthesised.’~ The synthesis is achieved by reaction of the di-Grignard compound 1,3-(ClMgCH2)2C6H4with HgC12 to give I ,3-(ClHgCH2)2C6H4 which gives 77 upon reaction with InC1. In a similar vein partial transmetallation, using indium(1) halides as the indium source, followed by spontaneous ring closure gives rise to the first mercuraindacycles including 78.94 The eight-membered dimetallacycle in 78 adopts a twisted structure and shows a conspicuously short In. - .Hg transannular distance. X-ray structural studies have been backed up by ‘H, I3Cand I9’Hg NMR spectroscopy in this work.

c7

77

C04

co

C03

78

Organometallic Chemistry

414

5

Thallium

The compounds [TlR,(S2PEt,)] (R = Me or Ph) have been synthesised by reaction of the corresponding hydroxide TlR2(0H) with NaS2PEt2.2H20.9sThe structure of the phenyl derivative is shown (79). Weak intermolecular interactions with one of the sulfur atoms of a neighbouring molecule make the coordination number of the thallium atom in 79 up to five. An alkylthallium(1) compound with a distorted tetrahedron of thallium atoms in the solid state Tl[F(SiMe&] (80) has been ~repared.’~ In 80 an average TI-T1 distance of 3.335 A is observed in the plane (Tll, TJ2,T13) but the distances to the atom T14 are significantly longer (3.461 to 3.638 A) which are in the range of weak interactions in pentabenzylcyclopentadienylthallium(1). A platinum(I1)-thallium(1) complex [PtTlZ(CbFS)(CC-t-Bu), has been synthesised; the complex is stabilised by alkynyl-thallium and platinumthallium interaction^.^^

79

s14

I I : Group 13: Boron, Aluminium, Gallium, Indium and Thallium

415

References 1. 2. 3. 4. 5. 6. 7. 8.

9. 10. 11. 12.

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416

Orgunometullic Chemistry

31. 32. 33. 34. 35.

B. Wrackmeyer and A. Sebald, J. Orgunumet. Chem., 1997,544, 105. G.E. Herberich, H.J. Eckenrath and U. Englert, Orgunometullics, 1997, 16,4800. M.P. Coles and R.F. Jordan, J. Am. Chem. Sue., 1997,119,8125. P. Wei and D. Atwood, J. Chem. Sue., Chem. Cummun., 1997,1427. C. Rennekamp, A. Gouzyr, A. Kemp, H.W. Roesky, C. Broenneke, J. Kaercher and R. Herbst-Inner, Angew. Chem. Int. Ed Engl., 1997,36,404. D.C. Bradley, I.S. Harding, LA. Maia and M. Motevalli, J. Chem. Soc.. Dulton Truns., 1997,2969. S . Horchler, E. Parisini, H.W. Roesky, H-G. Schmidt and M. Noltmeyer, J. Chem. SOC.,Dulton Truns., 1997,276I . S.D. Waezsada, F-Q. Liu, E.F. Murphy, H.W. Roesky, M. Teichert, I. Uson, H-G. Schmidt, T. Albers, E. Parisisni and M. Noltmeyer, Orgunometullics, 1997, 16, 1260. M.P. Coles, D.C. Swenson, R.F. Jordan and V.G. Young, Jr., Orgunometullics, 1997,16,5183. C. Schnitter, S.D. Waezsada, H.W. Roesky, M. Teichert, 1. Uson and E. Parisini, Organometullics, 1997, 16, 1197. K-H. Thiele, E. Hecht, T. Gelbrich and U. Duemichen, J. Orgunumet. Chem., 1997, 540,89. J.A. Jegier and D.A. Atwood, Inorg. Cliem., 1997,36,2034. C. Paek, S.O. Kang, J. KO and P.J. Carroll, Orgunometullics, 1997, 16, 1503. C. Paek, S.O. Kang, J. KO and P.J. Carroll, Organometallics, 1997, 16, 21 10. R.J. Wehmschulte and P.P. Power, J. Am. Chem. Soc., 1997, 119,8387. J. Storre, C. Schnitter, H.W. Roesky, H-G. Schmidt, M. Noltmeyer, R. Fleischer and D. Stalke, J. Am. Chem. Soc., 1997, 119,7505. C.N. McMahon, S.G. Bott and A.R. Barron, J. Chem. Soc., Dulton Truns., 1997, 3129. W. Liu, A. Hassan and S. Wang, Organometullics, 1997,16,4257. J. Lewinski, J. Zachara and I. Justyniak, Orgunumetullics, 1997, 16,3859. C.E. Bethley, C.L. Aitken, C.J. Harlan, Y. Koide, S.G. Bott and A.R. Barron, Orgunometallics, 1997, 16, 329. C.J. Harlan, S.G. Bott, B. Wu, R.W. Lenz and A.R. Barron, J. Chem. Sue., Chem. Commun., 1997,2183. W-Y. Cheng, C. Eaborn, I.B. Gorrell, P.B. Hitchcock, M. Hopman and J.D. Smith, J. Chem. SOC.,Dalton Truns., 1997,4689. M.R. Mason, R.M. Matthews, M.S. Mashuta and J.F. Richardson, Inorg. Chem., 1997,36,6476. J. Lewinski, J. Zachara and I. Justyniak, J. Chem. Soc., Chem. Commun., 1997, 1519. J. Lewinski, J. Zachara and K.B. Starowieyski, J. Chem. Sue.. Dulton Truns., 1997, 4217. J. Lewinski, J. Zachara and I. Justyniak, Orgunomrtullics, 1997, 16,4597. F.A.R. Kaul, M. Tschinkl and F.P. Gabbai, J. Orgunomer. Chem., 1997,539, 187. D.A. Atwood, M.S. Hill, J.A. Jegier and D. Rutherford, Orgunometullics, 1997, 16, 2659. H. Wessel, C. Rennekamp, S-D. Waezsada, H.W. Roesky, M.L. Montero and I. Uson, Orgunometullics, 1997, 16, 3243. C-C. Chang, J-H. Chen, B. Srinivas, M.Y. Chiang, G-H. Lee and S-M. Peng, Organometallics, 1997, 16,4980. P.C. Andrews, C.L. Raston, B.W. Skelton and A.H. White, J. Chem. Suc., Chem. Cummun., 1997, 1 183.

36. 37. 38.

39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51.

52.

53. 54. 55. 56. 57. 58. 59.

60. 61.

1 I: Group 13: Boron, Aluminium, Gullium, Indium and Thallium

62. 63. 64.

65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89.

417

P. Yu, H.W. Roesky, A. Demsar, T. Albers, H-G. Schmidt and M. Noltmeyer, Angew. Chem. Int. Ed. Engl., 1997,36, 1766. J. Weiss, D. Stetzkamp, B. Nuber, R.A. Fischer, C. Boehme and G. Frenking, Angew. Chem. Int. Ed. Engl., 1997,36, 70. J. Su, X-W. Li, R.C. Crittendon and G.H. Robinson, J. Am. Chem. Soc., 1997, 119, 547 1. D. Loos, E. Baum, A. Ecker, H. Schnoeckel and A.J. Downs, Angew. Chem. Int. Ed Engl., 1997,36, 860. M. Yamaguchi, T. Sotokawa and M. Hirama, J. Chem. Soc., Chem. Commun., 1997, 743. N.S. Hosmane, K-J. Lu, H. Zhang and J.A. Maguire, Orgunometullics, 1997, 16, 5163. R.C. Crittendon, X-W. Li, J. Su and G.H. Robinson, Orgunometullics, 1997, 16, 2443. S.J. Schauer, C.H. Lake, C.L. Watkins, L.K. Krannich and D.H. Powell, J. Orgunomet. Chem., 1997,549,3 I . M.R. Kopp and B. Neumueller, Orgunometullics, 1997, 16, 5623. O.T. Beachley, Jr. and J.D. Maloney, Orgunometullics, 1997, 16,4016. R.D. Culp, A.H. Cowley, A. Decken, R.A. Jones, M.R. Bond, L.M. Mokry and C.J. Carrano, Inorg. Chem., 1997,36, 5165. J.F. Janik, R.L. Wells, V.G. Young, Jr. and J.A. Halfen, Orgunometullics, 1997, 16, 3022. O.T. Beachley, Jr., J.P. Maloney and R.D. Rogers, Orgunometullics, 1997,16, 3267. S.T. Barry, S. Belhumeur and D.S. Richeson, Orgunometullics, 1997, 16, 3588. R.L. Wells, E.E. Foos, P.S. White, A.L. Rheingold and L.M. Liable-Sands, Organometullics, 1997, 16,4771. J . Storre, A. Klemp, H.W. Roesky, R. Fleischer and D. Stalke, Orgunometallics, 1997,16,3074. H. Rahbarnoohi, R.L. Wells, L.M. Liable-Sands, G.P.A. Yap and A.L. Rheingold, Organometullics, 1997, 16, 3959. R.A. Fischer, M.M. Schulte, E. Herdtweck and M.R. Mattner, Inorg. Chem., 1997, 36,20 10. J. Su, X-W. Li, R.C. Crittendon, C.F. Campana and G.H. Robinson, Orgunomrtullics, 1997, 16,45 1 1. A.B. Kurbakova, S.S. Bukalov, L.A. kites, L.M. Golubinskaya and V.I. Bregadze, J. Orgunomet. Chem., 1997,536,519. T. Hirashita, S. Inoue, H. Yamamura, M. Kawai and S. Araki, J. Orgunornet. Chem., 1997,549, 305. M.A. Dam, T. Nijbacker, B.C. de Pater. F.J.J. de Kanter, O.S. Akkerman, F. Bickelhaupt, W.J.J. Smeets and A.L. Spek, Orgunometallics, 1997, 16,511. D.C. Bradley and I.S. Harding, J. Chem. Soc., Dalton Trans., 1997,4637. R.A. Fischer, €4. Sussek, A. Miehr, H. Pritzkow and E. Herdtweck, J. Organomet. Chem., 1997,548,73. C. Paek, S.O. Kang, J. KOand P.J. Carroll, Orgunometullics, 1997,16,4755. A. Voigt, M.G. Walawalkar. R. Murugavel, H.W. Roesky, E. Parisini and P.Lubini, Angrw. Chem. Int. Ed. Engl., 1997,36, 2203. W . Uhl, R. Graupner, W. Hiller and M. Neumayer, Angew. Chem. Int. Ed. Engl., 1997,36,62. S.L. Stoll, S.G. Bott and A.R. Barron. Polyheclron, 1997, 16, 1763.

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90.

M. Tschinkl, A. Schier, J. Riede, E. Schmidt and F.P. Gabbai, Orgunometullic.s, 1997,16,4759. W. Uhl, S.U. Keirnling, M. Pohlmann, S. Pohl, W. Saak, W. Hiller and M. Neumayer, Inorg. Chem., I997,36, 5478. D.L. Freeman, J.D. Odom, W.R. Nutt and L. Lebioda, Inorg. Chem., 1997, 36, 2718. M. Tschinkl, A. Schier, J. Riede and F.P. Gabbai, Inorg. Chem., 1997,36,5706. F.P. Gabbai, A. Schier, J. Riede, A. Sladek and H.W. Goerlitzer, Inorg. Chem., 1997,36,5694. R. Carballo, J.S. Casas, E.E. Castellano, A. Sanchez, J. Sordo, E.M. Vazquez-Lopez and J. Zukerman-Schpector, Polyhedron, 1997,16,3609. W. Uhl, S.U. Keimling, K.W. Klinkhammer and W. Schwarz, Angew. Chem. Int. Ed. Engl., I997,36,64. 1. Ara, J.R. Berenguer, J. Fornies, G. Gomez, E. Lalinde and R.I. Merino, Inorg. Chem., 1997,36,6461.

91. 92. 93. 94. 95. 96. 97.

12 Group 1: The Alkali and Coinage Metals BY R. SNAITH

1

Alkali Metals

1.1 Introduction: Organisation and Major Advances. - As last year, this part of the report is organised in sections according to the type of organic anion (R-) within the alkali metal (M+)organometallic (R-M+). Within each section, publications on the synthetic uses of alkali metal derivatives are dealt with first, along with mechanistic aspects of such syntheses. Thereafter, structural studies are noted in order according to the technique involved: solid-state structures elucidated by (mainly) X-ray diffraction, solution structures determined by spectroscopic techniques (NMR in particular), and MO calculational optimisations of structures. In 1997, as in the previous twenty or so years, studies on lithium species continued to dominate Group 1 organometallic chemistry. Nonetheless, research on the heavier metal derivatives is increasing, with potassium being seemingly to the fore. These general points apart, the year saw particular activity in the following areas: (i) the continuing development of new or amended alkali metal reagents, especially for organic syntheses, and alongside this an increased interest in mechanistic studies aimed at probing how such reagents actually operate; (ii) the use of increasingly refined MO calculational methods to predict or rationalise structural and bonding features; and (iii) the experimental elucidation of structures, still mainly by single-crystal X-ray diffraction but also (and increasingly so) by powder diffraction and by NMR spectroscopy in solution and in the solid state.

1.2 Alkyl Derivatives. - Alkyllithium compounds and complexes continue to have a pivotal role in synthetic organic chemistry, both as reagents in their own right and as precursors for the in situ generation of new reagents. Such use requires determination of the concentration of the alkyllithium solution and a new titrimetric method, based upon the formation of a deep blue dianion when PhCONHCH2Ph is treated with a slight excess of BuLi (n-, s-, or t-), has been developed for this end.' In a similarly practical vein, a kinetic study has determined the half-lives of butyllithium reagents in common ethereal solvents.* The low-temperature nitration of butyllithium and of various aryllithiums by N204 proceeds specifically, the NO2 group substituting at the site of l i t h i a t i ~ n . ~ The continuing role of butyllithium reagents in generating new and synthetically Organometallic Chemistry, Volume 27 0The Royal Society of Chemistry, 1999 419

420

Orgunometullic Chemistry

valuable lithiated organic molecules has been illustrated by three especially interesting studies: s-BuLiRMEDA has been used to synthesise enantiomerically enriched thiocarbamatolithium species which show marked configurational stability when reacted with electrophiles? n-BuLiD‘HF effects Li-Se exchange in MeSeCH2C( = CH2)CH2SiMe3and the resulting alkyllithium intermediate can then be derivatised to give 2-substituted pr~penylsilanes;~ and t-BuLi doubly deprotonates diamines of type MeN(R)CH2N(R)Me, the dilithiated species then being reacted with RZ’SiC12 and R’PC12 to give sila- and phospha-heterocycles.6 The chiral Lewis base (-)-sparteine has found increased use as a complexant to butyllithium and other alkyllithium reagents for various enantioselective syntheses, e.g., of aryl amino acids and ester^,^ of phenylglycines,* and of chiral disubstituted cyclopr~panes.~ Interesting lithium reagent (butyl- and allyl-lithium) complexants based on halo-substituted aluminium tris(2,6-diphenylphenoxide) derivatives have been developed; these provide coordination sites for the RLi react ant alongside ‘recognition centres’ for a,p-unsatura ted a Idehydes, thus facilitating conjugate additions. l o Mixed-anion and mixed-metal reagents continue to be developed and used. Regarding the former type, the new unimetal alkyl/alkoxy superbase n-BuLi. MezN(CH2)ZOLi has been shown to effectively metallate pyridine and (seemingly) 2-methoxypyridine, the latter at the unexpected C-6 position; however, in this latter case, it has been shown that a lithiated intermediate does not exist but rather that the reaction proceeds via a radical precursor stabilised by some sort of lithium aggregate. The mixed-metal superbase n-BuLi/t-BuOK has been employed to metallate and subsequently functionalise methyl isopropenyl ether and various hydroxy- and carboxy-allyl~ilanes,’~ and also to generate alk-2enylpotassium intermediates with endo conformations which allow the syntheses of specific (a-alkenyl derivatives. l4 Several new synthetic applications of lithium organocuprate reagents (RzCuLi) have been reported, notably the use of t-Bu2CuLi to cleave C-S bonds in propargylic dithioacetals so giving t h i ~ e t h e r s ’ ~ and of (a-aminoalkyl)cuprates, prepared by reactions of lithiated carbamates with soluble adducts such as CuCN-2LiC1, to effect conjugate additions to a,P-unsaturated carboxylic acid derivatives. l 6 The mechanisms of reactions involving alkyllithium and related reagents have continued to gain attention. Single electron transfer pathways have been established for reactions of alkyllithiums with quinones, initial reduction of the quinone giving alkyl radicals and quinone radical anion^,'^ and for ring substitution reactions of t-BuLi with arylimines which appear to proceed via formation of t-Bu radicals. * Metallations directed by coordinating groups within the organic precursors have been the subjects of several investigations. An isotope effect study on the orrho-directed lithiation of anisole by n-BuLi/Et20 with or without added TMEDA has established that hydrogen abstraction is the rate determining step; such a finding would be consistent with complexation of the lithiating reagent by the directing group (the ‘complex induced proximity effect’) but also with such directing and activation effects being transition-state phenomena (as predicted by calculations). l 9 Metallation reactions of various (trifluoromethyl) alkylthiobenzenes by butyllithiums and by n-BuLi/t-BuOK have been probed by

12: Group I : The Alkali und Coinuge Metals

42 1

analysis of products after quenching; the positions of monometallations appear to be directed by the sulfur atom alone whereas bimetallations are controlled both by this atom and by the CF3 group.20 Carbolithiation reactions (i.e., intramolecular additions of RLi species across C = C bonds) have been examined using vinyl sulfides and n-BuLi/THF solutions, the overall conclusion being that the process is non-concerted and relies on breakage of the C-Li bond; the solventseparated ion pair then determines the configuration of the addition product.21 Ab initio MO calculations on the model metal-halogen exchange system LiCH = CH2/MeI reveal a transition state of form I(vinyl)(Me)(Li) and show that introduction of solvent to this monomeric species accelerates the reaction, i.e., solvent effects in such reactions are not due to deaggregation of the lithium reagent but rather they serve to stabilise the transition state.22 Calculations have also been used to optimise the structures of lithiated phosphine oxides [e.g., the model species H2P(0)CH2Li,which has both Li-0 and Li-C bonds] and to rationalise the anti-selectivity of their subsequent Horner-Wittig reactions with carbonyl compounds.23Two especially interesting papers have concerned the compositions and reaction mechanisms of lithium organocuprate reagents. A detailed 'H/13C NMR spectroscopic study on cyanocuprates such as MezCuLieLiCN has shown that in the presence of HMPA they exist as mixtures with their corresponding CN-free cuprates and uncoordinated LiCN whereas in THF no free LiCN is of present, thus suggesting the existence of higher order c ~ p r a t e Reactions .~~ BuLi/CuI mixtures in toluene with a,P-unsaturated ketones proceed by 1,2addition but in the presence of Et2O the 1,4-product is strongly preferred; such results are interpreted in terms of BuLi/BuCu equilibrium mixtures being present in toluene, the equilibrium shifting towards a lithium cuprate on addition of ~ t ~ 0 . ~ ~ Several important solid-state structures of Group 1 metal-alkyl compounds and complexes appeared in 1997. The THF complex of neohexyllithium, tetramer whose p-C atoms are staggered ( ~ - B u C H ~ C H ~ L ~ * Tis H Fa )cubane ~, with respect to the Li3 faces, an arrangement reflecting the fact that THF complexation precludes Li. -p-C interactions.26 The involvement of metal centres with heteroatoms (notably N, P; 0, S) within the carbanion R- is a common feature of many structures and a review has included alkali metal species with N-heteroaromatic substituted anions such as Ph2(Pyr)C- and ( P Y ~ ) ~ C HIn -.~~ this vein, the (aminomethy1)lithium complexes Li2(CH2NPh2)2*3THF and Li4(CHzNCsH &*2THF show an interesting contrast, the former having a central Li2C2 ring whose Li' ions bear two and one THF molecules but exhibit no Li-N contacts whereas in the latter, a cubane tetramer, two of the Li+ centres each have two bonds to the N atoms of p3-piperidinomethyl anions.28 A similar contrast has been seen in the structures of two (thiomethy1)lithium complexes, Li2(CH2SPh)2*4THFbeing a simple Li2C2 ring dimer having no Li-S contacts whereas [Li(CH2SMe)-THF], is a polymeric ladder with alternating fourmembered Li2C2 and six-membered Li2C2S2 fused rings.29An isolated and single six-membered ring, now of type Li2C2P2, is the key feature of the dimeric (phosphinomethy1)lithium complex, ( P ~ ~ P C H ~ L ~ O T M E Dwhich A ) ~ ,had ~ ' earlier been reported as a monomer. The first structure of an uncomplexed lithiated

422

Organometallic Chemistry

phosphane oxide (a Horner-Wittig reagent) has been described, [Ph,P(O) CHLiC(H)MeEtI4 being a (LiO)4 cubane tetramer with several unique features: each unit of the tetramer contains two stereogenic centres, and each has a Li-C ~' heavier alkali metal bond and so an sp3-hybridised carbanionic ~ e n t r e . Several alkyl derivatives have had their solid-state structures solved. A new modification of the organo-potassium complex (P~~CKSPMDETA), has a polymeric zig-zag chain structure (cf., a discrete molecule reported previously) in which there are two distinct K+ environments; one cation is bonded to a tridentate Lewis base molecule, to the carbanionic centre of its Ph3C- anion and to four C atoms of two phenyl rings within this anion, while the other K+ ion is PMDETAcomplexed and has contacts to C atoms of the third phenyl group (of the Ph3Canion which belongs formally to the first K+ ion) and to phenyl C atoms of its own Ph3C- m ~ e i t yAn . ~ important ~ paper has illustrated strikingly that the justnoted plethora of M . - C(especially M...aryl) interactions is likely to be a common feature of many heavier alkali metal organometallics, such reflecting their high ionicity and the relatively large sizes of their metal cations. It describes a series of structures of MC(SiMe3)3 - n(SiMe2Ph)n compounds and complexes (n = I, 2 or 3; M = Li, Na, K, Rb or Cs), the most significant general finding being that the heavier metal derivatives MC(SiMe2Ph)3 form polymeric chains with large numbers of both intra- and inter-molecular Me - .Ph interaction^.^^ Finally, several mixed-anion aggregates have been isolated from reactions of organic molecules with excesses of butyllithium reagents. A 1:2 reaction of 2,6-(Me2NCH2)2-3,5-Me2C6HCH2SiMe3 with n-BuLi gives a 2:2 mixed alkyl product having a CLi2C2LizC ladder structure whose central (C') centres are provided by n-Bu- anions.34 Lithiations of the chiral amine N-isopropyl-0methyl valinol with n-, s- and t-BuLi have afforded three trimeric ring structures each with two amide anions and one butyl anion.35 A complicated cluster (Ph2NLi)-[Ph(C6H4Li)NLi]2-(n-BuLi)2*(Et20)4containing both mono- and di-lithiated amide anions, and a dimeric (n-BuLi);! ring, was isolated from . ~ ~ findings reactions of Ph2NH with a large excess (1:6) of the a l k y l l i t h i ~ mSuch may be important since it is common practice to employ an excess of the metalcontaining reagent in lithiation reactions of organic molecules: co-aggregates such as those just described might then be formed in reaction solutions and might thereby play a role in the overall reaction. Structural aspects of metal alkyl derivatives have also been probed by various spectroscopic methods (in the solid and gaseous phases as well as in solution) and by theoretical calculations. The use of millimetre spectroscopy has afforded the first structural characterisation of uncomplexed and monomeric CH3Li and CH3Na, and of various of their isotopomers; the derived geometrical parameters compare favourably with those from ab initio calculations save that the experimental C-Li and C-Na bond distances are somewhat shorter.37 Solid-state 13C N MR spectroscopy on a-(dimethylamino)benzyllithium and several of its complexes has shown that all are q3 species, with Li+ bonded to the benzylic C atom and to the @so and one of the ortho-C atoms of the phenyl ring3* The rates of topomerisation of substituted 9-fluorenyllithiums and of a-(benzylthio) benzyllithium in various ether solvents were determined by the dynamic NMR

12: Group I: The Alkali and Coinuge Metuls

423

technique; the rates are smaller in solvents composed of bulky molecules, the results being ascribed to the tumbling of the anion in solvent-separated ion pairs and to the rate-determining step being further inclusion of solvent molecules within such ion pairs.39 Labelled [I5N, "N'] TMEDA has been synthesised and the solution structure of its complex with n-Bu6Li probed by "N and 6Li NMR spectroscopy, the results showing conclusively that the solution species is dimeric with two chelating TMEDA ligand~.~' Scalar 6Li, 15N coupling across coordinative Li-N bonds has also been detected in a 2:2 mixed aggregate of n-BuLi with a bis(dimethylamino)benzyllithium, such detection showing that the solid tetrameric cubane structure is retained in s ~ l u t i o n . Multinuclear ~' NMR spectroscopy has also shown that axial 5-methyl-2-dithiazinyllithium and its equatorial complex with BH3 are dimers and that they are confornationally stable in solutions.42A density functional study of axial and equatorial 2-lithio derivatives of 1,3-dithianes has revealed a strong preference for an equatorial orientation of the ionic C-Li bond, the computed data suggesting that this is due to stabilising nc-+cT*,-, orbital interactions in such equatorial isomers.43 Density functional theory calculations have also been carried out on a substituted lithium pyrrolidide and on its complex with methyllithium, the results agreeing with experimental NMR data in suggesting norbornyl-like folding of the pyrrolidide ring.44

1.3 Alkenyl, Allyl, Vinyl, Alkynyl and Related Derivatives. - The major advances have been in the structural chemistry of these acyclic unsaturated organolithuim derivatives. However, one paper has noted the synthetic use of the phosphaethenyllithium (2,4,6-t-Bu3C6H2)P= C( Br)Li which eliminates LiBr, the resulting phosphinidene carbene then inserting into a C-H bond of an ortho t-Bu N,C-dilithio-2-allylpyrrole undergoes to produce a pho~phanaphthalene.~~ solvent-controlled reactions with electrophiles, 2-isomers being produced from THF solutions but E-isomers from Et2O ones.46 Reduction of the tetrasilylethene (HMe2Si)2C= C(SiMe2H)2by Li metal in Et2O affords the dilithium derivative of the ethene dianion which has a lithium doubly bridged structure in the solid; the structure is highly twisted due to significant Li. - .H(Si) agostic interactions which persist in solution.47 The a-lithiostyrene complexes 2,6-Me2C6H3C(Li-L)= CH2, L = Et2O or t-BuOMe, have been synthesised by LUBr exchange reactions and shown to be dimeric (alkenylC-Lih rings in the solid and (by 'H, 6Li and I3C NMR experiments) in ether and toluene solutions; NMR spectroscopy was also used to determine rate constants and thermodynamic parameters for the E, 2 lability of these systems in solutions.48 Lithiation of a dibenzo-N-t-butylaminotoluene in ether has yielded a remarkable complex of an $-azapentadienyllithium which is monomeric in the solid state with a Li(Et2O)Z' unit located above a near-planar U-shaped azapentadienyl moiety and bonded to all five (NC4) ligand centres; computations show that this structure is a global minimum while 'H NMR results have quantified a dynamic rearrangement process undergone by the complex in solution.49 The lithium phosphoranylidene ylide ArylP( = E) = C(H)Li*3THF [Aryl= 2,4,6-t-Bu$6H2; E = C(SiMe3)2] is monomeric with the solvated Li+ cation occupying the exo-position at the ylidic C atom.50 The solidstate (LiO)6 hexamers [(2-C4H3S)SiMe20Li]b and [(2-C4H3S)CH(i-Pr)OLi]6 fail

Orgunometullic Chemistry

424

to show Li. athienylS interactions but instead there are significant n-interactions between Li and C = C units of the thiophene rings; calculations have rationalised this 'lithio-aversion' by showing that the electrostatic potential of thiophene is much more negative in the out-of-plane n-region than at the S atom in the ring plane.5' The acyl(formy1) anion equivalents based on 3-lithiated 4-t-butylimidazoyl-2-ylidene and 3-lithiated 4-t-butyl-thiazol-2-ylideneform remarkably stable carbene structures (in the solid state a tetramer and a dimer, respectively), the carbene nature of the C-Li bonding persisting in solution as shown by I3C NMR studies; calculations have shown that such stability is due to p(n) stabilisation of the carbene C atoms by the adjacent amino(thio) s ~ b s t i t u e n t sSeveral .~~ aza-ally1 derivatives have been synthesised and characterised structurally by X-ray crystallography. Insertion of PhCN into dilithiated 2-methylpyridine in which some of affords a Lil2 aggregate {[C5H,NCHC(Ph)N]2-2Li+}6-4THF the cations have combined C-Li and N-Li coordinations to the (pyridylN = C)C( H)C(Ph)(iminoN) units.53 The polymeric complex { [PhC(H)...N ,C(H)Ph]-K+.PMDETA) cc also shows two kinds of bridging anion-K+ interactions involving q3-CTN ,C and ortho-C-@so-C-a-C units.54 In a similar vein, both q3-azaallyl and phosphinimine coordinations have been identified in the molecular structure of dimeric { [Me3SiN = P(Ph)2C(H)C(Ph)NH]K+-TMEDA}2.55 The relative importance of alkali metal/acetylene n-interactions has been probed via the crystal structures of (MeOC6H4SiMe2C= CLi)6, in which there are near-symmetric Li-(acetylide)C, and -Cp contacts but significant variations in the Li-C, distances (shown computationally to be due to side-on-n and end-on-o bonding), and of the 'non-metallated' acetylene (HC = CCMe20Li)6 in which there are longer range electrostatic n-interactions between Li' cations in the (LiO)6 core and the intact acetylene unit.56 Calculational studies have included one on lithiated cyclopropenyl cations, showing that these are favoured energetically over their acyclic isomers but that such a preference is diminished as the degree of lithiation increases.57 A b initio optimisations of monomeric 2- and E-2-methoxy- 1-iodo- 1-1ithio-2-phenyl-1alkenes have revealed a Liee-phenyl interaction in the former and a rather stronger Li-0 chelating interaction in the latter, both effects disappearing on s ~ l v a t i o n .Solvated ~~ lithium enolates (CH2 = CHOLi),-(Me20),, n = 1-4 and x z 0 - 4 , have also been studied theoretically; in the equilibria among the aggregated species and in the relative stabilities of the tetrameric isomers, solvation is critical but it is balanced by Ir-interactions between lithium and the enolate double bond.59 a

1.4 Aryl Derivatives. -- Reactions of T H F solutions of lithium and sodium biphenylide with substituted polystyrenes have afforded paramagnetic, polymersupported metal naphthalenides; these can be used to generate metal reagents, separable from spent polymer by simple filtration.m Transmetallation reactions of polymeric [2,3,5.6-(Me2NCH2)&- 1,4-Li2],x, gave aryltrimethyl-silanes and -stannanes which in turn could be racted with Pd(I1) or Pt(I1) substrates to give organometallic products arising from both aryl and methyl group transfer.61 Similarly, 1,3,5-trilithiobenzene has been synthesised from reaction of the

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425

tribromobenzene with lithium-4,4’-di-t-butylbiphenyl and then used to prepare 1,3,5-C6H3X3 derivatives with X = MgBr, SnMe3 and HgBr.62 Reactions of olithiated N,N-dialkylnaphthamides with aldehydes have been shown to be highly diastereoselective, the stereochemistry being controlled by the conformation of the CONR2 amide The syntheses and structures of several Group 1 aryl species have been reported, including some which are solvent-/Lewis base-free. Four rn- or p-substituted aryllithiums provide models for the (unknown) structure of phenyllithium itself since the lack of o-groups likely allows similar association; thus, significantly, (3,5-f-Bu&H&i)6 is hexameric in the solid (and probably also in solution, from I3C NMR data) with six of the eight Li3 faces of the distorted octahedron capped by aryl @so-C atoms.64 The sodium aryl (2,6-Mes2C6H3Na)2 is dimeric (reflecting the fact that the aryl substituents are now ortho) with the Na+ cations coordinated almost equally strongly to ipso-phenyl and @so-mesityl C atoms.65Several structures have emerged in which intramolecular coordination of metal centres is provided by o-amino or hydrazino groups within the aryl anions. Thus, [2,6-(Et2NCH2)2C6H3Li]2 is a dimer with @so-C bridges, each Li’ also interacting with one amino group of each aryl ligand.66 The complexes [2-Me2NCH2-4,6-(Me)2C6H2Li]2-OEt, and [2-Me2N(Me)NC6H4Li]2-TMEDA are also dimers with (Q~so-cLi)~ rings but here one Li+ in each structure is complexed by ‘external’ Lewis base (Et2O or TMEDA) whilst the other is attached to two ‘internal’ N atoms provided by the two substituted aryl groups.67 A strongly emerging feature of numerous crystallographic studies is the structural importance of alkali metal (M+)-. -aryl interactions in species lacking formal M’-C-(aryl) bonds, i.e., such species are not aryl organometallics as such but they contain anions within which there are aryl groups. The anionic centres of the deprotonated ligands can be drawn from a wide variety of electronegative elements (Si; N and P; 0, S and Se). A further aspect is that the occurrence of such M’. wyl contacts (and so, arguably, their thermodynamic importance) increases as the size of M+ increases, presumably reflecting the greater ionicity and coordinative needs of the heavier alkali metals. Since such structures fall strictly speaking outside the remit of this report, but since also M+.- aaryl contacts play a key structural role in many species with aryl-substituted anions, a brief and selective listing is now provided. The uncomplexed dimeric lithiosilanes [Me( PhMe2Si)2SiLiI2 and [Ph(Me3Si)$iLiI2 each show short Li. - .@soC and Lie .oC contacts to phenyl rings and 7Li NMR data show that such stabilising, largely electrostatic interactions are retained in hydrocarbon solvents.68 Regarding compounds with Group 15-based anions ( N or p), 1:I ether solvates of the sodium phenylhydrazide (Me3Si)2N-N(Ph)Na form chains in the solids viu intermonomer Na+. . .phenyl (q2 or q3) contacts;69 in contrast, the potassium phosphanylamide (Ph2P)zN K-PMDETA is monomeric with intramolecular q or q2 coordinations from the two Ph rings to the K+ cation.70 An unprecedented cyclic tetramer has been observed in the solid state for a diphenyl-substituted dihydrotriazinide rubidium complex, the sixteen-membered (NCN R b k ring core involving Rb’. . -oC interaction^.^' The first heavier alkali metal salt of a primary phosphane, polymeric [Mes*P(H)K],{ Mes* = 2,4,6-t-Bu&H*), has a ladder a

’

426

Organometullic Chemistry

structure with each K+ ion coordinating to three P anions and (approximately q3) to the It-cloud of a neighbouring Mes* ring.72 For M-Group 16 (0, S, Se) species, powder X-ray diffraction structure solutions of the phenoxides C6HSOM ( M = K , Rb, Cs) show some M+ ions in three-fold oxygen coordination with additional weak interactions with phenyl rings.73 The tetralithiated calixarene complex (Li4L-2HMPA)*, L = t-butylcalix[4]arene, has one Li+ cation bonded to only three 0 atoms, so prompting a minteraction with one of the calixarene aryl groups;74 much more extensive Na+. C(arene) contacts are seen in the related dimer (Na2L’)2,H 2 L= 1,3-dimethylether p-t-b~tylcalix[4]arene.~~ In each of the hexameric thiolates (Ph3SiSNa)6, (Ph3CSK)6*2HMPAand (Ph3CSK)6, the M6S6 core is stabilised through numerous M + . . . I ~interactions with several of the eighteen Ph groups making up the organic periphery.76 The dimeric metal selenolates (2,6-Trip&H$eM)2, Trip = 2,4,6-i-Pr3C6H2, M = K or Rb, each exhibit significant metal. earyl contacts.77 1.5 Cyclopentadienyl and Related Derivatives. - The syntheses of n-BuC5Ph4Na, 1,4-[4-RC(0)C6H4]2CSH3Na (R = Me or c-hexyl), and (4-RCH2C6H&C5HNa [R = Me or n-Pr] have been reported.78 The reagent C5Me5K has been used in cyclopentadienyl ring metathesis to convert Cp2M species (e.g., M = Sn or Pb) to (CSMes)2M products.79 High-resolution X-ray powder diffraction has provided the structures of four of the five alkali metal cyclopentadienides. Both CpLi and CpNa have ‘multidecker’ arrangements in which each of the M+ ions are linearly coordinated by two qs-bonded Cp- rings, these rings being orientated in an absolutely coplanar and eclipsed fashion; in contrast, in polymeric CpK the K+ ions form a zigzag chain.80 In CpCs there is also a chain consisting of an infinite array of bent -Cp-Cs-Cp- units,8’ A series of polymeric alkali metal (+)-neomenthylcyclopentadienyl compounds and complexes, for example (q5-CSH4RM),, M = Li, Na or K, R = neomenthyl and (q5-CSH4RM-L),, M = Na, L = THF and M = K, L=DME, has been made and shown by single-crystal X-ray analysis to have multidecker zigzag chain structures.82 Several interesting mixed-metal cyclopentadienide species have been described. The solid-state structure of Cp3YbNa consists of a highly symmetrical array of alternating Na and Yb atoms bridged by qS-Cp rings in a near-linear Na-Cp-Yb arrangement.83 Reactions of [(C5MeS)Sm(OAr)l2complexes {Ar =4-R-2,6-t-Bu2C6H2 and R = H or Me or t-Bu} with two equivalents of C5Me5K have yielded polymeric complexes [(p,qS-CSMeS)Sm(OAr)(p,qs-C~MeS)K*2THF]m in which the (CSMeS)K*2THF units can be viewed as neutral l i g a n d ~In . ~contrast, ~ the monomeric complexes (q5-Cp)2M‘(p-Cp)Na*PMDETA,M’ = Sn or Pb, each have a trigonal planar (qS-Cp)3M’- unit in the solid state, this being linked via one p,q5-Cp- unit to a PMDETA*Na+ complexed cation; ab initio MO calculations showed that the precise structural formulation of such species (neutral Cp2M’ + neutral CpNa, or Cp3M’- + Na+) is highly dependent upon the extent of alkali metal comp~exa t ion .85 Density functional calculations on Cp2M- sandwich anions (M = Li, Na, K, Rb) predict coparallel, staggered rings although the energy needed to bend the

12: Group I : The Alkuli and Coinuge Metals

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molecules is small when M = K or Rb, a feature ascribed to the increased overlap of the metal dx2-y2 orbital with the a l ligand function.86Ab initio methods have been applied to the question of the aromaticity of various Group 14 ( E = C , Si, Ge, Sn, Pb) metalloles, including the lithiated species C4H4EHLi and C4HdELi2; in the former reduced aromaticity is apparent but this is partly compensated for by stabilising Li- . H interactions, whereas the dianions (C4H4E2-and C4H4ELi2) show enhanced ar~maticity.'~

2

Copper, Silver and Gold

2.1 Introduction: Organisation and Major Advances. - The sub-sections here deal with the three metals in turn. Within each sub-section, the ordering is largely according to ligand type (alkyl, aryl, alkynyUacetylido, carbene, ylide etc.). Some general comments are appropriate regarding the subjects of 1997 publications in this area. Most interest has centred on organogold compounds, with rather less activity in Cu-containing species and decidedly less activity in organosilver chemistry. This apart, the majority of papers report in the main the syntheses and X-ray single-crystal structures of new complexes. Such reflects the fact that most effort is being directed towards applications via, in particular, non-linear optical and other photophysical properties. Species of interest (acetylido ones especially) are thus usually quite highly aggregated, often polymeric, and so not amenable to, for example, solution studies nor to high level calculations. 2.2 Copper Compounds. - The uses of organocopper reagents (including lithium cuprates) in regio- and stereo-selective transformations have been reviewed.88A new organocopper-Lewis acid reagent RCu-TMEDA-n-Bu2Btriflate (R = benzyl or allyl) has been developed and shown to be extremely effective in promoting conjugate addition of R groups to chiral a,P-unsaturated imide~.'~ The unusually stable 2-(ethy1thio)phenylcopper and its soluble 1:1 complexes with copper(1) halides have been synthesised and used in reactions with various electrophile~.~~ Cryoscopic methods have been applied for the first time to study the aggregation states of organocopper and lithium cuprate species in THF solutions, monomers or dimers (alone or together in equilibrium) being the norm." The aggregation state of mesitylcopper (known to be a pentamer in the solid state when recrystallised from toluene) has been re-examined and several new solid phases have been characterised by X-ray diffraction, e.g., a squareplanar tetramer with four THF molecules occupying spaces between the mesityl ligands, and a pentamer with THF molecules in the crystal lattice; such results, and others from cryoscopic molecular mass measurements, imply that a tetramer - pentamer equilibrium occurs in both ethereal and aromatic solvents.92 Four Cu(1) complexes with bidentate (N,O)anions have been designed as photosensitizers to assist the norbornadiene (NBD) to quadricyclene (Q) isomerisation, and [Cu2Lz(p-N BD)], L = 2-methyl-8-oxoquinolat0, is the most promising of these; in the solid each Cu centre is planar, bonded to N and 0 of the chelate L and to the C = C double bond of NBD, and this species is the precursor,

42 8

Orgunometullic Chemistry

in the presence of NBD, of the photoactive monomer [CUL(NBD)].~~ The photophysics of several associated Cu(1) acetylides has come under scrutiny. Twenty soluble trinuclear cationic complexes with bicapped p3-q alkynyl hgands, [Cu3(p-PNP)3(C=CR')2]+ {PNP= (Ph,P),NR; R, R' = diverse alkyl and aryl groups), have been made and shown to be phospholuminescent at ambient t e m ~ e r a t u r e Intense .~~ luminescence is displayed also by the hexanuclear species [CU~(CL-P~~PCH~PP~~)~(P~-T~ I-C E CC6H4C C-~)CU~(P-P~~PCH~PP~~)~]~+ in the solid state the cation consists of two Cu3 triangular arrays whose edges are bridged by dppm ligands, the two resulting cu3P6 cores then being bridged by the acetylide d i a n i ~ n A . ~ series ~ of trinuclear copper(1) complexes [Cu,(C = CR) (C 3 NR')(dppm)3]2+-[BF4-]2 have also been synthesised, the cation when R = R' = 4-CH3C6H4 consisting of a Cu3 triangle bridged by the dppm ligands with an unusual, near-linear isocyanide ligand bridging the shortest edge while the acetylide anion shows an asymmetric p3-q' bridging mode.96 Dinuclear [CuCl(cycloheptyne)]2 complexes containing the strained cycloheptynes Me@CH2(E)CH2CMe2C =&, E = CH2, S or SiMe2, have been studied by X-ray diffraction, the key finding being that the strength of the Cu-alkyne bond increases on going from the least strained alkyne (E = SiMe2) to the most strained one (E = CH2).97Interesting cuprate complexes of Eu and Yb have been obtained by reacting these lanthanide metals (Ln) in the appropriate solvent with PhC = CCu; the resulting complexes ([(PhC EE C)3Cu]*[Eu(pyr)(THF)2])2and ([(PhC = C)3Cu]*[Yb(THF)2])2are centrosymmetric dimers in the solid state with the Ln-Lewis base units being bridged by the (PhC-C)3Cu fragments.98

2.3 Silver Compounds. - Silver(1) and silver(II1) species containing the CF2Hanion have been synthesised and characterised by multinuclear (including Io9Ag) N MR spectroscopy, e.g., the thermally unstable moiety [Ag(CF2H)2]- and the air-stable solid [PNP]+[Ag(CF2H)4]- ; the latter, whose anion contains a square planar silver atom, has been shown by thermogravimetric analysis to decompose in two steps with formal elimination of one and three CFH units.99 The first two stilbene silver complexes were obtained from treating AgN03 with stilbene crown ethers having four or five 0 centres; in the solid state the surprise is that the Ag+ ion coordinates at the central C = C double bond (as well as to the crown and NO3- oxygen atoms) but shows no interaction with the arene units."' In contrast, the polycyclic hydrocarbon complexes [Ag2(pyrene)(C104)2] and [Ag2(perylene)(C104)2]exhibit extensive Ag+. w e n e solid-state contacts, the former being a polymer in which each metal centre is coordinated to two C = C 7t bonds from two different pyrene molecules whilst the latter has a 2D-framework of Ag' ions bridged by bidentate C104- ions and tetra-q2-arene groups; the irradiated complexes exhibit ESR signals attributable to aromatic hydrocarbon radicals and they become conducting upon iodination. Aryl. .Ag+ interactions have also been observed in the solid-state structures of Ag(q4-TFBP)(C6H412) and Ag(q 3-TFBP)(2,2'-bipyr), where T F BP is the anion tetra kis[3,5-bis(t rifluoromethyl)phenyl]b~rate,~'~and in that of the first compound with an Ag-Sn bond, the dimer { MeSi[SiMe2N(p-tolyl)]3SnAg}2.103A series of soluble trinuclear Ag( I) complexes containing capping acetylide anions have been synthesised and shown +

12: Group I : The Alkali rind C'oincige Meru1.v

429

to be luminescent both in the solid and in solution; the crystal structures of monocapped [Ag3(dppm)3(C= CC6H4N02-p)]2+ and bicapped [Ag3(dppm) (C 3 CC6H4NO2-p)2]+were established. Io4 The mixed-metal acetylides of general formula trcms-[PtAg(C104)(p-C = CR)2(PMe2Ph)2] show interesting structural variations in the solid state: a cyclic dicationic dimer is formed when R = t-Bu and when the C104- ions are non-coordinating, whereas when R = H and when C104- is bonded to Ag' the result is a neutral linear polymer.105

2.4 Gold Compounds. - The gold([) methanide complex [Au(C6F5) (PhZPCH PPh2Me)I reacts nucleophilically with heterocumulenes such as CS2 and with RNCS to afford gold( 111) species { Au[P~~PC(PP~,M~)C(X)S]~}+ [ A u ( C ~ F ~ ) counteranions ~](X = S, NR).Io6The first (hydrosulfid0)- and anionic sulfurdiorgano-gold( I) complexes have been prepared by reacting salts containing the [Au(CGF5)CI]- anion with H2S in the presence of diethylamine; typical products include ( Me4N)2([Au(C6F5)]3(p3-S)} and Et4N[A~(C6F5)SH].'*7 Coordination of the vinylidene disulfide H2C= C(SPPh2)2to an Au(1II) centre activates the C = C double bond so that the complex {Au(C6F5)2 [(SPPh&C = CHZ]}+C104-reacts rapidly with nucleophiles Nu- (e.g., CN -, Cp- , EtO-) to give methanide derivatives A u ( C ~ F ~ ) ~ [ ( S P P ~ ~ ) ~ C Cthe H~NU]; crystal structure of the Cp- derivative displays a square planar metal centre with a cis arrangement of the C6F5groups and the S atoms of the chelating ligand."' The compound [ A u ~ ( C ~ H ~ P P ~ ~ ) ~ ] + * C was F ~ Ssynthesised O~by reacting A U Z ( U - C ~ H ~ Pwith P ~ methyl ~ ) ~ triflate; the most remarkable structural feature of the cation in the solid state is the presence of two Ph2PC6H4ligands which each bridge three Au centres, one centre being coordinated to P and the other two being bridged by the aryl ipso-C atom in a 3c,2e intera~tion.'~'The diphenylmethane and diphenylethane derivatives P~~PAu(~-C~H~)(CH~)~(C AuPPh3, n = 1 or 2 respectively, have been synthesised and reacted further to give species such as Au(o-C6H4)CH2(C6H4-u)Au(dppe) and [ ( C H & ( C ~ H ~ - U ) ~ (AuPPh3)4I2'*(BF4-)2; the complexes have been characterised by spectroscopy (MS, IR, NMR) and by X-ray diffraction studies which have revealed numerous Au. . -H-C agostic interactions involving the CH2 unit(s) of the diphenylmethane and diphenylethane ligands. l o The homoleptic anion Au(C&I&- has been made for the first time and crystallised along with the bis(ethy1enedithio)tetrathiafulvalene radical cation; in the solid the anion has a square planar coordination around the silver with the c6c15 groups arranged propeller-like. I Several important papers have targeted gold acetylides, particularly in respect of their solid-state structures, properties and possible applications. The new reacts with monodentate ligands trinuclear compound [C6H3(C= C A U ) ~1,3,5] (L) and with bidentate ones (L-L) to give (C6H3c-cAu-L)~ and [CbH3(C= C A U ) ~ ] ~ - ( ~ - Lcomplexes, -L)~ respectively ( c g . , L = isocyanide or phosphine, L-L = diisocyanide or diphosphine); in the solid the former are polymers with weak intermolecular Au. . .Au interactions whereas the bidentate hgands of the latter lead to covalently-linked network polymers. I 2 The emission spectra of conjugated polymers of type [-Au-C = C-Ar-C = C-Au-L-L-1, (L-L = diisocyanide or diphosphine) have been compared with those of analogous

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''

430

Organometallic Chemistry

mono- and bi-nuclear alkynylgold complexes, a red shift being apparent on going from mono- to bi- to poly-nuclear systems (in line with the polymers having extended conjugation); the paper reports also the first X-ray structure of a digold diacetylide, Me3p.A~-C= C-C6H2Me2-C= CAwPMe3. I I 3 A series of gold o-arylacetylides have been synthesised and have had their nonlinear optical properties assessed by measurement of bulk second-order susceptibilities using the Kurtz powder technique and by measurement of quadratic optical nonlinearities using hyper-Rayleigh scattering; the solid-state structures of several of the compounds so investigated are reported. l 4 Regarding related isonitrile ligands, the unusual compound MesNCAuGeC13 exists in the solid as linear ]+ and [Au(GeC1,)2]- anions linked strings of alternating [( M ~ s N C ) ~ A Ucations by weak Au. . .Au interactions."5 There have been several interesting reports on gold species having more unusual carbon-based ligands such as carbenes, ylides, and carboranes. Reactions of Au(C@5)(SC&) with diazoalkanes such as Ph2CN2 have been studied by FAB mass spectrometry and carbenes [e.g.,Au( = CPh2)(c&,)] were identified as key intermediates; such species could not be detected during analogous reactions in solution even though the final products are the same.'16 Cationic imidazolinylidene and thiazolinylidene gold( I1 I) complexes were synthesised by oxidative addition of halogens to corresponding bis(carbene)gold( I) compounds; the X-ray structure of one of the cationic species [Au(CNMeCH = CHNMe2)2C12]+revealed trans and planar imidazolinylidene ligands with typical Au-C(sp2) bond lengths, and hybrid density functional theoretical calculations on model Au(1) and Au( 111) complexes of this type have demonstrated good agreement between experimental and geometry optimised structures. I 7 Liquid-crystalline gold dicarbenes {[(R)2-bimyI2Au)'Br-, with (R)2-bimy = 1,3-dialkylbenzimidazoI-2ylidene, have been made under mild phase-transfer catalytic conditions; one of them (with R=C16H33) has been shown to have a lamellar solid-state structure made up of highly ordered stacked bilayers.'" Reaction products of tetrathiometallates (NH&MS4, M = Mo or W, with gold([) ylides depend upon the steric demands of the ylide, MePh2PCH2AuC1giving [MS4(AuCH2PPh2)2]with two three-coordinate Au centres whereas Ph3PCH2AuCI affords [MS4(AuCHzPPh2)2] having one three- and one two-coordinate Au centres.' l9 The bis(ylide) complex Au2[p-(CH2)2PPh2]2 reacts with weak protonic acids such as pyridine-2-thiol(C5H5NS) in the presence of atmospheric oxygen to give ~ H ~ Ncrystal S)~), gold(I1) complexes such as { A u ~ [ ~ - ( C H ~ ) ~ P P ~ ~ ] ~ ( Cwhose structure has been determined; this appears to be the first example of oxidation of Au(1) to Au(I1) being brought about by oxygen.12' The first gold([) derivative of rn-carborane, [Au2(p-1,7-C2BloH10)(PPh3)2], has been synthesised and shown to have a solid-state structure in which the carboranyl ligand bridges to two AuPPh3' fragments. 12' Reaction of the diazomethane Me3SiCHN2 with [(Ph3P)AuI30'BF4has led to the hexaauriomethanium(+2) salt {[(Ph3P)Au]&) 2'-2BF4- ; the solid-state structure of the dication has a CAugP6 core which is significantly distorted from being regular octahedral, seemingly because carbon is far from being a perfect match for the interstice in the Au6 octahedron. '22

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12: Group I : The Alkali und Cuinuge Met&

43 1

References 1. 2. 3. 4.

5. 6. 7. 8. 9. 10. 11.

12. 13. 14. 15. 16.

17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35.

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432 36. 37. 38. 39. 40. 41.

42. 43. 44.

45. 46.

47. 48. 49. 50. 51. 52. 53.

54. 55.

56. 57. 58.

59. 60. 61.

62. 63.

Orgunometullic Chemistry

R.P. Davies. P.R. Raithby, and R. Snaith, Angcw. Cliem. Int. Ed. Engl., 1997, 36, 1215. D.B. Grotjahn, T.C. Pesch, J. Xin, and L.M. Ziurys, J. Am. C17em. Sue., 1997, 119, 12368. H. Ahlbrecht, J. Harbach, H . - 0 . Kalinowski, A. Lang, and G. Maier, C17em. Ber.1 Recueil, 1997, 130,683. M. Oki, H. Ikeda. K . Kodama, and S. Toyota, Bull. Cliem. Suc.. Jpn., 1997,70,2791. D. Waldmuller, B.J. Kotsatos, M.A. Nichols, and P.G. Williard, J. Am. Cliem. Six, 1997, 119,5479. D. Huls, H. Gunther, G. van Koten, P. Wijkens, and J.T.B.H. Jastrzebski, Angew. Cliem. tnt. Ed. Engl., 1997,36, 2629. C. Guadarrama-Perez, G. Cadenas-Pliego, L.M .R. Martinez-Aguilera, and A. Flores-Pam, Cliem. Ber.lRecrieil, 1997, 130, 8 13. G. Cuevas and E. Juaristi, J. Am. Clwrn. Suc.,1997, 119, 7545. C. Fressigne, A. Corruble, J.-Y. Valnot, J. Maddaluna, and C. Giessner-Prettre, J. Urgunomet. Clwm., 1997, 549. 8 1. S. Ito, K. Toyota, and M. Yoshifuji, C'lwn. Cummiin., 1997, 1637. B. Wrdckmeyer, I. Ordung, and B. Schwarze. J Orgunomvt. Cliem., 1997,527, 163. A. Sekiguchi, M. Ichinohe, M. Takahashi. C. Kabuto. and 11. Sakurai. Angrw: Clwm. tnt. Ed Enngl.. I997,36. 1533. R. Knorr. C. Behringer, H. Noth. M. Schmidt, E. Lattke, and E. Rapple, Clicw?. Ber.lRec*ueil.1997, 130, 585. M. Konemann, G. Erker. R. Frohlich, and E.-U. Wiirthwein, J. Am. Chem. Soc... 1997, 119, 1 I 1 5 5 . T. Baumgartner, B. Schinkels, D. Gudat, M. Nieger, and E. Niecke, J. Am. Ciiem. SOL'., 1997, 119, I24 10. B. Goldfuss, P.von R. Schleyer. and F. Hampel, Orgunometullics, 1997, 16, 5032. C. Hilf, F. Bosold, K. Harms, J.C.W. Lohrenz, M. Marsch, M. Schimeczek, and G. Boche, Cliem. Ber.lRecueil, 1997, 130, 1201. S.C. Ball, J. Cobb, R.P. Davies, P.R. Raithby, G.P. Shields, and R. Snaith, J. Urgunomet. Chem.. 1997, 534,24 I , P.C. Andrews, D.R. Armstrong, W. Clegg. F.J. Craig, L. Dunbar, and R.E. Mulvey, Chem. Commun., 1997, 3 19. P.B. Hitchcock. M.F. Lappert, and 2.-X. Wang, J. Chom. Soc:, Dulron Truns., 1997, 1953. B. Goldfuss, P.von R. Schleyer, and F. Hampel, J. Am. Chem. Suc., 1997, 119, 1072. E.D. Jemmis, G. Subramanian, A.J. Kos, and P.von R. Schleyer, J , Am. Cliem. Suc., 1997, I 19,9504. J. Barluenga. J.M. Gonzalez, I Llorente, P.J. Campos, M.A. Rodriguez, and W. Thiel, J. Orgunumet. Chem.. 1997, 548, 185. A. Abbotto, A. Streitwieser. and P.von R. Schleyer, J. Am. Chem. Sue., 1997, 119, 1 1255. T.R. van den Ancker, G.R. Hanson, F.-C. Lee, and C.L. Raston, Chem. Cummim., 1997, 125. P. Steenwinkel, J.T.B.H. Jastrzebski, B.-J. Deelman. D.M. Grove, H. Kooijman, N. Veldman. W.J.J. Smeets, A.L. Spek, and G. van Koten, Orgunumetullics, 1997, 16, 5486. N. Rot and F. Bickelhaupt, Orgunomrtullic~s,1997, 15, 5027. P. Bowles, J. Clayden, M. Helliwell, C. McCarthy, M. Tomkinson. and N. Westlund, J. C'hem Soc., Perkin Truns. 1. 1997,2607.

12: Group I : The Alkali and Cuinage Metals

64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85.

86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96.

433

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Orgunometullic Chemistry

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P. Schulte, G. Schmidt, C.-P. Kramer, A. Krebs, and U. Behrens, J. Orgunomet. Chem., I997,530,95. L.N. Bochkarev, O.N. Druzhkova, S.F. Zhiltsov, L.N. Zakharov, G.K. Fukin, S.Y. Khorshev, A.1. Yanovsky, and Y.T. Struchkov, Orgunometullics, 1997,16, 500. R. Eujen, B. Hoge, and D.J. Brauer, Inorg. Chem. 1997,36,3160. T. Futterer, A. Merz, and J. Lex, Angew. Chem. Int. Ed Engl., 1997,36,611. M. Munakata, L.P. Wu, T. Kuroda-Sowa, M. Maekawa, Y. Suenaga, and K. Sugimoto, Inorg. Chem., 1997,36,4903. J. Powell, A. Lough, and T. Saeed, J. Chem. Soc., Dulton Truns., 1997,4137. B. Findeis, L.H. Gade, I.J. Scowen, and M. McPartlin, Inorg. Chem., 1997,36,960. V.W.-W. Yam, W. K.-M. Fung, and K.-K. Cheung, Orgunometullics, 1997, 16,2032. S. Yamazaki, A.J. Deeming, D.M. Speel, D.E. Hibbs, M.B. Hursthouse, and K.M.A. Malik, Chem. Cummun., 1997, 177. M. Bardaji M.C. Gimeno, P.G. Jones, A. Laguna, M. Laguna, F. Merchan, and 1. Romeo, Orgunomelullics, 1997, 16, 1083. J. Vincente, M.-T. Chicote, P. Gonzalez-Herrero, C. Griinwald, and P.G. Jones, Orgunometullics. 1997, 16, 338 I . E.J. Fernandez, M.C. Gimeno, P.G. Jones, A. Laguna, J.M. Lopez-de-Luzuriaga, and E. Olmos, J. Chem. Sue., Dalton Truns., 1997,3515. M.A. Bennett, L.L. Welling, and A.C. Willis, Inorg. Chem., 1997,36, 5670. T.V.Baukova, L.G.Kuz’mina, N.A.Oleinikova, D.A. Lemenovskii, and A.L. Blumenfel’d, J. Orgunomet. Chern., I997,530,27. J.A. Schlueter, U. Geiser, H.H. Wang, M.L. VanZile, S.B. Foz, J.M. Williams, A. Laguna, M. Laguna, D. Naumann, and T. Roy, Inorg. Chem., 1997,36,4265. M.J.Irwin, L. ManojloviC-Muir, K.W. Muir, R.J. Puddephatt, and D.S. Yufit, Chem. Commun., 1997,2 19. M.J. Irwin, J.J. Vittal, and R.J. Puddephatt, Orgunometullics, 1997, 16, 3541. I.R. Whittall, M.G. Humphrey, M. Samoc, B. Luther-Davies, and D.C.R. Hockless, J. Orgunomet. Chem., 1997, 544, 189; R.H. Naulty, M.P. Cifuentes, M.G. Humphrey, S. Houbrechts, C. Boutton, A. Persoons, G.A. Heath, D.C.R. Hockless, B. Luther-Davies, and M. Samoc, J. Chem. Soc., Dultun Truns., 1997, 4167; I.R. Whittall, M.G. Humphrey, S. Houbrechts. J. Maes, A. Persoons, S. Schmid, and D.C.R. Hockless, J. Orgunomet. Chem., 1997,544,277. A. Bauer, W. Schneider, and H. Schmidbaur, Inorg. Chem. , 1997,36,2225. R. Bertani, R.A. Michelin, M. Mozzon, P. Traldi, R. Seraglia, L. Busetto, M.C. Cassani, P. Tagliatesta, and G. D’Arcangelo, Orgunometullics, 1997, 16,3229. H.G. Raubenheimer, P.J. Olivier, L. Lindeque, M. Desmet, J. Hrusak, and G.J. Kruger, J. Orgunomet. Chem., 1997,544, 91. K.M. Lee, C.K. Lee, and I.J.B. Lin, Angew. Chem. In[. E d Engl., 1997,36, 1850. F. Canales, M.C. Gimeno, P.G. Jones, and A. Laguna, J. Chem. Soc., Dulton Truns., 1997,439. M. Bardaj, E. Cerrada, P.G Jones, A. Laguna, and M. Laguna, J. Chem. Sue., Dalton Truns., 1997, 2263. 0. Crespo, M.C.Gimeno, P.G. Jones, and A. Laguna, J. Orgunomel. Chem., 1997, 531, 87. F.P. Gabba, A . Schier. J. Riede, and H. Schmidbaur, Chem.Ber./Recueil, 1997, 130, 111.

98. 99. 100. 101.

102. 103. 104. 105.

106. 107. 108.

109. 110. 111.

112. 113. 114.

115.

116. 117. 118.

119. 120. 121. 122.

13 Group 2 (Be-Ba) and Group 12 (Zn-Hg) BY DOMINIC S. WRIGHT

1

Scope of the Review

This review almost exclusively concerns organometallic complexes defined in terms of the strictest definition of compounds containing Group 2 or 12 meta1-C bonds. Although the organisation of the review involves an essentially structural (‘Inorganic’) focus, other aspects such as the applications of organometallics in organic synthesis and theoretical investigations are also considered. However, particularly bearing in mind the extensive, standard use of magnesium and zinc reagents as synthons for carbanions in the spheres of organic and inorganic chemistry, only novel reagent applications or new synthetic methods to existing reagents have been included.

2

Group2

Continuing from the perspective of the organometallic complexes of Group 2 and 12 for 1996,’ the structural characterisation of simple Grignard reagents (RMgX; X=halogen) has declined further and there appear to have been few new complexes of this type reported in 1997.2 However, despite the fall off in interest in structural aspects in this field, mechanistic studies involving these reagents continue to be a focus of research. Fundamental insights into the formation of RMgX have recently been obtained. The two most important possible pathways in the reactions of RX with Mg metal, both of which involve the formation of radicals at the metal surface, are outlined in Figure 1. Significantly, the so-called Kharasch-Reinmuth-Walborsky mechanism (KRW) suggests that reduction of the rate constant (K,) for the reaction between solvent defused radicals (Re) and the solvent (SH) will not affect the observed product distribution of RR and RMgX. In contrast, the so-called D Model suggests that reduction in K, will increase the yield of the latter. The increase in the yields of RR and RMgX observed in the reactions of cyclopropyl bromide under various conditions in deuterated Et2O and thf solvents favours the D ModeL3 The increase in the yields of RMgX under most of the conditions examined of ca. 12-14%0 also illustrates that this proportion of solvent diffused radicals can be available for reduction to RMgX. It is also worth mentioning the recent detection of radicals in the

Organometallic Chemistry, Volume 27 0The Royal Society of Chemistry, 1999

435

Orgunometullic Chemistry

436 KRW Mechanism

D Model

Figure 1

reactions of thiocarbonyls [R'C( = S)R2] with RMgX, resulting from addition of R. to the organic substrate or from single electron t r a n ~ f e r . ~ The application of Grignard reagents in organic synthesis continues to be an extremely active area of research. Most notable are new applications which offer enantioselectivitys or regioselectivity.' A variety of novel coupling and crosscoupling systems involving Grignard and diorganomagnesium intermediates have also been recently d e ~ e l o p e d .Among ~ the latter has been a study of the asymmetric Grignard cross-coupling reaction of vinyl halides (CH2 = CHX; X = CI, Br) with I-chloro-I-phenylethane [PhCH(X)CH3] in the presence of NiC12 and chiral P,N ligand~.~' Although a similar reaction system has been previously investigated with chiral diphosphanes, in this new study (working at -10 to 0°C) the precipitation of MgC12 and the isolation and subsequent structural characterisation of the diorgano-magnesium complex [(PhC*H(Me)]zMg.2Et20] (1) (consisting of a racemic mixture of R,R and S,S isomers in the solid state) suggests for the first time that this species is involved in transmetallation to the Ni centre. The use of vinyl chloride and I with chiral P,N ligands gives the highest enantioselectivity yet reported in this system. Also noteworthy in this area, is the development of a new soluble copper catalyst [CuBr/LiSPh/LiBr/thf] which is highly efficient in the C-C coupling of a wide range of Grignard reagents with primary and secondary t~sylates.~' This new system (for which only one equivalent of RMgX need be used in the reaction) is more efficient and reactive than methods involving CuBr, Li2CuC14and Gilman reagents. An ongoing development in the elucidation of inorganic and organic reaction mechanisms is the isolation of crystalline intermediates and their separate characterisation. This approach is generally more well established as a tool in the

13: Group 2 (Be-Ba) and Group I2 ( Z n -H g )

437

elucidation of reaction mechanisms involving lithium reagents. An important new study shows the inherent value of this strategy not only in providing unequivocal evidence of the nature of intermediates but also in uncovering new reactions. The reaction of commercially available Bu2Mg (containing essentially a 50:50 mixture of "Bu and "Bu groups) with two molar equivalents of (Me3Si)2NH followed by addition of Ph2C = 0 gives [{(Me3Si),NMg(p-0C(H) Ph2)-(0 = CPh2)) 21 (2).8This product presumably results from partial amination of the diorgano-magnesium reagent followed by P-hydride transfer to a metalbonded ketone (Figure 2) and is the first example of this type of reaction to be observed for Mg. This conclusion is supported by the isolation of the ketone complex [{(Me$3)2N}2Mg.(0 = CPh2)2] (3) only from the reaction of pure [ {(Me3Si)2N}2Mg] with Ph2C= 0. Quenching studies of the product(s) of the reveal reaction of [MeMgBr] with 1,4-bis(chloromercurio)-2,5-tert-butylbenzene that clean (at least 71%) conversion to the 1'4-dimagnesiated species O C C U ~ S . ~ Spectroscopic investigations of the isolated intermediates have again proved invaluable in probing the mechanism involved. The intermediate is thought to consist of a complex mixture of 1,4-dimagnesiated oligomers formed by shifting of the Schlenk equilibrium and the irreversible elimination of MgC12. This conclusion is also supported by the observation of the lower selectivity of the magnesiation reaction in solvents (such as Et20 and NEt3) in which MgC12 is more soluble.

-

[(Me3Si)2NMg"Bu]

t

Ph

Ph

.

Cl$ I

(Me3Si)pNMg'

-

- CHpCHCHgH3

f 2

H

J

&transfer is shown for "Bu,but a similar mechanism would apply for SBu.

Figure 2 Recent studies of the reactions of low oxidation state transition metal dihalides with Grignard reagents and with Mg metal, motivated primarily by the relevance of the resulting species t o catalysis, reveal some interesting mechanistic contrasts. l o I 3 Unlike (C5H5,,Me,)TiCl2/Mg/thf/Me3SiC= CSiMe3 reaction systems which result in [(C5HSnMen)2Ti{q2-C2(SiMe3)2}2],'Oa the reduction of [ { CsMe4SiMe3) 2TiIVC12] with Mg metal gives the heterobimetallic complex [{ q5-C5Me4SiMe3J{ rl5-C5Me4SiMe2CH2)Ti'"( p-H2Mg.thf}]2 (4) in which activation of a SiMe group has occurred (Figure 3).'Ob A similar intermediate appears t o be present in the (C5Me5)TiC121iPrMgCl/Et20system which catalyses head-to-tail dimerisation of terminal actetylenes (RC- CH; R = Me, Et, nPr, "Bu, cyclohexyl, Ph, SiMe3) to 2,4-substituted 1-buten-3-ynes. Recent ESR studies have shown that 'tweezer' complexes of the type [(C5Me&Ti(C z CR)2

438

Orgunometullic Chemistry

MgCLEtzO] (in which the Mg is x-bonded to the alkyne groups) are involved in this process. I The complex [(C5Me5)2Ti(C= CSiMe&MgCl.thf] (5) (synthesised separately) catalyses head-to-tail dimerisation with the same selectivity and with similar turnover numbers to the (CSMeS)TiC12/'PrMgCl/Et20 system. Insights into the bimolecular deactivation process occurring in [(q5-C5HS)VNRCl2],a pro-catalyst in Ziegler-type polymerisation systems, have been obtained from a study of the reactions of [(qs-CSH5)V= N(2,6-'PrC6H3)C12] (6) with MeMgX in various solvents. l 2 The paramagnetic complex [ ((q5-C5HS)V= N(2,6-'PrC6H3) Me2)2Mg] (7)(Figure 4) obtained from 6 and MeMgBr (2.5 equivalents)/Et20 and structurally characterised is a model catalyst in this system. The rapid deactivation of this species as a catalyst after a few minutes is presumably accounted for by further methylation, as is illustrated by the reaction of 6 with excess MeMgC1/Et20/thf which generates the Me-bridged paramagnetic complex [(q5-CSH5)V{CI-N(2,6-'PrC6H3)}2]2(CI-Me) (8).

'

4

Figure 3

7

Figure 4

Fundamental structural investigations of the organometallics of the heavier Group 2 metals have continued to be an active area of study. However, reflecting the technical difficulties of crystallisation and the greater air-sensitivity of such

13: Group 2 (Be-Bo) and Group 12 ( Z n - H g )

439

complexes only a handful of structurally characterised species have been reported recently. The complex [ {(Me3Si)*C}2Ca](9), which is prepared by the reaction of Ca12 with [{(Me3Si)2C}K] in benzene, is the first example of a solvent-free 0-bonded organocalcium complex to be structurally characterised. l 4 The complex has a monomeric, bent structure in the solid state in which further intramonomer agostic contacts are made between the Ca centre and the ligand Me groups. The angle at the Ca atom (C-Ca-C 149.7") is similar to that in Cal2 (gas phase) and [(C5Me5)2Ca](solid state) and may be a result of crystal packing rather than arising from electronic factors. The reactions of 9 with various ethyl ethers (ROEt) give quantitatively RH, ethene and [Ca(OEt)2]. Since the key (most readily accessible) pentamethylcyclopentadienide sandwich complexes have now been characterised, recent attention has switched to more elaborate ligand systems containing aromatic groups linked by heteroatom or organic bridges. Examples of this type are [Ph2P{CH2(4-MeC6H4)}2]& [ { Me@(C&)}Ba.4thfI (ll),I6[(Me*Si(C,lHs)}Ca.3thf] (12),16 and [{ PhCH(CSH5)}2Ca.2thf] (13)," all of which have similar monomeric stuctures in which the metal centres are n-bonded to the two aromatic rings of the ligand. Contrary to the report of 10, this is actually the second example of an organobarium complex not to belong to the cyclopentadienide series (the first being [Ba{q5-PhCH(C5H4N-2)}2{MeO(CH2)20(CH2)20Me} .thf] (14)j8). Ab initiu MO calculations reveal that despite the complexation of the Ba2+ cation by the two benzene rings in 10 the majority of the negative charge of the ligands resides on the ylidic C atoms. The synthesis of the ansa-calcocene 13 is of some interest. In contrast to the reductive coupling of dimethylfulvene (CsH4CHMe2) with Group 2 metals (M = Mg-Ba) which gives inseparable mixtures of [ { Me2C(C5H4)}2M]and [('PrC5H&M], the reaction of phenylfulvene (C5H4CH2Ph)with Ca metal in thf yields 13 as a mixture of the cis and trans CPh(H)-C(Ph)H bridged isomers. The trans isomer (Figure 5 ) crystallises selectively and provides a versatile reagent for transition metal derivatives containing C2-symmetric (trans) ansu-metallocene ligand arrangements.

13

Figure 5

3

Group 12

Structural investigations of Zn'9-26 and Hg27-38compounds have dominated research into Group 12 organometallics. A variety of zincate complexes containing [ZnR3]- 19-21 and [ZnR4J2- 2o units have been characterised in the

440

Orgunometullic Chemistry

solid state. In the ion-separated structure of [Zn(C =CPh)3]-[thf.Zn (C=CPh)3]-2[{Na( 12-cr0wn-4)~}+](15),19 the presence of two differently solvated triorgano zincate anions may be attributed to the reduction in Lewis acidity of the Zn centres in these anionic units. This view is borne out also in the ion-separated structure of [Mg(thf)6]2f2[Zn(CH2Ph)3]- (16) in which no solvation of the Zn atoms occurs despite the potential for thf coordination.2' This study also reveals that the formation and stability of zincates of this type is highly dependent on the nature of the Lewis base present; addition of TMEDA ({Me2NCH2},) to 16 resulting in the formation of a 1:2 mixture of [Zn(CH2Ph)2-TMEDA](17) and [Mg(CH2Ph)yTMEDA] (18). In this context it is interesting that reactions of [ {(2-Me2N)C6H4}Li] (19) with [ {(2-Me2N)C6H4}2Zn] (20) result in either [{(2-Me2N)C6H4}Zn((2-Me2N) C6H4}2Li.thf] (21) or [Li{(2-Me2N)C,jH4}2Zn{(2-Me2N)C6H4}2Li] (22) (containing [ZnR3]- and [ZnR4I2- anions) depending on the stoichiometry.20 The latter have ion-paired structures in the solid state in which the Zn and Li centres are linked by Zn(p-aryl-C)Li and Me2NLi bridges. The structures and react ivities of various neutral o-alkyls and aryls containing R2Zn or RZnX units have also been investigated.22-26The spectacular metallacyclic structure of [[C1ZnMe]{CH(Me)PEt2NSiMe3>112(23), composed of eightring units linked membered heterocyclic [Zn(p-CI)(CH(Me)PEt2NSiMe3)]2 together by Zn(pC1)Zn bridges, is particularly worthy of note.22Other structural investigations of diorgano Zn complexes have been of value in augmenting mechanistic and synthetic studies of these species as reagents. An example is the synthesis and characterisation of the enantiomerically pure S,N-chelated Zn bis(aminoarenethio1ate) complex [(R,R)-ZnMe((2-Me2NC*(Me)H)sC&}]2 (24).24aAlthough the dimeric sulfur-bridged structure of this complex is not remarkable in itself, in the presence of R2Zn reagents this complex catalyses 1,2-addition of R - to aliphatic and aromatic aldehydes, the secondary alcohols being produced almost quantitatively with optical yields of 69-99'% ee under mild conditions, The mechanism of this reaction has the same general characteristics as reported earlier by N ~ y o r i with , ~ ~coordination ~ of R2Zn to the sulfur centre of 24 giving the active monomeric species in this reaction followed by coordination of the aldehyde to Zn and subsequent addition R- to the carbonyl group. In another study of the mechanism of' regioselective alkylation of 1,4-ditert-butyl-l,4-diaza-l,3-butadiene('BUN = CH-CH = N'Bu) with RzZn, the intermediacy of organozinc radical species has been confirmed by spectroscopic and structural investigations. Reduction of the coordination complex [R2Zn('BuN = CHCH = N'Bu)] (25) with K metal gives radical anion species K+[R2Zn('BuN-CH-CHN'Bu)]'- (26) which rapidly decompose by singleelectron transfer to a mixture of the metallocyclic zincate complexes K+[RZn('BuN CH = C H N'Bu)]- (27) and K'[RZn('BuN-C(R) = CH-N'Bu)](28). As one would expect, the application of a variety of organo zinc reagents (including R2Zn and CH2(ZnI)2) in organic synthesis has featured strongly in the literature in the past year, particularly in regard to stereoselective synthesis, cyclopropanation and new methods of C-C bond f ~ r r n a t i o n Owing . ~ ~ to the

13: Group 2 ( Be- Bu) und Group I2 (Zn-H g )

441

tremendous and growing use of organo zinc reagents, the development of new synthetic methods for their preparation and to new reagent species is an important area of re~earch.~' A particular advantage of Zn reagents is that, as a result of the greater covalency of C-Zn bonds compared to C--Mg or C-Li bonds, organozinc compounds are more configurationally stable. It was shown earlier that organoboranes (obtained by hydroboration of alkenes) can be converted to diorganozinc compounds with Et2Zn.4' However, the exchange reaction is slow with secondary organoboranes and not stereoselective. Using 'Pr2Zn in place of Et2Zn the exchange reaction occurs rapidly with cycloorganoboranes (generated by hydroboration of cyclic alkenes), giving the first examples of stereochemically pure cyclo-organozinc The latter react with a range of electrophiles with retention of configuration at the carbanionic C centre. Despite the greater reactivity of R2Zn over RZnX (Xxhalogen), a particular problem with the diorgano reagents is that frequently only one R group is used in reactions with organic substrates. A new development has been the preparation of fJ-silyl diorganozinc compounds ([RZn(CH2SiMe3)]) which have similar reactivity to R2Zn but give cost-effective transfer of only one R group!0r A novel method of preparing benylzinc reagents has also been reported, utilising homologation of triorgano~incates.~'~ Treatment of p-iodobenzyl mesylate (Ms) with [Bu3ZnLi] (Bu= 'Bu, "Bu, "Bu) results in substitution of Ifollowed by 1 ,Zmigration of an R group and rearrangement into p-substituted benzylzinc reagents (Scheme 1 ).

p I

-

Q ZnBu

OMS Scheme 1

Two fundamental mechanistic studies involving organo zinc reactions are particularly worthy of note. The first is a report that the Reformatsky reaction (Scheme 2) can be carried out efficiently (8-82% yields) in concentrated aqueous salt solutions [preferably NH&I/Mg(CIO& or CaCI2/NH&I)] without c o - s ~ l v e n t sThis . ~ ~ is all the more remarkable bearing in mind that the mechanism is normally assumed to involve intermediate fl-organozinc complexes [BrZn(CR'R2C(=O)OR3)]. The enhancement of this reaction by the addition of catalytic amounts of organic peroxides or peracids suggests that a radical chain reaction involving *CR3R4C(= O)OR5 radicals is occurring under these conditions. The second study is a model Density Function Theoretical calculational study of the Simmons-Smith reaction between CIZnCHZCI and CH2 = The study illustrates that out of the two possible reaction routes, addition

Orgunomet u l k Chemistry

442

(producing cyclopropane) and insertion (producing propene), the addition route is preferred by ca. 11.3 kcal mol-'. This is the first theoretical study of this reaction and there is clearly a great deal of scope for further calculational work in explaining aspects of regio- and stereo-selectivity in reactions involving organo zinc reagents.

R5 Scheme 2 The distinctive character of Hg in terms of its coordination requirements, the low polarity of C-Hg bonds and the greater ability to form metal-metal bonds is again underlined by the very diverse natures of the organometallic species structurally characterised in 1997. These studies, unlike many on Mg and Zn, have been of largely fundamental value rather than relating to the applications of the species as reagents. A continuing active area of research concerns mercurated aromatic and related system^.^^**^ The permercurated complex [(q4-PhC)4Co { q5-C5(Hg02CCF&f] (29), a potential precursor for the formation of squaregrid polymers containing Ph groups capable of linear coupling through the p-positions and a pedestal {q5-C5(Hg02CCF3)5) group with a high affinity for a liquid mercury surface, has been prepared and structurally ~ h a r a c t e r i s e d The .~~ reaction of permercurated cyclopentadienide rings with Me2Zn provides an excellent method of performing further functional group modifications. For example, the reaction with [(C5Me5)Ru{C5(HgC12)5)] (30) gives the perzincated complex [(C5Me,)Ru(C5(ZnMe2)s)](31).44The advantage of the zincated intermediates over Li or Mg analogues is their lower reactivity and lower tendency to abstract hydrogen from solvents. A range of organometallic Hg(1I) complexes containing biologically important hgands have been investigated. The hydrolysis of [Hg(NO3)(1,3-dimethyluracil-5yl)] [ = Hg(N03)( 1,3-DiMeU-C5)] (32) in H 2 0 gives rise to the tris( 1,3-dimethyluracil-5-yl)mercurioxonium salt (33).38 The remarkable structure of 33 contains two independent [Hg3(1 ,3-DiMeU-C5)30]' cations (one with a planar Hg30 and one with a pyramidal H g 3 0 unit) which are associated by H g . . .Hg interactions to symmetry related (structurally equivalent) cations - giving two different loosely associated [Hg3( 1 ,3-DiMeU-C5)30]22t units. The Hg. - .Hg separations within and between these pairs are shorter than those in dimeric Hg(1) complexes or in Hg(0) clusters.45This association is similar to that occurring in phosphinegold(1) oxonium compounds (containing [ { (Ph3P)Au) 301' cations).46 The reaction of [Hg(OAc)( 1,3-DiMeU-C5)] (34) with the model nucleobase 9-methyladenine (9-MeA) gives the complex [Hg(9-MeA-N6)( 1,3-DiMeU-C5)] NO+H20 (35).37The binding of N(6) of the 9-MeA ligand to Hg(1I) [with N(1) being protonated] means that this ligand is in an unusual imino tautomer form

13: Group 2 ( Be-Bu) and Group 12 ( Z n - H g )

443

(Figure 6). The structure of 35 is relevant to cross-linking in D N A and potential mispairing of bases.

\ Me

Figure 6 The association of Hg organometallics with other metals and with anions has been examined in a number of recent s t r u c t ~ r a l and ~ ~ -~~a l~c u, ~l a~t i o n astudies. l~~ Heterometallic complexes containing Hg(I1) can be constructed by the formation of metal-metal bonds or by the use of bridging or functionised ligands. Two interesting examples illustrating these approaches are shown in Figure 7. The n-complex 36 is prepared by the reaction of the dianionic Pt framework with HgC12, giving symmetrical bonding of the Hg(I1) centres to the planar tetraethynylplatinum complex (a so-called double-twee~er).~~ A series of complexes similar to 37 (with different substituents on Hg) can be prepared by the complexation of Hg(I1) salts with the neutral complexes [trans-Fe(C0)3(PPh2 (2-p~rimidine))~I (38).36Here association of the Hg and Fe centres is achieved by a combination of metal-metal, N-Hg and (to a minor extent) Hg..-CO interactions. A related approach has also been employed in the preparation a trimetallic Fe/Cu/Hg complex containing the first example of a Cu-Hg bond.35

1*-

37

36

Figure 7

Organometallic Chemistry

444

Finally, two further studies concerning Hg(I1) reagent systems stand out as of particular importance. These are the synthesis and characterisation of the first anionic fluoromercury complex [(CF&Hg( p-F)]22-2[(Me2N)2SNMe2]+ (39)29 and the formation and in-depth study of stable Hg(I1) h y d r i d e ~ Unlike . ~ ~ the in which the very strong Hg-C previously reported complex [(CF3)2Hg] (a), bonds render it unreactive as a source of CF3- anions,49 the weakening of the Hg-C bonds in 39 as a result of the presence of fluoride substituents means that it is a useful CF3- transfer reagent (e.g., reacting with NSF3 to give NSF2CF3). The reactions of the cyclopropenone acetal framework 41 (Scheme 3) with Hg(AcO)2 give exclusively the (2)-olefinic mercury chlorides Z-42.4gConversion to the E-isomers (E-42) can be achieved by photolysis. The corresponding hydrides [Z-(43),E-(43)] are easily generated separately by reduction of E- and 2-42 with NaBH4. The stabilities of these species vary from t f of 34h to 201 h (at 75 "C in benzene), with the most stable complex ( R ' = H, -R2 = p-N02C6H4) surviving for several weeks as a solid or in benzene solution at 25 "C (cf MeHgH with t f = 100min/25"C/benzene). MO calculations show that the stabilities of these species rely on the electron-acceptor ability of the organic groups. These calculations also reveal that whereas the [MeHg]. radical resembles a complex between Hg(0) and Me., the relatively stable radicals generated by thermolysis of 43 (which can be trapped intermolecularly) are of the form [RHg].. This study provides the first experimental proof of the mechanism of formation of radicals (R.) from [RHgH], a commonly employed method of generating organic radicals.

'f NaBH4

0

Scheme 3

References I.

2.

D. S. Wright, in Organometallic Chemistry, ed. M. Green, Vol. 26, The Royal Society of Chemistry, Cambridge, 1998, p. 15. The only structurally characterised complex containing an RMgX fragment has a

13: Group 2 ( Be-Bu) and Group I2 (Zn-Hg)

3. 4. 5.

6.

7.

8. 9. 10.

11.

12. 13.

14. 15.

16. 17. 18. 19. 20. 21.

22, 23.

445

complicated bicyclic arrangement, A. Muller, M. Krieger, B. Meumuller, K. Denicke and J. Magull, Z. Anorg. Allg. Chem., 1997,623, 1081. J. F. Garst, F. Ungvaryand J. T. Baxter, J. Amer. Chem. Sue., 1997, 119,253. A. Alberti, M. Benaglia, D. Macciantelli, M. Marcaccio, A. Olmeda, G. F. Pedulli and S. Roffia, J. Org. Chem., 1997,62, 6309. (a) T. Ichiyanagi, M. Shimizu and T. Fujisawa, J. Org. Chem., 1997, 62, 7937; (b) N. M. Heron, J. A. Adams and A. H. Hoveyda, J. Am. Chem. Suc., 1997,119,6205; (c) D. M. Spero and S. R. Kapadia, J. Org. Chem., 1997, 62, 5537; (d) J. Mulzer, C. Pietschmann, J. Buschmann and P. Luger, J. Org. Chem., 1997,62,3938. (a) F. F. Fleming and T. Tao, J. Org. Chem., 1997,62,7890; (b) A. M. Klos, G. R. Heintzelman and S. M. Weinreb, J. Org. Chem., 1997, 62, 3758; (c) R. H. L. Kiebooms, P. J. A. Adriaensens, D. J. M. Vanderzande and J. M. J. V. Gelan, J. Org. Chem., 1997,62, 1473; (d) J. Srogl, G. D. Allred and L. S. Liebeskind, J. Am. Chem. Soc., 1997,119,12376. (a) N. A. Bumagin and E. V. Luzikova, J. Orgunomel. Chem., 1997, 532, 271; (b) M. van der Sluis, A. Klootwijk, J. B. M. Wit, F. Bickelhaupt, N. Veldman, A. L. Spek and P. W. Jolly, J. Orgunomet. Chem., 1997, 529, 107; (c) N.-S. Li, S. Yu and G. W. Kabalka, J. Orgunomet. Chem., 1997, 531, 101; (d) R. A. Aitken, P. K. G. Hodgson, A. 0. Oyewale and J. F. Morrison, J. Chem. Soc., Chem. Cummun., 1997, 1163; (e) U. Nagel and G. Nedden, Chem. Ber., 1997,130,535; (f) D. H. Bums, J. D. Miller, H.-K. Chan and M. 0.Delaney, J. Am. Chem. Soc., 1997,119,2125. K. W. Henderson, J. F. Allan and A. R. Kennedy, J. Chem. Soc., Chem. Commun., 1997, 1149. C. E. Reck and C. H. Winter, Orgunometullics, 1997,16,4493. (a) V. Varga, K. Mach, M. Polaiek, P. Sedmera, J. Hiller, U. Thewalt and S. I. Troyanov, J. Orgunomet. Chem., 1996, 506, 241; (b) M. Horackk, J. Hiller, U. Thewalt, M. Polasek and K. Mach, Organometullics, 1997, 16,4185. V. Varga, L. Petrusova, J. Cejka and M. Mach, J. Organomet. Chem., 1997, 532, 251. M. C. W. Chan, J. M. Cole, V. C. Gibson and J. A. K. Howard, J. Chem. Soc., Chem. Commun., 1997,243, K. McNeill, R. A. Andersen and R. G. Bergman, J. Am. Chem. Soc., 1997, 119, 11244; ibid., 1995, 117, 3625. C. Eaborn, S. A. Hawkes, P. B. Hitchcock and J. D. Smith, J. Chem. Soc., Chem. Commun., 1997, 1961. S . Harder and M. Lutz, Orgunometallics, 1997, 16,225. S . Harder, M. Lutz and A. W. G. Straub, Orgunometullics, 1997, 16, 107. K. M. Kane, P. J. Shapiro, A. Vij, R. Cubbon and A. L. Rheingold, Orgunometullics, 1997,16,4567. M. G. Gardiner, C. L. Raston and H. Viebrock, J. Chem. Soc., Chem. Commun., 1996, 1795. M. A. Putzer, B. Neumiiller and K, Dehnicke, Z. Anorg. Allg. Chem., 1997,623,539. E. Rijnberg, J. T. B. H. Jastrzebski, J. Boersma, H. Kooijman, N. Veldman, A. L. Spek and G. van Koten, Orgunumetallics, 1997,16,2239. E. Rijnberg, J. T. B. H. Jastrzebski, J. Boersma, H. Kooijman, A. L. Spek and G. van Koten, J. Orgunornet. Chem., 1997,541, 181. A. Miiller, B. Neumiiller and K. Dehnicke, Angew. Chem., 1997, 109, 2447; Angerv. Chem. Int. Ed. Engl., 1997,36,2350. M. Westerhausen, M . Wieneke, B. B. T. Rademacher and W. Schwarz, Chem. Ber., 1997,130, 1499.

446

Orgunometullic Chemistry

24.

(a) E. Rijnberg, N. J. Hovestad, A. W. Kleij, J. T. B. H. Jastrzebski, J. Beorsma, M. D. Janssen, A. L. Spek and G. van Koten, Orgunometallics, 1997, 16, 2847; see also (b) M. Kitamura, S. Okada, R. M. Noyori, J. Am. Chem., Soc., 1989, I l l , 4028. E. Rijnberg, J. Boersma, J. T. B. H. Jastrzebski, M. T. Lakin, A. L. Spek and G. van Koten, Organometallics, 1997, 16, 31 58. M. H. P. Rietveld, P. Lohner, M. G. Nijkamp, D. M. Grove, N. Veldman, A. L. Spek M. Pfeffer and G . van. Koten, Chem. Eur. J . , 1997,3,817. R. M. Harrison, T. Brotin, B. C. No11 and J. Michl, Organometullics, 1997, 16, 3401; see also T. F. Magnera, L. M. Pesherbe, E. Korblova and J. Michl, J. Orgunornet. Chem., 1997,548, 83. Y. J. Wu, X. L. Cui, Y. H. Liu, H. Z. Yuan and X. A. Mao, J. Orgunornet. Chem., 1997, 543, 63. D. Viets, E. Lork, P. G. Watson and R. Mews, Angew. Chem., 1997, 109, 655; Angew. Chem. Inl. Ed. Engl., 1997,36,623. J. S. Casas, A. Catiiieiras, I. Haiduc, A. Sanchez, J. Sordo and E. M. VazquezLopez, Polyhedron, 1997, 16,781. T. Schaper and M. Preetz, 2. Nuturforsch., B., 1997,52,57. D. Zhang, D. B. McConville, C. A. Tessier and W. J. Young, Organometullics, 1997, 16, 824. G. G. Lobbia, P. Cecchi, G. Gobetto, G. Digilio, R. Spagna and M. Camalli, J. Orgunornet. Chem., 1997,539,9. H. Migasaka and N. Matsumoto, Chem. Let., 1997,427. M. Bknard, U. Bodensiek, P. Braunstein, M. Knorr, M. Stampfer and C. Strohmann, Angew. Chem., 1997, 109,2890; Angew. Chem., Int. E d Engl., 1997,36,2758. S.-L. Li, Z.-Z. Zhang and T. C. W. Mak, J. Organomet. Chem., 1997,536,73. F. Zamora, M. Kunsman, M. Sabat and B. Lippert, Inorg. Chern., 1997,36, 1583. F. Zamora, M. Sabat, M. Janik, C. Siethoff and B. Lippert, J. Chem. Soc., Chem. Commun., 1997,485. For examples, see (a) B. V. Nguyen and D. J. Burton, J. Org. Chem., 1997,62, 7758; (b) C. Lutz and P. Knochel, J. Org. Chem., 1997,62,7895; (c) S . D. Rychnovsky and N. A. Powell, J. Org. Chem., 1997,62,6460; (d) S. E. Denmark and S. P. O’Conner, J. Org. Chem., 1997,62, 584; (e) S. E. Denmark and S. P. O’Conner, J. Org. Chem., 1997,62, 3390; (0 K. R. K. Prasad and N. N. Joshi, J. Org. Chem., 1997,62, 3770; (g) M . G. Organ and A. P. Murray, J. Org. Chem., 1997,62, 1523; (h) K. Utimoto, N. Toda, T. Mizuno, M. Kobata and S. Matsubara, Angew. Chem., 1997,109,2886; Angew. Chem., Int. Ed. Engl., 1997, 36, 2804; (i) A. B. Charette and J. Lemay, Angew. Chem., 1997,109, 1163; Angew. Chem., Int. Ed Engl., 1997,36, 1090. (a) L. Micouin, M. Oestreich and P. Knochel, Angew. Chem., 1997, 109, 274; Angeiv. Chem.. Int. Ed. Engl., 1997, 36, 245; (b) R. D. Rieke, S.-H. Kim and X. Wu, J. Org. Chem., 1997, 63, 6921; (c) R. Rossi, F. Bellina and D. Ciucci, J. Organomet. Chem., 1997,542, 113; (d) T. Harada, T. Kaneko, T. Fujiwara and A. Oku, J. Org. Chem., 1997,62, 8966; (e) S. Berger, F. Langer, C. Lutz, P. Knochel, T. A. Mobley and C. K. Reddy, Angew. Chem., 1997,109, 1603; Angew. Chem., Int. Ed. Engl., 1997,36, 1496. P. Knochel and R. Singer, Chem. Rev., 1993,93,2117. L. W. Bieber, I. Malvestiti and E. C. Storch, J. Org. Chem., 1997,62,9061. F. Bernardi, A. Bottoni and G. P. Miscione, .I. Am. Chem. Soc., 1997,119, 12300. K. N. Seneviratne and C. H. Winter, Organometullics, 1996, 16,2498. K. Wurst and J. Strahle, 2. Anorg. Allg. Chem., 1991, 595, 239, and references therein.

25. 26. 27.

28. 29. 30. 31. 32.

33. 34. 35.

36. 37. 38. 39.

40.

41. 42.

43. 44. 45.

13: Group 2 (Be-Bu) anti Group 12 (Zn-Hg) 46. 47. 48. 49.

447

For example, see K. Angermaier and H. Schmidbauer, Inorg. Chem., 1994,33,2069. A. L Christykov, I. V. Stankevich, N. P. Cambaryan, Y. T. Struchkov, A. I.

Yanovsky, I. Tikhonova and V. B. Shur, J. Orgunornet. Chem., 1997,536,413. E. Nakamura, Y. Yu, S. Mori and S. Yamaga, Angew Chem., 1997, 109, 422; Angew. Chem., Int. Ed. Engl., 1997, 36, 374. H. J. Emeleus and R. N. Haszeldine, J, Chem. Soc., 1949,2953.

Author Index

I n this index fhe number in parenthesis is the Chapter number of the citation and this is followed by the reference number or numbers of the relevanl citations within that Chapler.

Aaliti, A. (5) 404 Aarnts, M.P. (1.111) 12; (2) 39; (3) 36,37, 103; (4) 192,342,343 Abad, J.-A. (2) 271 Abbasali, Q.A. (1.11) 5; (5) 261 Abbotto, A. (12) 59 Abboud, K.A. (1.111) 34-36; (1 I ) 30 Abcl, E. (6) 33 1 Aberle, C. (6) 353 Abernethy, C.D. (4) 49; (6) 45 Abcssolo, H. (6) 343 Abinati, A. ( 5 ) I17 Abram, U.(4) 66 Abruna, H.D.(6) 303 Achland, M.J. (5) 238 Acum, G.A. (4) 248 Adams, C.J.(4) 165, 166; ( 5 ) 461, 462 Adams, H. (1.111) 38.96; (4) 321323; ( 5 ) 406; (6) 68 Adam, J.A. ( I 3) 5 Adams, M.C. (6) 135; (9) 115 Adams, R.D. (3) 77,86,87; (4) 196,226,364,377 Adams, T.A. (2) 167 Adatia, T. (4) 179 Addison, S.J. (1.1V) 20; (5) 169 Adlcr, D.L.(4) 395 Adriacnsens, P.J.A. (13) 6 Afanasova, O.B. (5) 9 Afra, T. (2) 333 Agarkov, A.Yu. (8) 25 Agcr, D.J. (7) 18 Agganval, V.K. (7) 42 Aguirrc, A. (4) 290; (1 2) 96 Ahlberg, P. (6) 301

Ahlbrccht, H. (12) 38 Ahlcrs, W. (1.1) 62-64, 67; ( 5 ) 302, 338,339; (6) 209; (1 I ) 22 AhlgrCn, M. (3) 170; (4) 25,360 Ahlrichs, R. (4) 260; (9) 62 Ahmad, M. (2) 229 Ahman, J. (7) 13 Ahmed, S.Z. (6) 290 Ahmcd Aka, A.M. (2) 239 Ahrcns, B. (4) 307; (10) 88 Aime, S.(4) 106, 212; ( 5 ) 417 Airola, K. (1.111) 101; (6) 355 Aistars, A. (4) 50; (6) 44 Aitken, C.L. (1 1) 50 Aitkcn, R.A. (13) 7 Ajjou, J.A.N. (1.111) 19 Ajulu, F.A. (4) 223; (9) 63 Akabori, S.(6) 345 Akagi, K. (6) 219 Akai, S.(8) 85 Akcrmark, B. ( 5 ) 37, 125 Akhnoukh, T. (2) 214; (5) 256 Akita, M.(2)45, 61, 92, 134; (4) 154, 155,353; (5) 196, 233; (6) 133 Akiyama, T. (2) 341; (6) 154 Akkcrnian, O.S. (5) I6 I; (1 1) 83 Al Ahmcd, S. (5) 258; ( I 1) 20, 2 I Alaimo, P.J. (2) 198; (5) 101 A1 Allaf, T.A.K. (6) 344 Alata, M. ( 5 ) 363 Albadri, A. (9) 25 Albruio, V.G. (2) 97,98,273; (3) 160; (4) 376; ( 5 ) 145 Albcniz, A.C.(5) 135 Albhiz, M.J. (2) 123, 124; (5) SO 449

Albers, I. (9) 106 Albers, T. ( I 1) 38,62 Albert, J. (2) 300 Albcrti, A. (13) 4 Albertin, G.(1.IV) 35 Alberto, R. (4) 66 Albinati, A. (5) 205 Alcaraz, C. (8) 84 Aldridge, S.(6) 85 Alcksccv, V.I. (4) 366 Alcxandcr, N.C. (4) 30 Alias, F.M. (2) 301 Allan, J.F. (1 3) 8 Allaond, S.( 5 ) 356 Allcgeicr, A.M. (6) 309 Allen, A.D. (6) 21 Allen, F.H. (1 0) 2 Allcnspach, P. (8) 109 Allinger, N.L. (10) 5 Allrcd, G.D.(13) 6 Al Malikc, K.M.( 5 ) 405 Al-Mandhary, R.A. (4) 239.380 Almazova, O.G. (6) 368; (8) 52 Almcida, S.S.P.R. (1.IV)11 Alonso, B. (6) 302,303,391 Alonso, P.J. (2) 259 Alper, H. (2) 263 Alt, H.G. ( I .I) 86 Al-Tawcel, S.M.(I 1) 25 Altman, M.(5) 253,470; (6) 3 15 Alvarado, Y. ( 5 ) 105 Alvarez, B. ( I .1V) 33; (3) 85 Alvarez, C. (3) 71,78; (6) 82 Alvarez, M.A. (3) 73, 78; (6) 60 Alvarcz, S . (3) 161; (4) 5, 92 Alvarcz, T.C.(6) 358 Alvarez-Rua, C. (1 .Ill) 107

450 Alvarez-Toledano, C. (1.111) 11 1; (2) 1 18; ( 5 ) 64,234 Amador, U. (1 XI) 29; ( 5 ) 42; (6) 72 Amane, M.E. (5) 377 Amaral, L. (6) 27 1 Amatore, C. ( I N ) 34; (3) 84, 103; (5) 189; (6) 145 Ambcrger, H.-D. (8) 110-1 12 Amclunxen, M.S. (9) 35 Amendola, M.C. (6) 382 Amiens, C. (4) 287 Amor, F. (1.1) 34; (6) 36 Amor, J.I. (1 .I) 85; (6) 229 Amoroso, A.J. (1.1V) 41; (3) 42; (6) 101 Amouri, H. (5) 344,377; (6) 144 Andersen, R.A. (2) 60; ( 5 ) 293; (13) 13 Andcrson, G.K. (2) 321 Andcrson, O.P. (5) 44 1; (10) 31 Anderson, S. (1 .HI) 77; (1 0) 49 Andcrsson, T. ( 5 ) 336 Andrcs, J.M. (4) 43 Andrews, L. (1.111) 17 Andrcws, P.C. (9) 70; (1 1) 6 1; (12) 54 Andricvskaya, N.V. (4) 108 Ancctha, H. (2) 75 Ancsta, M. ( 5 ) 112 Ang, H.G. (3) 40; (4) 74 Angclaud, R. (7) 48 Angcrmeier, K. (4) 304; (13) 46 Angermund, K. (5) 259,260 Anillo, A. (4) 320 Anson, C.E. ( 5 ) 229 Ansorge, M. (6) 379 Antinolo, A. (1.11) 3,4,20; ( 5 ) 304; (6) 46, 243,244 Antipin, M.Yu. (2) 260; ( 5 ) 68; (6) 138,365; (8) 49; (10) 22 Antonaroli, S. (5) 137 Antonelli, D.M. (1.11) 22,24; (5) 167; (6) 47 Antoniutti, S. (1.IV) 35 Antwi-Nsiah, F.H. ( 5 ) 380 Anwuidcr, R. (8) 37, 59 Aoc, K. (5) 237 Aoki, K. (2) 203; (4) 114; (5) 420 Aoyagi, I<. (10) 69, 73 Aplcr, H. (4) 341 Aponick, A. (12) 17 Apostolidis, C. (8) 1; (12) 83 Ara, I. (2) 339; (5) 473-475; (1 1) 97 Arai, Y. (9) 72 Araki, S. (1 1) 82 Arancibia, V. (2) 54; (6) 164

Orgamttterallic Chemistry Arasingham, R.D. (2) 115 A m , A.J. (1.IV) 31; (3) 89; (4) 28, 125, 139, 221; ( 5 ) 409, 43 1 Archavics, A. (6) 27 Arduengo, A.J. (9) 21,69 Arcnas, M. (1.IV) 56 Arif, A.M. (1.111) 20; (1.1V) 4144; (2) 48, 190; (3) 42; (4) 207, 208; ( 5 ) 294,3 11, 407; (6) 95, 101 Arikawa, Y. (5) 48 I ; (6) 265 Arliguic, T. (8) 70 Arlinghaus, H.F. (10) 90 Armstrong, D.R. (6) 186; (12) 23, 54,85 Amason, 1. (4) 45; (6) 30 Arnauld, T. (9) 99 Amdt, P. (5) 305 Arndtscn, B.A. (2) 198; ( 5 ) 101 Arncy, D.S.J. (1.11) 26; (6) 372 Arnold, J. ( I .I) 7; (1.11) 6, 7; (6) 360 Arnold, L.A. (7) 49 Amold, P.L. (2) 343; (8) 42; (9) 54,s Arnold, U. (1.111) 69 Artoinonov, E. (6) 12 Artus, G.R.J. ( I N ) 69; (2) 14, 348; (8) 59 Artyomov, V.A. (10) 7 1 Arynyos, A. ( 5 ) 128 Ashc, A.J., 111 ( 5 ) 258; (1 1) 6, 20, 21,25 Askadskii, A.A. (10) 75 Askcnazi, A. ( 5 ) 2 13 Assclin, C.M. (6) 347 Ast, T. (8) 10 1 Astruc, D. (6) 4, 304, 387, 390, 391 Atencio, R. (1.IV) 31; (3) 89; (4) 125; ( 5 ) 409 Athanasscnas, K. (8) 98 Atoumyan, L.O. (6) 203 Attwood, M.R. ( 5 ) 229 Atwood, D.A. (1 I ) 34,42,58 Atwood, J.D. (1.111) 81;(2) 1x5; (3) 140 Atwood, J.L. (6) 33 1 Au, Y.-K. (3) 14; (4) 200 Aubcl, P.G. (2) 251,319 Aubcrt, M. (2) 27 Aubke, F. (2) 3 I ; (3) 54 Aullon, G. (4) 5 Aumann, R. (1.111) 9, 108, 109, 112, 113 Avarvari, N. (9) 79 Avcnt, A.G. ( 5 ) 148

Avila-Roson, J.C. (2) 265 Avis, M.W. (2) 280,281 Avtomonov, E.V. (1 .I) 32; (6) 7, 247; (9) 87,96 Axcn, A. (5) 141 Ayucla, A. (8) 94 Azncr, F. (1.111) 107, 119 Ba, X. (8) 75 Babailov, S.P. (4) 214 Baccircdo, A. (9) 41,42 Bach, I. ( 5 ) 110 Bachmclnn, P. (2) 79; (6) 293 Badyal, K. (2) 223; (4) 87 Bickvall, J.E. ( 5 ) 128 Back, Y.G. (6) 339 Bacnzigcr, N.C. (4) 48; (6) 252 Bacrcnds, E.J. (1.111) 12; (3) 22, 36, 37; (4) 343 Bailcy, N.A. (1.111) 38; (4) 321, 323; ( 5 ) 406; (6) 68 Bailcy, N.J. (6) 250,253 Bain, A.D. (1 .IV)36; (2) 49; (3) 96 Baird, M.C. ( I .I) 74-76; ( 5 ) 136; (6) 32 Bajaj, H.C. (6) 28 I Baker, B.J. (3) 77; (4) 226 Bakcr, I.J. (9) 110 Baker, P.K. ( 5 ) 34,398 Bakir, M. (3) 80 Balagurova, E.V. (10) 55 Balasubramanian, K. (8) 95-97 Balavoinc, G.A. (6) 352 BaIch, A.L. (2) 115; (4) 300 Baldoli, C. (2) 36 1 Baldovino, 0. (1.111) 11 1 Balducci, G. (8) 99 Ball, S.C. (12) 53 Ball, T.W. (1.111) 115 Ballantini, V. ( 5 ) 246 Ballcsteros, A. (1.111) 126 Ballinger, J.C. (2) 102 Balssa, F. (1.111) 93; ( 5 ) 390, (6) 385 Balzani, V. (3) 6 Ban, H. (3) 24 Ban, S. ( 5 ) 236 Bancroft, G.M. (5) 6 Bancroft, M.N.(1 .III) 96; (4) 323 Bandoli, G. (6) 333 Banejee, S. (3) 122; (4) 85, 348 Bannai, H. (6) 219 Baratta, W. ( I .II) 30 Barbado, P. (6) 342 Barbcris, C. (1 2) 8 Barbini, D.C. (6) 75

A ufhorIndex Bardaji, M. (12) 106, 120 Bardia, M.-F. (6) 276 Bar-Haim, Ci. (I I) 23 Barijbin, M.V.(6) 377 Barlow, S.(6) 364 Barlucnga, J. (1.111) 79, 107, 119, 126, 127, 130-132; (12) 58 Barlucnga, S. (1.111) 107 Bamard, T.S.(4) 364 Bamcs, C.E. (1.11) 10; (4) 57, 197, 252,254,255,258; (5) 433 Bamcy, A.A. (3) 5 1 Barnum, B.A. (10) 19 Barr, D. (12) 23 Barrcro, A.F. (5) 386 Barrett, A.G.M. (7) 35 Barrie, P.J. (6) 381 Barriola, A.M. (1.1) 92 Bamsta, A.M. (6) 213 Barron, A.R. (1 1) 47,50,5 1,8Y Barry, S.T. ( I I ) 75 Barthcl-Rosa, L.P.(2) 104; (3) 1 18; (4) 193; (5) 69,232; (6) 128 Bartohis, T. (1.W) 55 Barton, D.H.R. (9) 99 Barton, L. (10) 30 Bortsch, R. (9) 47 Baryshnikova, E.A. (10) 75,93 Barzoukas, M. (2) 100 Bashilov, V.V. (4) 284 Basickcs, N. (1 1) 19 Bwsct, J.-M. (3) 131; (4) 98 Bassetti, M.(2) 135 Batchclor, R.J. (1.IV) 51; (2) 200; (3) 97, 98; (4) 235; (5) 175; (8) 65 Bates, C.M.(2) 289; (4) 84; (6) 22 Bats, J.W. (2) 297,298 Batsanov, A.S. (4) 362; (6) 65, 263,267 Battaglini, F. (4) 4 Batten, S.A. (10) 32 Bau, R. (4) 15, 17,33 Baudry, D. (6) 15; (8) 5, 15 Baucr, A. (4) 298,303,304; (12) 115

Baucr, J.K. (1.1V)37 Baucr, W. (12) 70 Baugh, S.P.D.(7) 35 Baukova, T.V. (I 2) 1 10 Baum, E. (5) 228; (1 1) 65 Bauman, N. (6) 227 Baumann, M. ( 5 ) 385 Baumann, R.(1.1) 15 Baumonn, W. (1 .I) 58-60,88; ( 5 ) 300,301,438 Baumgartncr, T. (9) 34; (12) 50

Bauschlichcr, C.W., Jr. (8) 102 Baxtcr. 1. (5) 3 I0 Baxtcr, J. (1.Il1)50; (13)3 Baydal, K. (3) 119 Baylcr, A. (4) 298 Bazan, G.C. (1 .I) 38; ( 5 ) 267,270; (6) 39; (1 1) 20 Beace, Y. ( 5 ) 344 Bcachlcy, O.T., Jr. (1 1) 71, 74 Bcak, P.(12) 7 Bear, J.L. (2) 94 Bcatty, A.M. (2) 213 Beck, J. (1.111) 49; ( 5 ) 52; (6) 55 Beck, W. (1.HI)33,88, 90, 1 18; (1.1V) 22,25,27; (3) 47; ( 5 ) 396,400,402,457 Bccke, F. (2) 306; (12) 28,29 Bcckcr, G. (9) 17,98 Bcckhaus, R. (1.1) 30,4648; (6) 233 Bcckmann, E. (6) I12 Bcdford, R.B. ( 5 ) 204; (9) 7,27, 28 Bccr, F. ( 5 ) 470; (6) 3 15 Bccr, P.D.(6) 291,320 BCCZ,V. (6) 166; (10) 16 Beglcy, M.J. (9) 103 Bchni, R. ( 2 ) 2 13 Bchrens, U. (5) 388; (6) 187; (12) 80,97 Bchringer, C. (12) 48 Bci, X.H. (1.1) 13 Bckasova, N.I. (10) 75,93 Bdlangcr-Garicpy,F. (6) 180 Bclanzoni, P. (1 .IV) 23; (2) 21 Bcldcrrain, T.R. (2) 301, 363,364 Bclctskaya, I.P.(4) 202; (5) 428; (6) 193; (8) 4,25 Belhumeur, S. (1 I) 75 Bcll, P.T. (5) 284 Bcll, R.G. (4) 4 1 Bcll, W.L. (6) 279 Bellachioma, G. (2) 27-29 Beller, M.(7) 11, 22 Bcllina, F. (7) 1;(13) 40 Bclscr, P.(3) 6 Bclsky, V.K.(4) 400; (6) 302; (9) 94 Bclyakov, P.A. (8) 49 Bclyclkova, O.A. (4) 352,387; ( 5 ) 442 Belzncr, J. (12) 67 Bcmis, J.M. (4) 42 Bcnaglia, M. (1 3) 4 Bcnakki, R. (10) 84 Bdnard, M. (4) 374; (13) 35 Ben-David, Y.(2) 204 Bcndclc, G.M.(12) 8 1

45 1 Bcnnctt, B.L.(6) 383 Bcnnctt, D.W.( 5 ) 288 Bcnnctt, J.L. (1.11) 18 Bennett, M.A. (2) 10, 18,285; (3) 1, 17; (4) 301; ( 5 ) 16, 17,246; (12) 109 Bcnsimon, C. (2) 263; (4) 34 1 Bcnson, J.W. (3) 39, 137; (4) 185 Bcnson, M.T. (2) 15 1 Bcntele, H.(3) 47; (5) 396 Bcnvenutti, A. (1 .HI) 2 1 Bcnvenutti, M.H.A. (5) 397; (9) 8, 9, 31 Bcnyci, A.C. (6) 319 Bcnyuncs, S.A. ( 5 ) 235 Bcrcaw, J.E. (2) 358; (5) 163; (8) 64 Bcrces, H.-P. (8) 106 Bercngucr, J.R. (2) 339; (5) 474, 475; (1 1) 97 Berg, D.J. (1.1) 17; (8) 65 Bcrgamo, M. (3) 91; (4) 65, 346 Bcrgcns, S.H.(2) 55 Bcrgcr, S.(1 3) 40 Bergman, R.G. (1.1) 41; (2) 60, 183, 198,208; (5) 101, 158, 293; (6) 157; (13) 13 Bcrgstriisscr,U. (9) 19,32,59,60 Bcringhclli, T.(3) 38,91; (4) 6365,346 Bcrke, H. (1.1) 91; (2) 141, 147; (4) 9.8 1; ( 5 ) 32 1 Berkovich, E.G.(1.1) 72; (6) 201 Bernard, P.L.,Jr. (1 .III) 130 Bcrnardi, F. (13) 43 Bcrnardinclli, G.(9) 25 Bcrnasconi, C.F. ( I .Ill) 7 Bcrnasconi, G. (4) 34 Bcrnhard, S.(2) 187; (3) 6,3 1 Bcmhardt, P.V. (3) 65 Bcrrcs, S. (5) 234 Bcrtani, R. (12) 116 Berthct, J.C. (6) 189 Bertran, J. (8) 103; (10) 51 Bertmd, G.(9) 3,41,42 Bcrtuleit, A. (1.l) 28 Bcswick, M.A. (3) 176; (4) 39,40 Bcthlcy, C.E. (1 1) 50 Bettiol, M. (1 .IV)35 Bctzemeicr, B. (7) 61 Beverwijk, V. (2) 302 Bcydoun-Sutter, N. (5) 322 Bezuidcnhoudt, B.C.B. (12) 89 Bhadbhadc, M.M.(6)28 I Bhambri, S. (6) 394 Bhattacharya, P. (6) 88 Bianca, F.D. ( 5 ) 137 Bianchi, M. (2) 180; (3) 132; (4)

452 22, 147 Bianchini, C. (2) 120,207, 21 1; (5) 15, 105; (6) 342 Bickclhaupt, F. (2) 302; (5) 161; (9) 24; (1 I) 83; (12) 62; (1 3) 7 (13) 42 Bicbcr, L.W. Bildstcin, B. (6) 285,286,298 Bindcr, H. (10) 24 Bingcr, P. (5) 161; (9) 59, 60 Biot, C. (6) 343 Birk, U. (5) 333 Bissinger, P. (5) 276-278 Bisson, A.P. (4) 323 Biswas, B. (2) 244 Bittenvolf, T.E. (2) 81; ( 5 ) 358; (6) 41 Bjorgvinsson, M. (4) 45; (6) 30 Black, S.J. (9) 75-78 Blackwell, J. (8) 58 Blacquc, 0. (3) 150; (6) 196,230 Blher, D. (1 .III) 66; (2) 306; (3) 53; (4) 273; (6) 61, 125, 178; (9) 71; (10) 22; (12) 28 Blais, J.-C. (6) 390 Blake, A.J. (3) 135; (4) 172, 173, 178; ( 5 ) 465-467; (9) 103, 112, 117; (12) 75 Blanipain, G. (6) 343 Blanch, R.J. (10) 82 Blanchard, S.S. (1.1V)18 Blars, J.-C. (6) 304 Blaschcttc, A. (9) 90 Blaurock, S.(6) 76; (12) 30 Blechcrt, S. (5) 25; (7) 36 Blcckc, I.R. (2) 213 Blcnkiron, P. (1.111) 38; (3) 1 11; (4) 141,329,363; (5) 362, 449,460; (6) 68 Blcucl, E. (2) 350 Bley, B. (2) 31 Block, M.H. ( 5 ) 62 Bliimel, J. (6) 357 Blonski, C. (2) 150; (6) 152 Blough, A.M. (6) 143 Blumcnfcl'd, A.L. (12) 110 Boca, R. (4) 241 Bochc, G. (12) 52 Bochkarcv, M.N.(6) 368; (8) 5052, 68, 69; (12) 98 Bochmann, M. (1 .I) 16,39,40, 79, 81; (5) 159,266, 337; (6) 33, 195; (1 1) 17 Bock, M. (2) 142 Bodcnsicck, U. (4) 374; (13) 35 Bodcs, G. (5) 183 Bocckcr, C.A. (3) 39 Btigcl, H. (5) 335 Bochmc, C. (6) 2; ( 1 1) 63

Orgationierullic Cheniisrry Biihmc, M. (I.IV) 41 Biihmcr, J. (2) 357; ( 5 ) 274, 275 Bocrakker, M.J. (2) 220 Borner, A. (5) 192 Boersma, J. (13) 20,21,24,25 Bocsc, R. (1.111) 66; (2) 306; (3) 53; (4) 103,273; (5) 213; (6) 61, 125, 178; (9) 71; (10) 22; (12) 28 Bocse, W. ( I .IV) 5; (2) 8 Bottchcr, H.-C. (4) 354,355 Boffi, L.S.(8) 32 Bogdanovic, B. (2) 195 Bogdanovic, S.(7) 22 Bogels, G. (5) 394 Bogsinyi, D. (2) 325 Bohlc, D.S. (4) 197 Bohnic, U. (1 .I)46 Bohringcr, M. (9) 17 Bois, C. (3) 73, 78; (6) 60 Boisson, C. (6) 189 Bollingcr, J.C. (3) 107 Bolm, C. (4) 123; (5) 422 Bolzati, C. (6) 284 Boncclla, J.M. (1.111) 34-36; (1 1) 30 Bond, A.M. (3) 4,83; (6) 3 13 Bond, M.R. (9) 52; (I1) 72 Bondictti, G. (4) 267 Boni, G. (6) 25 I Bonitatcbust, P.J., Jr. (2) 365; (5) 66 Bonnet, G. (6) 25 I Bonrath, W. (5) 332 Borchcrt, T. (4) 257; (5) 432; (6) 161 Bordignon, E. ( I N ) 35 Bordoni, S. (2) 97 Borge, J. (2) 108, 109, 128, 130; (6) 116 Borgman, C. (1 .Ill) 46; (5) 40 Borgmcicr, 0. (8) 109 Boring, E. (1 .]I) 1 I;(6) 42; (10) 27 Borns, S. (5) 192 Borrmann, H. (10) 24 Bsruc, K.J. (1.111) 13 Bosch, B.E. (1.1) 33 Bosold, F. (12) 52 Bosquc, R. (2) 284; (6) 262,276, 283,287,307 Bott, S.G. (4) 131; (6) 146; (1 1) 47,50,5 I , 89 Bottchcr, H.-C. (4) 130 Bottchcr, P. (1 .I) 4 Bottomlcy, F. (4) 49; (6) 45 Bottoni, A. (1 3) 43 Bouauchcau, C. (1 .Ill) 125

Bould, J. (10) 30 Bourdon, C. (6) 196,230 Bourgalt, M. (2) 121 Bourissou, D. (9) 4 1 Boutry, 0. (5) 105,297 Boutton, C. (2) 326; (12) 114 Bouwkamp, M. (5) 159 Bovcns, M. (5) 205 Bowers, M.T.(5) 154 Bowlcs, P. (12) 63 Boyd, E.P. (4) 210 Boys, D. (6) 164 Bozek, J.D. (10) 10 Brackcmcyer, T. (1 .I) 94,95; (6) 220 Braddock, D.C.(7) 35 Bradlcy, D.C. (1 1) 36,84 Bradlcy, J.S. (4) 93,287 Bradshaw, J.D. (5) 330 Brady, M. (1.N)41 Brady, R.C. (6) 177 Braga, D. (2) 12; (3) 125, 144; (4) 13, 14, 101, 143, 144, 177, 178, 265,396; (5) 423,448, 467,472 Branchadcll, V. (3) 19, 20; (8) 102, 103 Brand, U. (4) 68,69 Brandsma, L. (12) 12 Brmdt, D.E. (3) 39 Brasch, N.E. (2) 177 Brassat, L. (3) 45; (6) 264,3 1 1 Brauer, D.J. (1 1) 8; (12) 99 Braun, T. (2) 113 Braunschweig, H. (6) 78; (1 1) 27 Braunstein, P. (2) 278; (4) 1 17, 247,350,361,374; (13) 35 Breckenridgc-Estcs, S.M. ( 5 ) 245 Brecn, T.L. (1.1) 56 Bregadze, V.I. (10) 33,71; (1 1) 81

Brcgman, F.R. ( 5 ) 198 Brcit, B. (9) IS, 19 Brenton, P. (4) 259 Brcucr, K. (5) 194 Breunig, H.J. (9) 66, 84, 86, 102, 119, 120 Bricout, H. (7) 27 Bridgeman, A.J. (12) 86 Bridgewater, J.S. (2) 187; (3) 31 Bridson, J. (6) 172 Briggs, P.M. (1.11) IS, 31 Brinkmann, P.H.P. (1 .I) 80 Brintzingcr, H.H. (6) 235, 238, 258 Brisbois, R.G. (5) 249 Brison, H.A. (1 .HI) 54 Britovsck, G.J.P. (2) 282

Aullior Index Broadhurst, P.V. (2) 93; (4) 227 Brocard, J.S. (6) 343 Brocnnckc, C. (1 1) 35 Brook, M.A. (2) 49; (3) 96; ( 5 ) 346,455 Brookhart, M. (2) 188, 3 1 I; (5) 88 Brooks, K.A. (10) 28 Broomhall Dillard, R.N.R. (8) 5 1 Broschk, B. (9) 17 Brost, R D . (3) 49 Brotin, T. (10) 77; (13) 27 Broussier, R. (6) 196,203,230 Brown, D.A. (3) 69,70; (5) 2 I4 Brown, D.B. (3) 126; (4) 101, 144, 168, 174; (5) 365,423, 424; (6) 136 Brown, D.W. (12) 18 Brown, J.M. (2) 337; (5) 134 Brown, K.L. (2) 169 Brown, P.H.(10) 3 Brown, S.N. (2) 363 Brown, T.M. (2) 178 Bruce, D.W. (6) 323 Bruce, G.C. (3) 49 Bruce, L.A. (4) 99 Bruce, M.I. (1.111) 5; (2) 4, 110; (3) 16; (4) 6, 21,23,24, 111, 113, 136, 164-166, 171, 378, 379; ( 5 ) 412416,453,459, 461,462 Bruck, M.A. (1 .Il) 26; (6) 372 Bruckmann, J. (9) 60 Brudgarn, I. (2) 368; ( 5 ) 393 Bruescr, W.T. (8) 56 Bruhn, C. (2) 264,288; (4) 130 Bruncko, M. (7) 47 Bruncan, C. (2) 17 Brunncr, H. (6) 110 Bruno, J.W. (1.II) 29 Brussaard, H.C. (5) 394 Brussee, E.A.C. (8) 60,61 Bruzinski, P.R(7) 41 Bryce, M.R.(6) 263,267 Buchcrt, M. (1.111) 120 Buchhcim-Spiegcl, S. (1 1) 8 Buchncr, R.(6) 142 Buchowicz, W.(4) 272; (6) 179 Buchwald, S.L. (7) 3,8, 12-14 Budzclaar, P.H.M. (1 .lI) 9; (6) 9 Buhl, M. ( 5 ) 179 Bucrgcr, H. ( 1 1) 8 Buil, M.L. (2) 69, 123; (3) 46,95; ( 5 ) 80, 86 Buisman, G.J.H. (3) 141 Buittard, J. (6) 304 Bukalov, S.S. (1 1) 8 1 Bulychcv, B.M. (8) 23 Bumagin, N.A. (13) 7

Bunz, U.H.F. ( 5 ) 13, 253,470; (6) 315 Burchat, A.F. (12) 1 Burckhardt, S.(5) 59 Burckhardt, U.(4) 382; (5) 385 Burdcniuc, J . (2) 16 Burctea, M.A. (6) 260 Burghaus, 0. (5) 262; (6) 40,373 Burkey, D.J. (1.111) 24; (6) 91, 363 Burla, M.C. (2) 27 Burlakov, V.V. (1 .I) 45,57-60; ( 5 ) 300,438 Bums, D.H. (13) 7 Burns, J.C. (3) 69,70; (5) 214 Burns, R.M. (1 .IV) 37 Burstcn, B.E. (8) 114 Uurtli, D. ( 0 ) 33X Burton, D.J. (13) 39 Busatto, F. (1.lV) 35 Buschmann, J. (1.1V) 55; ( 1 3) 5 Buschmann, W.E. ( I N ) 14 Busetto, L. (2) 97,98; (12) 116 Bushncll, G.W.(1.1) 17 Butcnschon, H. (5) 14 Butin, K.P. (6) 193; (8) 4 Butler, 1.R. (6) 1 Byrnc, L.T. (4) 135; (9) 11 Cabbon, R. (6) 10 Cabcza, J.A. (3) 130; (4) 116, 121, 132-134, 170; ( 5 ) 364; (12) 24 Cabiddu, M.G. (12) 20 Cabiddu, S.(12) 20 Cabrcra, A. (2) 1 IS; ( 5 ) 64 Cacclli, 1. (6) 50 Cadcnas-Plicgo,G. (12) 42 Cadierno, V. (2) 108, 130; (6) 116 Cadoni, E. (12) 20 Cafim, A.J.M. (3) 143 Caliicz, G.(1.IV) 10 Cai, J.P. (10) 73, 96 Cai, R.-F. (8) 20, 2 I, 47 Calabrese, J.C. (9) 69 Calderazzo, F. (1.I) 77, 78; (3) 59; (6) 2 12,370 Caldcroni, F. (3) 147 Calliorda, M.J. (4) 101, 144, 256, 305, (6) 84, 277 Caliman, V. (9) 49, 50, 53 Calvo, E.J. (4) 4 Calvo, M. (6) 83 Camalli, M. (13) 53 Camanycs, S.(6) 243 Cambaryan, N.P. (13) 47 Camiletti, C. (2) 97,98

453 Caninlack, J.K. (4) 103 Campagna, S.(2) 274 Campagnola, D. (4) 390 Campana, C.F. (3) 97; (4) 235; (11) 80 Campos, P.J. (12) 58 Canalcs, F. (4) 305; (12) 119 Canct, I. ( 5 ) 28 1 Canct, J.L. ( 5 ) 28 1 Cano, A.M. (1.1) 92; (6) 213 Canovcsc, L. (2) 341, 342 Canty, A.J. (2) 247 Cao, Y. (2) 176; (5) 218 Capon, J.-F. (3) 66; (5) 345 Capparelli, M.V. (1.IV) 31; (3) 89; (4) 28, 125, 139; (5) 409, 43 1 Caproii, L (5) 55 Carballo, R. (1 1) 95 Carboni, B. (1 1) 14 Cardaci, G. (2) 27-29 Cardcnas, D.J. (2) 293 Cardin, C.J. (5) 404 Cariati, E. (4) 97 Cariiio, R.S.(1 .IV) 58; (3) 90; ( 5 ) 352; (6) 104 Carlot, D. (4) 120; ( 5 ) 419 Carlucci, L. (1 .IV) 32 C m a l t , C.J. (9) 21, 68, 104 Carmen, M.(6) 141 Carrnichacl, D. (3) 143 Cmnona, D. (6) 164 Carmona, E. (1.111) 28, 29; (2) 301; ( 5 ) 41.42, 105, 297,383; (6) 72 Caro, B. (1.111) 128; ( 5 ) 376 Carpcntcr, G.B. ( I .lV) 30; ( 5 ) 216-218, 222; (6) 275, 386 Carpenticr, J.-F. (7) 27 Carrano, C.J. (9) 52; (1 1) 72 Cmcin, E.M. (7) 38 Carrillo-Hermosilla, F. (1.11) 4; (6) 243,244 Carroll, P.J. (10) 19, 37, 95; (11) 43,44, 86 Carrondo, M.A.A.F. de C.T. (6) 84 Carter, K. (2) 22 Carty, A.J. (3) 111; (4) 89, 141, 150-152, 328,329,363; (5) 362,440,443,449,460 Carvalho, N.N.(1.IV) 1 1 Cary, D.R. (6) 364 Casado, C.M. (6) 302,303 Casanova, M.-J. (4) 287 Casarcs, J.A. (2) 120,211,252 Casarrubois, L. (1.111) 64, 65; (5) 316,317

454 Casas, J.S. (I 1) 95; (13) 30 Casellato, P.(2) 135 Caselli, A. (1.1) 18-20 Casey, C.P. (1.rv)50, 58; (3) 90; ( 5 ) 152, 155, 173, 352; (6) 104; (8) 28 Cassani, M.C. (8) 22; (12) 116 Castanet, Y. ( 5 ) 386 Castano, A.M. (5) 128 Castellani, M.P. (3) 35 Castcllano, E.E. (1 1) 95 Castcllari, C. (2) 98 Castiglioni, M. (4) 390,391 Castillo, A. (2) 121; (5) 186 Castillon, S.(5) 203 Casty, G.L.(1.1) 6 1 Catalh, M.P. (2) 189 Catalano, V. ( 5 ) 99 Catiiieiras, A. (13) 30 Caubke, P. (12) 11 Caubert, A. (6) 283 Caulton, K.G. (2) 37,38, 102, 127,217,219,345; (3) 55,56, 107 Cauzzi, D. (4) 83 Cavaglioni, A. (2) 210 Cavallo, L. (2) 248; ( 5 ) 109 Cavanaugh, M.D. (1.IV) 45,53; (2) 41; (6) 103, 113 Cavell, K.J. (2) 282,323 Cayton, R.H. (6) 63 Cea-Olivares, R.(9) 119 Cecchi, P. (13) 33 Cecum, A. (5) 189,391; (6) 145 Cejka, J. (1.1) 69; (13) 11 Ccnac, N. (6) 225; (9) 8, 23 Cenac, Y. (9) 41,42 Cerrada, E. (12) 120 Ccsson, A. (3) 155 Cetinkaya, B.(2) 349 Chabert-Couchouron,N. (6) 266 Chadwick, S.(12) 76 Chakravorty, A. (2) 66,67 Chaloner, P.A. ( 5 ) 119, 144.204 Chan, A.S.C. (6) 28 Chan, E.Y.Y. (6) 156 Chan, H.-K. (13) 7 Chan, J. (6) 100 Chan, M.C.W. (1.IV) 12; (2) 105; ( 5 ) 75; (13) 12 Chan,W.C. (2) 35 Chandrasckharam, M. (1.111) 44; (5) 5 1

Chang, C.C. (1 I) 60 Chmg, C.-K. (6) 3 12 Chang, J. (6) 199 Chang, S.C. (3) 99; ( 5 ) 283 Chao, W.-J. (3) 156; (4) 326; ( 5 )

Orgatiomelaiiic Chcniistry 463 74,248,255 Chapman, J. (2) 173 Chemg, 1.-J. (4) 82 Charettc, A.B. (13) 39 Chernysheva, T.V.(4) 394 Charles, C. (4) 361 Chemyskcv, E.A. ( 5 ) 9 Charlton, M.A. ( 5 ) 6 1 Chcung, K.-K. (2) 105; (3) 81; (4) Chatani, N. (3) 57; (4) 393; (7) 20, 29 I , 399; (6) 349; (12) 95, 21,23 104 Chattcrjee, S.(2) 3 13 Chi, K.-M. (2) 96; (4) 203; (5) 429 Chaturvcdi, A. (9) 89 Chaudhury, S. (2) 305 Chi, Y. (1 .HI) 48,97; (3) 52, 156, Chaudrct, 8. (4) 287 177; (4) 141, 161, 169,309, Chauvin, Y. (2) 278 324-329; ( 5 ) 399,440,456, 460,463; (6) 254 Chc, C.-M. (1.IV) 12; (2) 105 Che, D.-J. (6) 274 Chialli, R. (2) 46 Chen, B.-H. (6) 270 Chiang, J.P. (1 .N) 63; (7) 46 Chen, C.C. (4) 309 Chiang, M.Y. (1.111) 31; (2)75, Chen, D.-J. (1.111) 45; (5) 49; (6) 213; (3) 76,79; (5) 315; (6) 62 86; (1 1) 60 Chcn, D.-Y. (1 XI) 73; (5) 3 12 Chiang, S.-J. (3) 177; (4) 327 Chcn, H. (2) 369; (3) 119; (4) 87; Chicote, M.-T. (4) 306,307; (12) 107 ( 5 ) 85 Chie, C-M. (5) 75 Chen, H.L. (2) 223 Chien, S.-M. ( 5 ) 3 13,3 14 Chcn, H.-S. (3) 163; (4) 82 Chcn, H.-W. ( 5 ) 153 Chicsi-Villa, A. (1.1) 18, 19; (2) Chcn, I.-T.(1.111) 31; (3) 76; ( 5 ) 352,353; (5) 209; (1 2) 93 315 Chihara, T. (4) 181, 182; (5) 468 Chin, C.S. (2) 2 18 Chen, J. (1 .IV) 59; (2) 366; ( 5 ) 354,355,401 Chin, K.Y. (10) 60 Chen, J.-B. (3) 114 Chin, R.M.(2) 212 Chisholm, M.H. (1.III) 52,53,55; Chen, J.-H. (1 1) 60 (4) 55; (5) 348; (6) 63 Chen, J.-T. (5) 103, 104, 153 Chiu, C.F.(6) 270 Chen, J.-X. (6) 29 Chen, J.-Y. (5) 72 chi^, K.-Y. (8) 39 Chen, M.-C. (5) 295,296; (6) 5 1 Chiulli, R.J. (I.IV) 53; (2) 41; (6) 113 Chen, P. (2) 158, 184; (6) 159 Chen, W. (5) 202; (6) 28 Chizhevsky, I.T. (10) 33,56 Chcn, X.(4) 397; (6) 28 Chrnielcwski, P.J. (2) 266 Chen, Y. (1.1) 26 Choi, D.S.( 5 ) 22 1,222 Choi, J.-C. ( 2 ) 216; (5) 91,95 Chen, Y .-H. (1.IIl) 92 Chen, Y.-K. ( 5 ) 104 Choi, N. (2) 304; (4) 100; (5) 425; Chen, Y.-X. (1.1) 26, 31; (6) 200, (11) 15 207 Choi, Y.-Y. (4) 232 Chen, Y . 2 . (2) 35 Chong, J.M. (12) 1 Chcn, 2.( 5 ) 67 Choo. J.-J. (4) 209; ( 5 ) 430 C ~ O UC.-C. , (3) 99; (5) 283 ChCnard, S. (12) 8 Chou, Y.-C. (3) 177; (4) 327 Chenega, A.N. (2) 64 Choukroun, R. (1.11) 21; (5) 157, Chcng, C.-H. ( 5 ) 121 342; (6) 208 Chcng, J.-J. (3) 163 Chowdhuy, S.K. (2) 170; (5) 31, Cheng, L. (3) 82 32; (1 1) 26 Chcng. R.-J. (3) 41; (4) 191 Christiaans, B.E.C. (2) 220 Chcng, S. (2) 169 Christophcr, J.N. (1.044 Chcng, T.-Y. (3) 67; ( 5 ) 30 Christykov, A.L. (13) 47 Cheng, W.-Y. (1 I) 52 Chrostowvska, A. (6) 225; (9) 22, Cheng, Y.-J. (3) 79; (6) 86 23 Chcorcy, A. (6) 263 Chu, H.S.(2) 35 Cheradame, S. (6) 284 Chu, J.-B. (5) 104 Chercpanov, LA. (6) 380 Chu, S.-Y. (2) 21, 154, 157; (3) 30 Chcmcga, A.N.(1.111) 23; (6) 64,

AufhorIndex Chuang, L.-W. (3) 99 Chubb, R.W.J. (6)263 Chui, K.(8) 27 Chuilli, R. (6) 134 Chun, S.-H. (3) 131;(4)98 Chung, C. (3) 177;(4) 327 Chwg, J.-H. (4) 210 Chung, J.K. (6)275 Chug, K.-K.(5) 75 Chung, L.W.(5) 283 Chung, M.-C. (2) 134;(6) 133 Chung, S.(5) 152 Chung, Y.K.(5) 217,221,222, 35 1; (6)327,362 Churakov, A.V. (6) 7;(9) 87 Cian, A.D. (1 .HI) 91 Ciani, G.(1 .IV)32;(4)34,346 Cihcntcs, M.P. (2)99,325,326; (4) 183, 184;(12) 114 Chi, R.(2)163,210 Cinquantini, A. (4) 35 1 Circra, M.R. (10) 40 Ciriano, M.A. (2) 240;(4)265 Ciruelo, G.(1.1) 73;(6)26 Cisiuova, I. (10)20,62 Ciucci, D. (7) 1; (13)40 Claridgc, T.D.W. (2)337;(5) 134 Clark, A.M. (2)50 Clark, D.L.(8)6 Clark, G.R. (2)36,59;(3) 101, 102;(6)384 Clark, J.R (1 .II) 14,27;(5) 263 Clark, J.S. (7)32 Clark, T. (3)48;(9)40 Clarlic, L.P.(4)218 Claver, C. (5) 203,404 Claydcn, J. (12)63 Clcgg, w . (2) 74;(3) 109-112;(5) 359-362;(6)67;(11) 12;(12) 33,54,71 Clokc, F.G.N. (1 .XI) 5; (2)343;(5) 261;(6)24,375;(8)42;(9) 54,55 Clybume, J.A.C. (9)21,68 Coat, F. (2) 117;(3)44;(6) 109 Cobb, J. (12)53 Coffer, J.L. (4)68 Coffcy, D. (1 0) 7 Colacia, E. (2)265 Colbert, M.C.B. (2)95;(6)294 Colblcy, C.J. (5) 146 Colbran, S.B. (3) 104;(6) I17 Cole, J.M. (13) 12 Colcrnan, K.S.(4) 188 Coles, M.P. (1 1) 33,39 Collado, M.I.(9)41 Collin, J. (6) 18; (8) 12 Collins, B.E.(4)77

Colquhoun, H.M.(10) 79,80 Colton, R. (3) 4, 83; (6)3 13 Colurnbo, M.(3) 32 Combs, D. (6) 199 Cornpora, J. (5) 383 Cornstock, M.C. (3) 145;(4)270, 344; (5) 328;(6)160, 167, 169 Corntc, V. (3) 150;(6)226 Concellon, J.M. (1.111)130 COMCIIY,N.G.(3)35 Conner, J.A. (1.W) 20;(5) 169 Conole, G.(4) 179 Conovesc, L. (5) 137 Constablc, E.C. (3) 94 Contel, M.(4)293 Contrcras, R. (2)54;(6) 164 Cook, D.J. (1.111)68,77,78 Cook, J. (6)255 Cook, R.L. (6)279 Cooke, J. (2)82 Coopcr, A.C. (2)2 17,219 Coopcr, J.A. (6)253 Cooper, N.J. (1.111)40;( I N ) 16, 17;(5) 220 Corain, B. (6)333 Corchado, J.C. (2) 156 Cornils, B.(2)7;(7)59 Corradi, E.(5) 378 Corradi, M.M. (5) 156 Corrcia, J.D.G. (1 .IV) 69 Comas, R.(1 2) 20 Corrigan, J.F. (3) 1 11, 127;(4) 153; (5) 362;(9) 12 Corriglio, G. (5) 24 Corrochano, A.E. (2)33;(5) 18I Conublc, A. (12)44 Cotton, F.A. (1.11)25 Coucouvanis, D. (4) 313 Coudret, C. (6) 354 Coutinho, K.J.(2) 221 Covillc, N.J. (3) 82 Cowie, M.(3) 171;(5)380 Cowlcy, A.H.(9)21,52,64,68, 69, 104; (1 1) 72 Cox, L.R. (5) 57,59 Cox, S.R (5) 58 Crabtrcc, R.H. (2) 16;(12)22 Craig, F.J. (12) 54 Craig, R.A. (5) 285 Cramer, R.E. (2)205 Ctancll, J. (2)300 Crascall, L.E. (2) 318 Crawford, C.A. (4)3 12 Crcmer, D. (1 1) 5 Crcspo, M.(2)255,269 Crespo, 0.(10)39,414,87-89; (12) 121

455 Crkvisy, C. (5) 174;(6)96 Crispini, A. (2)274 Crittcndon, R.C. (1 1) 64,68,80 Crochet, P.(2) 109 Crociani, B.(2) 341,342;(5) 137 Crowthcr, D.J. (10)58 Cuadrado, I. (6) 302,303 Cubbon, R.(13)17 Cucciolito, M.E. (2)334 Cuenca, T.(1 .I) 73,79,85,92;(6) 26,213,229 Cuesta, A. (2) 189 Cucvas, G.(12)43 Cui, L. (8) 75 Cui, Q.(5) 114 Cui, X.L. (6)292;(13)28 Culp, R.D. (1 1) 72 Cumrnins, C.C. (1 .IlI) 63 Cundari, T.R(2) 15 1 Cunningham, A.F., Jr. (6) 329 Cunningham, D. (3)26,43;(5) 272 Curnow, O.J. (3) 154;(4)333 C u m , D.P. (7)60 Curtis, M.A. (6) 166;(10)16,26 Curtis, M.D. (3) 153, 154,174, 175;(4)318,332-335;(6)56 Cushinc, C.-D. (5) 288 Cutler, A.R.(1.IV) 45,46,53; (2) 41,46;(6) 103, 113, 134 Cterkie, D.(2)58; (6) 106 CzcMinski, C.J. (1.N)50

Daff, P.J. (1.111) 28,29;(5) 41,42 Dagorne, S. (1 .I) 89 Dahl, L.F.(3) 148, 149;(4)35, 36,42;(9) 116 Dahlenburg, M.(2) 139, 142 Dahmen, K.-H. (4) 382 Dai, S.(8) 100 DAlfonso, G. (1 .IV)32;(3)38, 91;(4) 16,63-65,346 Dam, M.A. (1 1) 83 Daniel, T.(2) 113 Daniels, J.A. (10)79 Daniels, L.M.(1 .II) 25 D d s , T.M.(5) 238 Danopoulos, A.A. (3) 1 da Piedade, F.M. (6)84 D a m , J.-C. (6) 352 DArcangelo, G.(1 2) 1 16 Darcnsbourg, D.J. (6) 130 Darcnsbourg, M.Y. (6) 130 Daridon, A. (2) 132 Damish, A.D. (5) 148 Das, A. (6)281 Das, I. (2) 170

456 Dasgupta, B. ( 5 ) 284,285 Dash, A.K. (4) 110; (5) 458 da Silva, J.L. (6) 375 D a s h , W. (4) 106,390; ( 5 ) 417 Dat, Y. (9) 22 Date, T. (5) 237 Datsenko, S. (9) 47 Daucr, B. (6) 288 Daul, C. (6) 8 Daus, W.M. (6) 382 David, M.-A. (9) 38 Davidson, J.P. ( 5 ) 367 Davidson, M.G. (6) 186; (12) 23, 74,85 Davidson, 0. (6) 301 Davies, D.A. (6) 389 Davics, D.L. (6) 397 Davies, H.M.L. (7) 40,41 Davics, J.E.(3) 172; (4) 52,53, 90, 356; ( 5 ) 347,445; (6) 5 I, 70, 73, 89, 174; (10) 2; (12) 31 Davics, M.B. (3) 15 Davics, R.P. (12) 3 1.36, 53 Davis, S.E. (5) 119, 144 Davis, W.M. ( I .I) 15; (1.111) 5759; (9) 73 Davison, A. (1 .IV) 18 Day, M. (4) 119, 120; ( 5 ) 163, 419 Dcabate, S. (4) 10,390, 391 Dcacon, G.B.(8) 1, 8; (12) 83 Dcak, J. (4) 48; (6) 252 dc Arcllano, M.C.R. (2) 271; (3) 176; (4) 39,40, 167; (6) 141 dc Azevcdo, C.G. (6) 84 Debab, J.D. (1.111) 24; (6) 9 1 de Biani, F.F. (5) 478; (6) 335; (1 1) 29 de Boer, J.L. (2) 89; (4) 26 DcBord, J.R.D. ( 5 ) 230 dc Bruin, B. (2) 220 Dc Cian, A. (1 .IV) 29; (2) 278; (5) 171 Dcck, K.J. (4) 259 Dcck, P.A. (6) 316 Dccken, A. (1 .rv)36; (4) 49; (6) 45; (9) 68; (1 1) 72 Decker, A. (4) 44 Dc Cola, L. (3) 6 Dcdieu, A. (2) 246, 247 dc Dios, A. (5) 273 Declman, B.J. (1.1) 10, 11; (12) 61 Dccmie, R.W. (6) 374 Dccming, A.J. (1.1V) 3 1; (3) 89, 129; (4) 102, 129,22 1; ( 5 ) 405,409,451; (12) 105 De Felicc, V. (2) 334

de Cicldcr, R. (2) 220 Dchncrt, U. (12) 67 Dehnicke, K. (4) 56; (13) 2, 19, 22 Dehnninger, U. (4) 273 de Jesus, E.(4) 43 de Kanter, F.J.J. (1 1) 83 de la Fuentc, J.R. ( 5 ) 483 Dclancy, M.O.(13) 7 Dclgado, E. (4) 141 Dclgado, M. (7) 33 dcl Hierro, I. (1.II) 4; (6) 244 Dclis, J.G.P. (2) 249-25 1, 3 19; (5) 116; (6) 335 Della Pergola, R. (4) 35 1 dc 10s Rios, I. (2) 138, 144; (5) 323 Dcl Rio, 1. (3) 130; (4) 133, 134, 170; ( 5 ) 364 Dclvillc, M.-H. (6) 387 Dcma, A.C. (2) 336 dc Mantauzon, D. (3) 161; (4)75, 92 Dc Maria, G. (8) 99 Deniartin, F. (3) 147 dcMatos, A.P. (6) 20 Dcmbcck, G. (1 .Ill) 66 Dcmcrscman, 13. (2) 109 Dcmonccau, A. (10) 45 Dcmsar, A. ( I 1) 62 Dcmtschuk, J. (6) 184; (8) 36 Dcmuth-Ebcdc, G.L. (1.HI) 49; ( 5 ) 52; (6) 55 Dcng, L. (2) 155,242,245; ( 5 ) 87, 108, 109 Dcng, X. (8) 82 Dcnifl, P. (6) 285 Dcnis, R.(2) 143 Denise, B. (1.IV) 62 Denisov, V.R. (4) 112; (5) 4 I 1 Denisovich, L.I.( 5 ) 38 1 Dcnkcr, M. (9) 102 Dcnmark, S.E.(2) 268; (13) 39 Dcnningcr, u. (6) 19, 178; (8) 35 Dcnnis, S.M. (9) 52 Dcnter, R. ( 5 ) 470 Dentschuk, J. (8) 50 dc Pablo, E. (2) 255 dc Patcr, B.C. (1 1) 83 Deravahion, A. (5) 374 de Renzi, A. (2) 272; (5) 120 dc Rio, I. (4) 121, 132 Derricn, N. (4) 123; ( 5 ) 422 Dc Sanctis, Y. (1.m31; (3) 89; (4) 28, 125, 139,221; ( 5 ) 409, 43 1 Dcschamps, B. (6) 299; (9) 48 DcSinionc, J.M. (2) 188

Orgationtet a l k Chemistry Dc Simonc, T. (2) 22 1; (5) 379; (6) 170 Desiraju, G.R. (4) 14 Desjardins, S.Y.(2) 323 Desmet, M.(12) 117 Desmors, P.(6) 15; (8) 15 de Souza, A-L.A.B. (5) 38 Dcur, C. (1.111) 116 dc Vrics, A.H.M. (7) 49 Dcwa, S.Z. (5) 204 DeWeerd, P.J.(5) 249 dc With, J. (1.1) 6 Dhillon, R. ( 5 ) 188 Diana, E. (4) 11,35 1; (6) 14 Dias, A.R. (6) 38,84,375 Dias, H.V.R. (1.1) 29; (9) 69 Diaz, D.J. (6) 303 Dibcncdctto, A. ( 5 ) 112 Di Bianca, F. (2) 342 Dickson, R.S. (2) 221; ( 5 ) 379; (6) 170 Dicbold, J. (6) 238 Dicgncz, M. ( 5 ) 203 Dietcr, R.K. (12) 16 Dietrich, U. (6) 222 Dictz, S.D. (6) 279 Dicz, J. (4) 290; (12) 96 Digilio, G. (13) 33 Dillon, K.R. (1.111) 42 DiMarc, M. (1 1) 9 Ding, E.-R (4) 383,385,386 Ding, F. (5) 122 Ding, L. (2) 283 Ding, M. (6) 17; (8) 13 Ding, Y.(3) 29 Dinncbicr, RE. (4) 197; (6) 187; (12) 73,80, 81 Dioumaev, V.K. (1.1) 49; (6) 237, 239 Dirk, R. (1 1) 27 Dive, P. (6) 343 Di Viara, M. (2) 289 Dixit, V. (2) 164 Dixncuf, P.H. (2) 17, 79, 132, 349,361,362; (6) 293 Djakovitch. L. (6) 224 Djukic, J.-P. ( 1 . w 29 Do, Y. (10) 48 Dobbs, D.A. (1 .HI)57, 59 Dobson, G.R. (3) 64; (5) 27 Doctorovich, F. (4) 4 DBtz, K.H. (1.111) 72,80,99-101, 122; (1.IV) 29; ( 5 ) 171,308, 309 Doherty, N.M.(4) 50; (6) 44 Dohctty, S.(3) 109-112; ( 5 ) 359362 Doig, M. (8) 113

A uthor Index Dolgushin, F.M. (2) 90; (3) 169; (4) 107, 108, 112, 137, 195, 202,205,206,237,238,389, 398; ( 5 ) 41 I, 428,452,480; (10) 33,55 Domarir, 0. (6) 343 Domingos, A. (6) 18; (8) 12 Don, M.-J. (6) 146 Donaghy, K.J. (1 0) 37 Donaldson, W.A. (2) 57; (5) 284288

Dong, T.-Y. (6) 312 Dong, X.-W. (4) 159 Dong, Y.-B. (3) 151; (4) 384; (6) 54 Donkcrvoort, J.G. (1.1) 10, 11 Donnadicu, B. (I.I) 52,54,55; (1 .II) 2 1; (5) 306,342; (6) 225; (9) 23,SO-82 Donncrs, J.J.J.M. (2) 220 Donovan-Merkert, B.T. (6) 173 Doris, E. (9) 99 Dormann, E. (6) 259 Dormond, A. (6) 15; (8) 5, 15 Dornbcrgcr, E. (8) 1; (12) 83 Dorsselaer, A.V. (6) 390 Dosa, P.I. (7) 53 Dossctt, S.J. (1 .N)40; ( 5 ) 223; (6) 98 Dowbcn, P.A. (10) 10 Downcy, J. (6) 316 Downs, A.J. ( 5 ) 44; (I 1) 65 Drabnis, M.H.(4) IS, 33 Drake,S.R. (4) 179 Drciss, A. (5) 40, 389 Drescher, C. (1 1) 25 Drew, M.G.B. (6) 291,320 Drcw, M.J. (6) 364 Dricdigcr, J. (4) 15 1 Dricss, A. (1 X I ) 46 Driver, M.S. (2) 3 16; (6) 272 Drommi, D. (5) 130 Dronsficld, A.T. (2) 178 Druker, S.H. (3) 175; (4) 334, 335; (6) 56 Drumrnond, A.M. (12) 71 Druzhkova, O.N. (8) 68; (12) 98 Du, B.-S.(6) 274 Duan, J.P.( 5 ) 121 Duartc, M.T.(6) 84 Duatti, A. (6) 284 Dubberley, S.R.(12) 75 DuBois, M.R. (6) 79 Duchateau, R.(8) 60,61; (1 I) 17 Duczmal, W. (5) 199 Dudcrstadt, R.E. (6) 363 Duemichcn, U. ( I 1) 41 Ducr, M.J. (6) 186; (12) 85

Diirr, M. (6) 1 1 1 Ducslcr, E.N. (I.HI)32 Duff, P.J.(6) 72 Dujic, T.J.-P. (5) 171 Dullaghan, C.A. (I.IV) 30; (5) 216,217,222; (6) 386 Dumitrcscu, I.S.(9) 121 Dumitrescu, L.S. (9) 121 Dunbar, L. (12) 31,54 Duncalf, D.J. (I.IV) 28; ( 5 ) 156 Dunn, S. (6) 37; (10) 47 Dunwoody, N. (2) 186; (3) 34 Dupuis, A. (6) 352 Dupuis, L. (1.I) 53.54; (9) 80,8 1 du Toit, A. (2) 3 12; ( 5 ) 392 D'yachov, P.N. (4) 279 Dykcr, G. (2) 19 Dyson, P.J. (3) 126, 135; (4) 143, 168, 172, 176, 178; (5) 424, 448,465,467; (6) 136,334 Eaborn, C. (I1) 52;(12) 33; (13) 14 East,M.B. (7) 18 Eaton, P.E. (I 2) 3 Ebcrlc, T. ( I .I) 24 Ebcrt, K.H. (9) 102 Echarri, R. (5) 203 Echavarrcn, A.M. (2) 131,293 Eckcnrath, H.J. (4) 263,264; (6) 151; (10) 15; (11) 32 Eckcr, A. (9) 105; ( 1 1 ) 65 Eckcrt, M. (7) 22 Eckcrt, R. (5) 212 Edclbach, B.L. (2) 193; (6) 150 Edclmann, F.T. (8) 1,29,53, 55, 56, 112; (12) 83 Edclstcin, N.M. (8) 112 Edcren, T. (1 .HI)33; (1 .IV) 27 Edwards, A.J. (2) 240,355; (3) 94, 108; (4) 146,265; (5) 185; (6) 67 Edwards, D.A. (4) 292 Edwards, J.P. (2) 268 Egli, A. (4) 66 Egncr, J. (9) 98 Egold, H. (4) 373 Eguchi, T. (4) 27 I Ehlc, M.(3) 48; (9) 40 Ehlcnz, R. (1.111) 100, 101 Ehlcrs, A.W. (3) 22 Ehlietcr, Y.(9)105 Eichler, U. (3) 60 Eilbract, P. ( 5 ) 239 Eilton-Ely, J.D.E.T. (2) 146 Einstcin, F.W.B. (I.IV) 51; (2) 200; (3) 97,98; (4) 29,235;

457 (5) 175; (8) 65 Eintracht, J.F. (10) 24 Eiscnmann, J. (9) 62 Eisenstadt, A. (7) 18 Eisenstcin, 0. (2) 37.38, 127; (3) 56 Eisfcld, W.(9) 18 Elding, L.I. (2) Z 6 , 3 10; (9) 108 Elduquc, A. ( 5 ) 188 El Firdoussi, L. ( 5 ) 386 Elipc, S. (3) 95, 108 Ellermann, J. (12) 70 Ellert, O.G. (1 .I) 57; (4) 400 Ellis, J.E. (6) 377 Elschcnbroich, C. (5) 262; (6) 40, 373 Elscgood. M.R.J. (2) 74; (3) 109112; (5) 359-362; (1 1) 12 Elscvicr, C.J. (2) 89,280,281, 338; (4) 26; (5) 206 El-Shehwy, A.A. (1 1) 1 Emclhs, H.J. (13) 49 Emclyanova, N.S.(8) 69 Emrich, R. (1.111) 26; ( 5 ) 26 Endcrs, D. (2) 70; ( 5 ) 22, 194, 289; (6) 395 Endo, T. (5) 11 1,252 Engel, P.F. (1.111) 91; (4) 264 Englcrt, U. (1.1) 30,78; (4) 263; (5) 70; (6) 121, 151,233,369, 370; (10) 11-13, 15; (11) 16, 18,32 Englich, U. (12) 76 Enkclmann, V. (6) 3 IS Enright, G.D. (4) 89, 141, 151, 152,363; ( 5 ) 443,449 Ephritikhinc, M. (6) 189; (8) 70 Eppingcr, J. (8) 37 Erabi, T. (9) 93 Erbert, K.H.(9) 119 Erbstein, F. (6) 184; (8) 36,38 Eremcnko, I.L. (4) 9,81,339,400 Eremcnko, N.K. (4) 284 Erhelmann, V. (5) 253 Erickson, L.E.( 5 ) 122 Eriksson, H.(4) 288,289; (12) 92 Eriksson, L. (5) 37 Erker, G.(1.I) 28,33,35-37, 6268.94.95; ( 5 ) 160-162,302, 338,339; (6) 183, 197,209, 214,220; (1 1) 22; (12) 49 Emst, R.D.(2) 48; (5) 294 Emsting, J.M. (2) 202; (5) 198 Ershova, V.A. (4) 216 Eskelrnann, V. (5) 470 Espcnson, J.H. ( 1 . N ) 66,67 Espinct, P. (2) 252; ( 5 ) 135 Espinosa, E. (6) 283

458 Espinosa-Garcia, J. (2) 156 Espinoza, G. (1.111) 11 1 Espitia, D. (4) 119 Esprinosa, P.G. (6) 358 Estcruelas, M.A. (2) 69, 107, 121, 123, 124, 129,228,234; (3) 46, 95, 108; ( 5 ) 71,79, 80,86, 185, 186,201,202, 326; (6) 132 Estroff, L.A. (5) 273 Eticnnc, M.(1.11) 2; (5) 306 Eujen, R. (12) 99 Evans, W.J. (6) 13,20; (8) 31,51 Eveland, J.R (3) 121; (4) 78,79, 88 Ewart, S.W. (1 .I) 75,76; (6) 32 Ezcrnitskaya, M.G.(4) 108,398; (8) 88 Fabbin, D. ( 5 ) 404 Fabrc, S.(2) 5 1 Fabrizi de Biani, F. (6) 326 Faccy, G.A. (2) 263; (4) 34 I Faggi, C. (4) 22 Fagin, A.A. (8) 50,5 1 Fajardo, M.(1.11) 3,4,20; (5) 304; (6) 46,243,244 Fallon, G.D. (2) 22 1; (5) 379; (10) 82 Falloon, S.B. (1 .IV) 42, 43; (4) 207,208; (5) 407 Falvello, L.R. (2) 259,277,279, 317,333; (3) 73, 146; (4) 281; ( 5 ) 436,473; (6) 60 Fan, H.-T. (4)80 Fan, J.4. (1.111) 43,44; (5) 5 I Fan, M.-F. ( 5 ) 299 F a h ~ hF.J. , (1.111) 79, 131, 132 Fandos, R (1.1) 93; (6) 215 Fang, X.(5) 240 Fantacci, S.(1.111) 14 Fanwick, P.E. (1.1) 2, 5 ; (1.11) 14, 27; (I .IV) 38,39; (3) 5 1, 88; (4) 186; (5) 263; (6) 171 Farnctti, E. (2) 207 Farrar, D.H. (3) 133; (4) 163 Farrugia, L.J. (3) 18, 156; (4) 12, 326; (5) 463 Fattuoni, C. (12) 20 Faurc, R. (6) 27 Fauscher, A . M . (2) 268 Fawcett, J. (2) 320; (6) 88,346, 397; (9) 92 Fawzi, R. (1.IV) 26; (2) 68; (6) 24 1

Faza, N. (4) 56 Fedushkin, I.L. (8) 50,s 1

Organometallic Chemistry Fchcr, R. (6) 256; (9) 45 Fehlner, T.P. (3) 58; (4) 249-25 1, 259,33 1; (6) 85 Feichtinger, D. (2) 158 Feikcn, N. (2) 52; ( 5 ) 247; (6) 392 Felernan, M.(6) 259 Feisberg, R. (6) 76 Feng, D.-F. (4) 302 Fcng, X.(2) 75 Fenske, D. (1 .IV) 25; (4) 44,45, 260; ( 5 ) 457; (9) 61,62, 85 Fercmia, S.(2) 171 Ferguson, G.(2) 299; (5) 207; (10) 53 Fcrhati, A. (1.111) 16; (5) 43 Fcringa, B.L. (7) 49 Fcmanda, M.(1.IV)1 1 Fcmandcz, E.J. (12) 108 Femandez, F.J. (1.1) 91, 92; (6) 213 Femandez, M. (1.111) 119 Femindez, S.(2) 277,279,333; (5) 436,473 Fcmindcz-Accbas, A. (1 .lH) 127 FcmandczGalcn, R. (6) 306 Fcmandez-Rivas, C. (2) 293 Ferrand, V. (1XI) 87; (3) 168; (4) 122, 123, 158,359; (5) 421, 422 Ferrcira, D. (12) 89 Fcrrcncc, G.M.(4) 186 Ferrer, M. (3) 152; (4) 375 Fcrri, 1. (6) 370 Ferstl, W. (5) 322 Fcttinger, J.C. (4) 372; (5) 33; (6) 53,80,374 Fiedlcr, A. (2) 26; (5)54 Fiedlcr, C. (7) 55 Fiedler, D.A. (6) 3 13 Fiedlcr, W. (9) 10 Field, J.S. (6) 142 Field, L.D. (2) 42, 145; (6) 313 Ficld, R.J. (4) 213 Ficldhouse, R.(7) 42 Filippou, A.C. (1 .III) 61,62 Filippov, 1. (1.II) 3 1 Fill&, J.-L. (6) 304 Finch, A.G. (6) 5 1 Findcis, B. (12) 103 Finkc, R.G. (2) 165; (5) 441 Finn, M.G.(1.11) 11; (6) 42; (10) 27 Firth, A.V. (4) 46 Fischer, C.(5) 301 Fischcr, H. (1 MI) 84, 85; (1.W) 24; (2) 20 Fischer, J . (1.111) 91; (1.IV) 29; (2) 104,278,348; (3) 1 IS; (4)

76, 193; ( 5 ) 69, 171,232; (6) 9, 128 Fischer, P. (8) 109 Fischer, R. (1.I) 50; (5) 34 1 Fischcr, R.A. (6) 2,357; (1 1) 63, 79,85 Fischcr, R.D. (8) 45,46 Fischer, R.W. (1 .IV)64 Fischer, T.S. (6) 3 16 Flack, K.(7) 35 Flcischcr, R. (2) 233; ( 5 ) 482; (6) 317;(11)46,77 Fleming, F.F. (13) 6 Florke, U. (4) 67,24 1,373 Flood, T.C. (2) 197 Flores, F.X. (1 .Ill) 7 Florcs-Pa- A. (1 2) 42 Florez, J. (1.111) 127 Floriani, C. (1.1) 18, 20; (1.111) 14; (1.W) 23; (2) 24,352,353; (5) 209; (6) 371; (12) 93 Floris, C.(12) 20 Flower, K.R. (5) 1 Fluck, E.(9) 58 FBrsterling, F.H. (4) 252,254,255 Fiirtsch, W.(2) 356; (5) 63,275 Fogel, L.E. ( 5 ) 249 Fokken, S.(1.1) 3 Folting, K.(1XI) 55; (2) 2 19; (4) 55; ( 5 ) 348; (6) 63 Fong, B.S.(5) 100 Fong, R.H. (3) 157; (6) 1I9 Font-Bardia, M. (2) 269,284; (6) 262,287,307 Fooladi, E. (2) 182 Foos, E.E.(9) 111; (1 1) 76 Ford, P.C. (1.IV) 5; (2) 8, 187; (3) 31 Forde, C.E. (3) 92 Foresti, E. (2) 29 Fomib, 1. (2) 258,259,333,339, 340; (3) 146; (4) 281; (5) 404, 436,473475; (1 1) 97 Forrestal, K.J. (8) 3 1 Forsyth, C.M. (8) 8 Fort, A. (2) 100 Fort,Y.(12) 1 1 Fortuiio, C. (3) 146; (4) 281 Fox, M.A. (10) 23,66,67 Fox, P.A. (1.11) 26; (6) 372 Fox, T. (1 .I) 62; (5) 302; (1 1) 22 Foz, S.B.(12) 111 Fmanje, J. (2) 39; (4) 192,342; (5) 116; (6) 335 Francheschi, F. (5) 209; (12) 93 Francis, M.D. (9) 7, 74,75,77 Francisco, L.W. (5) 318 Franco, R.J. (4) 116,121; (5) 364

A ulhor Index Frank, W. (6) 367 Franken, A. (10)61-64 F m t z , R (1.11)21;(5) 342 Franzini, L. (12) 13.14 Frapper, G. (4)6,89, 166; (5) 443,453,462 Fraser, G.C. (6)347 Frascr, S.L.(2)260 Frediani, P. (2) 180;(3) 132;(4) 22, 147 Freedman, D.A. (6) 143 Freeman, D.L. (11) 92 Freeman, G. (3) 136;(4) 160 Freiser, B.S. (5)56;(8) 101 Freni, M.(3) 38;(4) 63 Frenkel, A.I.(4)395 Frenking, G. (1.111) 11; (1.IV) 41; (3)21,22;(5) 5; (6)2;(1 1) 63 Frcssignk, C. (12)44 Friedrich, J. (5)470;(6)315 Frisell, H.(5) 37 Fritz, C.(1.1)28;(12) 17 Frohlich, R.(1.1)28,33,35,37, 62-65,67,68,94,95; (1.111) 108, 109, 112,113;(5) 160162,302,338,339;(6)34, 183, 197,209,214,220;(10) 61;(11) 22; (12)4,49 Frohner, W. (5) 242,244 Frocsc, R.D.J. (2)241 Frohn. M.(5) 295 Frohnapfcl, D.S.(3)73;(5) 53 Fruehauf, H.-W. (1.111)2; (2)2; (5) 21; (6)5 Fry, A.J. (7) 9 Fryzuk, M.D.(1.111) 51; (8)43 Fu, G.C. (6)382;(7) 52-54;(1 1) 799 Fu, P.F. (1 .I) 3 1;(6)29 Fu, T.Y. (5) 191 Fu, W.-F. (3)63,68 Fuchita, Y. (2)275 Furstner, A. (7)3 1 Fujika, E.(2) 160 Fujisawa, T.(13) 5 Fujita, H.4. (2)367 Fujita, K.-I. (5) 403 Fujiwara, F.Y. (3) 144;(4)268 Fujiwara, T.(13)40 Fukin, G.K. (6)368;(8)52,68; (12) 98 Fukita, N. (1.IV) 13 Fukumoto, H.(8) 54 Fukumoto, M.(4) 181 Fukumoto, Y.(7)23 Fukunishi, Y. (5) 151 Fukuoka, A. (2)45,56;(5) 76 Fukuta, Y.(4)392

459 Fulde, P. (8) I1 3 Fuller, J.L. (6)336 Fulton, G.D. (6) 170 Fumagalli, A. (4)34 Fung, A S . (4)345 Fung, E.Y. (4)300 Fwg, W.K.-M. (4)291,399;(12) 94,95,104 Furenlid, L.R.(2) 160 Furrer, A. (8) 109 Fusek, J. (10)20,21,63 Fusto, M. (2)322;(5) 150 Futtcrcr, T. (12) 100 Gabbai, F.P. (4)308;(1 1) 57,90, 93,94;(12) 122 Gabel, D.(10)92 Gable, K.P. (1.IV)4 Gabor, B. (5)259,260 Gade, L.H. (3) 25;(4)299;(12) 103 Gaede, P.E. (2)214;(4) 100,176; (5) 256,425 Gacrtncr, P. (7)7 Gagliardini, V. (6)385 Gailus, H.(6)253 Gal, A.W. (2)220 Galakhov, M.(1.1)79,85;(6)83, 229 Galan, A. (2) 13 I Galan, R.F. (5) 483 Galassi, R. (4)372 Galhdo, A. (1.111) 60;(5) 29 Gallacher, M.L.(1 .HI)104 Gallagher, J.F. (2)299;(5) 207 Gallagher, S.(6)41 Gallegc-Planas, N.(3)56 Galloy, J.J. (10)2 Galswotthy, J.R (4) 117, 149 Galuzina, T.V. (4) 387;(5) 442 Galvao, A.C. (6)38 Galvao, A.M. (6)38,84,375 Gamasa, M.P. (2) 108, 109, 128, 130, 135;(4)290;(6) 116; (12)96 Gambaro, A. (3) 155;(5)391 Gambarotta, S. (1.11) 16 Gambs, C. (4) 123;(5)422 Gamelas, C.A. (6)84 Gamusa, M.P. (1 .lIl) 60 Gancsh, P. (5) 371 Ganis, P. (5)391 Ganis, S.(3) 155 Gansiiucr, A. (1 .rv)65 Gantcr, B. (1.1) 30;(3)45;(6)78, 121, 168,233,264,318;(9) 44;(10)11, 14

Ganter,C. (3)45;(6)264,311 Ganter, R.(6)31 1 Gantzel, P.K. (5) 100 G ~ o ,W.-Q. (4)314 Garces, A. (6)46 Garcia, G. (3)72 Garcia, M.E. (3) 71-73,78;(6)60, 82 Garcia, M.P. (2) 189 Garcia, V. (5) 200 Garcia-Gmda, S.(1.111)79, 107, 130;(1.IV) 33;(2) 108, 109, 128, 130;(3)85, 130;(4) 133, 134,290,320;(6) 116;(12) 96 Garcia-Mellado, 0. (1 .HI)1I 1; (2) 118;(5) 64,234 Garcia-Rio, L.(1XI) 7 Garcia-Yebra, C. (1 .II) 20;(5) 304 Garcia-Yuste, S.(6)243 Garde, R.(2) 317,340 Gardiner, M.G. (10)82;(12) 32; (13) 18 Garjc, S.S. (9)88 Garlaschclli, L. (4)33,35 1 Garlitz, F. (6)25 G a d d a , M.A. (5) 200 Garrett, C.E. (7)52 Garrido, J. (4)293 Garrone, E.(4)391 Garst, J.F. (13) 3 Gasanov, R.G. (4)389 Gassrnan, P.G. (3) 118;(4)193; (5) 232;(6)128 Gateau, C.(5) 280 Gatehouse. B.M.(8)8 Gates, B.C. (4)345 Gates, D.P. (1 1) 27 Gauss, C.(2) 141, 147;(5) 321 Gauter, B. (5) 70 Gauthcron, B. (6) 196,203,230 Gauthron, I. (4)278 Gavrilova, E. (2)302 Gazard, P.A. (6)65 Gebert, S. (2) 12;(4)396 Geib, S.I. (1.111) 54;(1.IV)16, 17; (5)220 Geier, S. (5) 180 Geiger, D.K. (3) 15 Geiger, W.E.(4)252 Geisbaucr, A. (1.111) 88 Geisbcrgcr, M.R. (1.N)69 Geiser, U.(12)1 1 1 Geissler, H.(7)22 Gelan, J.M.J.V.(13) 6 Gclas, J. (5) 28 1 Gclbrich, T.(6)76;(1 1) 41 Gemcl, C. (2)112;(5) 248,291,

460 292 Gcnin, H. (9) 97 Geofioy, M.(9) 25 Geoffroy, P. (5) 276-278 Georg, A. (5) 350 George, A.J. (6) 343 George, A.V. (2) 145 George, M.W. (2) 32; (3) 23,32, 33; (4) 187; (6) 93 George, T.A. (5) 230 Gcrbase, A.E. (6) 271 Gerhards, F. (2) 282 Gerisch, M. (2) 288; (5) 298,335 Gcrlach, C.P. (1.11) 6, 7 Gerold, A. (12) 88, 91 Gcrvasio, G. (2) 238; (3) 120; (4) 73;(5) 408 Gcvcrt, 0. (2) 113,227,232; (5) 325,329 Ghose, S. (4) 85,3 17; (6) 77 Ghosh, P. (2) 66,67 Ghosh, S. (3) 115, 116, 122; (4) 142; (5) 446 Giannini, L. (1.1) 18-20; (2) 352 Giannini, M. (2) 276 Giannoccaro, P. (5) 112 Gibbons, M.N. (9) 103,117, 118, 121 Gibson, D.H. (1 .IV) 47; (3) 105; (6) 105 Gibson, M.T. (3) 118; (4) 193; ( 5 ) 232; (6) 128 Gibson, S.E. (5) 235; (7) 34 Gibson, V.C. (1.111) 42; (6) 67; (7) 34,35; (11) 12; (13) 12 Gidden, J. (5) 154 Giclen, H. (2) 70; ( 5 ) 194; (6) 395 Giclen, R. (1 1) 8 Gicssncr-Prcttre, C. (12) 44 Gigmcs, D. (9) 42 Gill, L.J. (4) 321, 322; ( 5 ) 406 Gill, T.P. (6) 143 Gillctt, D.(8) 98 Gillis, D.J. (1.1) 74 Gil-Sanz, R. (1.11) 3 Gimeno, J. (1.111) 60; (2) 108, 109, 128, 130, 135; (4) 290; (6) 116; (12) 96 Gimcno, M.C.(4) 293, 305; (10) 39, 4144,87-89; (12) 106, 108, 119,121 Gindetti-Grcpt, R. ( 5 ) 23 1 Giordano, F. (2) 322; (5) 150 Giordano, R. (4) 10, 128, 390, 39 1; (5) 426 Girard, L. ( I .IV) 36 Girolami, G.S. (1 .I) 42; (5) 265, 387,450

Orgatlometallic Chemistry Gislcr, A. (2) 122 Giusti, M.(2) 352 Gladiali, S. (5) 404 Gladysz, J.A. (1 .IV)41-44; (2) 190; (3) 42; (4) 207,208; ( 5 ) 407; (6) 95, 101; (7) 63 Glass, W.K. (3) 69,70; (5) 214 Gleitcr, R. (2) 48; ( 5 ) 11,254, 294,389; (6) 87 Glendcnning, L. (2) 207 Glewis, M. (2) 285 Glidewell, C. (6) 290,319 Glinsbockcl, C. (6) 3 11 Gloeckle, A. (1 0) 18 Glorian, G. (6) 343 Glowiak, T. (4) 272; (5) 178; (6) 179 Glucck, D.S.(9) 38 Glushove, D. (2) 84 Gmcinwicser, T. (6) 326; (1 1) 29 Gobctto, G. (13) 33 Gobctto, R.(4) 106, 119, 120, 212; ( 5 ) 417,419 Goddard, R (4) 253; ( 5 ) 110, 180, 193; (6) 147 Godfrcy, P.D.(10) 83 Gocller, A. (9) 40 Gocrlich, J.R. (9) 69 Gocrlitzcr, H.W. (1 1) 94 Giirls, H. ( 5 ) 33 1,472 Gogoll, A. (5) 141 Gogovancva, I.F. (5) 442 Gokcl, G.W. (6) 33 1 Goldbcrg, I. (2) 58;(6) 106 Goldberg, K.I. (2) 261 Goldhss, B. (6) 139; (12) 51,56, 87 Goldsmith, S.L. (3) 118; (4) 193; ( 5 ) 232; (6) 128 Gollcr, A. (3) 48 Golovaneva, I.F. (4) 387 Golovin, A.V. (4) 215,2 16 Golubinskaya, L.M.(1 1) 81 Golubovskaya, E.V. (4) 214 Gomcs, P.T. (1.11) 8,24; (6) 47 Gomcz, A.V. (2) 107 Gomcz, G. (1 1) 97 Gomcz, J. (2) 339 Gomcz, R. (1.1) 73; (1 .II) 3; (6) 26 Gomcz, S. (6) 149; (10) 51,52 Gomez-Elipc, P. (6) 321 Gomcz-Garcia, R.(6) 83 Gomcz-Sal, P. (1 .I) 73, 85, 9 1, 92; (1.11) 20; (3) 159; (4) 43, 91; (5) 304; (6) 26,83,213,229 Gomez-Saso, M.A. (2) 258 Goncalvcs, I.S. (6) 84 Gondrum, R. (6) 373

Gontcharov, A.V. (5) 219 Gonzalez, J.J. (2) 131 Gondlez, J.M. (12) 58 Gonzalez, R. (1 X I ) 131 Godlcz-Bernardo, C. (2) 128, 135 GowIcz-BI~~co,0. (3) 19, 20; (5) 271 Gonzailez-Herrero, P. (4) 306; (12)

107 Gooben, L.J. (2) 347 Goodson, F.E.(2) 254 Goodwin, N.J. (6) 346 Gooscn, M. (2) 280 Goosscn, L.J. (2) 14; (3) 175; (4) 334 Gorbunowa, E. (9) 58 Gordon, G.J. (1.I) 5 1 Gordon, J.C. (8) 6 Gorrcll, I.B. (1 1) 52 Gossagc, R.A. (6) 23 1 Goto, H. (6) 219 Goubitz, K. (2) 39; (4) 192,342; ( 5 ) 116; (6) 335 Gouygou, M.(6) 352 Gouzyr, A.I. (1.11) 10; (1 1) 35 Govindaraj, A. (6) 365 Grachova, E.V.(4) 112; ( 5 ) 4 I 1 Graf, D.D. (6) 378 Graf, M. (4) 130,354,355 Grahani, A.I. (1.111) 23; (2) 64; (6) 74 Graiff, C. (4) 83,247 Gramlich, V. (4) 66; (5) 385; (6) 328 Grandjean, D. ( 5 ) 366 Grant, B.E. (5) 88 Graquinta, D.M. (6) 295 Graupncr, R. (1 1) 88 Gravcny, J.A. ( 5 ) 173 Gray, T.G. (10) 24,28 Graziani, M. (2) 207 Grcatrex, R (10) 23 Gred, R. (5) 174,282; (6) 96 Grecn, J.C.(2) 343; (6) 7 1 Green, J.R ( 5 ) 61 Grccn, M. (1 .IV) 40; (5) 39,223; (6) 98 Green, M.J. (2) 282 Grcen, M.L.H. (1.11) 8,24; (1.111) 23; (2) 64; (3) 1; (6) 47,48, 64, 74,248,250, 253,255, 370 Grcenbcrg, H. (5) 141 Grecnc, J.B. (1.111) 104 Grccnc, T.M. (5) 44 G r e g , B.T.(1.N) 53; (2) 41; (6) 113

Author Index Grcgorio, J.R.(1.IV) 62 Grehl, M. (6) 214 Grellier, M.(5) 139 Grenzer, E.M.(7) 26 Grepioni, F. (2) 12; (3) 125, 144; (4) 13, 14, 101, 121, 143, 144, 170, 177, 178,268,396; ( 5 ) 364,423,448,467,472 Griffith, W.P. (3) 1 Griffiths, D.G. (2) 308 Grigg, R.(7) 25,57 Grigsby, W.J. (10) 83 Grills, D.C.(6) 93 Grimes, R.N. (1.11) 11; (6) 42, 166; (10) 16,26,27 Grimmc, W. (5) 187 Grishin, Y.K. (6) 249 Grissom, C.B. (2) 179 Grobe, J. (9) 17 Grocn, J.H. (2) 249,250; (5) 138 Gros, P. (12) 11 Gross, L.M. ( 5 ) 280 Grosscl, M.C.(6) 334,336 Grossrnann, B. (6) 300 Groth, U.(8) 84 Grotjahn, D.B. (12) 37 Grow, D.M. (1.11) 12, 13, 19, 28; ( I N ) 68; (12) 61; (13)26 Grubbs, R.H. (2) 363,364; (7) 30 Gruber. L. (1.111) 6 1 Griiner, B. (10) 21 Griinwald, C. (4) 306; (12) 107 Gruscllc, M.( 5 ) 377 Grushin, V.V. (2) 260,263; (4) 34 1 Grutcr, G.J.M. (8) 14 Grzgorzewski, A. (2) 368; (5) 393,395; (6) 92 Gu, Z. (5) 28 Guadanama-Perez, C. (12) 42 Gum, J. (8) 45,46 Guardigli, M.(5) 209; (1 2) 93 Gubin, S.P. (4) 214,352,387; (5) 442; (10) 8 1 Gudat, D. (12) 50 Gudat, G. (9) 4, 34 Gucn, F.R.-L. ( 5 ) 376 Gucnnou, K. (2) 86,87; (4) 19; (5) 444 Giinthcr, H. (12) 4 1 Giinthcr, K. (9) 59 Guerchais, V. (2) 355,360 Gucrin, C. (1.11) 21; ( 5 ) 342 Guerin, F. (1.1) 12 Gucrrct, 0. (9) 3 Guesmi, S.(2) 79, 132 Guest, M.F. (1.111) 14 Gucumi, S. (6) 293

46 1 Guibc, F. (5) 23 Guillcmin, J.-C. (5) 174; (6) 96 Guillevic, M.-A. (2) 117, 190; (6) 109 Guillon, C. (5) 226 Gulbis, J.M. (4) 379; ( 5 ) 413 Guldi, D.M. (6) 3 14 Gullcvic, M.-A. (3) 44 Gunnoc, T.B.(14 1 ) 64, 65,7 1, 89; (5) 316,317,349 Gunzner, J.L. (7) 7 GUO,A.4. (2) 214 Guo, L. ( 5 ) 330 Guo, S.(5) 288 Gupta, B.D. (2) 164, 166, 168, 170 Gupta, H.K. ( 5 ) 346; (6) 376 Gupta, M. (2) 205,206 Gurttard, J. (6) 390 GUS,A.-L. ( 5 ) 256 Guscv, O.V. ( 5 ) 68,381; (6) 138 Gustafsson, M. (6) 222 Gutierrez, E. (5) 105 Gutierrez-Pcrcz, K.(1.111) 1 11; (2) 118; ( 5 ) 64,234 Guttcnbcrger, C. (8) 110 Guzci, I.A. (2) 106; ( 5 ) 295; (6) 123 Gycpcrs, R. (2) 362; (6) 202 Ha, Y. (5) 152 Haak, S. (3) 168; (4) 156,359; (6) 398 Haaland, A. (6) 71 Haarrnan, H.F.(2) 202; (5) 198 Haasc, D. (4) 94 Haase, W. (4) 24 1,249 Habata, Y. (6) 345 Habcr, S.(9) 40 Hadida, S.(7) 60 Haener, J.L. (2) 8 1; (5) 358 Hacttel, S.(8) 104 Hafa, H.E. ( 5 ) 377 Haga, M.(4) 104 Hagadom, J.R. (1 .I) 7; (6) 360 Hagcn, C. (2) 205 Hagen, H. (1.11) 12,28 Hagen, J. (4) 273; (6) 61, 178 Hagenan, V. (5) 394 Haggitt, J. (1.111) 23; (2) 64; (4) 173; ( 5 ) 466; (6) 74 Hahn, C. (5)90 Hahn, F.E. (1.1V) 19 Haiduc, I. (9) 121; (13) 30 Haincs, R.J. (4) 186; (6) 142 Hairc, G.R (3) 94 Hajcla, S.(4) 119, 120; (5) 419;

(8) 64 Hhnsson, M.(4) 288,289; (12) 92 Halet, J.-F. (4) 6, 166; (5) 453, 462 Halfcn, J.A. (1 1) 73 Hall, C.D. (6) 330 Hall. H.K., Jr. (6) 347 Hall, M.B. (2) 149, 153; (5) 94, 170 Hallbcrg, A. (7) 60 Halldorsson, S. (4) 45; (6) 30 Hallcnbcck, S.L. (5) 155; (8) 28 Haltcrman, R.L. (6) 199 H m m , B.C. (7) 4 Hambley, T.W.(2) 42, 145 Hamcd, 0. (5) 123 Hamilton, D.G.(6) 336 Hammer, M.S.(4) 48; (6) 252 Hamor, T.A. (2) 223; (3) 119; (4) 87 Hampcl, F. (2) 356, 357; ( 5 ) 63, 274;(12)51,56 Hanm, M.S.A. (2) 177 Han, B. (2) 94 Han, B.-S. (4) 3 14 H a , L.-B. (2) 304 Han, R. (2) 292 Han, Y. (2) 155; ( 5 ) 87 Hanks, T.W.(6) 325 Hannon, M.J. (3) 14 Hansen, L. (2) 162, 172 Hanscn, T. (7) 40,41 Hanscn, V.M. (3) 98 Hanson, G.R (12) 60 Hanson, L.G. (1.11) 14 Hanusa, T.P. (6) 185, 194,363; (8) 2; (12) 79 Hanzawa, Y. (5) 164 Hao, J. (4) 163 Hao, L. (4) 286, 347 Haquette, P. (2) 132,227; (5) 325 H a d , H. (1.N) 9 Hamda, S.(5) 164 Harada, T. (13) 40 Harakas, G.N. (4) 1 I5 Harbach, 1. ( I 2) 38 Hardcastlc, K. (4) 119, 120; ( 5 ) 419 Harder, S.(13) 15, 16 Hardie, M.J. (5) 36 Harding, I.S.(1 1) 36, 84 Harding, R.A. (4) 271 Harker, R.M.(4) 292 Hiirkiincn, A.U. (3) 170; (4) 25, 360 Harlan, C.J. (1 1) 50,51 Harling, J. (5) 366

462 Harman, W.D. (2) 369; (5) 20,Xl85 Harmjanz, M. (4) 94 Harms, K. (5) 262; (6) 7, 40; (9) 87; (12) 52 Hamman, A. (6) 181 Hams, J.D. (4) 47 Harris, P. (2) 209 Harris, S. (2) 22,23, 150; (4) 7, 93; (6) 152 Hams, T.A. (3) 39 Harrison, R.M. (10) 77; (13) 27 Harrison, W.M. (3) 104; (6) 117 Hamty, J.P.A. (1.111) 105, 106 Harrcd, J.F. (1.1) 49; (6) 218,237, 239 Hartbaum, C. (1 .HI) 84; (1.IV) 24; (2) 20 Hartl, F. (1 .IV) 34; (3) 84, 103; (5) 206 Hartl, H. (2) 368; ( 5 ) 393 Hartung, H. (3) 61 Harhvig, J.F. (1.1) 96; (2) 316; (6) 272; (7) 4, 9, 15 Harvey, P.D. (4) 278 Hascgawa, M. (4) 274,275 Hasegawa, T. (5) 78 Hash, K.R. (4) 118,213 Hashiguchi, S. (7) 43 Hashmi, A.S.K. (2) 297,298 Haso, J. (3) 133 €lassan,A. (9) 100; (1 1) 48 Haszeldine, R.N.(13) 49 Hatanaka, Y. (11) 15 Hattcrsley, A.D. (4) 357 Halibrich, S. (1.11) 21; (1.111) 52; (5) 342 Haupt, H.-J. (4) 67, 241, 373 Hautot, D. (4) 249 Havighurst, M.D. (4) 276,277 Hawkes, S.A. (13) 14 Hawhomc, M.F. (10) 33,65 Hayakawa, T. (8) 73,74 Hayase, S. (9) 93 Hayashi, R.K. (1.IV) 50; ( 5 ) 173 Hayashi, Y. (2) 137; (5) 236,441; (6) 296 Hayner, M.W. (3) 39 Hays, M.L. (6) 363 He, L. (4) 244 Hc, M. (2) 330 He, T. (6) 313 (I.IV) 51, 52; ( 5 ) 175, Hc. Y.-X. 176; (6) 102 Hmly, P.C. (4) 338; ( 5 ) 439; (6) 165 Heard, P.J. (2) 309 Hcath, G.A. (2) 99,325,326; (4)

Orgartometallic Chemistry 1114; (i2) I14 Hcaton, B.T. (4) 271 Hecht, E. (1 1) 4 1 Hccht, J. (1.111) 113 Heck, J. (1,111) 85; (5) 394 Hcckmann, G. (9) 58 Hcdingcr, R.(4) 66 Hcgcdus, L.S.(1.111) 8, 98, 116; (2) 5; (3) 13; (7) 37 Hegcmann, M. (9) 17 Hegctschweiler, K. (4) 66 Heidel, H. (5) 195 Heidcn, M. (2) 330 Heinckcy, D. (5) 93 Hcinemann, F.W. (2) 239,288; (5) 183, 184,298,335; (12) 28,29, 70 Hcinemann, 0. (1 .HI) 26; (5) 26, 259,260 Hciningcr, M. (5)228 Hcintzclman, G.R. (13) 6 Hcinzc, J. (6) 300 Helena, M. (1.HI)2 1 Heller, D. (1.1) 88; (5) 192; (6) 227 Hclliwell, M. (12) 63 Helmchen, G. ( 5 ) 1 18; (7) 29 Hclquist, P.(5) 125 Hemling, H.Z. (8) 38,66 Hcmmer, B. ( 5 ) 342 Henbach, K. (5) 472 Hendcrson, K.W. (13) 8 Henderson, R.A. (1.iv) I 1; ( 5 ) 48 Hcndcrson, W. (6) 346 Hcndrickx, E. ( 5 ) 479; (6) 359 Hcncin, M.M. (6) 185, 194; (8) 2; (12) 79 Hcnggclcr, W. (8) 109 Hcnig, G. (2) 62 Hcnling, L.M. (5) 163 Hcnly, T.J. (4) 68 Hcnncr, B. (1.II) 2 1 Hcnrion, 0. (6) 361 Henry, P.M. ( 5 ) 123 Henry, R. (5) 285 Henschcl, D. (9) 90 Hcrbcr, RH. (6) 285 Hcrbcrich, G.E. (4) 263,264; (6) 151, 318,369;(9)44;(10) 1115; (11) 16, 18,32 Herbertson, P.L.(10) 79,80 Herbst-Imicr, R. (2) 35 1; (1 1) 35 Hcrdtwcck, E. (1 .[I) 30; (1.111) 67; (3) 50; (6) 57,300,324, 326, 357; (9) 83; (1 1) 28,29,79, 85 Hcrkcr, M. (12) 6 Hcrmanek, S. (10) 62

Hermans, L. (2) 148 Hcrminghaus, S.( I .III) 85 Hcniandcz, F.-S.(2) 271 Hernandez-Ortega, S. ( 5 ) 234 Heron, N.M. (1.111) 105; (13) 5 H e m , M.J. (1.II) 3 Herrco, J. ( 5 ) 202 Herrera, L.E.E. (8) 23 Hcrrmann, M. (4) 256 Hermiann, R. (6) 277 Herrmann, W.A. (1.II) 30; (1.HI) 10; (I.IV) 60,61,64,68, 69; (2) 7, 14,346-348; (6) 224; (7) 11; (8) 37,59 Hersh, W.H. (3) 157; (6) 119 Hertwig, J.E. (6) 217 Hesscn, B. (1.I) 43; (1 .II) 9; (5) 159, 165, 166 Hcydt, H. (3) 48; (9) 40 Hcy-Hawkins, E. (6) 76; (12) 30, 66 Hcyn, R.H. (2) 37, 102; (3) 107 Hibbs, D.E. (5) 134,405; (6) 268; (9) 74,78; (12) 105 Hibner, K. (5) 100 Hidai, M. (4) 262; (5) 434,481; (6) 115,265,308 Hidalgo, M.A. (2) 265 Hicrso, K. (4) 278 Higgct, C. (5) 172 Higgins, S.J. (3) 15 Highcs, D.W. (3) 96 Hii, K.K. (2) 337 Hiibner, K. (2) 2 15 Hikichi, S. ( 5 ) 196 Hdf, C. (12) 52 Hill, A.F. (1.111) 50,68, 77,78; (2) 146; (5) 3 10; (9) 7,27,28 Hill, A.M. (9) 106 Hill, E.W. (4) 93 Hill, J.E. (1 .I) 2 Hill, M.M. (2) 369; (5) 85 Hill, M.S. (1 1) 58 Hill, W.E. (10) 68 Hill, Y.D. (8) 101 Hillcbrand, G. (5) 305 Hillcr, J. (1.1) 70, 84; (6) 206; (13) 10 Hiller, W.(1 1) 88.91 fillcs, J. (6) 202 Hillhouse, G.L.(1.111) 30; (2) 292; (3) 67; (5) 30 Hilmersson, G. (6) 301 Hindcrling, C. (2) 158, 184; (6) 159 Hinterding, P.(2) 110 Him, I. (1.111) 61, 62 Hiraishi, S. ( 5 ) 237

Aurhor Index Hiraki, K. (2)65 Hirama, M.(I 1) 66 Hirano, M.(2)45,56;(5) 76 Hirashita, T,(1 1) 82 Him, C.-C. (6)94 Hitchcock, A.P. (10) 10 Hitchcock, P.B. (1.U) 5; (1.111) 21; (3) 122;(4) 85; (5) 119, 144, 204,208,261,382,397;(6) 24,77;(8)42,62,63;(9)9,

463

Huang, D. (2) 38, 102;(3) 107 Humg, H.H.(3)40; (4)74 Holz, J. (5) 192 Huang, J. (6) 28;(8) 100 Honda, K. (5) 334 Hum& J.-Y. (2)96;(4)203; (5) Hondrogiannis, G.(10)72 429 Hong, G.(8) 105 Huang, K.-C. (4)58 Hope, E.G.(4) 188;(6)88 Huang, L. (4)244 Hopkins, M.D.(1 .lII) 54,56 Huang, M.(4)I96 Hoprnan, M.(1 1) 52;(12) 33 Huang, S.D.(4)57 Hoppc, D. (12)4 Hor, T.S.A.(2)307;(4)59,362; Huang, S.-L.(6)58 Huang, W. (3)40;(4) 74 13,31,46,49,50,53,54;(11) (6)332 Huang, W.-Y. (3) 113 52; (12)33,55;(13) 14 HoraEek, M.(1.1) 84;(6)206; Huang, X.-Y. (3) 151;(4)54,86, Hitomi, K. (4)95 (13) 10 330,384;(6)54;(8) 20,21 Horchler, S.(1 1) 37 Hnyk, D.(10)20; (1 1) 4 Huang, Y. (8) 101 Ho, C.-L. (1.III) 31; (3)76;(5) Hori, A. (6)340 Huang, Z.-E. (8)20,21,47 315 Horncr, M.(6) 271 Hubcr, R.S. (5) 367 Ho, C.T. (2) 146 Hornung, F.M. (2) 133 Hubler, K. (3) 27 Ho, E.N.-M. (4) 228 Horton, A.D. (1.1) 6 Huck, V. (6)23 Hoang, M. (4) 99 Horvath, I.T. (2) 190;(7)63 Hudson, R.D.A. (5) 227 Hoare, J.L. (2)323 Hoshino, M.(7)60 Hobbold, M.(1 31) 74;(5) 397; Hosmane, N.S.(10)4,24,28,29; Hudson, R.H.E. (4)222 Hiibcr, M.(4)241 (9)30, 31 (11) 67 Hobi, M.(6) 328 Hiiffer, S.(1 .N) 22; (5) 402 Hosomi, A. (1 .rv)9 Hockless, D.C.R. (2)99,285,313, Hossain, M.M. (2)91;(3) 122;(4) Hlils, D. (1 2) 4 1 324,326;(4)336;337;(6)81; Huff, RL. (1 .IlI)34,36 85, 110,142,317;(5) 446, (12) 114 Huffman, J.C. (1.111) 52, 53; (2) 458; (6)77 Hodgson, P.K.G.(13)7 217,219;(6)242 Hou. Z. (6) 190;(8)30,78;(I 2) Hughbanks, T.(4)47 84 Hodson, A.G.W. (5) 343 H o f f k i ~ D.M. ~ , (1.111) 53;(4)60- Houbrcchts, S. (I .Ill) 85;(2)99, Hughes, A.E. (4) 99 62 324-326;(12) 114 Hughes, A.K. (1 .I) I; (4) 198;(6) 66 Hof%nann, A. (9) 15, 16 Moulton, A. (2)74 Hoflhann, D.(12)26 Housecroft, C.E. 2; (3) 14; Hughcs, A.N. (4) 276,277 Hoffmann, H.(2)338 (4)27, 148, 149,357;(5) 3,4; Hughes, D.L. (5) 48, 147 Hoffmann, J. (3) 48;(9)40 Hughcs, D.W.(2)49 (10) 1 Hughes, R.P. (1.111) 41;(2) 191, Hoffmann, M.(1.111) 120 Houser, E.J. (10) 26 192, 194; (5) 215,250,257 H o f f m a ~R.W. , (9)97;(1 2) 2 1 Hovestad, N.J. (13)24 Hui, J.W.S. (3) 167, 173; (4) 233, Hofinann, M.(10)23 Hovcyda, A.H. (13)5 365;(6)348 Hofinann, P.(6) 8 Howard, J.A.K. (1 .lll) 42;(4) H o w l e r , S.A. (2) 262 362;(6) 7,65,193,245,249, Hultzsch, K.C.(6)246; (8)9, I0 Hogarth, G.(2) 83-85;(4)89;(5) Humphrey, J.S. (4) 148 263,267;(8)4,25;(9)87, 356,357,443 Humphrey, M.G.(2)25,99,324113;(12)74;(13)12 326;(4) 183,184,336-338; Hoge, B.(1 2) 99 Howclls, M.E.(5) 238 Hoh, K.(5) 420 (5) 439;(6) 81;(12) 114 Hoy, V.J.(6)267 Hohmann, F. (1 .llI)72;(5) 308, Humphrey, P.A. (4) 23, 136, 171, Hradsky, A. (6)286,298 378,379;(5) 413,414,416, 309 Hrusak, I. (12) 117 Hoic, D.A. (6) 382;(1 1) 7,9 459;(6)313 HSU,C . 4 . (2) 126 Hojo, M.(1.N) 9 Hung, J.-T. (4) 127,229 HSU,H.-F. (3) 134;(4) 105, 162, Hung, S. (5) 469 Holah,D.G. (4) 276,277 180;(5) 410,464;(6)393 Hung, S.Y.-W. (3) 166;(4) 38 Holand, S.(9)43 HSU,R.-H. (5) 103 Holle, S.(5) 73, 180 Hunt, P.A. (3)27 Hsung, R.P. (1 XI) 1 17 Holliday, B.J. (2) 191, 192;(5) Hupe, E.(5) 384 Hu, J. (8) 18,79 Hursthouse, M.B. (4) 230;(5) 250 Hu, J.-P. (8) 3 Holloway, J.H. (4) 188;(6) 88 134,405;(6)268; (9) 74,78; Hu, J.-Y. (8)26 (12) 105 Holm, R.H. (4) 3 12 Hu, Q.-M. (3) 113, 117, 151;(4) Hussain, Z.I.(1.111) 47;(5) 38, Holmes, A. (3) 77;(4)226 54,80,86,314,384;(5) 47; Holmcs, J.L. (6) 127 477;(6)35 1 (6)54 Huttenoch, M.E.(6)235 Holrnes, N.J.(9) 107, 109 Hu, Y.(2) 197 Huttncr, G.(5) 195,389 Hua, R (4) 154, 155; (5) 363 Holtcamp, M.W.(2) 358 Holub, J. (10) 2G, 21

(1.w

464 Hutton, G.(12) 23 Huy, N.H.T. (9) 39 Hwang, J.W. (10) 48 HWU,C.-C. (1.IV) 48,49; (6) 97 Hwu, J.R (4) 127,229 Hyla-Kryspin, I. (2) 48; (5) 294, 389 lakovcnko, S .A. (10) 8 1 Ianelli, S. (3) 132; (4) 22, 147 Iapalucci, M.C. (3) 147, 160; (4) 376 Ichinohc, M. (12) 47 Ichiyanagi, T. (13) 5 Icnco, A. (4) 320 Igau, A. (1.I) 52-55; (6) 225; (9) 23, 80, 82 lgnaticv, N.V. (9) 47 Ihara, E. (8) 7,73,74 Ihczawa, H.(5) 468 Ikariya, T. (7) 43 Ikcda, H. (12) 39 Ikcda, 1. (2) 296; ( 5 ) 142 Ikcda, S.(2) 34; (5) 182 Ikcda, Y. (2) 275 Ikczawva, H. (4) 182 lmbos, R. (7) 49 Imhof, D. (4) 382 Imhof, L. (1.IV) 19 Imhof, W. (5) 33 1,472; (6) 289 lmoto, H.(4) 18 Inagaki, A. (4) 104; (5) 418 Incmatsu, K. (8) 72 Ingham, S.L. (3) 136; (4) 100, 160, 201; ( 5 ) 425,447 Ingold, F. (4) 283 Inomata, S. (4) 95 Inoue, R.(1.IV) 8 Inoue, S. (1 1) 82 Inubushi, Y. (9) 39 Ipaktschi, J. (1.111) 49; (5) 52; (6) 55 Irvinc, G.J. (2) 59; (3) 101 Irwin,M.J.(12) 112, 113 Ishibashi, T. (1.111) 124 Ishida, T. (3) 137; (4) 185 Ishihara, K. (1 1) 10 Ishii, R. (2) 359 lshii, Y. (3) 57; (4) 262,393; (5) 434; (6) 1 IS; (7) 20,21; (8) 90-92 Ishimap, T. (1 1) 13 Islam, S. (10) 68 Isobc, K. (2) 236 lssbcmcr, K. (1.111) 80 Ito, H. ( I .IV) 9 lto, K. (2) 367; (3) 56; ( 5 ) 403;

Orgatiometallic Chemistry (11) 1 lto, M.( 5 ) 237 lto, s. (9) 20; (12) 45 ltoh, K. (4) 114,392 Itsuno, S. (1 1) 1 Ivanov, S.V. (10) 3 1 Ivanov, V.L. (10) 71 Ivchcnko, P.V. (6) 21 1 Iwasaki, F. (2) 354 Iwasawva, N. (1.111) 103, 110, 114; (5) 373 Iyoda, M. (4) 72; ( 5 ) 353 Izod, K. (12) 33 Jaaskclaincn, S. (4)246 Jablonski, C. (6) 172 Jackson, K.F.W.(5) 62 Jackson, W.R.(2) 221 Jacob, K. (6) 261; (8) 29 Jacobsen, E.N.(7) 50,5 1 Jacobscn, H. (1.1) 91 Jacgcrman, W. (6) 361 JWc, F. ( 5 ) 478; (6) 324, 326; (1 1) 28,29 Jagcssor, R (6) 320 Jain, V.K. (2) 305; (9) 88 Jaitncr, P. (1.HI) 83; (6) 298 Jalon, F.A. (2) 33; (5) 181,483; (6) 306 Jamak, C. (6) 25 Jamcs, J.T. (6) 48,248,253 James, S.L. (2) 332 Jandelcit, 8. (5) 22, 289 Jandrasics, E. (3) 6 Janik, J.F.(1 I ) 73 Janik, M. (13) 38 Jank, S. ((I) 111, 112 Jansscn, J.P. (7) 29 Jansscn, M.D. (13) 24 Jany, G. (6) 222,241 Jaoucn, G. (6) 288 Jaroszcwski, M. ( 5 ) 44 Jastrzcbski, J.T.B.I-1. (1.1) 10, 11; (1.11) 13; (12) 34,41, 61,91; (13) 20,21,24,25 Jeanjean, M. (9) 43 Jcdlicka, B. (2) 16; (5) 483; (6) 306; (12) 22 Jcffcry, J.C. (1.111) 70; (10) 32, 34,49 Jcffrics, J.M. (6) 242 Jegicr, J.A. (1 1) 42,58 Jelinek, T. (10) 2 1 Jelliss, P.A. (10) 34 Jclonck, S. (6) 76; (12) 66 Jemmis, E.D.(10) 7; (12) 57 Jenkins, A.E. (5) 34

Jcnkins, H.A. (2) 270 Jcnscn, C.M.(2) 174,205,206 Jenscn, V.R. (1 .HI)13 Jcntzsch, T. (2) 103; (6) 140 Jeon, Y.-M. (5) 303 Jeong, N.(5) 368 Jeremic, D. (1.1) 74 Jeske, J. (1.HI)74; (9) 30 Jcsorka, A. (4) 182; ( 5 ) 468 Jcung, G.-H. (8) 104 Jia, G. (2) 35,71,72, 76-78, 80, 140 Jia, L. (6) 240; (1 1) 3 Jiang, C.(4) 59 Jiang, D.W. (5) 122 Jimencz, G. (1.1) 79 Jirnencz, J. (4) 293,305 Jirnhcz, M.V.(2) 189 Jimcncz-Catano, R. (2) 149; (5) 94 Jin, X.(5) 28; (6) 28 Jin, Y. (8) 75 Joantcguy, S. (9) 22 Jochern, G.(9) 37 Jogl, G. ( 5 ) 483; (6) 306 Johns, B.A. (7) 6 Johnscn. E. (6) 388 Johnson, B.F.G. (3) 125, 126,135, 136; (4) 27,41,71, 100, 101, 143, 144, 160, 168, 172-174, 176-179,201,224; (5) 224, 365,423-425,447,448,465467; (6) 136 Johnson, C.R. (7) 6 Johnson, E.S. (1.I) 2 Johnson, F.A. (10) 68 Johnson, J.A. (4) 135; (9) 11 Johnson, 0. (10) 2 Joho, F. (4) 382 Jolly, P.W.(1.111) 26; (5) 26,73, 180; (9) 24; (13) 7 Jonas, A.J.P. (9) 27,28 Jonas, K.( 5 ) 259,260 Jones, A.G. (1.IV)18 Jones, C. (9) 7,27,28,74-78 Joncs, G.B.(5) 367 Jones, N.C. (1.IV) 14 Jones, N.D. (6) 295 Joncs, N.E.,Jr. (6) 75 Jones, P.G.(1.111) 74; (4) 293, 305-307; (9) 30.90; (10) 39, 41-44,87-89; (12) 106-108, 119-121 Joncs, P.L. (10) 32 Jones, R.A. (1 I) 72 Joncs, R.V.H. (7) 42 Joncs, W.D.(2) 150,193, 196, 212,224; (6) 150, 152, 155

Author Itidex h c h i s a , N.(5) 435; (8)7 Kaneko, C.(3) 24 Kmeko, S.4. (5) 264 Kaneko, T. (13)40 Kanellakopulos, B.(8) 1; (12)83 Kang, J.K. (6)275 Kang, S.O. (10)95;(1 1) 43,44, 86 Kantceva, N.l.(4)37 GO, S.-C. (6) 177 Kapdia, R.(2) 245 Kapadia, S.R. (13)5 Kaptcijn, G.(2) 246 Karam, A. (4) 139 Karban, J. (10)34 Karch, E.E.(3) 39 Kardzu, M.(6)43 Karim, A. (5)386 Karl, J. (1.1) 35-37;(5) 160-162; (6) 197 Karlsson, A. (6)301 Karol, F.J. (6) 177 Karsch, H.H.(12)6 Kabalka, G.W. (10)72,90.94; Kashio, M.(7)28 Kaska, W.C.(2)205,206 (13)7 Kabir, S.E.(4) 120,230;(5) 419 Kasuga, N.C.(2)45 Kabuto, C. (12)47,68 Katad3, M.(2) 137 Kaddour, R. ( I 0) 82 Kataoka, Y.(1 .I1) 23 Kadish, K.M. (2)94 Katsukawa, Y. (4)243;(6)278 Kacrcher, J. (1 1) 35 Kauffmann, T.(1 .Ill) 6 Kaganovich, V.S.(4) 175 Kaul, B.B.(6)79 Kai, Y.(5)435; (8)7 Kaul, F.A.R. (1 1) 57 Kaidzu, M.(5) 268 Kawaguchi, H.(4)5 1,319,369, 370 Kaini, W. (10)28 Kainz, S. (5)346 Kawai, M.(1I) 82 Kawamura, K. (3)56;(6) 131 Kaiser, B.(12)4 Kajitani, M.(2) 344;(6) 154 Kawana, M.(5) 1 13 Kakiuchi, F. (3) 57;(4)393;(7) Kawano, H. (2)65 20,21,50,51 Kawasaki, Y.(8) 91 Kakiya, H. (1 .IV) 8 Kawata, Y.(2)125;(6)345 Kalck, P. (2) 51 Kay, K.-Y. (6)339 Kalinin, V.N.(6) 380;(8)88 Kaya, K. (8) 41 Kalinowski, H.-0. (12)38 Kayscr, B.(1 .Ill) 1 18 Kallincn, K.O. (4)140 Kamlkova, M.A. (4)202;(5) 428 Kal'sin, A.M. (5) 381 Kazantscva, V.V. (10)75 Kalt, D. (5) 292 K a Z e ~ o v aN.B. , (6) 12,249 Kaltsoyannis, N.(4)294;(8) 114 Kazimirchuk, E.I. (8)88 Kalyuzhnaya, E.S. (8)23 Kc, M.(2)110 Kamalov, G.L. (4)339 Kcatcs, J.M. (8) 107 Kmcpalli, S.(9)52 Kccn, S.P.(7)34 Kamer, P.C.J. (2) 181;(3) 141;(6) Kcese, R. (5) 12,23 1 269 Kchr, G. (5) 375 Kaminski, 0. (9)29 Kcily, A.F. (5) 163 Kampf, J.W. (3) 153, 154, 174, Keim, W. (2)323 175;(4)318,332-334;(5) Keimling, S.U.(1 1) 91,96 258;(1 1) 6,20,21,25 Keiter, E.A. (3)39 Keitcr, RL.(3)39 Kamyshova, A.A. (6)280 Kckia, O.M.(6)216 Kanc, K.M. (6) 10; (13) 17

Jordan, G.T., IV (6) 232; (1 I) 24 Jordan,R.F. (1.1) 13, 14,44,89; (6)205;(10)58,59;(I 1) 33, 39 Jordi, L. (1 .HI)102;(5) 370 Joseph, S.C.P. (1.11) 5; (5) 261 Joshi, N.N. (13) 39 Joshi, V.S. (5) 31 Joslin, F.L. (3) 49 Jost, C.(4)256 Jouaiti, A. (9)25 Juaristi, E.(12)43 Julia, A. (3) 152;(4)375 Julictte, J.J.J. (7)63 Ju~C , . 4 . (4)209;(5) 430 Jung, S.(5)303 Jung, T.(2)330 Junicke, H.(2)264 Justyniak, 1. (1 1) 49,54,56 Jutand, A. (7)58 Jutzi, P. (6) 210,297

465

Kcllcr, T.M.(10) 78 Kclley, M.J. (4)345 Kelsch, B.A. (5) 82 Kelton, T.F.(5) 367 Kemmitt, R.D.W. (2) 320;(9)92 Kemp, A. (1 1) 35 Kcmpe, R. (1.1) 57-60,88;(5) 192,300,305,438;(6)227 Kcnnard, 0. (10) 2 Kenncdy, A.R. (1 3) 8 Kcnncdy, J.D. (10)21 Keogh, D.W. (6)50,53 Kergoat, R. (3) 66;(5) 345 Kcrr, M.E.(1 .II) 29 Kerr, W.J. (1.111) 105, 106 Kcrsten, J.L. (1.111) 39 Kcrth, J. (9)32 Kcrzina, Z.A. (4) 175 Kcsslcr, M.(4) 179;(5) 332 Kettle, J.G. (7)32 Kettle, S.F.A. (4)11; (6)14 Khan, K. (6) 198;(9)55 Khan, M.A. (6) 199 Khan, S.A. (10)35 Khandozliko, V.N.(8) 88 Khanin, V.V.(10)81 Khanna, P.K. (2)289 Khomutov, G.B.(10)81 Khorshcv, S.Ya. (8)68;(12)98 Khroustalyov, V.N.(2)260 Klwostov, A.V.(8) 23 Khvovost, A.(6)12 Kiang, F.-M. (1.111) 129 Kickelbick, G. (2) 112;(4)361 Kicbooms, R.H.L. (13)6 Kilcoync, A.L.D. (10) 10 Kilncr. M.(6)65 k m , D . N . (2)315 Kim, H.-J. (5) 303 Kim, J.H. (10) 48 Kim, K. (5) 303 Kim, S . H . (13)40 Kim, Y.-J. (2)315 Kincaid, J.A. (1.IV)20;(5) 169 Kmg, P.J. (4)390 King, R.B. (1 .IV) 6;(5) 8 King, W.D. (4) 258;(5) 433 Kingsbury, C.L.(12)25 Kingslcy, A.J. (1.1) 1; (6)66 Kinoshita-Kawashima, J. (2)275 Kiplingcr, J.L. (1 .In)20-22;(5) 311;(9) 9 K i m , B. (1 0) 7 Kirchhoff, R. (3)53;(6) 125;(9) 71 Kirchner, K. (2) 101, 1 11, 112;(5) 72,248,291; (6) 126 Kirillova, N.I.(5) 9

466 Kirin, V.P.(4)214-216,236,366 Kirkland, T.A. (7) 30 Kirmse, R.(6) 76 Kirova, N.(5) 2 10 Kirsch, H.(3) 68 Kirschbaum, K. (5)36 Kirsten, R.(6)235 Kisclcva, L.N.(6)280 Kishishita, M.(1.111) 37 Kissncr, R. (4)66 Kita, Y.(8) 85 Kitagaki, S.(8)85 Kitagawa, S.(5) 133 Kitamura, M.(13)24 Kittrcdgc, K.W.(1.111) 7 Kivckas, R. (6) 149;(10)40,51, 52,84 Kiyono, H. (5) 164 K i m , O.A. (4)204 Klahn, A.H. ( I N ) 56;(5) 172 Klccklcy, T.S.(1.11) 18 Kleij, A.W. (13)24 Klcin, H.-F. (2) 329,330;(4)24 1 Klcin, R.A. (5) 206 Klein, W.(I1) 25 Klcindl, P.J. (5)287 Klcinebckcl, B. (6) 297 Klcmcnkova, Z.S. (1 .I) 45;(4) 389 Klcmcnt, I. (1 .IV)10;(7)62 Klcmp, A. (1 1) 77 Klcttke, T.(5) 33 1,472 Klcwitz, S.(1.111) 85 Klimova, B.T. (6) 358 Klimova, E.I. (6)358 Klinga, M.(6)222 Klingcr, C. (9) 37 Klinkhammer, K.W. (1 I) 96 Klodwig, J. (5) 184 Kloo, L.A. (9) 110 Kloostcr, W.T.(4)33 Klootwijk, A. (9)24; (13) 7 Kloppcnburg, L. (1 .I) 27 Nos, A.M. (13)6 Klose, A. (2)353 Klumpers, E.G.(1.11) 13 Klunduk, M.C. (4)52;(6) 89 Klyagina, A.P. (4)387;(5) 442 Knight, D.A. (6) 374 Knizck, J. (12)69 Knizhnikov, V.A. (5) 255;(6)162 Knjazhanski, S.Ya. (8)23 Knobler,C.B.(10)33 Knoch, K.(5) 184 Knochel, P. (1.W) 10; (7)2,61, 62;(13)39-41 Kikilker, H.J. (5) 228,241-244 Knorr, M. (13)35

kiorr, R ( I 2) 48 Knox, S.A.R. (2)92;(5) 363 KO, J. (1 1) 43,44,86 KO, S.(8)76,77 Kobata, M.(13)39 Kobayashi, K. (4)367; (6) 176 Kobcrstein, R. (12)21 Koch, J.L.(6)120 Koch, W.(1 .II) 33 Kwiok-Kiilmn, G.(1.111) 61, 62 Kockclmann, W.(4) 16 Kodama, K. (12)39 Kkher, C.(1.111) 10; (2) 14,346 Koefod, R.S.(6) 143 Kohler, F.H. (6)256.300; (9)45 Ktihlcr, J.U. (4)219;(5) 427 Kiihlcr, K.(5) 389 Kocllc, U. (6) 121, 124 Koclle, V. (5) 70 Koncmann, M. (6) 183;(12)49 Koppc, R.(6)350 Klirblovti, E. (13)27 Kktlmcier, S.(1 .IV)60 Koctzlc, T.F.(4)33 Kofod, P.(2)209 Koga, N.(2) 152;(3)29;(5) 324 Koidc, Y. (4)77;(1 I) 50 Koizumi, T. (1.111) 121;(2) 216; (5) 91 Kol, M.(1 1) 23 Kolb, P.(5)259 Kolchmaincn, E. (4) 175 Kolis, S.P.(5) 81 Kollbach, G. (5) 259 Kollc, U. (1 .I) 78 Komiya, S.(2)45,56;(3) 56 Konchcnko, S.N.(4)20,31,315, 316 Kondo, M.(5) 133 Kondo, T.(2)367;(4)388;(5) 403;(6)305;(7)24 Kond0.Y. (8) 86;(12)10 Kong, F.-S.(4)220 Koningsbergcr, D.C.(4)345 Konishita, Y.(2)65,236 Kono, Y.(1 1) 10 Konsiya, S.(5) 76 Konslcr, R.G. (7)5 1 Konstantinovsky, L.(2) 199;(5) 89 Kooijman, H. (1.1) 10; (1.11) 12, 28;(2)202,280,302;(12)61; (13) 20,21 Kopach, M.E.(5) 81.84 Kopacka, H.(6)286 Kopf, J. (5) 394 Kopishc, C.(5) 110 Kopp, M.R (1 1) 70

Orguriometallic Chemistty Koracs, I. (5) 19 Koraeik, I. (5) 92 Koridze, A.A. (3) 169;(4) 107109,204-206,237,238, 398; (5) 452,480 Korrcstal, K.J. (6) 13 Kos, A.J. (12)57 Koshino, H. (6) 176 Kosugi, N. (10)10 Kotila, S.(1.111) 72;(5) 308 Kotov, V. (6) 12 Kotsatos, B.J. (12)40 Kottke, T.(12)26,27 Kotula, S.(6) 183 Koutsantonis, G.A. (4) 135;(6) 135;(9) 11, 1 I5 Kovacik. 1. (2)235 Kovacs, I. (2)9;(3)12 Kovalchuk, O.S. (10)76 Koyama, S.(2)65 h k ,H.-B. (2) 199;(5) 89 Krafczk, R. (6) 397 Krambowski, P. (4) 153 Kramcr, C.-P. (5) 388;(12)97 Kramcr, K.S. (4)55 Kramcr, P.C.J. (5) 116 W o w s k i , P. (3) 127;(9) 12 Krammcr, M.J. (5) 288 Krancnburg, M. (2)202;(5) 116 Krannich, L.K. (1 1) 69 Kratzcr, RM.( 1 . W 64 Krause, N. (12)88,91 KrautliZuscr,S.(5) 187 Kravchenko, R.(6)234 Krebs, A. (5) 388;(12) 97 Krcindlin, A.Z. (6)280 Krcifll, F.R.(1 .HI)67,83;(3)50; (6)57;(9) 83 Kreiter, C.G. (5) 212,350 Krcmer, R.K. (1 0) 28 Krctschik, 0.(1.111)122 Knef, A. (I 2) 21 Krieger, M.(13)2 Krivykh, V.V.(4)204 Kronenburg, C.M.P. (1 .I) 11; (12) 91 Krossing, I. (12)69 Kroto, H.W. (5) 148 Kriiger, C.(I X I ) 26;(4)253,273; (5) 26, 110, 180,259,260, 332;(6)61, 147, 178;(9)60 Kriiger,T.(9) 120 Kmg, A. (3)61 Krug, J. (3) 127;(4)153;(9) 12 Krugcr, G.J. (12) 117 Kruglova, N.V.(6) 280 Kruppa, A.I. (2) 179 Krysa, E.(4)276, 277

Author lridex Ku, R.-2. (1.111) 73, 129 Kubiak, C.P.(3) 5 1; (4) 186; (6) 171 Kubicki, M.M. (2) 33; (3) 150; (5) 181; (6) 196, 230,251 Kubota, H. (4) 181 Kucharczyk, R.R (1.111) 39 Kudinov, A.R. (4) 261 Kuehl, C.J.(2) 262 Kiibl, 0.(12) 30 Kuhn, F.E. (1.N) 61,69 Kiihn, J. (6) 137 Kuhncn, T. (5) 455 Kuhnigk, J. ( 5 ) 73 Kuipers, B. (6) 384 Kukolich, S.G. (5) 245 Kukushkin, V.Yu. (2) 236 Kumagai, K. (2) 45 Kumar, G.R. (3) 122; (4) 85, 348; (9) 13 Kumaresan, S. (4) 127,229 Kunsman, M. (13) 37 Kunzcl, A. (6) 35 Kurasov. S.S.(4) 284 Kuratq H.(9) 95 Kurbakova, A.B. (11) 8 1 Kurikawa, T. (8) 4 1 Kuroda-Sowa, T. (5) 476; (12) 101 Kurosawa, H. (2) 296; (5) 124, 129, 142, 151,435; (6) 175 Kurth, C.J. (6) 377 Kusamiya, M. (2) 354 Kushi, Y. (2) 286 Kuslos, M.(6) 223 Kusuyama, Y. (2) 286 Kuwajima, I. ( 5 ) 369 Kuwatani, Y.(4) 72; ( 5 ) 353 Kuz'mina, L.G.(6) 193,245,249; (8)4,25;(9) 113;(12) 110 Kumctsov, V.F.(2) 263; (4) 341 Kwak, J. (4) 209; ( 5 ) 430 Kwm, K.S. (6) 270

Laali, K.K. (9) 10 Labassi, M. (5) 282 Labella, L. (6) 255 Labinger, J.A. (2) 358 Lachot, B. (8) 5 Ladogana, S.(3) 64; (5) 27 Lafontaine, J.A. (5) 273 Lagow, R.J. (12) 26 Laguna, A. (4) 293, 305; (10) 39, 41-44, 87-89; (12) 106, 108, 111, 119-121 Lagutla, M. (4) 293; (12) 106, 111, 120

467

M.-C.(4) 307

La-,

Lagunova, V.Yu. (3) 169; (4) 107, 109,237,398; (5) 480 Lahoz, F.J. (2) 189,228,240; (3) 108; (4) 265; (5) 185,202, 326; (6) 164 Lai, C.-H. (6) 130 Lai,C.P. (4) 57 Lai, C.-Y. (1.IV) 49; (2) 114; (5) 65; (6) 97,99 Lai, M.-L. (3) 99 Lai, R (6) 27 Laio, F.-L. (1.111) 44 Lake, C.H. (3) 28; (1 1) 69 Lakin, M.T.(13) 25 Lalindc, E.(2) 333,339; (5) 436, 473-475; (1 1) 97 Lanmla, M.P. (6) 164 Lamb, S.(12) 74 Lamcrtz, c. (1 0) 1 1 Lammerstsma, K. (3) 28 Lamrani, M. (6) 149; (10) 48,5 1, 52

Lancastcr, S.I. (1 I ) I7 Lance, M. (6) 189; (8) 70 Landais, Y. (7) 48 Landau, S.E.(3) 92 Landis, C.R. (5) 155; (8) 28 Landman, M. (2) 3 12; (5) 392 Landrum, G.A.(9) 97 Lancman, S.A. (7) 18 Lanfrmchi, M. (1.1) 4, 93; (1.111) 60; (2) 189; (4) 83; ( 5 ) 112; (6) 215 Lang, A. (12) 38 Lang, H.(1 .I) 7 1; (5) 389,454 h g , J.-P. (4) 369,370 Langc, I. (9) 90 Langcmann, K. (7) 31 Langcr, F. (13) 40 Langford, C.H. (3) 8 Lapintc, C. (2) 117, 143; (3) 44; (6) 109 Lapointc, A.M. (2) 3 1 1 Lappas, D. (4) 62 Lappert, M.F. ( 5 ) 208,382; (8) 22,62,63; (12) 55 Larhcd, M. (7) 60 Larrow, J.F. (7) 50,5 1 Larscn, S.(2) 209 Larsson, A.L.E. (5) 384 Laschi, F. (4) 35 1; (6) 326; (8) 22; (1 1) 29 Lass, R.W.(2) 232; (5) 329 Laswick, P.H.(3) 13I; (4) 98 Latham, H.A. (7) 54 Latos-Grazynski, L. (2) 266 Lattkc, E. (12) 48

Lau, C.P. (2) 35 Laubcnder, M. (2) 222,235,35 1; (5) 92, 190 Laumay, J.-P. (6) 354 Launcy, J.-P. (6) 298 Laurcnczy, G. (4) 267 Lavastre, 0.(2) 79,362; (6) 25 1, 293 Lavender, M.H.(2) 83, 84; ( 5 ) 356 Lavignc, G.(2) 5 1 Lavoie, G.G. (1.1) 41; (5) 158 Lawless, G.A. (5) 156; (8) 107; (9) 46 Lawrancc, G.A. (3) 65 Lawrencc, S.E.(4) 280,282 Layland, R. (4) 377 16, 17 Leach, P.A. Leadbcater, N.E.(2) 93; (3) 94, 124; (4) 96, 124, 146,227 Lebbi, J. (6) 343 Lcbcdev, V.N.(4) 211; (10) 34, 36,55 Lc Bcrrc-Cosqucr, N. (3) 66; ( 5 ) 345 Lcbioda, L. (11) 92 Lebius, A.M. (6) 218 Leblanc, 3 . 4 . (1.111) 25; (6) 90, 257 Le Borgne, G. (5) 322 Lc Bozcc, H.(1 .HI)87 Le Bras,J. (6) 144 Lecante, P. (4) 287 Le Corre-Susanne, c. (1.III) 93; (5) 390; (6) 385 Ledford, B.E.(7) 38 Lee, B.(1 .IV)5; (2) 8, 187; (3) 3 1 Lee, C.K. (12) 118 (12) 60 L ~ CF.-C. , Lee, F.-Y. (4) 127 Lee, G.-H. ( 1.HI) 43,45,48, 73, 97; (3) 52, 163, 177; (4) 58, 82, 141, 161, 169,309,324, 325, 327-329; ( 5 ) 49, 103, 104, 153,3 12,314,399,440, 456, 460; (6) 58,62,254; (1 1) 60 Lce, H.K. (2) 218, 226; (6) 275, 327,332 Lcc, H.M. (2) 71,72 Lee, J.S. (5) 221 Lee, J.-Y. (2) 315 Lee, K. (3) 137; (4) 162, 185; (5) 464 Lee, K.K.-H. (4) 126, 190 Lee, K.M. (12) 118 Lcc, L.( I .I) 17; (1.111) 45; (2) 35; (5) 49; (6) 62; (8) 65

(1.w

Orgationtetallic Chemistry

468 LCC,S. (3) 15 Lee, S . 6 . (6) 327 Lee, S.H. (6) 312 Lcc, S.S. ( 5 ) 217,221,222, 35 1; (6) 275,327,362 Lce, S.-W. (2) 315; (5) 221 Lce, T.-Y. (5) 221 Lee, V.W.-M. (6) 349 LCC,W . 4 . (6) 130 Leech, M.A. (6) 250,253 Lccs, A.J. (2) 186; (3) 34 Lcfebcr, C. (1 .I) 88; (6) 227 Lcfcvre, V. (9) 22 LcFloch, P. ( 5 ) 340; (9) 56, 57,79 Lcgoupy, S. (5) 174; (6) 96 Le Gucn, F.R.(1,111) 128 Lcgzdins, P.L. (1.111) 24,27, 82, 86; (5) 46; (6) 49, 59,69,9 I Lchman, S. (2) 239 Lchmann, C. (2) 35 I ; (12) 74 Lchotkay, T. (1 .IIl) 93; (3) 50; (6) 57; (9) 83 Lehr, C. (8) 58 Lc Huscbo, T. (2) 191, 192; ( 5 ) 250,257 Lci, X. (3) 58; (4) 249-25 1, 33 1 Lcibfritz, T. (1 .IV) 26; (2) 68 Lcigh, G.J. ( 5 ) 147 Lcighton, J.L. (7) 19 Lciningcr, S. (9) 16, 19, 59, 60 Lcins, A. (1 4 ) 22 Leipoldt, J.G. (2) 3 10 Liter, W. (5) 77 Lcitcs, L.A. (1 1) 8 1 Lcitncr, W. (2) 195 Lcizc, E. (6) 390 Lemay, J. (13) 39 Lcincnovskii, D.A. (6) 12,249; (9) 112; (12) 110 Lencnko, V.S. (1.1) 72; (6) 201 Lcnges, C.P. ( 5 ) 88 Lctitz, A. (12) 78 Lentz, D.(1 .IV) 55 Lcnz, R.W. (1 1) 5 1 Lcong, W.K. (3) 97; (4) 29,235 Leoni, P. (2) 303 Lc Pichon, L. (2) 132 Le Pod, P. (1.111) 128 Lesader, I. (6) 302 Lcshina, T.V. (2) 179 Lcskcla, M. (6) 222 Lcung, K.S.Y. (3) 138; (4) 234 Leung, W.-H. (6) 156 Lcung, W.-P. (2) 226; (3) 74; (6) 11; (12) 82 Lc Van, D. (9) 17 Lcvason, W. (9) 106, 107, 109 Lcvin, A.A. (4) 279

Lcvicv, M.A.(5) 381 Lcvy, C.J. (2) 253 Lewe, T. (9) 101 Lcwinski, J. (1 1) 49,54-56 Lcwis, A. ( 5 ) 167 Lcwis, D.F. (10) 79,80 Lcwis, J. (2) 93, 95,332; (3) 94, 124, 176; (4) 27,39,40,96, 124, 146, 167, 179, 219,224, 227, 239,380; ( 5 ) 427; (6) 141,294 Lcx, J. (12) 100 Ley, S.V. ( 5 ) 57-59 Leycs, A.E. (1.111) 7 Leznoff, D.B.(1 .HI) 5 1 Lhotkay, T. (1.111) 67 Li, C. (3) 5 5 ; (6) 33 1 Li, C.-S. (2) 126 Li, G. (6) 28,274 Li, G.H. (6) 274 Li, G.-Q. ( 1 . w 37 Li, H. (5) 285; (9) 67 Li, J. (1.IV) 33; (3) 95 Li, K. (8) 75 Li, L. (1.11) 17; (4) 17; (8) 105 Li, N.-S. (13) 7 Li, R. (1 .IV) 59; (5) 401; (6) 100 Li, S . (1 .II) 32; (4) 48; (6) 252, 332 Li, S.-L. (13) 36 Li, W.-T. (1.111) 76 Li, X. (5) 6; (6) 7 Li, X.W.(9) 87,96; (1 1) 64, 68, 80 Li, Y. (2) 94 Li, Z. (4) 364 Liablc-Sands, L.M. (1.11) 16; (2) 91, 106, 119, 161, 167, 191, 192, 194,215; (3) 164, 165; (4) 110.310,311;(5)74,215, 250, 257,158; (6) 123, 399; (9) 38, 111; (11) 76,78 Liang, K.-W. (1.111) 76 Liao, F.-L. (3) 156; (4) 161,326; (5) 51, 121,463 Liso, S. (8) 87 Liao, Y.H. (10) 49,50 Licandro, E. (1.111) 93 Liebcskind, L.S.(13) 6 Lightfoot, P. (6) 290.3 19 Lirnbcrg, C. (1.111) 46; ( 5 ) 40 Lin, C.H. (1 .lIl) 45; ( 5 ) 49; (6) 62 Lin, C.-J. (1.111) 92 Lin, H.-M. (6) 3 12 Lin, I.J.B. (4) 302; (1 2) 118 Lin, J.-L. (2) 126 Lin, J.T. (2) 126 Lin, K.-J. (1.IV) 48; (2) 96, 126;

(4) 203; (5) 429; (6) 94,3 12 Lin, L.-C. (4) 229 Lin, S. (1 .IlI) 92 Lin, S.-H. (3) 41; (4) 191 Lin, W. ( 5 ) 387, 450 Lin, X.(8) 105 Lin, Y. ( 5 ) 441; (6) 17; (8) 13,48 Lin, Y.-C. (1.111) 45; (5) 49; (6) 58,62 Lin, Y.-H. (8) 26,44 Lin, Y.-S. (2) 252; (5) 135 Lin, Z. ( 5 ) 299 Lincandro, E. ( 5 ) 390 Lindall, C.M. (6) 313 Linden, A. (2) 122 Lindcquc, L. (12) 117 Lindncr, D.C. (2) 194 Lindncr, E. ( 1 .IV) 26; (2) 68;(5) 327 Lindquist, M. (12) 18 Lindscll, W.E. (6) 347 Linti, G. (6) 350 Linton, C. (8) 106 Liou, S.-Y. (2) 204 Lippard, S.J. (1.1) 21-23 Lippcrt, B. (13) 37,38 Litvinov, V.P.(10) 71 Liu, C.S. (5) 74 Liu, C.W. (4) 302 Liu, C.-Y. (1.111) 129 Liu, F. (2) 129; (5)71 Liu, F.-C. (6) 232; (1 1) 24 Liu, F.-Q. (1 1) 38 Liu, H.(4) 362 Liu, J. (1.111) 115; (4) 210 Liu, L.-K. (1.111) 92; (4) 59,229, 302 Liu, N. (2) 106; ( 5 ) 74; (6) 123 Liu, Q. (6) 17; (8) 13,44 Liu, R.(5) 81 Liu, R.-S. (1 .III) 43,44, 76; ( 5 ) 50,51 Liu, S. ( 5 ) 140 Liu, S.-M. (4) 383,385 Liu, S,-T. (1.111) 73, 129; ( 5 ) 312 Liu, W. (8) 113; (1 1) 48 Liu, X.-H. (6) 323 Liu, Y.H. (2) 283; (6) 292; (13) 28 Liu, 2.( 5 ) 191; (6) 191; (8) 24, 27,39 (10) 60 Liu, Z.X. Livinghousc, T. (12) 5 Llamazares, A. (4) 116 Lledos, A. (2) 124; (6) 243 Llorcntc, I. (12) 58 Lloyd, J. (1.111) 23; (2) 64; (6) 74 Lluch, J.M. (6) 243 LO,Y.-H. (1 .III) 45; (5) 49; (6) 62

Author Index Lobbia, G.G. (13) 33 Lobkovsky, E.B. (1.11) 18 Lock, P.E. (6) 376 Lockc, A.J. (6) 268 Lockwood, M.A. (1.11) 14 Lohncr, P. (1.11) 19; (13) 26 Lohrenz, J.C.W. (12) 52 Lokshin, B.V. (1.1) 45; (4) 389; (8) 88 Long, G.J. (4) 249 Long, J.M. (5) 134 Long, N.J. (2) 95; (6) 294,337 Longato, B. (6) 333 Longen, A. (1.HI)99 Longoni, G. (3) 147, 160; (4) 271, 376 Loo, L. (1.11) 17 Lowk, H.-P. (8) 106 Loos, D. (1 1) 65 Lopes, P.E.M. (4) 256; (6) 277 Lbpez, A.M. (2) 69, 107, 123; (3) 46; (5) 79, 80,86, 185; (6) 132 Mpez, C. (2) 284; ( 5 ) 204; (6) 262,276,283,287, 307 Lbpez, J.A. (2) 131, 189; (5) 383; (6) 164 Lbpez, 0. (2) 269 Mpcz-de-Luzuriaga, J.M. (12) 108 Lopez-Gonzalez, M.C. (2) 108; (6) 116 Lopcz-Mardomingo, C. (1.II) 3, 20; (5) 304; (6) 46 Lorber, C. (3) 14 Lorberth, J. (6) 7, 12; (9) 96, 112 Lork, E. (9) 84,86, 102, 119, 120; (13) 29 Losada, J. (6) 303 Lotz, s. (1.111) 94; (1.1v) 21; (2) 3 12; (5) 392 Lough, A.J. (2) 295; (5) 96,484; (6) 322; (12) 102 Louie, J. (7) 9 Love, J.B. (8) 43 Lovell, T. (2) 25 Low, P.J. (2) 110 Low, P.M.N. (6) 332 Lowendahl, M. (6) 301 Lu, K.J. (10) 24,28; (1 1) 67 Lu, K.-L. (2) 96; (4) 127,203; ( 5 ) 429 Lu, S.-M. (4) 269; (6) 273 Lu, Y.-H. (5) 47 Lubini, P. (1 1) 87 Lucas, D. (6) 46 LUC~S, N.T. (4) 336-338; (6) 81, 165

Lucchini, V. (1.1) 32 Lucenti, E. (3) 139; (4) 97, 199 Lucus, N.T. ( 5 ) 439 Luecke, H.F.(2) 208 Lucken, H. (8) 109 Liitjcns, H. (7) 62 Lugan, N. (1.IV) 57; (5) 168, 197 Luger, P. (1.N)55; (13) 5 Lugmair, C.G. (1.1) 61 Luh, T.-Y. (12) 15 Luinstra, G.A. (1 .I) 80 Lukchart, C.M. (2) 336 Lukin, K. (12) 3 Lumb, S.A. (1.111) 27; (6) 59 (4) 159 Lun, Y.-Z. Luo, J. (2) 126 Luo, L. (3) 40; (4) 74; ( 5 ) 67 Luo,W. (3) 157; (6) 119 Luo, Y. (8) 81 Luth, B. (9) 17 Luthcr-Davies, B. (2) 99, 325, 326; (12) 114 Lutz, C. (13) 39,40 Lutz, F. (5) 180 Lutz, M. (13) 15, 16 Luzikova, E.V. (13) 7 Luzzini, P.(4) 35 1 Lydon, D.P.(2) 287 Lynam, M.M. (1.Iv) 1, 3; (3) 14 Lynn, M.A. (1.111) 55; (5) 348 Lysscnko, K.A. (5) 68; (6) 138, 365; (8) 49 Ma, J.-F. (6) 356 Ma, W.-W. (8) 20,47 Maas, G. (9) 32 McAlccs, A.J. (2) 299; ( 5 ) 207 McArdle, P. (3) 26,43; ( 5 ) 10, 272 McBcath, C. ( 5 ) 208,382 MacBridc, J.A.H. (10) 66,79 McBride, K.T. (3) 86; (4) 377 McCanimon, C.A. (6) 389 McCandlcs-Northins,J. (I ,111) 53 McCarroll, A. (1 1) 14 McCarthy, C. (12) 63 McCarty, B.M. (3) 1 18; (4) 193; (5) 232; (6) 128 Macchado, R.(4) 125 Macchi, P.(4) 3 Macchioni, A. (2) 27-29 Macciantclli, D. (13) 4 McConnachie, C.A. (1.IV)15 McConville, D.B.(5) 330,437; (13) 32 McConville, D.H. (1 .I) 8, 9, 12; (2) 290,328

469 McCrindlc, R. (2) 299; (5) 207 McCullcy, D.J.(5) 273 McDonald, C.J. ( 5 ) 48 Macdonald, P.M. (6) 321 McDonald, R.(3) 171 McElfresh, M. (4) 48; (6) 252 McElwee-White, L. (1.111) 75; (5) 45 McEneancy, P.A. (10) 53 McFarlane, K. (1.W) 5; (2) 8 McGlinchcy, M.J. (I .rv)36; (2) 49; (3) 96; (5) 346,455 McGlinsky, M.J. (6) 376 McGrady, J.E. (2) 25; (4) 176, 183; (6) 198 McGrath, T.D. (5) 39 McGrcgor, S.A. (2) 37 Mach, K. (1 .I) 69,70,84; (6) 202, 206; (13) 10, 11 Machado, R (1.W) 31; (3) 89; (4) 139; ( 5 ) 409 Machnitzki, P. (4) 76 Macho, L. (5) 132 Macicjcwska, B. ( 5 ) 199 Macicjcwski, L.A. (6) 343 McIlroy, D.N. (10) 10 McInncs, E.J.L. (1.111) 47; (5) 477; (6) 351 MCIMCS,J.M. (1.IV) 40; (5) 223; (6) 98 Mack, A. (9) 2, 19 McKcc, M.L. (10) 6 McKcndry, S. (1.111) 105 McKenzie, J.A.M. (3) 80 McKinis, G.F. (5) 366 McKinlcy, J. (12) 17 MacKinnon, P.(8) I ; (12) 83 McKnight, A.L. (6) 236 McMahon, C.N. (5) 147; (1 1) 47 McMahon, T.B. (1.111) 16; (5) 43 McNeil, W.S.( 5 ) 320 McNeill, K. (2) 60; ( 5 ) 293; (13) 13 McPartlin, M. (3) 136; (4) 100, 160, 179; (5) 425; (1 2) 103 McPhillips, T. (4) 120; ( 5 ) 419 Macrae, C.F. (10) 2 MacTavish, D.I.(2) 308 McWhanncfl, M.A. (10) 85 McWhinnie, W.R.(2) 223; (3) 119; (4) 87 Maczek, K. (4) 44 Maddaluno, J. (12) 44 Maddock, S.M. (1.111) 4 1; (3) 27; (5) 215 Madsen, S.K.(4) 197 Maoda, H. (4) 72; (5) 353 Mackawa, M. (5) 476; (12) 101

470 Maes, J. (2) 324; (12) I14 Macyama, K. (1.111) 103, 110, 114 Mager, M. (4) 241 Maggini, M. (5) 149; (6) 3 14 Magnera, T.F.(13) 27 Magnus, P. (5) 366 Magnuson, V.R. (4) 276,277 Maguire, G.E.M. (6) 33 1 Maguirc, J.A. (10) 4,24,28; (1 1) 67 Magull, J. (4) 45; (6) 30; (8) 71; (13) 2 Mah, M.S. (5) 22 1 Mahicu, A. (1 .I) 52 Mahon, M.F. (1 .IV) 40; (4) 292, 3 17; (5) 223; (6) 98; (12) 18 Mahr, N. (2) 350 Maia, LA. (1 1) 36 Maia, J.R. da S. (6) 65 Maichle-Mossrncr, C. (4) 37 1; (6) 27 1 Maier, G. (12) 38 Maicr, N.A. (5) 255; (6) 162 Main, A D . (1 JII) 75; ( 5 ) 45 Maiorana, S. (1.111) 93; (2) 361; (5) 390 Maisel, H.E. (5) 375 Maisonhaute, E. (1.IV) 34; (3) 84 Maitlis, P.M. (6) 138 Maitra, K. (2) 104 Maiwald, S. (8) 67 Majoral, J.-P. (1.1) 52-55; (6) 225; (9) 23, 80-82 Mak, T.C.W. (1.IV) 12; (2) 75, 226, 307; (3) 74, 117; (4) 80, 362; (6) 11, 191,332; (8) 16, 24, 27, 39; (10) 38,60; (12) 82; (13) 36 Makihara, N. (2) 203 Makihira, I. (1 .II) 23 ~aksakov,V.A. (4) 20,214-216, 236,366 Malc, J.L. (3) 98, 158 Malc, N.A.H. (1.1) 16; (2) 308 Malfant, I. (1.11) 21; ( 5 ) 342 Malget, J.M. (1.111) 50; (5) 3 10 Malik, 1. (6) 173 Malik, K.M.A. (4) 230; (9) 74, 78; (12) 105 Mallcicr, R.(6) 286 Mallors, R.L. (3) 135; (4) 178; (5) 465,467 Malm, B. (12) 18 Maloney, J.D. (1 1) 71,74 Malouf, E.Y. (2) 145 Malvestiti, I. (13) 42 Manpc, D. (3) 112 Manasscro, M. (4) 35 1

Orgatiometallic Chemistry Mandal, S.K.(1.IV) 37 Mandel, A. (8) 71 Manger, M. (2) 222; ( 5 ) 190 Manimaran, 9.(2) 88,91 Mann, B.E. (4) 70,397; (5) 246 Mann, G. (7) 15 Mann,K.R. (6) 143,378 Manna, J. (2) 262 Manners, I. (2) 295; (5) 484; (6) 321-323; (1 1) 27 Manning, A.R. ( 5 ) 10 ManojloviC-Muir, L. (4) 19,32, 286; (5) 444; (12) 112 Manriquez, V. (1 .IV)56 Manscl, S. (1 .I) 88; (6) 227 Mansour, M.A. (3) 174; (4) 318, 332 Mantovani, L. (3) 155; (5) 39 1 Manz, B. (9) 32 Manzanero, A. (1.I) 8 5 , 9 1,92; (6) 213,229 Manzano, B.R. ( 5 ) 483; (6) 306 Manzi, L. (3) 160; (4) 376 Manzur, J. (1 .IV) 3 1; (3) 89; (4) 125, 139; ( 5 ) 409 Mao, L. (6) 188; ( 8 ) 19, 80 Mao, S.S.H. (10) 29 Mao, X.A. (2) 283; (6) 292; (13) 28 Mapolic, S.F. (2) 148 Marabcllo, D. (3) 120; (4) 73; ( 5 ) 408 Marayama, Y. (5) 182 Marcaccio, M. (13) 4 Marcalo, J. (6) 20 Marcellin, M. (6) 181 Marchag, A. (2) 161 Marchetti, F. (2) 303 Marcinicc, B.(3) 106 Mardcr, S.R. (2) 100 Marek, I. { 12) 9 Margel, P. (5) 108 Margcl, P.M. (5) 109 Margl, P.M. (2) 242,248 Maringgclc, W. (1 1) 11 Marken, F. (3) 83; (6) 313 Markewich, R.T. (4) 277 Marko,L. (2) 201 Marko, M. (3) 142 Marks, T.J. (1.1) 26,31, 87; (1.11) 17; (6) 19,29, 192,200,207, 240; (8) 33-35; (1 1) 3 Marr, A.J. (8) 98 Marsch, M. (12) 52 Marshall, W.J. (6) 153; (9) 69 Martin, A. (1.1) 73; (1 .II) 3,20; (2) 258,333; (3) 146, 159; (4) 43,91,281; (5) 304,473; (6)

26,83 Martin, C.M. (3) 126; (4) 143, 168, 174; (5) 224,365,424, 448; (6) 136 Martin, F.(2) 360 Martin, J. (6) 337 Martin, J.D. (7) 33 Martin, K.F. (6) 325 Martin, M. (2) 228; (5) 202,326 Martinelli, A. (2) 201; (3) 142 Martincngo, S.(4) 33,34 Martinez, F. (2) 258,259; (5) 436 Martinez, G.M. (6) 358 Martinez, M. (2) 255 Martincz-Aguilera, L.M.R. (12) 42 Martincz-Ilarduya, J.M. (2) 252 Martincz-SariAcna, A.P. (3) 146; (4) 281 Martins, A.M. (1 .II) 8,24; (6) 47 Martin-Vaca, B. (2) 135 Marumo, T. (2) 56; (5) 76 Maruoka, K. (8) 86; (12) 10 Maruyama, Y.(2) 34 Marziimo, 1. (9) 46 Marzilli, L.G. (2) 162, 163, 172 Marzilli, P.A. (2) 172 Marzin, C. (6) 266 Maschmeyer, T. (4) 41 Masciocchi, N. (4) 16; ( 5 ) 378 Masdcn-Bulto, A.M. (5) 203 Mascras, F. (3) 56; (6) 243 Mascrus, F. (2) 124 Mashima, K. (1.11) 1;(5) 264, 268,269; (6) 43; (8) 54,83 Mashuta, M.S. (1.IV) 47; (3) 105; (6) 105; (1 1) 53 Masi, C.J. (1.IV) 45; (2) 46; (6) 103, 134 Masi, D. (2) 2 11 Mason, M.R.(1 1) 53 Mason, S.A. (4) 17 Masood, A. (6) 234,236 Massa, W. (4) 56, 117; (6) 7,247, 373; (9) 87 Mastcrs, A.F. (6) 3 13 Masuda, Y. (7) 16,17 Matano, Y. (9) 95 Matco, C. (2) 293 Mathews, J.E. ( 5 ) 367 Mathcy, F. (3) 143; (4) 223; (5) 340; (6) 299; (9) 39,43,48, 56,57,63,79 Mathieu, R. (1.W) 57; (5) 168, 197,306 Mathur, C. (6) 23 Mathur, P. (2) 88, 91; (3) 115, 116, 122, 164, 165; (4) 8,85,

Author Itidex

110, 142,310, 31 1, 317, 348, 349; (5) 446,458; (6) 77 Mathur, S. (6) 23 Matitra, K. ( 5 ) 69 Matlis, P.M. (5) 68 Matsubara, S. (13) 39 Matsubara, T. (3) 29 Matsuda, I. (4) 392 Matsuda, S.(8) 85 Matsui, T. (5) 369 Matsumoto, K. (2) 237 Matsumoto, N.(13) 34 Matsumura, K. (7) 43 Malumura, N. (2) 354 Matsuo, T. ( 5 ) 373 Matsuo, Y,( 5 ) 269 Matsuzaka, H. (6) 1 15 Matt, D. (6) 181 Matters, J.M. (4) 100; ( 5 ) 425 Matthcis, C. (6) 34 Matthews, R.M. (1 1) 53 Mattner, M.R. (1.IV) 69; (1 I) 79 Matzger, A.J. (4) 103 Mauipe, D. (5) 361 Maulitz, A. (10) 22 Mauthncr, K. (2) 101 Mavaud, V. (6) 390 Mavunkal, I.J. (3) 156; (4) 161, 326; ( 5 ) 463 Mawby, R.J. (2) 30; (5) 290 Mayer, H.A. (5) 327 Maycrs, A.W. (2) 150 Mayr, A. (2) 40 Mays, M.J. (4) 52,53,90, 248; ( 5 ) 347,445; (6) 51,70, 73, 89 Mcalli, C. (1.111) 60; (4) 320 Mcdina, J.C. (6) 331 Mcdnikov, E.G.(4) 37 Mechan, M.M. ( 5 ) 398 Mcehan, P.R. ( I 0) 53 Meek, G. ( 5 ) 57,59 Mectsma, A. (1 .II) 9; (5) 159, 166; (8) 60,61 Mcggcs, K. (6) 7; (9) 87 Mehncrt, C.P. (1.HI) 23; (2) 64; (6) 74 Mehta, J.M. (1 .IV)47; (6) 105 Meidine, M.F. ( 5 ) 148 Mcier, E.J.M. (2) 122 Meiscr, M. (9) 98 Mcister, G. (4) 156; (6) 398 Mcli, A. (2) 21 1; ( 5 ) 15 Melikyan, G.G. ( 5 ) 374 Mclis, S. (12) 20 Meller, A. (1 1) 11 Mellors, R.L. (4) 172 Melon, S.(3) 72 Mcna, M. (4) 43

Mcndizbal, F. (4) 295, 296 Mcng, Q. (1.IV) 30; (8) 93 Meng, W.-D. (1.111) 93; (5) 390 Mcnjon, B. (2) 258,259 Mcntcs, A. (2) 320; (9) 92 Mcnzcr, S. (4) 282,283 Mcrcandclli, P. (3) 91; (4) 2, 65 Mcrchan, F. (12) 106 Mcreitcr, K. (2) 101, 111; ( 5 ) 72, 248,29 1,292; (6) 126 Mercr, A.J. (8) 98 Merger, M. ( 5 ) 11 Merino, R.I. (2) 339; (1 1) 97 Menvin, R.(5) 100 Merq A. (12) 100 Mcrzweiler, K. (4) 122, 130,354, 355; (5) 421; (6) 261 Messcrlc, B.A. (2) 42 Mcsserlc, L.(4) 48; (6) 252 Mestdadgh, H. (5) 55 Mestroni, G. (2) 291 Mctail, V. (9) 22 Metten, K.-H. (5) 57 Mctz, B. (6) 373 Mctzlcr, M. (6) 384 Mctzlcr, N. (1.111) 23; (2) 64; (6) 74 Mcunier, P. (1.1) 53,55; (9) 80-82 Mews, R. (1 3) 29 Mcyer, J.M. ( 5 ) 320 Meycr, 0. (1.1) 33 Mcycr, T. (1 .Ill) 85 Mkaillcs, N. (6) 171 Mhinzi, G.S. (2) 3 18 Michaelidou, D.M. (10) 57 Michclin, R.A. (12) 1 16 Michl, J. (10) 77; (13) 27 Micouin, L. (13) 40 Middlcmiss, D. (1.111) 105, 106 Michr, A. ( I 1) 85 Migasaka, H. (13) 34 Miguel, D. (1 .IV) 33; (3) 85 Miguel, Y. (9) 8 1 Mihan, S. (1 .rv)25 Mihovilovic, M.D. (12) 2 Mijasaha, T. ( 5 ) 76 Mikarni, Y.(2) 203 Mikan, S.(5) 457 Milani, B. (2) 291 Miles, B. (6) 67 Milet, A. (2) 246,247 Milius, W. (1.1) 86; (10) 17, 25 Milke, J. (1 .III) 90; ( 5 ) 400 Millan-Barios, E. (6) 336 hliller, G.A. (1.111) 40 Miller, H.J. (1 1) 30 Miller, J.D. (13) 7 Millcr, J.R. (6) 389

47 I Miller, J.S. (1 .IV) 14 Miller, M. ( 5 ) 127 Miller, S.M. ( 5 ) 441; (10) 31 Millet, P. (6) 343 Millot, N.( 5 ) 226 Milonc, L. (4) 106, 119, 120; (5) 417,419 Milstcin, D. (2) 199,204, 267; (5) 89 Minachcva, M.K. (1.i) 45 Mingos, D.M.P. (4) 280, 282, 283; (10) 57 Mingucz, J. (2) 300 Mink, J. (1.N) 61 Miquceiz, E.M. (2) 3 17 Miqucl, Y.(1.1) 52,54 Mirkin, C.A. (6) 309, 399 Mirzaci, F. (1 .HI) 49; ( 5 ) 52; (6) 55

Miscione, G.P. (13) 43 Mishina, N.M.(1 0) 93 Mitchell, E.M. (10) 2 Mitchcll, G.F.(10) 2 Mitsopolou. C.A. (6) 381 Mitsudo, T.-a. (2) 367; (4) 388; ( 5 ) 403; (7) 24 Mitzi, D.B. (9) 97 Miura, T. (8) 86 Miyagi, K. (4) 271 Miyajica, S. (2) 237 Miyasch, T. (2) 56 Miyaura, N. (1 1) 13 Miyoshi, K. (1.111) 37; (2) 53; (6) 131 Mizobc, Y.(4) 262; (5) 434 Mizuno, T. (13) 39 Mizuta, T. (1.111) 37 Mkoyan, S.G. (6) 203 Mlodnicka, T. (3) 14 Mlynck, P.D. (3) 148, 149; (4) 35, 36; (9) 116 Mo, €1.-M. (3) 41; (4) 191 Mobley, T.A. (13) 40 Mock-Knoblauch, C. (3) 69,70; (5) 214 Modarrcs Tchrani, Z. (6) 46 Modrego, J. (2) 107; (4) 265 Miisch-Zanetti,N.C.(1XI) 57,58 Mohammadi, F. ( 5 ) 2 10 Moinct, C. (2) 79; (6) 293 Moke, C. (1 .III) 25; (3) 150; (6) 90,226,25 1,257 Moiseev, 1.1. (4) 394 Moisecv, S.K.(6) 380 Moizeau, K. (4) 119 Mok, K.F. (4) 362 Mokry, L.M. (1 1) 72 Molander, G.A. (8) 89

472 Molins, E. (6) 283 Moll, M. (2) 139; (12) 70 Molloy, K.C.(4) 292 Momblona, F. ( 5 ) 204 Monari, M. (2) 97,98; (3) 160; (4) 225,376; ( 5 ) 145 Moncricff, D. (6) 186; ( I 2) 85 Mongc, A. (1.111) 28; (5) 41, I05 Mongin, C. (1.IV) 57 Monsour, M.A. (3) 153 Montari, M. (2) 273 Montcro, C. (5) 273 Montero, M.L. (1 1) 59 Montgomcry, D. (12) 17 Moodlcy, K.G. (6) 63 Moody, M.W. (2) 369; (5) 85 Moore, A.J. (6) 267 Moore, J.N. (3) 32 Moore, M. (1.11) 16 Moore, M.H. (5) 172 Moore, S.J. (2) 172 Morales, M.D. (1.W) 33; (3) 85 Moran, M. (6) 302,303 Moran, P. (2) 2 14; ( 5 ) 256 Morcno, M.T. (2) 333; ( 5 ) 436; (6) 243 Moreno-Manas, M. (5) 13 I Moret, E. (12) 13, 14 Moret, M. (2) 201; (3) 91, 142; (4) 65,346 Moreto, J.M. (1.111) 102; (5) 370 Morcwood, C.A. (4) 167; (6) 141 Morgin, C. ( 5 ) 168 Mori, M. ( I X I ) 124 Mori, S. (13) 48 Morinioto, T. (7) 23 Morin, C. (6) 284 Morino, M.T. (5) 473 Morise, X. (4) 247 Morlcy, C.P. (2) 289; (4) 84; (6) 22 Morokuma, K. (2) 152,241; (3) 29; ( 5 ) 114, 115,324 Moro-oka, Y. (2) 61,92, 134; (4) 154, 155, 353; ( 5 ) 233,363; (6) 133 Morosha, Y. ( 5 ) 196 Morozova, L.N. ( 5 ) 68; (6) 138 Morrice, F. (4) 19; ( 5 ) 444 Morris, K.F. ( 5 ) 122 Morris, L.J. ( 5 ) 44 Morris, M.J. (1.111) 38, 96; (3) 15; (4) 321-323; ( 5 ) 406; (6) 68 Morns, R.H. (3) 92 Morris, R.J.(6) 242 Morrison, J.F. (13) 7 Morton, C. (1 .IV) 28 Mortreux, A. ( 5 ) 386; (7) 27

Orgartometallic Cliemistty Mosimann, L.L. (3) 39 Mossct, P. ( 5 ) 282 Mosul, L.J. (6) 344 Motcvalli, M.(6) 381; (1 1) 36 Motoori, F. (2) 359 Motoyama, I. (6) 340 Motoyama, Y. (2) 203 Moubanki, B. (4) 183 Mountford, P. (1 .II) 8, 24; (6) 37, 47; (12) 75 Mourad, 0. (3) 133; (4) 163 Mourges, P. (1 .III) 16; ( 5 ) 43 Mozzon, M. (12) 116 Muddiman, D.C. (2) 262 Miihlcbach, A. (1.11) 12 Mullcr, A. (13) 2,22 Muilcr, F. (2) 177; ( 5 ) 441 Mullcr, J. (2) 214; ( 5 ) 140,256 Mucllcr, M. (1 1) 27 Miiller, T.J.J. (6) 379 Mugnicr, Y. (I .II) 4; (4) 278; (6) 46,244 Muhoro, C.N. (6) 217 Muir, K.W.(2) 86, 87; (4) 19, 32, 286; ( 5 ) 444; (12) 1I2 Mul, W.P. (2) 89; (4) 26 Mulford, D.R. (1.11) 27; ( 5 ) 263 Mulhaupt, R (1.1) 3 Muller, B. (3) 60 Muller, C. (9) 47 Mullcr, G. (2) 300; (8) 67 Muller, T. (6) 166; (10) 16 Mullcr, T.E. (4) 283 Mullica, D.F.(4) 21 1; (10) 32, 36, 49,50 Mulvcy, R.E. (12) 54,7 I Mulzcr, J. (13) 5 Munakata, M. (5) 476; (12) 101 Munchow, V. (6) 223 Munck, F.C. (8) 59 Mundt, 0. (9) 98 Mufioz, P. (2) 54; (6) 164 Murahashi, T. ( 5 ) 435 Murai, S. (3) 57; (4) 393; (7) 20, 21,23 Mutakami, Y. (2) 3 14 Murata, M. (7) 16, 17 Muratakc, H. (7) 5 Muratov, D.V. (4) 261 Murillo, C.A. ( I .I]) 25 Murko, L. (2) 238 Murphy, E.F. (1.111) 4; (2) 3; (I 1) 38 Murray, A.P. (13) 39 Murray, K.S. (4) 183 Murugavel, R. (1 .HI) 4; (2) 3; (I 1) 87 Musacv, D.G. (2) 241; (3) 29; ( 5 )

114, 115 Musashi, Y.(5) 143 Musso, F. (6) 371 Muto, H. (4) 243; (6) 278 Myers, A.W. (2) 212,224; (6) 152, 155 Mynott, R. ( 5 ) 259,260 Nachtigal, C. (10) 62,64 Nadasdi, T.T. (2) 37 Naganishi, S.(5) 60 Nagasawa, A. (1 1) 10 Nagasawa, I. (2) 286 Nagasawa, T. ( 5 ) 372 Nagase, S. (9) 72 Nagashima, H. (4) 114,392; (5) 420 Nagel, U. (1 3) 7 Nagelholt, L. (1.IV)68 Nagclkerte, R. (2) 200 NagyGergcly, I. (2) 201; (3) 142 Nahar, S.(3) 172; (4) 356; (6) 174 Nahring, J. (4) 271 Naim, J.G.M. (3) 14; (4) 201; ( 5 ) 447 Naka, T. (8) 85 Nakai, T. (7) 56 Nakajima, A. (1.111) 121; (6) 176; (8)41 Nakajirna, K. (1 .I) 50; (5) 341 Nakaniura, A. (1.11) 1; (5) 268; (6) 43; (8) 54, 83 Nakamura, E. (13) 48 Nakamura, H. (10) 73 Nakamura, K.(2) 53 Nakamura, M. (9) 93 Nakamura, N. (4) 271 Nakaniura, S. (2) 236; (5) 113 Nakamura, T. ( 5 ) 369 Nakaniura, Y. (2) 63,237; (4) 189 Nakanishi, S. (2) 92; (4) 155; (5) 363 Nakano, T. (8) 92 Nakashina, S. (6) 340 Nakayama, H. (4) 271 Nakayama, Y. (1.11) 1; (5) 268; (6) 43; (8) 54,83 Nakazawa, H. (1.111) 37; (2) 53; (6) 131 Nandi, M. ( 5 ) 31 Nanjo, M. (12) 68 Narasovaka, N. ( 5 ) 236 Narayan, S. (2) 305 Nardelli, M. (3) 132; (4) 22, 147 Nardin, G. (2) 207 Nashner, M.S.(4) 395 Naskamura, H. (10) 69

Author hdm Nasluzov, V.A. (1 .XV)60 Natarajan, E. (2) 179 Natsume, M.(7) 5 Natsume, S.(9) 93 Naulty, RH. (1 2) 1 14 Naumann, D. (9) 91, 101; (12) 111

Naumann, F. (2) 297,298 Navarro, R (2) 277,279 Navametc, J. (2) 258 Nayak, S.K. (3) 64; (5) 27 Neagu, I.B. (5) 36 Neddcn, G. (13) 7 Ncfcdov, S .E.(4) 8 1,400 Nkgri, S.(7) 58 Nelson, J.H. (2) 104; (3) 118; (4) 193; (5) 69,232; (6) 128 Nemoto, H. (10) 73 Nesper, R.(4) 382; ( 5 ) 130 Ncttekovan, U. (6) 269 Nctzlcr, N. (6) 64 Neubcrt, I. (1 .IV)55 Neuburger, M. ( 5 ) 132, 140 Neumann, B. (6) 112,335; (9) 29 Neumann, H. (5) 246 Ncumann, M.F. (5) 276-278,280 Ncumayer, M. ( I 1) 88,91 Neumiillcr, B. (4) 56; (1 1) 70; (13) 2, 19,22 Ncve, F. (2) 274 Newton, C.(4) 50; (6) 44 Ng, S.C.(2) 307 Ng, W.S.(2) 77 Nguyen, B.V. (13) 39 Nguyen, M.H. (6) 384 Nguyen, M.T. (1.11) 27; (5) 263; (9) 26 Nguyen, P. (1 1) 27 Nicaise, J.-C. (5) 249 Nicasio, M.C. ( 5 ) 105 Nicholas, K.M. (5) 371 Nichols, M.A. (12) 40 Nichols, P.J. (10) 83 Nicholson, B.K. (6) 346 Nicholson, T. (1 .JY) 18 Nickias, P.N.(1.1) 87 Nicolaou, K.C.(7) 7 Nieckc, E. (1.111) 80; (6) 355; (9) 33,34; (12) 50 Nief, F.(6) 15,256; (8) 15; (9) 45, 114 Nicger, M. (1.111) 72,80, 99, 101, 122; ( 5 ) 308,309; (9) 33.34; (12) 50 Niclsen, N. (12) 1 Niemeyer, M. (12) 65,77 Nienabar, H. (1.111) 9 Nicrlich, M.(6) 189; (8) 70

473 Nifant'cv, 1.E. (6) 2 1 1 Nijbackcr, T. (I 1) 83 Nijkamp, M.G.(1.11) 19; (13) 26 Nikanov, G.I.(6) 249 Nikiforov, S.M.(6) 93 Nikol'skii, A.B. (4) 112; (5) 41 I Nikonov, G.I.(6) 245,247; (9) 112, 113 Nilsson, G.N. (12) 18 Nilsson, K. ( 5 ) 336 Ninan, A. (12) 18 Nishibayashi, Y.( 5 ) 481; (6) 265, 308 Nishihara, Y. (1 .I) 50 Nishikara, Y. (5) 341 Nishimura, J. (2) 286 Nishio, R. (5) 164 Nishioka, T. (2) 236 Nishiyama, H. (2) 203,354 Nishiyama, Y.(8) 90 Niu, S.(2) 149, 153; (5) 94 Nixon, D.M.(4) 149 Nixon, J.F. (1.111) 21; (3) 122; (4) 85,223; (5) 397; (6) 77; (9) 8, 9, 13,31,47,49, 50,53,63 Niyaz, N. ( 5 ) 210 Nkajima, H. (2) 47 Nlate, S.(2) 355; (6) 357 Nobata, M. (4) 114; (5) 420 Noels, A.F. (5) 68; (6) 138; (10) 45 Noth, H. (5) 375; (6) 300; (9) 35, 37; (12) 48,69 Nolan, S.P.(3) 55; (5) 67 Nolan, T.F. (3) 33 Noll, B.C. (6) 79; (10) 77; (13) 27 Noltcmeyer, M.(8) 56; (1 1) 11, 37,38,46,62; (12) 67 Nomura, Y.(4) 262; (5) 434 Nordlandcr, E.(3) 14; (4) 27,224, 225 Norman, N.C. (9) 104 Normant, J.F. (12) 9 Nomby, P.-0.(5) 37, 125 Norsiliian, S . (12) 9 Norton, J.R.(2) 161 Novak, B.M. (2) 254; (8) 32 Novak, I. (3) 40;(4) 74 Novotortsev, V.M. (4) 9 Nowicki, G.(9) 91, 101 Nowotny, M. ( 5 ) 224 Noyon, R.M.(7) 43; (13) 24 Nubcr, B. (1.1) 71; (1.111) 25; (5) 254, 454; (6) 2, 87,90, 1 10, 257; (1 1) 63 Nu~icz,R. (10) 45 Nunziante, C.S. (8) 99 Nutt, W.R (1 1) 92

Nuulty, R.H. (2) 326 Nyulaszi, L. (9) 18,50 Nziengui, R. (1 1) 14 Oberhanimer, H. (10) 24 Oberhoff, M.(1.1) 65 Ob~o-RosetC,R.(4) 320 Obora, Y.(1.1) 87; (8) 33 OBncn, P.(12) 23 Ochiai, T. (I .III) 103 OConncr, S.P.(13) 39 OConnor, J.M.(2) 215; (5) 100, 295,296 Odoni, A.L. (1.111) 63 Odom, J.D.(1 1) 92 O'Donoghuc, M.B.(1.111) 58; (9) 73 Ofclc, K. (2) 348 Ochlschlagcr, A.C. (12) 24 Oclchcrs. B. (5) 172 h e n d a h l , M. (4) 289 Ocstreich, M. (1 3) 40 Ozdcmir, I. (2) 349 Ogasawara, M. (2) 37; (3) 56 Ogawa, H. (4) 181 Ogawa, M. (5) 143 Ogino, H. (4) 95; (6) 122 Oglieve. K.E. (5) 48 Ogoshi, S. ( 5 ) 151 Ogric, C. (1.111) 67, 83; (3) 50; (6) 57; (9) 83 Oh, M.(2) 218 Ohancssian, G.(1 .III) 16; (5) 43 O'Hare, D. (6) 364 13 Ohba, M. (1.W) Ohe, K. (6) 265 Oliff, A. (2) 267 Ohff, M. (2) 267 Ohmka, A. (5) 142 Ohnishi, S.(4) 319,369 Ohsuka, A. (2) 296 Ohta, K. ( 5 ) 196 Ohta,T. (8) 33 Okada,J. (6) 246 Okada, S.(13) 24 Okada, T.(4) 388; (7) 24 Okamoto, K. (5) 60 Okamoto, Y.(1.111) 121 Okawa, H. (1.IV) 13 Okazaki, R. (9) 72 Okc, K.( 5 ) 48 1 Okcya, S. (2) 286 Oki, M. (3) 62; (12) 39, 90 Okiyama, H. (4) 18 Oh,A. (13) 40 Okuda, J. (1 .I) 3,24, 34; (6) 36; (819, 10

Organometallic Chemistv

474 Okuhara, H. (3) 62 Olbrich, F.(6) 187; (12) 80, 81 Oldenburg, K. (6) 282 Oldham, W.J. ( 5 ) 93 Oldroyd, R.D. (4) 4 1 O'Lary, S.R (5) 68; (6) 138 Oleinkova, N.A. (12) 110 Oliva, A. (8) 103 Olivan, M. (2) 127,345; (3) 55 Olivier, P.J. (12) 117 Olmeda, A. (13) 4 Olmos,E. (12) 108 Olmstead, M.M. (2) 115; (4) 300 Olshevskaya, V.A. (10) 70,74 Olshnitskaya, LA. (4) 81 Olson, D.M. (3) 39 Olthoff, S. (9) 14 Onaka, S. (4) 243 Ofiatc, E. (2) 69, 107, 121, 124, 129,228; (3) 46,95; (5) 71, 86, 185, 186,202,326 O'Ncil, D.N.(7) 19 Oweill, L. (3) 26 Ongania, K.-H. (6) 298 Onganici, K.-H. (6) 286 Onida, B. (4) 391 Oaozawa, S. (1 1) 15 Ooi, T. (8) 86; (12) 10 Orabona, I. (2) 272,273,322, 334; ( 5 ) 120, 145, 150 Orama, 0. (2) 141 Orchin, M. (1.IV) 37 Ordung, I. (12) 46 Orcjon, A. (5) 203 Organ, M.G. (5) 127; (13) 39 Oriaka, S. (6) 278 Oro, L.A. (2) 124, 189,228,234, 240; (3) 108; (4) 265; ( 5 ) 185, 188, 201,202,326; (6) 164 Ortiz, R. (2) 100 Owis, J.A. (4) 258; (5) 433 Osadhada, K. (5) 95 Osakada, K. ( 2 ) 216,331; ( 5 ) 91 Osawa, M. (6) 296 Osborne, S.A. ( 5 ) 227 Osella, D. (4) 119, 120; (5) 419 O'Shaughncssy, P.N. (1 2 ) 33, 7 1 Oshiki, T. (8) 54 Oshima, K. (1.IV) 8 Osina, M.A. (4) 202; (5) 428 Osintseva, S.V. (2) 90; (4) 137, 195 Oskam, A. (2) 39; (4) 192,342 Oskarsson, A. (2) 3 10 Oslob, J.D.(5) 125 Osman, R. (2) 120 Ossola, F. (6) 284 Oster, J. (1 .I) 30,47; (6) 233

Otcro, A. (1 .I) 93; (1 .lI) 3, 4,20; (2) 33; (5) 18 1,304; (6) 46, 215,243,244 Ottoson, C.-H. (1 1) 5 Ovcrby, J.S. (6) 185, 194; (8) 2; (12) 79 Oyewale, A.O. (13) 7 Ozawa, F. (2) 34; (5) 182 Ozkar, S. ( 5 ) 177 Ozkaya, D. (4) 4 I Padras, A.B. (6) 347 Padwa, A. (7) 39 Pack, C. (1 1) 4 3 , 4 4 8 6 Paiaro, G. (5) 47 1 Paii, M.( 5 ) 137 Paine, R.T.(1.111) 32 Pajuclo, F. (5) 13 1 Pakkanen, T.A. (3) 170; (4) 25, 140,246,360 Pakkancn, T.T. (4) 140 Pakusina, A.P. (9) 94 Palazzi, A. (2) 97 Palet, P.P. (6) 114 Paley, R.S.(5) 273 Palma, P. (1.111) 28; (5) 41, 383 Palmer, M. (2) 22, 150; (6) 152; (7) 45 Palmer, W. (5) 224 Palucki, M. (7) 3, 14 Palyi, G. (2) 201; (3) 142; (5) 378 Pampaloni, G. (1.1) 77, 78; (3) 59; (6) 212,370 Pan, G. (4) 244 Panajotva, B.V. (5) 122 Pandolfo, L. (5) 149,471 Paneque, M. (2) 301 Panigati, M. (3) 38; (4) 63,64 Panncll, K.H. (6) 3 10 Panunzi, A. (2) 322; ( 5 ) 150 Paoletti, M.(2) 303 Paolucci, G. (I .I) 32 Papagni, A. (1.111) 93; ( 5 ) 390 Papalco, S. (4) 22 Parella, T. ( 5 ) 131 Parisini, E. (4) 178; (5) 467; (6) 35; (1 1) 37,38,40,87 Park, J.T. (1 .I) 90; (4) 209; ( 5 ) 430; (6) 228 ( 5 ) 220 Park, S.-H. Park, Y.S. (12) 7 Parker, D.G. (3) 126; (4) 168; ( 5 ) 424; (6) 136 Parker, R.J. ( 5 ) 379; (6) 170 Parkin, B.C. (1 .II) 14 Parkin, R.P.G. (6) 7 1 Parlicr, A. (1.111) 125

Parodi, N. (5) 99 Parshina, I.N.(6) 193; (8) 4 Parsons, S. (3) 125, 126, 135; (4) 168, 172-174, 176-178; ( 5 ) 224, 365,424,465-467; (6) 136 Partridge, M.G. (5) 172 Parvez, M. (1 .I) 83 Pascu. s. (9) 121 Pascual, I. (2) 277 Passch, R. (5) 70 Pastor, A. (5) 29, 163 Pasynkicwicz, S. (4) 272; (6) 179 Pasynskii, A.A. (4) 339,400 Patcl, P.P. (2) 44, 119 Patcrniti, D.P. (2) 185 Patoux, C. (6) 354 Patterson, D.I.(3) 32 Pattison, D.I. (2) 120 Patton, J.T. (8) 11 Paul, F. (2) 117, 143; (3) 44; (6) 109 Pauson, P.L. (4) 245 Pawclke, G. (1 1) 8 Pearce-Batchilder, S.D.(8) 5 8 Pearsall, M.-A. (4) 100; (5) 425 Pcarson, A.J. (5) 35, 36,219,240 Pcat, K.L. (4) 198 Pedlcy, J.B. (2) 245 Pcdulli, G.F. (13) 4 Pcelen, K. (3) 103 Peganova, T.A. (5) 68; (6) 138, 365 Peinado, E. (3) 95 Pellinghelli, M.A. (1 .I) 93; (3) 152, 161; (4) 75,92, 375; (6) 215 Pellny, P.M. (1.1) 60; ( 5 ) 438 Penchcrt, U. (5) 338 Pcng, S.-M. ( I ,111) 43,48, 73, 76, 97; (2) 105; (3) 52, 163, 177; (4) 58, 82, 141, 161, 169,309, 324, 325, 327-329; (5) 75, 3 12, 3 14, 399,440,456,460; (6) 254; (1 1) 60 Peng, Z.-H. (1 .IlI) 15 Pcplow, M.A. (5) 235 Pcrcgudov, A S . (3) 169; (4) 237 Pcregudov, P.V. ( 5 ) 480 Pereira, R.M.S. (3) 144; (4) 268 Perera, S.D.(2) 229 Perez, P.J. (5) 105 Periasaniy, M. (3) 93 Pcron, D. (2) 361 Pcron, S. (3) 66; ( 5 ) 345 Peron, V. (1 .lII) 87 Pemn, J.L.(3) 87 Perron, P. (6) 203

Author Index Persoons, A. (2) 99,324-326; (5)

Pictschnig, R. (6) 355 479; (6) 359; (12) 114 Pictzsch, C. (6) 261; (8) 29 Pertici, P. (5) 246 Pifferi, C. (2) 163 Pertrovskii, P.V. (5) 452 Pike, R.D. (3) 35 Perutz, R N . (2) 32, 120; (3) 23, Pikramenou, Z. (3) I5 32; (4) 187; (5) 172 Pillani, G. (6) 333 Peruuini. M. (2) 120,207 Ph,C.-W. (1.HI) 48 Pcsch, T.C.(12) 37 Pindado, G.J.(1.1) 39,40; ( 5 ) 159, Pcshcrbc, L.M.(13) 27 266, 337; (6) 33 Petasis, N.A. (1 1) 2 Pificra-Nicolis, A. (1 .III) 130 Peterleitner, M.G. (5) 381 Pincschi, M. (7) 49 Petermann, A. (2) 329 Pinilla, E. (5) 200 Peters, J.C. (1.111) 63 Pinillos, M.T. (5) 188 Peters, J.4. (7) 36 Pink, M. (12) 73 Peters, K. (2) 225,230; (6) 148, Pinkcrton, A.A. (5) 36 163; (9) 14 Pinkes, J.C. (6) 134 Peters, R.G.(6) 383 Pinkes, J.R. (2) 46 Pctcrsen, J.L. (1 .I) 27,44; (2) 176; Pique, G. ( 5 ) 57 Pirio, N. (1 .I) 53,54; (9) 80 (5) 67 Peterson, L.K.(1.IV) 51; (5) 175 Pisarcva, LV. (10) 33 Pethc, J. (4) 371 Pistolcsi, L. (3) 132; (4) 147 Pbtillon, F.Y. (2) 86,87; (4) 19; Plass, J. (2) 79; (6) 293 (5) 444; (6) 52 Plasscraud, L. (4) 157, 158 Petrov, E.S.(8) 49 Plattner, D.A. (2) 158, 184; (6) Petrovskaya, T.V.(8) 5 1 159 Pctrovskii, P.V. (1.1) 45; (2) 90; Plcixats, R. (5) 13I (3) 169; (4) 108, 145, 195, Plcnio, H. (6) 204,338,353 205, 206,237,238,261,389, Pldck, J. (10) 61-64 398; ( 5 ) 381; (6) 280 Plcunc, B. (6) 53, 80 Petrowitsch, T. (5) 239 Plourde, G.W. ( 5 ) 367 Petruncnko, I.A. (4) 9 Plutino, M.R. (2) 256 Petrusovai, L. (1.I) 69; (13) 1 1 P l d , z. (10) 20,21 Pettig, S.J. ( 5 ) 191 Podberezskaya, N.V. (4) 20,3 1, Peuchcrt, U. (1.I) 67,95; ( 6 ) 220 214,236,315,316,366 Peulcckc, N. (1.I) 58-60; ( 5 ) 300, Podcr-Guillon, S. (6) 52 301,438 Podshadley, 0. (1.111) 85 Pcurta, M.C. (2) 136, 138, 144 P d , A.J. (3) 133; (4) 163,222 Pfcffer, M. (1.11) 19; (1.111) 91; Phchke, K.-R. (5) 110,332 ( 1 . v 29; (5) 139, 171,322; Pohl, S.(4) 94; (1 1) 91 (13) 26 Pohl, W. (2) 21 1 Pfciffcr, R. (4) 225 Pohlmann, M.(3) 162; (1 1) 91 Pfennig, V. (1 X I ) 18; (1.IV) 7 Poignant, G.(2) 355,360 Pfister-Guillouza, G. (6) 225; (9) Poisson, J.-F. (1 2) 9 22,23 Pojana, G. (1.I) 32 Pflug, K. (4) 103 Polamo, M.(6) 222 Phillips, S.L. (2) 115 PolaiSek, M. (1.I) 84; (6) 202,206; Philosof, A. (8) 8 (13) 10 Piacenti, F. (2) 180; (3) 132; (4) Polbom, K.(1 XI) 88, 1 18; (1.IV) 22, 147 22; (5) 402 Piao, G.(6) 219 Poli, R. (4) 372; ( 5 ) 33; (6) 50,53, Pichon, R.(2) 86 80 Picket, C.J. (9) 47 Poliakoff, M.(6) 93 Pidun, U. (1.111) 11; ( 5 ) 5 Poll, L. (6) 110 Picrs, W.E. (1.1) 82, 83; (8) 58 Pollagi, T.P. (1.111) 54 Pietraszuk, C. (3) 106 Polson, S.M. (2) 162, 163, 172 Pietrzykowski, A. (4) 272; (6) 179 Polyakova, L.A. (4) 352,387; (5) Pietsch, J. (2) 278 442 Pietschmann, C. (13) 5 Pombciro, A.J.L. (1.IV) 11

475 Pomcroy, R.K. (3) 97,98, 158; (4) 29,235 Pomitjc, M.K. (6) 377 Pook, E.J. (4) 53; (6) 70 Poon, K.S.M. (3) 74 Pore&, M.L. (5) 42,297 Porcrnba, P. (8) 53,55,56 Porhicl, E. (1 .Ill) 87 Posch, R. (6) 12 1 Poveda, M.L. (1 .IlI) 28,29; (2) 301; (5) 41, 105; (6) 72 Powcll, D.H.(1 1) 69 Powell, D.R. (1 .rv)50;(5) 152 Po\vell, H.R. (4) 248 Powell, J. (5) 96; (12) 102 Powell, N.A. (13) 39 Power, P.P. (1 1) 45; (12) 64,65, * 77 Powers, T.S. (1.111) 123 Pozhanskii, I.L. (5) 252 Pramanik, K. (2) 67 Prasad,K.R.K. (13) 39 Prat, V. (5) 376 Prato, M. (6) 314 Pratt, R (7) 25 Predieri, G. (4) 83, 128,391; (5) 426 Prcctz, M. (1 3) 3 1 Pregosin, P.S. (2) 52; (3) 75; (5) 53, 117, 130,247; (6) 392 Press, W.J. ( 5 ) 366 Preston, P.N. (6) 347 Prcstopino, F. (2) 97 Price, c . (2) 74 Priggc, J . (1.1) 95; (6) 220 Pringle, P.G. (5) 146 Pritzkow, H. (1.111) 69; (4) 256, 257; ( 5 ) 432; (6) 161, 166; (10) 16; (11) 85 Probst, J. (9) 119 Probst, R (2) 298 Procopiou, P.A. (7) 35 Profi, B.(5) 110 Proscnc, H.H.(6) 258 Proserpio, D.M.(4) 3,34 Prossak-Wieckowska, T. (6) 167, 169 Protchenko, A.V. (6) 368; (8) 52 Prussak-Wicckowska, T.(3) 145; (4) 270,344 Ptashits, G.M. (10) 71 Pu, L. ( 5 ) 78 Puddephatt, R.J. (2) 13,253,270; (4) 285, 286, 347, 368; ( 5 ) 6; (12) 112, 113 Puerta, M.C. (5) 323 Pumik, V.G. (3) 115; (5) 32; (1 1) 26

476 Purclics, G. (2) 207 Pursiainen, J. (3) 170; (4) 25,360 Putnikovic, B. (7) 57 Putzer, M.A. (13) 19 Pyati, R. (9) 21 PWkk6, P. (4) 295-298 Qmungo, K. (2) 166, 168 Qi, M. (8) 48 Qian, Y. (6) 28 Qiao, K. (2) 214; ( 5 ) 256 Qiao, S. (1 1) 7 Quadrelli, E.A. (4) 372 Quamta, E. ( 5 ) 112 QuasdorfT, B. (9) 29 Quessicr, J.A. (3) 87 Quinn, J.F. (1.111) 117, 123 Quintana, W. (6) 182; (10) 95 Quiros, M. (5) 386 Quyoum, R. (1 .I) 74 Raabc, G. (2) 70; (6) 124, 395 Rabc, G.W. (12) 72 Rabcr, J.C. (12) 17 Rabor, J. (1 .lV) 5; (2) 8 Radcmachcr, B.B.T. (13) 23 Radhaknshnan, U. (3) 93 Radinov, R. (7) 26 Radu, N.S. (1.1) 61 Racbiger, J.W. (4) 312 Rapplc, E. (12) 48 Ragcr, M.N. (5) 377 Rahbarnoohi, H. (1 1) 78 Raithby, P.R. (2) 93, 95,332, 355; (3) 94, 124, 172, 176; (4) 27, 39,40,52,53,90,96, 124, 146, 167,218, 219, 224,227, 239, 248, 356, 380; ( 5 ) 347, 427,445; (6) 5 I, 70, 73, 89, 141, 174, 294; (12) 31, 36,53 Ram, M.S. (2) 161 Ramaswamy, M. (2) 57; (5) 286 Ramirez, L.K.(6) 358 Ramirez dc Arellano, M.C. (2) 271; (3) 176; ( 4 ) 39,40, 167; (6) 141 Ramjoic, Y.(6) 168 Randaccio, L. (2) 171,291 Randall, E.W. (6) 381 Randall, T. (2) 73 Rao, C.N.R. (6) 365 Rao, C.R.K. (2) 75 Rao, R.J. (9) 89 Rasanen, T.M. (4) 246 Raston, C.L. (6) 198; (9) 70; (10) 82, 83; (11)61; (12)32,60;

Orgationietallic Chentistry (13) 18 Ratatunga, A. ( 5 ) 56 Ratli, N.P. (2) 321; (10) 30 (12) 117 Raubenhcimer, H.G. Rauch, M.U.(1.IV) 68 Rauchfuss, T.B.(4) 358 Ravclli, G.A. (1 .HI) 79 Ravcra, M (4) 120; (5) 4 19 Ravikuiwr, K. (2) 170 Raynham, T.M. (5) 229 Razzouk, H. (5) 377 Re, N. (I .l) 20; (1 .HI) 14; (1.lV) 23; (2) 24, 353 Rcck, C.E. (13) 9 Rcddmann, 14. (8) 108, 1 1 1, 112 Rcddy, C.K. (13) 40 Rcddy, K.L. ( I .lV) 63; (7) 46 Rcddy, N.P. (7) 10 Redckcr, T. (6) 2 10 Redmond, S.P. (2) 85; ( 5 ) 357 Rcdshaw, C. (1 XI) 42; (6) 67; (11) 12 Reed, A.D. (1.111) 98; (7) 37 Recs, N.H. (2) 74; (3) 110; (5) 359 Rectz, M.T.(5) 193 Rcfosco, F. (6) 284 Rcggclin, M. (5) I18 Rcgitz, M. (3) 48; (9) 2, 10, 15, 16, 18, 19,40, 60 Reibcl, C. (6) 266 Reibenspics, J.H. (6) 130 Rcichcnback, G. (2) 27-29 Reid, S.J. ( 5 ) 136 Rciff, W.M. (1.111) 58 Reina, R. (3) 159; (4) 75, 91 Reinhold, A.J. (3) 60 Reinmuth, A. (6) 238 Rcisacher, H.-U. (1.111) 32 Rcisc, U. (4) 56 Rcisingcr, C.-P. (7) 1 I RciB, G.J. (5) 350 Reissig, H. (1.111) 120 Rcissmann, U. (8) 56 Rclis, J.G.P. ( 5 ) 138 Remaclc, B. (12) 21 Rcn, J. (8) 18, 26, 79 Rcndina, L.M. (2) 13 Rcnlzcli, M. (6) 258 Rcnnckamp, C. (1 1) 35,59 Rcnner, M.W. (2) 160 Rcnnie, M.A. (4) 219; ( 5 ) 427 Renstaw, S. (6) 79 Repo, T. (6) 222 Repossi, A. (4) 35 1 Resendes, R. (1 1) 27 Reshcf, D. (2) 58; (6) 106 Rcspini, M. (4) 97

Retsch, W.H. (8) 89 Rcttig, S.J. (1.1) 8; (1.111) 51; (6) 69; (8) 43 Reuter, R (6) 3 15 Rhcingold, A.L. (1 .II) 16; (1 .III) 39, 117, 123; (2) 81, 91, 106, 119, 161, 167, 191, 192, 194, 215; (3) 39, 116, 164, 165; (4) 110, 142, 148, 149, 310,31 I , 357; (5) 74,215,250, 257, 295, 296,358,446,458; (6) 9, 10,41, 123,216, 399; (9) 38, 1 11; (10) 29; (1 1) 19,76,78; (12) 72; (13) 17 Rhcinwald, G. (4) 122, 156; ( 5 ) 421; (6) 398 Rhinchart, L.M. (6) 173 Riba, 0. (3) 159; (4) 91 Ricard, L. (3) 143; ( 5 ) 340,344; (6) 256,299; (9) 39,45,48, 56,57,79, 114 Ricart, S. (1,111) 102; ( 5 ) 370 Richard, P. (2) 33; (5) 181 Richards, C.J. ( 5 ) 25 1; (6) 268 Richardson, B.M. (2) 174 Richardson, D.E.(1 1) 30 Richardson, J.F.(1 .IV)47; (3) 105; (6) 105; (1 1) 53 Richeson, D.S.(I 1) 75 Richmond, M.G. (3) 10; (4) 1, 131; (5) 2; (6) 146 (1 .HI) 20-22; (5) Richmond, T.G. 311; (9) 9 Rickard, C.E.F. (2) 50; (3) 27; (9) 110 Ricde, J. (4) 308; (1 1) 90,93,94; (12) 122 k e f , U.(6) 238,258 Riegel, B. (9) 69 Rieger, A.L. (3) 35 Ricgcr, B. (6) 222,241 Riegcr, M. (6) 355 Rieger, P.H. (3) 35 hcke, R.D. (13) 40 Ricra, V. (1.IV) 33; (3) 71-73,78, 85, 130; (4) 121, 132-134, 170; (5) 364; (6) 60.82 Ricrmcicr, T.H. (7) 11 Rictmann, C. (6) 124 Rictveld, M.H.P. (1.11) 12, 13, 19, 28; (1 .lV) 68; (13) 26 Rigaut, S. (6) 387 Rigby, J.H. (5) 210,211; (7) 55 Rgby, S.S. (1.IV) 36 Rigny, S. (1.111) 25; (6) 90,226, 257 Riifcr, T. (2) 306 Rijnbcrg, E. (13) 20,21,24,25

A ufhorbidex Rilcy, P.N. (1 .I) 5 Riltcr, J.C.M. (2) 183 Rink, B. (2)271 Riordan, C.G. (2)161 Ripoche, I. (5) 28 1 Ripoll, J.L. (9)22 Ritler, J.C.M. (6) 157 Rix, F.C. (2)31 1 Rizzi, G.A. (5)471 Rizzo, A. (6) 50 Rizzoli, C.(2) 352,353;(5) 209; (12)93 Rizzoli, J. (1 .I) 18, 19 Roache, J.M. (2) 212 Robert, F.(6) 203 Robcrto, D.(3) 139;(4)97, 199 Robcrts, RM.G. (6)388 Robcrtson, N.(1 .HI) 18;(1.1V)7 Robinson, B.H. (4) 30 Robinson, G.H.(1 1) 64, 68,80 Robinson, K.D.(2) 2 13 Robl, C.(9)37 Robson, D.A. (6)37 Roby, J. (12)8 Rockwcll, J.J. (10)31 Roddick, D.M. (6) 383 Rodewald, S.(1.1) 89 Rodriguez, A.(4)287 Rodriguez, G. (1.1) 38,73;(1 .Ill) 132;(2)259;(5) 267,270;(6) 26,39;(1 1) 20 Rodrigucz, J.G.A. (9) 119 Rodrigucz, M.A. (12)58 Rodngucz-de la Fuente, J. (6)306 Rohr, M.(2)330 Roeofsen, A.(5) 394 Rosch, N.(1 .IV)60 Roesky, H.W. (1.1)4; (1.11)10; (1.111) 4;(2)3; (6)35;(1 1) 35, 37,38,40,46,59,62,77,87 Rocsky, P.W. (6) 19, 192;(8)34, 35 Rosler, R. (9)66, 84,86 Rottgcr, M.(1.1V)55 Rofia, S.(13)4 Rogcrs, R.D.(3) 86;(1 1) 74 Roidal, G.(5) 253;(6) 110 Roitershtein, D.M.(8)49 Rolando, C. (5)55 Roman, P.J. (3) 140 Romanenko, V.D. (9)5 Romao, C.C. (6)84 Romeo, I. (12) 106 Romco, R, (2)256 Romcrosa, A. (2) 265 Rooney, A.D. (1 XI) 104 Ropcr, W.R. (2)36,50,59;(3) 27, 101,102

Ros, R. (4)266,267 Rosa, P.(5) 340;(9) 57 Rosair, G.M. (10)46,47,85 ROSC,E. (1.111) 93;(5)390;(6) 385 RosC, J. (4)350 Rose-Munch, F.(1 .HI)93;(5) 390;(6)385 Rosenberg, E.(4) 118-120,213; (5) 419 Rosenberger, S.(4)81 Rosenplanter, J. (10) 12;(I 1) 16 Rosenthal, U.(1 .I) 57-60,88;(5) 300,301,438;(6)227 Rosi, L.(2) 180;(3) 132;(4) 147 Rosi, M.(1.111)14;(8)102 Ross, C.R. (5) 230 Rossell, 0.(3) 152, 159, 161;(4) 75,91,92,375 Rosscnaar, B.D. 34;(3)84 Rossctti, R. (4) 11; (6) 14 Rossi, R.(7) 1; (13) 40 Rossignoli, M. (3) 65 Rossmayer, S. (6)256;(9)45 Roszak, A.W. (1.1) 76;(6)32 Ro~zak,S. (8)95-97 Rot, N. (12)62 Roth, G.(1 .Ill) 85;(I .IV) 24;(2) 20 Rothe, J . (1 1) 8 Roths, K. (1.111) 112, 113 Rothwcll, I.P. (1.1) 2, 5; (1.11) 14, 27;(5)263 Rottgcr, D.(1 .l) 66 Roulct, R. (4)267 Rourke, J.P. (I.IV)28;(2)287 Roush, W.R. (5) 279 Roveda, C.(3) 139;(4) 199 Roy, S.(2) 170 Roy,T.(12) 1 1 1 Roylcs, B.J.L.(6)319 Royo, E.(1.I) 79 Royo, P.(1.1) 73,79,85,91;(6) 3,26,83,213,229 Ruban, A. (9)33 Rubino, M.B. (5)273 Rublc, J.C. (7)53, 54 Rudd, M.D.(10)32 Rudler, H.(1.111) 125;( I N ) 62 Rudolph, J. 63;(7)46 Rubenstahl, T.(4)50; (6)44 Ruck-Braun, K.(2)43;(6) 137 Rucffcr, T.(12)28 Riicggcr, H.(3)75;(5) 53,205 Rufanov, K.(6) 12 Ruffieux, V. (4)350 Ruffo. F.(2) 272,273,322,334; (5) 120,145,150

(1.w

(1.w

477 Ruffolo, R (5) 346,455 Rufmka, A. (5) 110 Ruhs, D. (5) 56 Ruhl, E.(10) 10 Ruhlandt-Scnge, K. (12)76 Ruiz, A. (5)203,404 Ruiz, C. (1 .III)28,29;(5) 4 1,42, 105,383;(6)72 Ruiz, 1. (6)304,391 RuiZ, M.A.(3)71-73,78;(6)60, 82 Ruiz, M.J. (1.1) 93;(6)215 Ruiz, N. (2) 121,361; (3)95;(5) 79, 186,404;(6)132 Rumin, R. (2) 86,87;(4) 19; (5) 444 Runebcrg, N.(4) 295 Runsink, J. (2)70;(6)395 Runte, 0.(8)37,59 Ruppet, 0.(6)328 Rusandcr, U.(4)225 Rush, T.M.(5) 367 Russell, C.A. (6) 186;(12)85 Russcll, D.R. (2)320;(6) 346, 397;(9)92 Russell, M.G. (12)31 Russcll, R.A. (6) 173 Rutbcrg, J. (7)41 Ruthe, F.(1.111) 74 Rutherford, D. (1 1) 58 Ryabour, A.D. (5) 322 Ryabstcv, A.N. (5) 255;(6) 162 Rybin, L.V.(2)90;(4) 137, 145, 195;(6)280 Rybinskaya, M.I.(2)90;(4) 137, 145, 175, 195,261,389 Rychnovsky, S.D. (13)39 Ryder, A.G. (3)43;(5)272 Ryter, K.(1 2) 5 Saadch, C. (3) 104;(6) 117 saak, w.(4)94;(1 1) 91 Sabat, M.(1.11) 11; (5) 82;(6)42; (10)26,27;(13)37,38 Sabatino, P. (2)29 Saccianoce, L. (5)448 Sachsingcr, N. (6)330 Sadighi, J.P.(7)13 Sadlcr, I.H.(4)201; (5) 447 Sadlcr, N.D.(4)321;(5) 406 Sadler, P.(9)67 Saeed, T.(5) 96;(12)102 Sahrin, M.(5) 52 Sah,R.N. (10)3 Saillard, J.-Y. (3)66;(4)78,79; (5) 345 Sainsbury, M. (12) 18

478 Saundcrs, J.F. (6) 48 Sainz, D. (2) 300; (6) 307 Saunders, J.I. (6) 250 Saito, H. (2) 237 Sawada, M. (2) 359 Saito, K.(1 1) 10 Saxena, A.K. (10) 4 Saito, T. (4) 18 Sayers, S.F. (1.111) 86; (6) 49 Saitou, M. (1.111) 110 Scaccianoce, L. (4) 143 Sakaba, H. ( 1 . w 58; (3) 90; (5) 352; (6) 104 Scalone, M. (5) 247 Scanlan, T.H. (3) 110; ( 5 ) 359, Sakaguchi, S.(8) 90,91 360 Sakai, H. (6) 340 Schaade, M. (2) 122 Sakalu, S. (2) 244; (5) 124, 143 Schiifer, W. (4) 16; (8) 64 Sakarya, N. (9) 50 Sakata, R (2) 33 1 Schar, D. (12) 67 Sakodinskaya, I.K. (5) 322 Schafer, 0. (6) 8 Sakurai, A. (2) 134; (6) 133 S c W e r , S. (5) 132, 140 Sakurai, H. (5) 236; (12) 47.68 Schager, F. (5) 332 Salem, G. (2) 313 Schallcy, C.A. (5) 307 Schanz, H.J. (10) 17,25 Salema, M.S.(6) 38 Salvini, A. (2) 180; (3) 132; (4) Schaper, F. (6) 235,258 22, 147 Schaper, T. (13) 3 1 Samanta, U. (5) 32; (1 1) 26 Schar, M. (6) 259 Sammakia, T. (7) 44 Schaucr, C.K. (4) 77 Schauer, S.J. (1 1) 69 Samoc, M. (2) 99; (12) 114 Samson, S. ( 5 ) 225,479; (6) 359 Scheer, M. (3) 61, 127; (4) 153; (9) 12,65 Samuel, E. (6) 2 18 Scheffer, J.R. (5) 191 Ssinchez, A. (1 1) 95; (13) 30 Sanchez, M. (9) 5 Scheffer, M.H.(6) 112 Schener, J. (5) 195 Sandig, N. (1 .II) 33 Schcnk, K. (6) 371; (7) 48 Sandoc, E.J. (5) 225 Schenk, W.A. (6) 11 1 Sang, J. (1.1) 46, 47 Schcrcr, O.J. (4) 340 Sankar, G.(4) 4 1 Schcrer, W. (6) 71 Sanni, B. (1.lII) 79; (3) 130; (4) 133, 134 Schibli, R. (4) 66 Sansoni, M. (4) 35 1 Schiemann, 0. ( 5 ) 262; (6) 40 Schicr, A. (4) 308; (6) 277; (1 I ) Santamaria, J. (1.III) 126 90,93,94; (12) 122 Santi, A. (2) 291 Santi, S. (3) 155; (5) 189, 391; (6) Schildcr, H. (8) 109 Schimeczek, M. (12) 52 145 Schinkels, B. (9) 33,34; (12) 50 Santos, A. (2) 131 Schlebos, P.P.J. (2) 220 Santos, I. (6) 18; (8) 12 Schlechtingen,G. (5) 241 Sanz, M. (6) 27 Sappa, E. (3) 120; (4) 10, 73, 128, Schlcngermann,R.(1 2) 66 Schleutcr, J.A. (12) 111 390,39 1;(5) 408,426 Sappenfeld, E.L. (4) 21 1; (10) 32, Schleyer, P. von R. (6) 139; (10) 20,23; (12) 51,56, 57, 59,87 36,49,50 Schliingloff,G. (7) 47 Sapunov, V.N. (2) 111; (5) 292 Schlosser, M. (12) 13, 14 Sarai, S. (2) 2 16; (5) 9 1 Schmid, C. ( I .I) 86 Sarfo, J.K. (6) 346 Schmid, G. (4) 350 Sarhan, A.A. (1 1) 1 Schmid, R. (2) 101, 111, 112; (5) Sarkar, A. (3) 115, 116; (5) 31, 72; (6) 126 32; (1 I) 26 Schmid, S. (2) 324; (12) 114 Sarsfield, M.J. (1.1) 75,76; (6) 32 Schmidbaur,H. (4) 298, 303,304, Sarveswaran, K. (4) 90; (5) 445 308; (12) 115, 122; (13) 46 Sasscn, K.J. (9) 91 Sclimidpetcr, A. (9) 35-37,5 1 Sato, M.(2) 125, 137; (6) 345 Schmidt, A. (4) 241; (5) 472 Satyanarayana, C.V.V. (2) 88; (3) Schmidt, B. (10) 12; (11) 16 115, 116, 122;(4) 85, 110, Schmidt, E. (6) 373; (1 1) 90 142,317; (5) 438,446 Schmidt, G.(5) 388; (12) 97 Saunders, G.C.(6) 88

Orgattometallic Chemistry Schmidt, H.G. (8) 56; (1 1) 37, 38,46,62 Schmidt, K. (6) 238,258 Schmidt, M. (12) 48 Schmidt, R. (5) 248, 291,292; (8) 94 Schmidt, U. (5) 192 Schmittel, M. (6) 22 1 Schmitz, A. (6) 369; (10) 13; (11) 18 Schmuelling, M. (2) 257 Schnabel, R.C. (6) 383 Schneider, H. (9) 101 Schneider, J.J. (4) 253,273; (6) 61, 147, 178 Schneider, N. (6) 235 Schneider, W.(4) 298,303,304; (12) 115 Schneller, T. ( 5 ) 327 Schnitter, C. (1 1) 40,46 Schnockcl, H. 105; (1 1) 65 Schnydcr, A. (6) 341 Schobert, R. (2) 356,357; ( 5 ) 63, 274,275 Schocller, W.W. (9) 35,42 Schoffers, E. (5) 35 Schollhammer, P. (6) 52 Schollmcycr, D. (6) 137 Schoonovcr,J.R. (2) 187; (3) 3 1 Schottck, J. (1.I) 68 Schottcnberger,H. (6) 285,298 Schreiber, K.-A. (12) 6 Schrcnder, M. (5) 161 Schrickcl, J. (2) 234; (5) 201 Schrwk, R.R (1.1) 15; (1.111) 5759 Schriidel, H.-P. (9) 35,36,5 1 Schrijdcr, D. (2) 26; (5) 54, 307 Schroeter, K. (5) 307 Schubert, U. (4) 361 Schubigcr, P.A. (4) 66 Schuetz, M. (12) 70 Schuler, N. (6) 298 Schulte, M.M. (1 1) 79 Schultc, P. (5) 388; (12) 97 Schulz, M. (2) 62, 113; (4) 24 Schumann, H.(6) 184,3 13; (8) 36,38, 50.66; (12) 78 Schuster, K. (3) 61 Schuster, M. ( 5 ) 25 Schwab, P. (2) 350 Schwartz,H. (5) 54 Schwarz, H. (2) 26; (5) 307 Schwarz, W. (1 1) 96; (13) 23 Schwarze, B. (12) 46 Schwefer, M. (4) 373 Schweiger, M.J. (1.111) 33; (1.IV) 27

AufhorIndex Schwenk, H. (6) 300; (12) 69 Schwerdtfcgcr, P. (3) 27 Scollard, J.D. (1.1) 8,9 SCOKU~O, G. (6) 3 14 Scott, B.L. (8) 6 Scott, F.P.E. (5) 208,382 Scott,J.S. (1.111) 105, 106 S ~ t t M.J. , (1.1) 21-23 Scott, P. (9) 55 Scott, S.L. (1.111) 19 Scowen, I.J. (3) 136; (4) 160; (12) 103 Scrock, R.R (9) 73 Scum, R G . (2) 343 Sebald, A. (2) 335; (1 1) 31 Seco, M.(3) 152, 159, 161; (4) 75,91,92,375 Scdniera, P. (6) 202; (13) 10 Secvogcl, K. ( 5 ) 110,332 Segalcs, G. (3) 161; (4) 92 Segawa, K. (5) 481; (6) 265 (1.111) 58; (9) 73 Seidel, S.W. Scifcrt, G. (8) 94 Seifcrt, T. (12) 69 Seiodel, S.W. (1.III) 57 Sekar, P.(3) 164, 165; (4) 310, 311,348,349 Sckiguchi, A. (12) 47, 68 Sekiya, K. (8) 7 Scmioshkin, A.A. (10) 7 1 Scmrau, M. (10) 63 Scmyannikov, P.P. (4) 236 Sen, R. (6) 365 SL.ndchal-Tocqucn,M.-C. (1.111) 128 Scncka Pcrcra, M.P. (4) 336 Scncviratne, K.N. (13) 44 Scnter, R A . (4) 131 Seppclt, K. (1.111) 18; (1.IV) 7 Scquieira, L.(1.HI) 42 Serafin, M. (1.III) 49; (6) 55 Seraglia, R. (12) 116 Scrgccv, V.A. (10) 75,93 Semetz, F.G. ( I .I) 3 Semio, J.L. ( 5 ) 204 Setsune, J . 4 . (2) 175 Seylcr, J.W. ( 1 . W 41 Sczowski, J.J. ( 5 ) 230 Sgamcllotti, A. (1.111) 14; (1.iV) 23; (2) 24 Shach, R. (I 1) 23 Shadc, J.E.(2) 81; (5) 358 Shang, L. (2) 57; (5) 286 Shang,M. (3) 58; (4) 249-251, 33 1; (6) 85 Shapiro, P.J. (6) 9, 10; (1 1) 19; (13) 17 Shaplcy, J.R. (3) 134, 137, 145;

(4) 68,69, 105, 162, 180, 185, 270,344,395; ( 5 ) 328.410, 464; (6) 167, 169,393 Shaplcy, P.A. (6) 120 Shaposhnikova, A.D. (4) 339 Sharma, H.K. (6) 3 10 Sharplcss, K.B. (1.W) 63; (7) 46, 47 Sharutin, V.V. (9) 94 Sharutina, O.K. (9) 94 Shashkova, V.T. (10) 76 Shaw. B.L. (2) 229 Shaw, L.E. (3) 8 Shaw, M.J. (4) 252 Shay, T.B. (3) 131; (4) 98 Shechan, S.M.(7) 39 Sheldrick, G.M. (6) 35 Sheldrick, W.S. (6) 396 Sheloumov, A.M. (3) 169; (4) 109,205,206,237,238,398; (5) 452 Shen, F . d . (8) 3 Shcn, H. (4) 131 Shen, Q.(6) 16; (8) 17-19,26,44, 48,79-8 1,87 Shcphard, D.S. (3) 125; (4) 41, 177 Shcridan, J.B. (2) 295; ( 5 ) 484; (6) 322 Shenvood, P. (1.111) 14 Shcshtakov, A.F. (8) 69 Shestakova, A.K. (4) 202; ( 5 ) 428; (6) 193; (8) 4,25 Shestopalov,A.M. (10) 71 Shcyslcy. J.R. (6) 160 Shi, G.-Q. (7) 7 Shi, N. (8) 100 Shi,Y.-M. (4) 265 Shibahara, T. (8) 83 Shieh, M. (3) 163; (4) 58,82 Shieh, M.-H. (3) 163; (4) 82 Shieh, S.-J. (1.111) 44; (5) 51 Shields, G.P. (3) 172; (4) 52,356; ( 5 ) 347; (6) 51,73,89, 174; (12) 53 (1.111) 57, 58 Shih, K.-Y. Shilov, A.E. (1.111) 3; (2) 1 Shim, S.C.(1.1) 90; (6) 228 Shimada, S. (2) 294; (5) 334 Shimizu, I. (6) 176 Shimizu, K.(6) 154 Shimizu, M.(2) 63; (4) 189; (13) 5

Shimomura, H. (4) 33 1 Shin, G. (4) 242 Shinokubo, H. ( 1 . w 8 Shinornura,H. (3) 58 Shintate, H. (6) 345

479 Shirakawa, H. (6) 219 Shiro, M.( 5 ) 164 Shirokii, V.L.(5) 255; (6) 162 Shiu, C.-W. (1.111) 48; (4) 328, 329; (5) 440,460 Shiu,L.H. (5) 50 Shore, S.G.(3) 131; (4) 98,210; (6) 232; (1 1) 24 Shriver, D.F. (4) 23 1 Shtel'ser, N.A. (4) 145 Shukri, K. (2) 83; (5) 356 Shul'pin, G.B. (1.111) 3; (2) 1 Shur, V.B.(1.I) 45, 57,72; (6) 201; (13) 47 Shvo, Y.(2) 58; (6) 106 Sickafoose, S.M.(5) 245 Siebert, W. (6) 166; (10) 16 Siefert, R (4) 67 Siegbahn, P.E.M. (2) 243; (5) 106, 115; (12) 22 Sieler, J. (5) 90; (12) 66, 73 Sicmeling, H. (6) 335 Sicmoneit, S. (1 .HI) 72; ( 5 ) 308, 309 Sicthoff, C. (13) 38 Siinkel, K. (1.111) 33 Sillanpaa, R. (6) 149; (10) 40,5 1, 52, 84 Silva-Trivino, L.M. (10) 68 Silver, J. (6) 389 Silverio, S.J. ( 5 ) 389 Simal, F. (10) 45 Simard, B. (8) 106 Simizu, K. (2) 344 Simon, A. (10) 24 Simon, F. (9) 61 Simpson, J. (4) 30 Simpson, R.D.( 5 ) 102; (6) 153, 158 Simpson, S.J. (6) 255 Sinbandith, S.(2) 36 1 Singaram, B. (10) 73 Singer, R. (7) 13; (13) 41 ' Singewald, F. (6) 399 Singh, M.S. (9) 89 Singhaus, R.R. (10) 94 Sinnema, P.J. (1.1) 25; (6)31 Siromakhova, Yu.(4) 108 Sironi, A. (2) 201; (3) 91, 142; (4) 2,3, 16,34,65,346 Sirovatka, J.M. (2) 165 Sisak, A. (2) 201; (3) 142 Sitzmann, H. (6) 259; (9) 105 Siurana, C.(2) 189 Six, C.(2) 195; (5) 77 Sizov, A.I. (8) 23 Sjognen, M.P.T. (5) 37 Skabara, P.J. (6) 267

480 Skeloumor, A.M. (5) 480 Skclton, B.W. (2) 110,221,282, 323; (4) 21,23, 111, 113, 135, 136, 165, 166, 171,378; (5) 412,414416,459,461,462; (6) 135, 198; (8) 8; (9) 1I , 70, 115; (1 1) 61 Skelton, J. ( 5 ) 10 Skowronska, A. (1 .I) 55; (9) 82 Sladek, A. (4) 304; (1 1) 94 Slater, D.M.(3) 27 Slawin, A.M.Z. (3) 123; (4) 138 Slcadd, B.A. (3) 105 Sliwinska, E. (5) 199 Slough, G.A. (5) 173 Slovokhotov, Yu.L. (4) 352,387; (5) 442 Slugovc, c . (2) 101, 111 Smaoc, M. (2) 325,326 Smcets, W.J.J. (1 .II) 12; (2) 89, 281; (4) 26; (1 1) 83; (12) 61 Smcmik, R.J. (2) 42 Smidt, J.P. (5) 27 Smit, J.P. (3) 64 Smith, A.K. (4) 271 Smith, D.K. (6) 291 Smith, D.M. (6) 3 19 Smith, H.W. (7) 42 Smith, J.D. (11) 52; (12) 33; (13) 14 Smith, J.M. (10) 2 Smith, K.M. (6) 69 Smith, M.B. (3) 123; (4) 138 Smith, P.J. (4) 183 Smith, R.A.J. (12) 25 Smith, R.D. (2) 262 Smits, J.M.M. (2) 220 Smyth, D.G. (5) 229 Snaith, R. (12) 23,31,36,53 Snapper, M.L. (2) 365; (5) 66 Sneddon, L.G. (10) 19,37 Snover, M.K. (5) 2 1 1 Sobolcv, A.N. (2) 323 Sodcrbcrg, B.C. (1.111) 1I5 Sodupe, M. (8) 102, 103 Soga, K. (8) 72 Sokolov, V.I. (4) 284 Sola, E. (2) 124, 129; (5) 71 Sola, M. (1.111) 12; (3) 36 Solan, G.A. (4) 248 Solans, X. (2) 269, 284; (6) 262, 276,287,307 Solari, E. (1.1) 18-20; (2) 352, 353; ( 5 ) 209; (6) 371; (12) 93 Soldatov, E.S. (10) 81 Solcil, F. (5) 157; (6) 208 Sollner, R (6) 221 Solntsev, K.A. (10) 3 I

OrganonietailicChemistry Soloway, A.H. (10) 96 Solva, J.R. (5) 232 Sommcr, C. (8) 67 Son, S.U.(5) 35 1; (6) 362 Son, Y. (4) 209 Song, F.-Q.(6) 11; (12) 82 Song, H.(4) 209; (5) 430 Song, L.-C. (3) 113, 117, 15 1; (4) 54, 80, 86, 3 14, 384; ( 5 ) 47; (6) 54 Song, M. (6) 270 Song, S . (8) 48 Song, X.(6) 195 Song, X.J. (1.1) 81 Sordo, J. (11) 95; (13) 30 Sorkau, A. (2) 201; (3) 142 Sotiropoulos,J.-M. (6) 225; (9) 23 Soto, J. (8) 11 Sotokawa, T. (1 I) 66 Soulivong, D. (6) 181 Souter, J. (1.111) 23; (2) 64; (6) 48, 74,255 Souter, P.F. (1.111) 17 Southern, J.S. (1.Ill) 30; (3) 67; (5) 30 Sowza, J.R., Jr. (3) 118; (4) 193; (6) 128 Sowerby, D.B.(9)103, 117, 118, 121 Spaar, M.T. (10) 90 Spagna, R. (13) 33 Spalding, T.R(10) 53 Spaniol, T.P. (1.1) 3,24,34; (6) 246; (8) 9 Spannenberg, A. (1 .I) 57-60; ( 5 ) 192,300,305,438 Spariid, T.P. (6) 36 Specht, U. (4) 253; (6) 147 Specl, D.M.(3) 129; (4) 102, 129; (5) 405,451; (12) 105 Spck, A.L. (1.1) 10, 11,25; (1.11) 12, 13, 19,28; ( 1 . W 68; (2) 89,202,220,250, 251,280, 28 1, 302,3 19; (4) 26, 342; ( 5 ) 116, 138, 198; (6) 31; (9) 24; (11) 83; (12) 34,61; (13) 7, 20,2 1,24-26 Spence, R. (1.1) 83 Spencer, J.L. (2) 3 18 Spcnccr, J.T. (10) 10 Spcnccr, M.D. (1.1) 42; (5) 265 Spera, M.L. (2) 369; (5) 83,85 Spero, D.M. (13) 5 Spcrrle, M.( 5 ) 24 Spcrry, C.K. (5) 270; (6) 39 Spiccr, M.D. (4) 245 Spiegler, M. (2) 347; ( 5 ) 478; (6) 300; (8) 37

Spivak, G.J. (4) 276,285, 286, 368 Spodine, E.(4) 28; (5) 43 1 Squircs, M.E. (2) 40 Srinivas, B. (2) 75; (1 1) 60 Srinrasans, N. (6) 334 Srivastava, R.R. (1 0) 94 Srogl, J. (13) 6 Stadtmullcr, H. (1.IV) 10 Stahr, H. ( 5 ) 254; (6) 87 Stalkc, D. (2) 222,233; ( 5 ) 190, 482; (6) 186,317; (8) 1; (11) 46,77; (12) 27,83,85 Stammler, H.C. (6) 112,335; (9) 29 Stampfcr, M. (13) 35 stanctty, P. (12) 2 Stanger, A. ( 5 ) 213 Stanghellini, P.L. (4) 11,35 1; (6) 14 Stankcvich, I.V. (13) 47 Stannck, J. (5) 161 Staplcs, R.J. (6) 9 Stark, G.A. ( 1 . N ) 44; (6) 95 Starova, G.L. (4) 112; (5) 41 1 Starowieyski, K.B. (1 1) 55 stasica, z. (3) 5 Stastch, A.I. (4) 400 Stavenger, R.A. (2) 268 Stecher-Rasmussen,F. (10) 91 Stecnwinkcl, P. (12) 61 Stcffey, B.D. (2) 46; (6) 134 Stcglich, W. (1.111) 118 Stchling, U. (6) 235 Stcimann, M. (1.IV) 26; (2) 68; (6) 241 Steimle, T.C. (8) 98 Stein, E. (6) 271 Stein, 2.(2) 58; (6) 106 Steinbom, D. (2) 239,264,288, 306; ( 5 ) 298,335; (12) 28,29 Steincr, A. (4) 143; ( 5 ) 448; (6) 186; (12) 85 Stcincr, T. (5) 395; (6) 92 Stcincrt, P. (2) 23 1,350; (5) 97, 98 Steinhagcn, H. (5) 118 Steinhorst, A. (6) 214 Stelk, D.S. (1 1) 19 Stellbcrg, P. (5) 213 Stelzer, 0. (4) 76 Sten, J.-Y. (6) 126 Sten, Q. (6) 188 Stcphan, D.W. (1.I) 56; (4) 46 Stcphcns, A.H.H. (6) 255 Stephens, P.W. (4) 197; (12) 73 Stephenson, G.R. (1.111) 93; ( 5 ) 225, 227,229, 390, 479; (6)

Author Index 359 Stephenson, I.R.(10)79 Stepnicka, P.(2) 362 Sterenberg, B.T. (3) 171 Stem,C.L. (1.1) 31, 87;(4)231; (6) 19, 29, 192,207,240,399; (8) 33-35;(1 1) 3 Stetzkamp, D. (6)2;(1 1) 63 Stcudel, R.(6)223 Stevens, A.M. (5)25 1 Stcvenson, M.A. (1.111) 56 Stibr, B. (10)20,21 Stichbury, J.C. (5) 347;(6) 5 1,73 Stichdroff, M.(3) 129;(4) 129 Stiefel, E.I. 15 Stobart, S.R (3)49;(6)23 1 Stochcl, G.(3)5 Stockland, R.A.,Jr. (2) 321 Stockman, K.E.(6)382 Stocckli-Evans, H.(2)276;(3) 168;(4)122, 123, 156, 158, 359;(5)231,421,422;(6) 398 Stoll, S.L. (1 1) 89 Stolzenberg, A.M. (2) 176 Stone, C.S. (6)399 Stone, F.G.A. (4) 21 I; (10)32,34, 36,49,50 Stoner, T.C.(1.111) 54 Storch, E.C. (13)42 Storre, J. (1 1) 46,77 Stourton, C. (6) 186;(12)85 Stradiotto, M. (3) 96;(5) 455 StrtihIe, 1. (4) 371;(13)45 Strampfer, M.(4)374 Strangeland, E.L.(7)44 Stranger, R (2) 25; (4) 183 Strarakis, M.(12) 19 stratmann,0.(12)4 Straub, A.W.G. (13) 16 Straub, W.(1.111) 101 Straus, D.A. (6)236 Strauss, I. (1 ,I) 47 Strauss, S.H. (1 0) 3 1 Strcib, W.E. (1.111) 52,55; (2)38; (3) 56;(4)55; (5) 348 Streitwiescr, A. (12)59 Strelets, V.V. (4) 109 Strcubel, R.(1.111)74;(5) 397;(9) 30,31 Stricklcr, B.S. (1 1) 30 Strohmann,C. (4) 374;(13) 35 StrGmberg, S. (2)243;(5) 106, 107, 115 Stromnova, T.A. (4) 394 Strong, P.J. (2) 262 Struchkov, Yu.T. (1.1) 57;(2)90; (4) 108, 112, 137, 195,202,

(1.w

205,238,284,339,398;(5) 9, 411,428,452;(6)365,368; (8)52, 68,69;(10)33,56; (12)98;(13) 47 Strunkina, L.I. (1.1) 45 Stryker, J.M. (1.11)22;(5) 167 Studiotto, M.(2)49 Stiidemann,T. (7)2 Stiier, W.(2)35 1 Stufkens, D.J. (1.111) 12; (1.1V) 34;(2)39;(3)36,37,84,103; (4) 192,342,343 Stumpf, A. (5) 368 SU,C.-J.(1.111) 48;(3)52;(4) 169,309,324,325,329; (5) 456,460;(6)254 Su, J. (1 1) 64,68,80 SU,M.-D. (2)21, 154, 157;(3) 30 SU,P.-C. (3) 52, 177;(4)325, 327;(5) 456;(6)254 Suirez-Sobnno,A. (1.111) 126 Suarez-Varela,J. (2)265 Subramanian, G.(12)57 Siihring, K. (6)313 Sucnaga, Y.(5)476;(12) 101 Siinkel, K. (1.111) 90;(1 .IV)27; (3) 47;(5) 333,396,400;(6) 6 Suss-Fink, G. (3) 168;(4) 122, 123, 156-158,359;(5) 421, 422;(6)398 Sugihara,T. (3)24 Sugimori, A. (2)344;(6) 154 Sugimoto, K.(5) 476;(12)101 Sugimoto, M.(2)244;(5) 124 Sugimoto, S.(2) 134;(6)133 Sugiura, M.(7)56 Sugiyama, T. (2) 344; (6) 154 Sumanja, M.(6)21 Sun, C.(12)35 Sun, C.C. (10)8, 9 Sun,H.(9)67 Sun, J. (1 .IV)59;(2)366;(3) 1 14, 15 1;(4)383-386;(5) 354, 355,401;(6) 16,54,100, 129, 188;(8) 17, 19,27,47,75 Sun, J.H. (10) 8 Sun, S.(5) 217 Sun, S . 4 . (2) 126 Sun, W. (1 .Ill)7 Sun, W.H.(1.1) 50; (5) 341 Sun, X.-Z. (6)93 Sun, Y. (8) 58 Sun, Y.M. (1.1) 82, 83 Sundar, R.A.(10)78 Sunghee, H.(5) 368 Suponitsky, K.Y.(10)5 Surgan, M. (1.111) 64;(5) 3 17

48 1 Surikova, M.A. (10)75,93 Surya, P.I. (5) 56 Surynt, RJ.(4) 113,379;(5) 412, 4 13

Suslick, K.S. (2) 116 Sussek, H.(1 1) 85 Sutton, D.(1.N) 5 1,52;(2) 200; (5) 175, 176;(6) 102 Suzuki, A. (4) 114;(5) 420 Suzuki, H.(4) 104;(5) 418; (9)95 Suzuki, K. (5) 372;(7) 17 Suzuki, N. (4)388;(7) 24 Suzuki, s.(9)93 Svensson, M. (2)241; (5) 107, 115 Sweigart, D.A. (1.W 30;(5) 2 16218,222;(6)386 Swcnson, D.C.(1.1) 13, 14;(11) 39 Switzer, R.C. (10)90 Szabo, K.J. (5) 126, 128,384; (11) 5 Szaiontai, G.(2)201,238;(3) 142 Szilagyi, R.K.(3)21 SZ~XWS~~-BUZU, T. (1.111) 1; (3) 7;(5) 7,44, 178 Tacke, M.(6)350 Tadokoro, M.(2)63,237;(4) 189 Tafipolsky, M.A. (6)71 Tagliatesta, P. (12) 116 Taguchi, T. (5) 164 Tahcrirastgar, F.(12) 12 Tahir, M.N.(5) 177 Tahmassebi, S.K. (5) 320 Tai, Y.-C. (4)82 Takada, K. (6)303 Takagi, K.(5) 1 1 1 Takagi, S.(4)243;(6)278 Takagi, Y. (6) 115 Takahashi, M.(12)47 Takahashi, S. (2)359 Takahashi,T. (1 .I) 50; (5) 341 Takahashi,Y. (4)353; (5) 196 Takahata, H.(4)274,275 Takai, Y. (2) 359 Takamura, N.(5) 237 Takata, T. (5) 60 Taka&,J. (2)82;(8)57 Takaya, Y. (4) 104;(5) 4 18 Takayama, C.(2)344;(6) 154 Takeda, H.(8)41 Takcda, K.(1.111) 121 Takei, I. (6) 308 Takcmori, T. (4) 104;(5) 418 Takeuchi, K. (5) 124 Takeuchi, R. (7)28

482 Talarmin, J. (3) 66; (5) 345; (6) 52 Tallanico, J.A. (2) 365; (5) 66 Tamm, M. (2) 103,368; (5) 393, 395; (6) 92, 140 Tan, A.L. (4) 362 Tanaka, M. (2) 134,294, 304; (4) 104, 155; (5) 334; (6) 133; (7) 10; (8) 7; (1 1) 15 Tanaka, T. (2) 359 Tan&, Y. (2) 294 Tanase, T. (4) 274,275,367,38 1 Tang, J. (I.IV) 8 Tang, K. (5) 28 Tang, S.S. (4) 302 Tang, Y. (5) 28 Tang, 2. (4) 262; ( 5 ) 434 Tani, K. (1.11) 23; (2) 45; (5) 264, 269; (8) 54; (12) 3 Taniguchi, K. (2) 286 Tanio, K. (5) 369 Tanner, M.J. (2) 188 Tanner, P.S. (6) 75, 185; (8) 2; (12) 79 Tanya, K. (5) 372 Tao, C. (2) 57; (4) 242; ( 5 ) 286 Tao, T. (13) 6 Taraban, M.B. (2) 179 Tarrago, G. (6) 266 Tashiro, D. (8) 90,91 Tashiro, S. (4) 72; ( 5 ) 353 Tassan, A. (4) 266 Tatsurni, K. (4) 51, 319,369,370 Taube, R (5) 90; (8) 66,67 Taupet, L. (6) 181 Taylor, G.M.(5) 366 Taylor, N.J. (3) 11 1; (5) 362; (9) 110 Taylor, R.(5) 148 Tedcsco, E.(2) 12; (4) 396 Tedcsco, V. (6) 3 13 Teichcrt, M. (1.11) 10; (2) 222; (5) 190; (1 1) 38,40 Teixidor, F. (6) 149; (10) 20,21, 40,45,5 1,52, 84, 85 Tcjcl, C. (2) 240; (4) 265 Tclcs, J.H. (2) 70; (6) 395 Temme, B. (1 .I) 62, 63; (5) 302, 339; (6) 209; (1 1) 22 Tcmple, K. (2) 295; (5) 484; (6) 322 Tcmpicton, J.L. (1.111) 64, 65, 71, 89,95; (3) 75; (5) 53,3 163 19,349 Tcng, H. (8) 75 Tenorio, M.A.J. (2) 136 Tenorio, M.J. (2) 136, 138, 144; (5) 323 Tenske, D. (6) 30

Teplova, M.V.(4) 339 Terada, M. (2) 61, 134; (5) 233; (6) 133 Terblans, Y.M. (1.111) 94 Tcrmatcn, A. (2) 302 Tessicr, C.A. (2) 290, 328; (5) 330,437; (13) 32 Tetrik, S.M. (1.W) 45, 46; (6) 103 Tcubcn, J.H. (1.1) 25,80, 93; (6) 31,215; (8) 60.61 Tcuber, R. (6) 350 Tcunissen, W. (1.11) 12 Thal, C. (5) 226 Tham, F.S. (1.IV) 46 Thappcr, A. (3) 14 Thcil, W. (5) 179 Theopold, K.H. ( I ,111) 39 Thcwalt, U. (1.I) 70, 84; (6) 202, 206; (13) 10 Thiei, W. (12) 58 Thick, K.-H. (1 1) 41 Thomas, C.J. (10) 24 Thomas, D. (t.1) 88; (5) 301; (6) 227 Thomas, J.L.C. (5) 170 Thomas, J.M. (4) 41 Thomas, R.C.(9) 78 Thomas,R.D. (12) 26 Thomas, R.L. (5) 39; (10) 47,86 Thommcn, M. (5) 12 Thompson, C. (5) 123 Thompson, R.C. (4) 49 Thorn, M.G.(1 .I) 2 Thornton-Pett, M. (1 .I) 16,39,40; (2) 229; ( 5 ) 159,266,337; (6) 33; (1 1) 17 Tian, S. (8) 62,63 Tidswell, H.M.(6) 250 Tidwcll, T.T. (6) 2 1 Ticdthe, D.B. (1 .HI) 55; (5) 348 Tickink, E.R.T.(4) 24,379; (5) 413; (9) 88 Tikhonova, I. (13) 47 Tillack, A. (1.I) 60; ( 5 ) 438 Tiiley, T.D. (1.1) 61; (6) 118,260; (10) 29 Tilsct, M. (2) 182 Timofceva, T.V. (10) 5 Tin, S.S. (4) 242 Ting, C. (4) 48; (6) 252 Ting, C.-S. (5) 314 Tinoco, P. (2) 131 Tiripicchio, A. (1 .I) 4; (1.III) 60; (2) 189; (3) 152, 161; (4) 75, 83,92, 128,247,375; (5) 112, 426 Tisato, F. (6) 284 Tjiong, H.1. (6) 173

Orgatiomelallic Chemistry "hchev, S.V. (4) 20.3 1,3 15,366 Tobita, H.(6) 122 Tochcr, D.A. (2) 308, 309; (6) 394 Tocquer, M.-C.S. (5) 376 Toda, H.(4) 367, 381 Toda, N. (13) 39 Togni, A. ( 5 ) 385; (6) 328, 341, 342 Tokitoh, N. (9) 72 Tokunaga, M. (7) 50,5 1 Tollhurst, V.-A. (12) 32 Tolman, W.B. (4) 103 Tolosa, J.I. (5) 79, 185; (6) 132 Tom&, M. (1.111) 126; (2) 317, 340 Tomaszewcski, S.E. (3) 131; (4) 98 Tomita, 1. (5) I 11,252 Tomkinson, M. (12) 63 Tommasi, I. (5) 112 Tompkin, P.K. (4) 52, 53; (6) 70, 89 Tong, V. (6) 69 Toomcy, L.M. (1.111) 81 Top, S. (6) 288 Torabi, A.A. (4) 32 Torkelson, J.R. (5) 380 Toro, A. (1 .IV)56 Torubaev, Y.V. (4) 400 Torwichc, B. (3) 53; (6) 125; (9) 71 Toscano, R.A. (1.111) 11 1; (2) 118; (5) 64; (6) 358 Touchard, D. (2) 132 Toupet, L. (2) 117, 132; (3) 44; (6) 109 Toyota, K. (3) 56; (9) 20; (12) 45 Toyota, S. (3) 62; (12) 39,90 Trabanco, A.A. (1.lU) 127 Trabesingcr, G. (2) 52; (5) 117, 130,247,385; (6) 392 Trakampruk, W. (2) 48; (5) 294 Traldi, P.(12) 116 Tran, E. ( I .III) 82; (5) 46 Trcmbiay, T.L. (1 .I) 75, 76; (6) 32 Tretyakov, A. (6) 199 Trifanov, A.A. (6) 18; (8) 12,69; (10) 81 Trinkaus, M. (6) 168 Trion, Y. (5) 281 Tripatlu, U.N. (9) 89 Tripepi, G. (1.1) 77,78; (3) 59; (6) 212 Trost, B.M. (7) 26 Trostyanskaya, I.G. (4) 202; (5) 428 Trotter, J. ( 5 ) 191 S.I. (13) 10 Trovanov. , I

I

.

483

Author I d e x Trudell, M.L. (5)67 Truhlar, D.G. (2) 156 Tsai, C.(2) 126 Tsai, C.-W. (1.N)48;(6)94 Tsai, F.-Y. (5) 153 Tsai, Y.C.(3) 163;(4)58 Tsang, C.W.(10)38 Tschinkl, M. (1 1) 57,90,93 Tschocmcr, C.M. (2) 201;(3) 142;(5) 117 Tseitlin, G.M. (10)76 Ts~ng,H.-R. (12) 15 Tseng, W.X.(4) 169 Tsuchihashi, T. (4)392 Tsuda, T. (2) 137 Tsuge, K.(2)47 Tsukahara, T. (1.1) 14 Tsutsumi, K.(5) 151 Tsuzuki, Y.(8) 85 Tubeville, M.J. (1 .HI) 115 Tudoret, M.J. (1.1) 74 Tuinstra, T. (8) 60 Tunaka, K.(2)47 Tunik, S.P. (4) 112;(5)41 1 Turner, D. (5) 62 Turner, J.J. (3)33 Turncr, P.(2)42, 145 Turner, P.S. (6) 194 Turney, T.W. (4)99 Turpeinen, U. (6)280 Tyler, D.R. (3) 158 Tylisczak, T.(10)10 Tyrra, W. (9) 101 Tyson, M.A. (4)3 13 Uccelli, L. (6) 284 Ueda, Y. (2)53 Uemura, S.(6)265 Ueng, C.-H. (3) 163;(4) 82,269; (6)273 Uffmg, C. (9) 105 Ugo, R.(3) 139;(4) 97, 199;(5) 378 Uguagliati, P. (2)341,342 Uhl, W. (3) 162;(1 1) 88,91,96 Ukaji, H.(4) 274 Ulbrich, D.(5) 455 Ulkii, D. (5) 177 Ullenius, C. (5)336 Umemoto, K.(1 1) 10 Umezawa-Vizzini, K. (2)73 Underiner, T.L. (5) 173 Ungviry, F. (2)6,9,201;(3) 9, 11, 12, 142;(5) 19;(13)3 Unoura, K. (6) 345 Unrecht, B. (8) 1 1 1, 112 Uo, A. (9)93

van Hccrdcn, P.S.(12) 89 Vankccr, A. (9)26 Van Kessel, M.(8) 14 van Koppen, P.A.M. (5) 154 van Koten, G.(1.1) 1 1;(1 .II) 12, 68;(2)246; 13, 19,28; (12)34,41,61,91;(13) 20, 21.24-26 van Lceuwcn, P.W.N.M. (2) 181, 202,249-251,319;(3) 141; (5) 116, 138;(6)269,335 van Neer, F.J.R. (2)3 19 Vanquickenborne, L.G.(9)26 van Rooy, A. (2) 181 van Rooyen, P.H.(1.W) 21 van Wijhoop, M. (5) 148 Van Zile, M.L. (12) I 1 1 Varga, V. (1.1) 69,70;(6)202; (13) 10, 1 1 Vahrenkamp, H. (1 .IV) 54;(4) Vargaftik, M.N. (4)394 230 Vargas, M.D. (3) 144;(4)268 Vaisserman, J. (1 31) 93;(1 .IV) 62;(5) 344,376,377,390;(6) Varghese, B.(2) 88 Varnai, P. (9) 18 144,288,385 Varnek, V.A. (4)20 Valderrama, M. (2)54;(6) 164 Vasil'eva, G.A. (1 .I) 72; (6)201 Valerga, P. (1 .HI) 28;(2) 136, Vaskag, S.(2)238 138, 144,300,301;(5)41, Vaughan, C.(1.N)40;(5)223; 323 Vddro, C.(3) 108; (6)304,391 (6)98 Vaughn, W.M. (1.111) 34 Vallat, A. (6) 196,230 Vazquez, A. (6)83,271 Vallcjo, M.I.(2) 109 Vazquez, C.(1.N) 14 Valls, E.(4)212 Vazquez de Miguel, A. (6) 83 Valnot, J.-Y. (12)44 VizqU~-I..bpC~ E.M. (1 1) 95; Van Beek, J.A.M. (8) 14 (13) 30 van Belzcn. R. (2)338 Veghini, D.(2) 141,147;(4)81; van Caemelbecke, E. (2)94 (5) 321 van den Ancker, T.R(12)60 Veiros, L.F. (4) 101,305 van den Bauken, E.(5) 225 van der Boom, M.E.(2)204,267, Veith, M, (6)23 Veldman, N. (1.1) 10, 11,25; 28 1 (1.11) 12, 13, 19,28;(1.W van der Hcijdcn, H.(1 .I) 43;(5) 68;(2) 202,250,25 1,280, 165 302,319;(4) 342;(5) 116, VanderLendc, D.D. (1.111) 34 138, 198;(6) 31;(9) 24;(12) van der Linden, J.G.M. (5)394 34,61;(13)7,20,26 van der Schaaf, P.A. (1 .II) 12 Velu, S.E. (12) 16 van der Sluis, M.(2)302;(9)24; Vemura, S.(5) 48 1 (13) 7 Vcnanzi, L.M. (5) 205 van der Veen, J. (3)39 Ventura, M.P. (5) 273 van der Veen, L.A. (1.1) 25;(3) Venturelli, A. (4)358 141;(6)31 Venturini, M. (6)284 Vandcrzande, D.J.M. (13)6 Venzo, A. (3) 155;(5)391 van der Zeijdcn, A.A.A. (6)34 Verbakel, W.F.A.R. (10)91 van de Water. L. (1 .II) 12.28 Verhavnik, G.P.J. (1.111) 26; (5) Van dc Weghe, P. (6) 18; (8) 12 26 Van Doremaele, G.H.J. (8) 14 Verma, A.K. (4)358 van Duijnen, P.T. (8) 60 Verpeaux, J.-N. (1 .nr)34;(3) 84, van Eldik, R. (i.IV) 21;(2) 177, 103;(5) 189;(6) 145 257;(3) 63,68 Viale, A. (4) 106;(5)417 van Gudenberg, D.W. (1.IV) 32

Uosaki, K. (6) 305 Urata, H.(5) I13 Urazowski, I.F. (6) 203 Urch, C.J. (7)57 Urieze, K. (5) 1 16 Urquhart, S.G. (10) 10 Umolabeita, E.P. (2)277,279, 317 Ushiroda, H. (2)65 Uson, I. (1.11) 10; (1 1) 38,40,59 Uson, R.(2)340 Ustpyuk, N.A.(5) 381;(6)365 Uthmann, S. (3) 53; (6) 125;(9) 71 Utirnoto, K. (13)39 Utz, T.L. (1.W) 16, 17

(1.w

484 Viafis, J.M. (1.111) 102 Viccntc, J. (2) 271; (4) 306,307; (12) 107 Vichi, E.J. (6) 271 Vicic, D.A. (2) 212,224; (6) 155 Vickery, J.C. (4) 300 Viebrock, H. (12) 32; (13) 18 Viets, D. (13) 29 Vigalok, A. (2) 199,204; (5) 89 Viguri, F. (6) 164 Vij, A. (6) 10; (13) 17 Vilar, R (4) 280,282 Vilardo, N.S.(1.11) 14 Villacampa, M.D.(10) 41,43,44 Villafanc, F. (3) 72 Vinas, C. (6) 149; (10) 20,2440, 45,5 1,52, 84, 85 Vinas, J.M. (5) 370 Vine, T. (6) 334 Vinogradova, L.E. (10) 70,74 Virovets, A.V. (4) 20, 3 1, 236, 284,315,316,366 Virrels, I.G. (2) 32; (3) 23, 32,33; (4) 187 Visciglio, V.M.(1.11) 27; (5) 263 Visentin, F. (2) 34 I, 342 Visseaux, M. (8) 5 Vitagliano, A. (2) 273; (5) 37, 145 Vites, J.C. (1.W) 1, 3; (3) 14 Vittal, J.J. (1.1) 9, 12; (4) 286, 347; (12) 113 Vizi-Orosz, A. (5) 378 Vizza, F. (2) 2 11 Vlcck, A. (3) 37; (4) 343 Vogtle, F. (1.111) 99 Vogler, A. (6) 282 Vogler, R (6) 338 Voigt, A. (6) 76; (1 1) 87 Voigt, F. (6) 261 Volhardt, K.P.C. (4) 103 Vollmcrhaus, R. (6) 180 Vollmuller, F. (7) 22 Vol'pin, M.E.(6) 201 von h i m , M. (9) 62 von Berg, S. (5) 22,289 Vondung, C. (4) 340 von Hacnisch, C. (4) 260; (9) 85 von Philipsborn, W. (2) 122 von Schncring, H.G. (2) 225,230; (6) 148, 163; (9) 14 von Zelewsky, A. (2) 276; (3) 6 Vorfcld, U. (6) 335 Vorontsov, E.V. (4) 204,398; (10) 33 Vosejpka, P.C. (5) 173 Voskoboynikov, A.Z. (4) 202; (5) 428; (6) 193; (8) 4,25 Voyer, N. (12) 8

OrganometallicChemistry Vrahami, M. (5) 4x3; (6) 306 Vricsc, K. (2) 202,249-25 I, 3 19; (5) 138, 198; (6) 335 Vuurman, M.A. (2) 89; (4) 26 Vyshinskaya, L.I. (1 .I) 72; (6) 20 1 Waas, J.R. (1 1) 6 Wachter, J. (6) 110 Wachter, W. (6) 300 Wada, A. (5) 237 Wada, H. (6) 122 Wada, M. (9) 93 Wade, K. (4) 198; (10) 66,67, 79, 80

Wadepohl, H. (1.111) 69; (2) 12; (4) 256,257,396; (5) 432; (6) 161 Waezsada, S.D.(1 1) 38,40,59 Wagner, M.(1.1) 47; (5) 478; (6) 324,326; (1 1) 28,29 Wagner, 0. (3) 48; (9) 40 Wagner, T. (1.1) 46 Wakabuki, Y. (6) 176 Wakatsuki, Y. (2) 152; (4) 181, 182; ( 5 ) 324; (6) 190,296; (8) 30, 78; (12) 84 Wakatsula, Y. (5) 468 Walawalkar, M.G. (1 1) 87 Waldbach, T.A. (1.1V) 21 Waldhor, E. (10) 28 Waldmiiller, D. (12) 40 Waldvogcl, S.R. (5) 193 Walkcr, A.P. (5) 39 Wallow, T.I. (2) 254 Walsgrove, T. (7) 45 Walsh, D. (9) 104 Walter, D. (5) 472 Walter, J.N. (3) 83 Walther, D. (1.IV)30; ( 5 ) 33 1 Walton, D.R.M. (5) 148 Walton, J.C. (1 1) 14 Walton, R.A. (1.N) 38, 39; (3) 88 Waltz, K.M.(1 .I) 96 Walzer, J.F. (1 .I) 6 1 Wanandi, P.W. (6) 118 Wang, B. (3) 28, 100 Wang, C. (2) 197 Wang, H.H. (12) 1 11 Wang, H.X. (2) 283 Wan& J. (5) 231 W a g , J.-J. (6) 58 Wang, J.-Q. (4) 54,3 14 Wmg, L.4. (1-11) 32; (5) 33 Wang, Q.Y. (1.1) 74 Wang, R.-J. (3) 74 Wang, S.(9) 97, 100; (11) 48 W a g , S.-L. (1.111) 44.76; (4)

161, 326; (5) 50,51, 121,463 W a g , S.-Y.S. (1.111) 34-36 Wang, T.-F. (1.IV)48,49; (2) 114; (5) 65; (6) 94, 97,99 W a g , W. (4) 141, 150-152 Wang, X. (1.II) 25 Wang, Y. (1.111) 45; (5) 49, 103, 104, 153; (6) 58,62; (10) 24, 28 wang, z.-x.(12) 55 wang, Z.Y. (1.1) 29 Wanitschek, M.(10) 24 Waminger, K. (9) 73 Waratuke, S.A. (1.I) 2 Ward, G.N. (3) 124; (4) 124 Ward, M.D. (1.W) 14; (3) 15 Ward, M.F. (3) 109; (5) 360 Ward, T.R. (6) 8 Wardhana, T.W. (2) 296; (5) 142 Warhurst, N.J.W. (5) 208,382 Waring, P. (2) 3 13 Wamccke, A. (6) 204 Warren, S. (12) 23,31 Waschbucsch, K. (9) 56 Wasicak, J.T. (5) 285 Wasserman, E.P. (6) 177 Watanabe, E. (5) 113 Watanabc, J.-Y. (2) 175 Watanabe, K. (1 1) 1 Watanabe, M. (6) 340 Watanabc, S. (5) 129; (6) 175; (7) 16,17 Watkin, J.G. (8) 6 Watkins, C.L. (1 1) 69 Watson, D.G. (10) 2 Watson, P.G.(13) 29 Waugh, M. (3) 109, 110; (5) 359, 360 Waugh, M.P.(2) 30; (5) 156,290 Way, C.-J. (3) 156; (4) 161, 326; (5) 463 Waymouth, R.M. (6) 234,236 Weber, B. (6) 300 Weber, C. (1.1) 71; (5) 454 Weber, J.C. (1.111) 101 Weber, L. (1.111) 66; (3) 53; (6) 112, 125; (9) 1, 6,29, 71 Wcbstcr, M. (9) 106, 107, 109 Wccrs, H.L. (5) 273 Wcgner, P. (5) 327 Wehausen, P. (8) 109 Wehmschulte, R.J. (1 1) 45; (12) 64 Wei, B. (6) 332 Wei, P. (1 1) 34 Weib, A. (2) 139, 142 Weidcmann, R. (2) 23 1,233; (5) 97

485

Author Index Weidenbruch, M. (9) 14 Wcidennann, R. ( 5 ) 482 Wcidlein, J. (9) 98 Weidman, T.W. (4) 103 Weidmann, T. (1.IV)25; ( 5 ) 457 Weigcnd, F. (4) 260 Weimann, R. (6) 25, 184; (8) 36 Weinmann, S.(1.1) 71; (5) 454 Weinrcb. S.M. (13) 6 Weinrich, V. (1 .IV) 25; (5) 457 Wcirda, D.A. (4) 62 Weisenberg, B.A. (1 .III) 1 17 Weiss, J. (6) 2; (1 1) 63 Wcissenborn, H. (8) 66,67 Wcissenstciner, W. (5) 483; (6) 306 Weitze, A. (9) 90 Welch, A.J. (10) 46,47,85, 86 Welker, M.E.(2) 44, 119, 167, 173; (6) 114 Wcller, AS. (1.110 70; (10) 46,47 Wcllcr, F. (9) 58 Wellcr, K.J. (1.11) 31 Welling, L.L. (4) 301; (12) 109 Wells, M.B. (5) 3 19 Wells, R.L. (9) 111; (1 1) 73,76, 78 Wclton, T. (6) 334 Wen, A.T. (10) 10 Wcn, Y.-S. (1.111) 92; (1,IV) 49; (4) 59, 127,229,302; (6) 97 Wendt, O.F. (2) 310; (9) 108 Wcng, L.-H. (2) 226 Wcng, W. (1 .IV) 4 1,43; (4)208; ( 5 ) 407 Wcnger, E. (2) 18,285; (5) 16 Went, M.J. (2) 11; (4) 240 Werncke, W. (2) 103; (6) 140 Wcmer, H. (2) 62, 113, 152, 159, 222,225,227,230-233,235, 350, 35 1 ; (4) 249; (5) 18,92, 97, 98, 190,324,325,329, 482; (6) 148, 163, 317 Wcsemann, L. (6) 168 Wesendrup, R. ( 5 ) 307 Wesennann, J.L. (6) 63 Wesscl, H. (1 .lI) 10; (1 I) 59 Wcsterhausen, M. (9) 58; (13) 23 Westcrlund, C. (12) 18 Westlund, N. (12) 63 Wcstphal, U. (6) 223 Wettling, T. (9) 19 Wcyland, T. (2) 143 Whang, D. ( 5 ) 303 Whcatley, A.E.H. (1 2) 3 1 Whitby, R.J. (1.1) 51 White, A.H. (2) 110,221, 282, 323; (4) 2 4 2 3 , 111, 113, 135,

136, 165, 166, 171,378; ( 5 ) 412,414416,459,461,462; (6) 135, 198; (8) 8; (9) 11,70, 115; (1 1) 61 White, A.J.P. (1.111) 50; (2) 95; ( 5 ) 310; (6) 294,334,337; (10) 57 White, P.A. (8) 8 Whitc, P.S. (1.111) 6465, 71,89, 95; (3) 75; (4) 77; (5) 53,3163 19, 349; (9) 111; (1 1) 76 Whiteford, J.A. (2) 262 Whiteley, M. ( 5 ) 477 Whitcly, M.W. (1 X I ) 47; ( 5 ) 38; (6) 35 1 Whitmire, K.H. (3) 121; (4) 78, 79.88 Whittaker, C. (4) 221 Whittall, 1.R (2) 99,324,325; (4) 336; (12) 114 Whittlesey, B.R. (4) 115 Wiittlcscy, M.K. (2) 32; (3) 23; (4) 187 Wicht, D.K. (9) 38 Wick, D.D. (2) 196,261 Widholm, M.(6) 269 Wicdc, P. (2) 111 Wiedcmann, R. (6) 317 Wiegelben, P. (12) 28 Wicnekc, M. (13) 23 Wieser, C. (6) 181 Wiesli, U. (6) 341 Wigal, C.T. (12) 17 Wigley, D.E. (1.11) 15, 26, 31; (6) 372 Wijkcns, P. (12) 34,41 Wilczok, U. (2) 195 Wild, S.B. (2) 15 Wilcs, J.A. (2) 55 Wilhelm, T.E. (2) 363 Wilkinson, A . 4 . (2) 178 Williams, D.J. (2) 95; (4) 280, 282,283; (5) 3 10; (6) 294, 334,337; (9) 28; (10) 57 Williams, D.L. (1.111) 50 Williams, I.D. (2) 71,77; (6) 156 Williams, J.M. (12) 111 Williams, M. (10) 82 Williams, M.L. (4) 336,338; ( 5 ) 439; (6) 165 Williams, R.E. (10) 23 Williard, P.G.(12) 35,40 Willis, A.C. (4) 301; (5) 246; (12) 109 Willncr, H. (2) 31; (3) 54 Wills, M. (7) 45 Wilms, M.P. (3) 37; (4) 343 Wilson, S.R. (1.1) 42; (3) 134,

137, 145; (4) 68,105, 180, 185,270,344; ( 5 ) 265, 387, 410,450; (6) 167, 169, 393 Wilton-Ely, J.D.E.T. (9) 7,27, 28 Windisch, H. (8) 66,67 Winemiller, M.D. ( 5 ) 82,84 Wing, S.-L. (3) 156 Winter, C.H. (13) 9,44 Wintcr, R.F.(2) 133 Wit, J.B.M. (13) 7 Wittchow, E.(1.111) 80 Witte, P.T.(1.11) 9; ( 5 ) 166 Wittke, 0. (1.W 56 Wittmann, K. (2) 195 Wittmcr, F . 4 . (6) 367 Wocadlo, S. (6) 7,373; (9) 87, 112 WZissner, D. (1.111) 61.62 Wolczanski, P.T. (1.11) 18 Wolf, A. (10) 32 Wolf, E. (4) 119, 120; ( 5 ) 419 Wolf, J. (2) 222,231,232,350; ( 5 ) 97, 190,329 Wolf, M.O. (6) 295 Wolfe, J.B. (3) 87 Wolfe, J.P. (7) 8, 12-14 Wolff, J.M. (6) 396 Wolmcrshacuser, G.(4) 340; (9) 105 Wolpert, M. ( 5 ) 243 Wong, E.H. (3) 15 Wong, K.M.C. (3) 8 1 Wong, M.-T. (12) 94 Wong, T.-S. (4) 217 Wong, W. (3) 14, 15 Wong, W.-T. (3) 138, 166, 167, 173; (4) 17,38, 126, 190,200, 2 17,220,228,232-234,365 ; (5) 469; (6) 156,348; (8) 16 Woo, B.W. (1 .I) 90; (6) 228 Woo,H.G. (6) 218 Woo, K. (5) 218 Woo, T.K. (2) 248; (5) 109 Woodgate, P.D. (6) 384 Woodworth, B.E. (1.111) 95 Woollins, J.D. (3) 123; (4) 138 Works, A.B. (5) 279 Worrall, J.M. ( 5 ) 57 Wmage, K.(1 .I) 4 Wrackmeyer. B. (2) 335; ( 5 ) 375; (10) 17, 18,25; (11) 31; (12) 46 Wright, D.S. (6) 186; (12) 85; (13) 1 Wright, J.M. (5) 155,367; (8) 28 Wright, L.J. (2) 36,50,59; (3) 27, 101,102 Wu, B. (11) 5 1

Orgartometallic Cheniisty

486

WU,B.-M. (2) 307; (3) 117; (4) 80 Yamaga, S. (13) 48 Wu, H. (1.11) 32 WU,H.-L. (1.111) 97; (4) 309; (5) 399 WU,H.-P.(4) 330 Wu, I.Y. (1.1) 71; (2) 126; (5) 454 Wu,L.P.(5)476; (12) 101 WU,M.-J. (5) 50 Wu, W. (1.IV) 38, 39; (3) 88 Wu, W.F. (2) 77, 80, 140 Wu,X. (13) 40 wu, Y. (10) 95 WU,Y.-D. (1.111) 15 Wu, Y.J. (2) 283; (6) 292; (13) 28 wu, z. (2) 100 Wu, Z.J. (8) 93 WU,Z.-Z. (8) 47 Wiindisch, M. ( 5 ) 184 Wiinsch, M. (4) 252 Wiirthwein, E . 4 . (9) 17; (12) 49 Wulff, W.D. (1.111) 117, 123 Wurst, K. (1 .I10 83; (6) 298; (13) 45 Xia, H.-P.(2) 76-78,80, 140 Xiao, J. (4) 347 Xiaolan, L. (2) 225; (6) 148, 163 Xic, W.H. (6) 129 X ~ CY.-F. , (2) 213, 307 Xie, Z . (4) 33; (6) 191; (8) 24,27, 39,40 Xie, Z.W. (10) 38,60 Xiing, Y. (8) 13 Xin, J. (8) 98; (12) 37 Xin, S.X. (6) 218 Xing, L.(6) 17 Xing, Y. (8) 26 Xu, G.J. (8) 105 Xu, S. (3) 100, 128; (4) 194; (6) 107, 108 Xu,S.S.(6) 129 Xu, Y. (8) 87 Xue, F. (2) 307; (6) 11, 191; (8) 16,24,27,39; (10) 38, 60; (12) 82 Xuc, M.(8) 19 Xue, M.Q.(8) 80 XUC,W.-M. (1.W) 12 Xui, F. (6) 332 Yabuki, M. (5) 133 Yada, T. (4) 72; (5) 353 Yam, V.W.-W.(3) 81; (4) 291, 399; (6) 349; (12) 94,95, 104 Yainada, K.(4) 3 19 Yamada, M. (3) 24

Yamapata, T. (1.11) 23; (4) 18 Yamagishi. T. (5) 133 Yamaguchi, H.(5) 60 Yamaguchi, M. (3) 24; ( 5 ) 133; (11) 66 Yamaguchi, Y.(1.111) 37; (6) 131 Yamamoto, J.H. (3) 77; (4) 226 Yamamoto, M. (1 1) 13 Yamamoto, S. (8) 72 Yamamoto, T. (2) 216,314,331; (5) 91,95 Yamamoto, Y. (4) 18 I, 274,275, 367, 381; (6) 356; (10) 69, 73 Yamamura, H. (1 1) 82 Yamasaki, K. (2) 237 Yamashita, H. (2) 294 Yarnazaki, S. (5) 405; (12) 105 Yan, C.-G. (3) 113, 117; (4) 80, 86 Ym, K. (1.111) 7; (6) 146 Yan, X. (2) 200; (6) 64,7 1 Yan, Y.K.(4) 59 Yanagida, M.(6) 305 Yang, G.-S. (8) 3 Yang, H.( 5 ) 197 Yang, J. (6) 28 Yaw, Q. (6) 28 Yang, S.-M.(2) 105; (5) 75 Yang, X. (6) 240; (1 1) 3 Yang, Y.-L. (6) 58 Yang,z . (7) 7 Yanovsky, A.I. (1.1) 57; (2) 90; (3) 169; (4) 107, 108, 112, 137, 195,202,205,206,237, 238, 339,389, 398; ( 5 ) 411, 428, 452,480; (8) 68; (10) 5, 33, 5556; (12) 98; (13) 47 Yao, J. (2) 72 Yao, J.W. (1.111) 42 Yao, Y. (8) 8 I Yap, G.P.A. (1.1) 82, 83; (1.11) 16; (1.110 39, 117, 123; (2) 81, 91, 161,270; (3) 39; (4) 110, 142,368; (5) 257,358,446, 458; (6) 9,41,399; (9) 38; (1 1) 78; (12) 72 Yap, V.P.D.(2) 36;(3) 102 Y a s u 4 H. (8) 7,73,74 Yasui, M.(2) 354 Yasuo, W. (8) 76,77 Yates, M.I.(2) 92; (5) 363 Ye, S. (8) 100 Ye, T.-Q. (3) 32 Ych, M.C.P. (3) 99; (5) 283 Yeh, W.-Y. (1.111) 31; (3) 76,79; (4) 231; ( 5 ) 313-315; (6) 86 Yclamos, C. (4) 43

Ycng, T.-Y. (1.111) 30 Yeung, L.K. ( 5 ) 218 Yeung, R.C.Y. (2) 78,80, 140 Yi, C.S. (2) 106; (6) 123 Yiaolan, L.(2) 230 Yin, Y.-Q. (4) 330,383,385,386 Yoon, S.C.(1 .I) 90; (6) 228 8 Yorimitsu, H. Yoshida, M. (4) 72; (5) 353; (6) 205; (10) 58,59 Yoshifuji, M. (9) 20; (12) 45 Yoshii, E. (1.111) 121 Yoshimura, H. (8) 76,77 Yoshimura, T. (6) 190; (8) 30; (12) 84 Yoshinaga, K. (2) 275 Yoshinaga, S.(1 .III) 37 YOU,X.-Z. (8) 20 Young, G.B.(2) 245,308 Young, V.G., Jr. (1.I) 44; (1.II) 15; (2) 55,57; (5) 258,286; (6) 69; (8) 58; (1 1) 21,39,73 Youngs, W.J. (2) 290,328; (5) 330,437; (13) 32 Younus, M.(2) 332 Yu, D. (8) 87 Yu,K.-B.(4) 159 Yu,P.(4) 244; (I 1) 62 Yu, S.(13) 7 Yu, S.-N. (8) 21 Yu, W.Z. (10) 8,9 Yu, Y. (1.N)59; (2) 366; (3) 114; (5) 354,355,401; (6) 100, 172; (13) 48 Yu,Z. (1.111) 109, 113 Yuan, F. (6) 16; (8) 17 Yuan, H.Z.(2) 283; (6) 292; (13) 28 Yuan, M. (8) 82 Yufit, D.S. (2) 86; (4) 286; (12) I12 Yun, Y.K. (2) 57; (5) 286

(1.w

Zablocka, M. (1.1) 55; (9) 82 Zachara., J. ( I 1) 49,54-56 Zacharias, P.S.(2) 75 Zagarian. D. (1.1) 61 Zagorcrski, D.V. (6) 127 Zahl, A. (2) 142, 177 Zahn, S.K.(10) 46 Zaitseva, N.N. (4) 21, 111; (5) 415 Zakharkin, L.I. (10) 54,55,70,74 Zakharov. L.N. (6) 368; (8) 52, 68,69; (12) 98 Zamora, F. (13) 37,38 Zanello, P. (4) 35 I; ( 5 ) 478; (6) 326,335; (1 1) 29

Author It tdcx Zanetti, N.C.M. (9)73 zang, s.-w.(2)359 Zangrando, E.(2) 291 Zannotti, V.(2) 97,98 Zanobini, F.(2) 120,207 Zanon, J. (1.1) 32 Zapadinskii, B.I. (10)76 Zargarian, D.(6) 180 Zavialov, LA. (1 1) 2 Zawarotko, M.J.(8)58 Zdanovich, V.I.(3) 169;(4) 107109,398;(5) 480 Zehnder, M.(5) 132, 140 Zeier, B.(2) 124, 129;(5)71 Zeigler, C.J. (2) 116 Zeigler, T.(5) 108, 109 Zeng, H.(5) 28 Zcnneck, U. (5) 183, 184 Zeppel, F.(5) 161 Zettcrberg, K.(2)243;(5) 106, 107,115 Zhang, D.(2)290,328;(5) 437; (13)32 Zhang, H. (1 I) 67 Zhang, H.M.(10)28 Zhang, L. (1.111) 60;(4) 196,364; (9) 16,48

487 Zhou, Z.-Y. (2)226;(3) 74 Zhu, J. (1.111) 116 Zhang, S.Y.(8) 93 Zhang, X. (1.IV) 30;(2)200;(6) Zhu, N.Y.(1 .IV)54 Zhu, Z.(1.IV) 66,67 108 Zhuang, B. (4)244 Zhang, X.-Q. (6)305 Zhuang, W.-W. (4)60,61 Zhang, Y. (3) 100, 128;(4) 194; (6) 107,108, 190;(8)30,78, Ziegler, T. (2) 155,242,248;(5) 87 87;(12)84 Zigm, T. (6)334 Zhang, Y.Q. (6) 129 Zhang, Z. (6) 191,274;(8)24,27 Ziller, J.W. (6) 13;(8)3 1,5 1 Zippcl, F. (1 .I) 63,64;(1.III) 108; Z h g , Z.-2. (13)36 (5) 339;(6)209 Zhao, D. (2) 169 Ziurys, L.M.(12)37 Zhao, Z.-Y. (4)385 Zou, X.(2) 169 Zhdanovich, V.1. (4)237 Zsolnai, L. (5) 389 Zheng, S.(5) 28 ZU,R.-Z. (5) 3 12 Zheng, Z.P.(10)65 Zubavichus, Ya.V. (4)352,387; Zhigarcva, G.G.(10)54,70 (5) 442 Zhiltsov, S.F.(8) 68;(12)98 Zucchi, B. (3) 142 Zhou, J. (4)3 12 Zucchi, C.(2)201 Zhou, J.W. (10)9 Zucchi. G.(8) 5 Zhou, R.(2) 197 Zue, M. (6) 188 Zhou, W. (4)41 Zhou, X. (3)100, 125;(4) 194; (5) Ziirchcr, F.(5) 130 Zukerman-Schpector, J. (1 1) 95 28;(6) 107, 108,231 Zummack, W.(2)26;(5) 54 Zhou, X.G. (8)20,21 Zybill, C.E.(3) 40;(4)74 Zhou, X.Z. (6) 129 Zhou, Y.(1.W 41

Zhang, M.Y.(10) 8 , 3