Organometallic Compounds of Low-Coordinate Si, Ge, Sn and Pb: From Phantom Species to Stable Compounds

443 Pages·2010·14.86 MB·English

by  Vladimir Ya. Lee

Organometallic Compounds of
Low-Coordinate Si, Ge, Sn and Pb
Organome tallic C ompounds of L ow - C oordinate Si, Ge , Sn and Pb: F rom P hantom Spe c ie s to Stable C ompounds
Vladimir Ya . Lee and Akira Sekiguchi © 2010 John Wiley & Sons, Ltd. ISBN: 978-0-470-72543-6
Organometallic
Compounds of
Low-Coordinate
Si, Ge, Sn and Pb
From Phantom Species to Stable Compounds
VLADIMIR Ya. LEE and AKIRA SEKIGUCHI
Department of Chemistry,
Graduate School of Pure and Applied Sciences,
University of Tsukuba, Tsukuba, Japan
A John Wiley and Sons, Ltd., Publication
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LibraryofCongressCataloging-in-PublicationData
VladimirYa.Lee,1960-
Organometalliccompoundsoflow-coordinateSi,Ge,Sn,andPb:
fromphantomspeciestostablecompounds/VladimirYa.Leeand
AkiraSekiguchi.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-470-72543-6 (cloth)
1. Organometalliccompounds. I.Lee,VladimirYa.II.Title.
QD411.S452010
547(cid:3).0568–dc22
2010013108
AcataloguerecordforthisbookisavailablefromtheBritishLibrary.
ISBN:9780470725436
Typesetin10/12ptTimesbyLaserwordsPrivateLimited,Chennai,India.
PrintedandBoundinGreatBritainbyAntonyRowe
Contents
Preface xi
Abbreviations xiii
1. Heavy Analogs of Carbenium Ions: Si-, Ge-, Sn- and Pb-Centered
Cations 1
1.1 Introduction 1
1.2 Synthesis of RR(cid:2)R(cid:2)(cid:2)E+ Cations (E=Si–Pb) 3
(cid:2) (cid:2)(cid:2)
1.2.1 From Halides RRR EX 3
(cid:2) (cid:2)(cid:2)
1.2.2 From Hydrides RRR EH 3
(cid:2) (cid:2)(cid:2) (cid:2)(cid:2)(cid:2) (cid:2) (cid:2)(cid:2) (cid:2) (cid:2)(cid:2)
1.2.3 From RRR E–R and RRR E–ERRR 3
(cid:2)
1.2.4 From Heavy Carbene Analogs RRE•• 5
1.2.5 From Free Radicals RR(cid:2)R(cid:2)(cid:2)E• 5
1.3 Reactions and Synthetic Applications of RR(cid:2)R(cid:2)(cid:2)E+ Cations16 6
1.4 Theoretical Studies 7
1.4.1 Structure of Cations 8
1.4.2 Stability of Cations 8
1.4.3 Calculation of the NMR Chemical Shift of Cations 9
1.4.3.1 29Si NMR Chemical Shift Calculations 10
1.4.3.2 119Sn NMR Chemical Shift Calculations 11
(cid:2) (cid:2)(cid:2) +
1.5 Early Studies of RRR E Cations: Free or Coordinated? 11
(cid:2) (cid:2)(cid:2) +
1.6 Stable RRR E Cations 16
1.6.1 Intramolecularly Stabilized (Coordinated) Cations 16
1.6.2 Free (Noncoordinated) Cations 29
1.6.2.1 Cyclic π-Conjugated Cations 29
1.6.2.2 Acyclic Cations Lacking π-Conjugation90 30
1.7 Summary and Outlook 35
1.8 References 36
2. Heavy Analogs of Organic Free Radicals: Si-, Ge-, Sn- and
Pb-Centered Radicals 45
2.1 Introduction 45
2.2 Early Studies: Transient Species RR(cid:2)R(cid:2)(cid:2)E• 47
2.2.1 Generation 47
vi Contents
2.2.2 Structure (Identification) 48
2.2.2.1 Electronic Spectroscopy 48
2.2.2.2 EPR and CIDNP Spectroscopy 49
2.2.2.2.1 EPR Spectroscopy 49
2.2.2.2.2 CIDNP Spectroscopy 50
2.2.2.3 Theoretical Calculations 51
2.2.3 Synthetic Applications 52
2.3 Persistent Radicals (Generation and Identification) 53
2.4 Stable Radicals 57
2.4.1 Neutral Radicals 58
2.4.1.1 Cyclic Radicals 58
2.4.1.2 Acyclic Tricoordinate Radicals 60
2.4.2 Charged Radicals 66
2.4.2.1 Anion-radicals 67
2.4.2.1.1 Cyclic Anion-radicals 67
2.4.2.1.2 Acyclic Anion-radicals 68
2.4.2.1.2.1 Heavy Carbenes Anion-radicals 68
2.4.2.1.2.2 Heavy Alkenes Anion-radicals 72
2.4.2.1.2.3 Heavy Alkynes Anion-radicals 74
2.4.2.2 Cation-radicals 77
2.4.3 Stable Biradicals of the Heavy Group 14 Elements 78
2.5 Summary and Outlook 81
2.6 References 82
3. Heavy Analogs of Carbanions: Si-, Ge-, Sn- and Pb-Centered Anions 89
3.1 Introduction 89
3.2 Synthesis 91
3.2.1 Alkyl-substituted Silyl Anions 91
3.2.2 Aryl-substituted Silyl Anions 91
3.2.3 Silyl-substituted Silyl Anions 92
3.2.4 Silyl Anions with Functional Groups 92
3.2.4.1 (Hydrido)Silyllithium Derivatives 92
3.2.4.2 (Halo)Silyllithium Derivatives 93
3.2.4.3 (Amino)Silyllithium Derivatives 93
3.2.4.4 (Alkoxy)Silyllithium Derivatives 94
3.2.4.5 (Acyl)Silyllithium Derivatives (Lithium Sila-enolates) 94
3.2.5 Cyclic Anions 94
3.2.5.1 Silole, Germole and Stannole Anions and Dianions 94
3.2.5.2 Cyclic Oligosilyl Anions 95
3.2.6 Polylithiosilanes 95
3.2.6.1 Tetralithiosilane 95
3.2.6.2 1,1-Dilithiosilane Derivatives 96
3.2.6.3 1,2-Dilithiodisilane Derivatives 96
3.2.6.4 1,3-Dilithiotrisilane and 1,4-Dilithiotetrasilane
Derivatives 97
Contents vii
3.2.7 Germyl, Stannyl and Plumbyl Anions 97
3.3 Structure 98
3.3.1 NMR Spectroscopy (Condensed Phase Structure) 98
3.3.2 X-ray Crystallography (Crystal Structure) 101
3.4 Reactions and Synthetic Applications 104
3.5 Recent Developments 109
3.5.1 sp3 Anions 110
3.5.2 sp2 Anions 120
3.5.3 Cyclic and Polycyclic Anions 123
3.6 Summary and Outlook 129
3.7 References 131
4. Heavy Analogs of Carbenes: Silylenes, Germylenes, Stannylenes and
Plumbylenes 139
4.1 Introduction 139
4.2 Generation 140
4.2.1 Photolysis of Acyclic Oligo- and Polymetallanes 140
4.2.2 Photolysis of Cyclic Metallanes 143
4.2.3 Thermolysis of Oligo- and Monometallanes 146
4.2.4 α-Elimination of Silylenoids 148
4.2.5 Heavy Alkene–Heavy Carbene Rearrangements 149
4.3 Spectroscopic Identification 150
4.4 Structure 152
4.4.1 Multiplicity: Singlet vs Triplet 152
4.4.2 Substituent Effects 153
4.5 Reactions of Transient Species 155
4.5.1 Insertion into Single Bonds 156
4.5.2 Addition to Multiple Bonds 159
4.5.2.1 Addition to Alkenes 159
4.5.2.2 Addition to Alkynes 161
4.5.2.3 Addition to 1,3-Dienes 163
4.5.3 Disilenes/Silenes from Silylenes: Dimerization,
Rearrangement 164
4.5.4 Complexation to Transition Metals 166
4.6 Stable/Persistent Silylenes, Germylenes, Stannylenes and
Plumbylenes 172
4.6.1 Singlet Species 172
4.6.1.1 Silylenes 173
4.6.1.2 Germylenes 175
4.6.1.3 Stannylenes 179
4.6.1.4 Plumbylenes 182
4.6.2 Triplet Species: Generation and Identification 184
4.7 Summary and Outlook 187
4.8 References 188
viii Contents
5. Heavy Analogs of Alkenes, 1,3-Dienes, Allenes and Alkynes: Multiply
Bonded Derivatives of Si, Ge, Sn and Pb 199
5.1 Introduction 199
5.2 Early Studies: Generation and Identification 200
5.3 Stable Derivatives (Synthesis and Structure) 201
5.3.1 Heavy Analogs of Alkenes (including cyclic compounds) 201
5.3.1.1 Homonuclear Compounds 201
5.3.1.1.1 Disilenes >Si=Si<3c−e,12 206
5.3.1.1.2 Digermenes >Ge=Ge<5c,71 225
5.3.1.1.3 Distannenes >Sn=Sn<5c,71b,d 237
5.3.1.1.4 Diplumbenes >Pb=Pb<5c,71d 243
5.3.1.2 Heteronuclear Compounds 246
5.3.1.2.1 Group 14/Group 14 Combinations:
>E =E (cid:2)<(E ,E (cid:2) =C,
14 14 14 14
Si,Ge,Sn,Pb) 246
5.3.1.2.1.1 Silenes >Si=C<124 246
5.3.1.2.1.2 Germenes >Ge=C<71a,c,124f,i 256
5.3.1.2.1.3 Stannenes >Sn=C<71b,124f,i 262
5.3.1.2.1.4 Plumbenes >Pb=C<5a 265
5.3.1.2.1.5 Silagermenes >Si=Ge<124i 265
5.3.1.2.1.6 Silastannenes >Si=Sn<124i 268
5.3.1.2.1.7 Germastannenes >Ge=Sn<124i 270
5.3.1.2.2 Group 14/Group 13 Combinations:
>E =E – (E =Si,Ge;
14 13 14
E =B,Ga,In) 273
13
5.3.1.2.3 Group 14/Group 15 Combinations:
>E =E – (E =Si,Ge,Sn;
14 15 14
E =N,P,As) 276
15
5.3.1.2.3.1 Silaimines >Si=N–179 276
5.3.1.2.3.2 Germaimines
>Ge=N–71a,c,191a,b 279
5.3.1.2.3.3 Stannaimines >Sn=N–71b,191a 281
5.3.1.2.3.4 Phosphasilenes >Si=P–203 282
5.3.1.2.3.5 Phosphagermenes
>Ge=P–71a−c,191a 287
5.3.1.2.3.6 Phosphastannenes
>Sn=P–71b,191a 288
5.3.1.2.3.7 Arsasilenes >Si=As–217 289
5.3.1.2.4 Group 14/Group 16 Combinations
>E =E (E =Si,Ge,Sn;
14 16 14
E =O,S,Se,Te) 290
16
5.3.1.2.4.1 >E =O Combinations 290
14
5.3.1.2.4.2 >E =S Combinations 293
14
5.3.1.2.4.3 >E =Se Combinations 294
14
5.3.1.2.4.4 >E =Te Combinations 295
14
Contents ix
5.3.2 Heavy Analogs of 1,3-Dienes and Allenes 295
5.3.2.1 Heavy Analogs of 1,3-Dienes237 295
5.3.2.2 Heavy Analogs of Allenes245 300
5.3.3 Heavy Analogs of Alkynes: Disilynes, Digermynes, Distannynes,
Diplumbynes, and their Valence Isomers260 309
5.3.3.1 Disilynes RSiSiR 310
5.3.3.2 Digermynes RGeGeR (and their Valence Isomers) 313
5.3.3.3 Valence Isomers of Distannynes RSnSnR 314
5.3.3.4 Valence Isomers of Diplumbynes RPbPbR 315
5.3.3.5 Heavy Analogs of Alkynes: Structure and Bonding 315
5.4 Summary and Outlook 319
5.5 References 319
6. Heavy Analogs of Aromatic Compounds 335
6.1 Introduction 335
6.2 Early Studies 338
6.2.1 Transient Species: Generation, Identification and Trapping 338
6.3 Stable Compounds (Synthesis and Structure) 339
6.3.1 2π-Electron Species 339
6.3.1.1 Cyclopropenylium Ion Derivatives 340
6.3.1.2 Cyclobutadiene Dication Derivatives 343
6.3.2 6π-Electron Species 344
6.3.2.1 Benzene (and its Homologs) Derivatives 344
6.3.2.1.1 Theoretical Studies 344
6.3.2.1.2 Experimental Accomplishments 346
6.3.2.2 Cyclopentadienide Ion Derivatives 352
6.3.2.3 Cyclobutadiene Dianion Derivatives 363
6.3.2.4 Cycloheptatrienylium (Tropylium) Ion Derivatives 369
6.3.3 Homoaromaticity 370
6.3.4 Antiaromaticity 375
6.3.4.1 Cyclobutadiene Derivatives 377
6.3.4.2 Cyclopropenyl Anion Derivatives 383
6.3.4.3 Cyclopentadienylium Ion Derivatives 384
6.3.5 Reactivity of Heavy Aromatics: Complexation to Transition
Metals 387
6.4 Summary and Outlook 402
6.5 References 403
Index 415
Preface
The variety of organometallic compounds based on the group 14 elements heavier than
carbonis tremendous, spanningthe wide range from low(mono, di, tri)- to normal tetra-
tohyper(penta,hexa)-coordinatederivatives.However,incontrasttothetwolastclasses
of compounds, the low-valent group 14 organometallics have never appeared in books.
The lack of such books, which is particularly surprising given the permanently growing
interest in this hot field of modern main group chemistry as reflected by the vast num-
ber of outstanding reviews and book chapters, prompted us to undertake an attempt to
survey, analyse and summarize the current state of affairs in this area. The fundamental
achievements in the field are associated, first of all, with the recent advances in state-
of-the-art sophisticatedsyntheticandspectroscopictechniques,aswellasrapidprogress
in theory and computational methods. This has enabled isolation and structural studies
of unique stable low-coordinate species, which only a few decades ago were believed
to exist only as fleeting intermediates, not isolable or even detectable. In our book,
subtitled From Phantom Species to Stable Compounds, we specifically deal with the
synthetic accomplishments that have been made in the field of isolable low-coordinate
derivatives of heavy group 14 elements, giving only short comments regarding their
transientcongeners.Havingspecializedinthistopic,wedonotaimtocompetewiththe
previously publishedbooks on the heavygroup 14 organometallics whichcover a broad
range of rather different topics (from theoretical insights to experimental achievements
and material science applications), such as the brilliant series TheChemistryofOrganic
SiliconCompounds andTheChemistryofOrganicGermanium,TinandLeadCompounds
(editedbyPatai,RappoportandApeloig)andOrganosiliconChemistry:FromMolecules
toMaterials (edited by Auner and Weis).
Given that the specific field of low-coordinate group 14 organometallics is flourish-
ing with many spectacular achievements that deserve mentioning, it is not realistic to
cover all of them in a single volume and we do not intend to do this. Instead, we
focus on the most important and most recent (the literature coverage is up to the end of
2009 – beginningof2010)milestoneadvancesthatarecrucialforageneralunderstand-
ing of the peculiar structural bonding and chemical properties of the low-coordinate
group 14 organometallics, which in many cases are distinctly different from those of
their organic analogs. The book is organized into six chapters, each devoted to an inde-
pendent class of the most fundamental low-valent species: heavy analogs of carbenium
xii Preface
ions (Chapter 1), heavy analogs of free radicals (Chapter 2), heavy analogs of carboan-
ions (Chapter 3), heavy analogs of carbenes (Chapter 4), heavy analogs of unsaturated
hydrocarbons:alkenes,1,3-dienes,allenes,andalkynes(Chapter5),andheavyanalogsof
aromaticcompounds(Chapter6).Eachchapterbeginswithareviewofgeneralsynthetic
approaches,continueswitha considerationofparticular structuralfeatures andsynthetic
applications, and concludes with a discussion of the most important recent advances in
the field of stable derivatives.
We are particularly grateful to many of our highly talented and greatly motivated
students, with whom we have been lucky to work with and who have made numerous
outstanding experimental contributions. We would also like to thank our distinguished
collaborators from many research groups from all over the world, both experimentalists
and theoreticians, with whom we have been very pleased to work with throughout our
research careers and whose names are listed in a number of our joint publications.
Regardingtheaudienceofourbook,wehopethatitwillbeusefultotheentirescien-
tific community; however, first of all, we address it to advanced graduate and postgrad-
uate students, especially to those who intend to specialize in the field of organometallic
chemistry.Webelievethatourcontributionswillalsobeofinterestandbehelpfultothose
who have already been involved in the fascinating and challenging world of organosil-
icon, organogermanium, organotin, and organolead chemistry. We hope that the book
will find its readers not only among specialists in the field of group 14, but also among
others working in the areas of both main group and transition metal chemistry, as well
as those from interdisciplinary fields such as polymer, material science, nanotechnology
etc.Letusfinallyhopethatourbookwillserveasausefulguideandreferencesourceto
interested specialists and even more importantly, to those inexperienced beginners who
are still seeking inspiration.
Vladimir Ya. Lee
Akira Sekiguchi
University of Tsukuba (Tsukuba)
January 2010