Organometallic Chemistry: Volume 23 (Specialist Periodical Reports, Band 23) - Hardcover

Hardcover

ISBN 10: 0851867111 ISBN 13: 9780851867113

Verlag: Royal Society of Chemistry, 1994

Inhaltsangabe

Organometallic chemistry is an interdisciplinary science which continues to grow at a rapid pace. Although there is continued interest in synthetic and structural studies the last decade has seen a growing interest in the potential of organometallic chemistry to provide answers to problems in catalysis synthetic organic chemistry and also in the development of new materials. This Specialist Periodical Report aims to reflect these current interests reviewing progress in theoretical organometallic chemistry, main group chemistry, the lanthanides and all aspects of transition metal chemistry. Specialist Periodical Reports provide systematic and detailed review coverage of progress in the major areas of chemical research. Written by experts in their specialist fields the series creates a unique service for the active research chemist, supplying regular critical in-depth accounts of progress in particular areas of chemistry. For over 80 years the Royal Society of Chemistry and its predecessor, the Chemical Society, have been publishing reports charting developments in chemistry, which originally took the form of Annual Reports. However, by 1967 the whole spectrum of chemistry could no longer be contained within one volume and the series Specialist Periodical Reports was born. The Annual Reports themselves still existed but were divided into two, and subsequently three, volumes covering Inorganic, Organic and Physical Chemistry. For more general coverage of the highlights in chemistry they remain a 'must'. Since that time the SPR series has altered according to the fluctuating degree of activity in various fields of chemistry. Some titles have remained unchanged, while others have altered their emphasis along with their titles; some have been combined under a new name whereas others have had to be discontinued. The current list of Specialist Periodical Reports can be seen on the inside flap of this volume.

Über diesen Titel

Über die Autorin bzw. den Autor

Professor Abel is an Emeritus Professor of the University of Exeter, UK.

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Organometallic Chemistry Volume 23

A Review of the Literature Published During 1993

By E. W. Abel

The Royal Society of Chemistry

Copyright © 1994 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-0-85186-711-3

Contents

CHAPTER 1 Group I: The Alkali and Coinage Metals By J.L. Wardell, 1, 
CHAPTER 2 Group II: The Alkaline Earths and Zinc and its Congeners By J.L. Wardell, 13, 
CHAPTER 3 Carbaboranes, Including their Metal Complexes By C.E. Housecroft, 23, 
CHAPTER 4 Group III: Boron, Aluminium, Gallium, Indium, and Thallium By K.C. Molloy, 41, 
CHAPTER 5 Group IV: The Silicon Group By D.A. Armitage, 78, 
CHAPTER 6 Group V: Arsenic, Antimony, and Bismuth By J.L. Wardell, 138, 
CHAPTER 7 Metal Carbonyls By J.A. Timney, 144, 
CHAPTER 8 Organometallic Compounds Containing Metal-Metal Bonds By G. Hogarth, 171, 
CHAPTER 9 Complexes Containing Metal-Carbon σ-Bonds of the Groups Scandium to Manganese, Including Carbenes and Carbynes By M.L. Turner and M.J. Winter, 221, 
CHAPTER 10 Complexes Containing Metal-Carbon σ-Bonds of the Groups Iron, Cobalt, and Nickel, Including Carbenes and Carbynes By M.J. Morris, 281, 
CHAPTER 11 Hydrocarbon-Metal π-Complexes, Other than π-Cyclopentadienyl and π-Arene Complexes By D.G. Evans, 325, 
CHAPTER 12 π-Cyclopentadienyl, π-Arene and Related Complexes By I.R. Butler, 376, 

CHAPTER 1

Group I: The Alkali and Coinage Metals

BY J. L. WARDELL

1 Alkali Metals

1.1 General. Reviews have been published on (i) polar allyl type organometallics as key intermediates in regio and stereo-controlled reactions: (ii) structures of organoalkali metal species and (iii) synthesis and reactions of organolithium species. More reports have been made on superbases, i.e. RLi/R'OK combinations; these reports include (i) the effects of lithium alkoxides on deprotonations by BuLi/t-C5H11OK and (ii) the differences in regioselectivities of metallation of RSC6H4OMe by ButLi/ButOK combinations and by BuLi. In cyclopentane, ButLi and ButOH react to form the aggregates [(ButO)ButLi4] and [(ButO)6- nButnLi6] (n=1 or 2) as shown by 13C and 6Li NMR spectroscopy. Two-dimensional 6Li,1H shift correlation experiments based on multiple quantum spectroscopy and polarization transfer have been proposed as new tools for the investigation of organolithium structures. The assignment of the δ6Li values in [o-LiC6H4CH=CHLi-(Z)] was made from the 6Li,1H spin-spin coupling constants. The stabilizing influence of intermolecular Li----H-C contacts in solid organolithium aggregates has been strongly stressed.

1.2 Alkyl species. The structure, 1H, 7Li and 13C NMR spectra, and heat of combustion of [MeLi.THF]4 have been reported. Crystal structures have also been presented for (i) [(BuLi)4.TMED]: BU4Li4 cubane cores linked into polymeric zig-zag chains, by bridging TMED groups; two Li centres are 4 coordinate and two are 3 coordinate, (ii)[BuLi.TMED]2: 4 coordinate Li, (iii) [(BuLi.THF)]4.hexane: each Li atom in the (BuLi)4 units is coordinated to 1 THF, (iv) DME units link (BuLi)4 cores into a polymeric network: each Li is 4-coordinate, (v) (BuLi)6: distorted octahedral units, similar to structure of (cyclohexyl-Li)6, (vi) (ButLi)4 and (viii) [ButLi.Et2O]2: 3 coordinate Li.

The crystal structure determinations of (Me3Si)3CLi.TMED and (Me3Si)3CLi.2THF revealed that they have ionic structures, [Li(TMED)2][direct sum][Li{C(SiMe3)3}2][??] and [Li(THF)4][direct sum][Li{C(SiMe3)3}2][??], in the solid state. Other forms also exist in solution as shown by a multinuclear NMR study. In the solid state [(Me2CCNNa.TMED)4], obtained from metallation of Me2CHCN by BuNa, contain N-Na, rather than C-Na linkages and a (NNa)4 cubane-type core. 1-Lithio-perfluoroadamantane (1) obtained by H/Li exchange using MeLi in Et2O, is thermally stable to 0 °C; of interest, 2-lithio-perfluoroadmantane rapidly converts to (1) below -60 °C.

α-Aminoalkyl-lithiums, e.g. MeOCH2CH2NMeCHRLi (R=C5H11 or Pri), obtained by Sn/Li exchanges, are configurationally stable for short times at -78 °C; 2-lithio-N-methyl-piperidines and pyrrolodines are configurationally stable for up to 45 minutes at -40 °C in the presence of TMED. The barriers to racemisation of PhCH2CHLiSeAr in THF-d8/C6D6 were calculated to be 12.4 and >14.5 k cal mol-1 for Ar=Ph and 2,3,5,6-Me4C6H respectively; the rate determining step for racemisation was suggested to be the rotation about the carbanion-heteroatom bond. A similar finding was deduced from an NMR study of (PhMe2Si)CHLi(YPh) (Y=S or Se).

α-Lithiated ethers, RCHLi(OR') (2), react with R2Li to give RR2CHLi. This finding, plus the value of δ13Cα in (2) being downfield of that in RCH2OR', gave support to the view that (2) can be classed as oxygen carbenoids. A very large primary isotope effect (kH/kDca 70) was found in reactions of (2) with BuLi.TMED at -78 °C, equation 1.

In aromatic solvents, 1,2-dilithio[tetrakis(trimethylsilyl)]ethane has a similar doubly bridged structure to that found in the solid state; in contrast the compound in THF exists as s.s.i.p. [Li(THF)4]+ [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. 1,1-Dilithiocyclopropane (4) has been calculated [3-21G//Dunning basis set level] to be more stable with a planar rather than a tetrahedral geometry. The preparation of (4), from 1,1-Br2-cyclopropane and Naph-·,Li+ has been reported. Reaction of 7,7- dihalonorcaranes (R2CX2) with [p- ButC6H4C6H4But-p]-·,Li+ at -80 ° has been shown to produce R2CXLi, R2CLi2 and R2CLiCLiR2 in amounts depending on X, T °C and added ligands. The reaction of 7,7- dilithionorbomane with butyl halides at -100 °C provides 7,7'-dilithio-7,7'-dinorbomyl (5); (5) undergoes ready loss of Li2 (i.e. oxidation) to give 7,7'-norbornylidene.

Calculations have been carried out on CLi8, CLi10 and CLi12 [SCF level: 3-21 G, DZ(P), DZP and TZ2P basis sets].

1.3 Benzylic species. Crystal structures have been determined for (i) [Ph3CK.THF.PMDT]: monomeric c.i.p. species; K+ is η6-coordination to one phenyl ring (there is no K coordination to the benzylic carbon); (ii) [Ph3CRb.PMDT]n: 1-d polymer with Rb+ bridging Ph3C groups by η6-coordination to two phenyl groups and (iii) [Ph3CCs.PMDT]n: 1-d polymer; Cs+ is η6- bonded to one phenyl group of a Ph3C unit as well as interacting with all three phenyl rings and the benzylic carbon of another Ph3C group.

In solid [PhCH(NMe2)Li.OEt2]2, lithium centres bridge benzylic carbon atoms; additional bonding to each lithium involves the amino and ether groups. In [(S)-PhCH[NMeCOBut)Li.(-)- sparteine], lithium is bonded to carbon, oxygen and the two nitrogens of the sparteine ligand. Crystal structures have also been determined for [Ph2C(C5H4N-o)Li.2OEt2], [Ph2C(C5H4N-o)Na.3THF] and [Ph2C(C5H4N-o)K.PMDT].

1.4 Aryl derivatives. A d-functional theory calculation has been carried out on C6Li6; a MNDO calculation has been conducted on lithiabenzene. A solid state 7Li NMR study of phenyl-lithium aggregates has been reported. A good agreement was generally found between the quadrupole splitting constant values determined in the solid state and in solution, i.e. the solid state structure is basically retained in solution. Crystal structures have been determined for the following unsolvated aryl-lithiums: (i) t2,4,6-Pri3C6H2Li]4: near planar array of lithium atoms; each Li is η1,σ-bonded to one aryl...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 1994
• Sprache: Englisch
• ISBN 10: 0851867111
• ISBN 13: 9780851867113
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 456
• Herausgeber: Abel E W
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: GPSR Kontakt; gpsr@libri.de; ; Europaallee 1; Bad Hersfeld; 36244; Deutschland