Organometallic compounds alkali metals

Pyrolysis of Alkali-Metal Organometallic Compounds Hydro-metallo-elimination... 

The chemical reactivities of the alkali metal organometallic compounds (RM) vary widely depending on metal M, basicity of the solvent systems used, and steric and electronic properties of the organic group R. In many reactions an important factor is the stabilization resulting from formation of a delocalized carbanion system as in the polymerization of dienes or aromatic substituted ethylenes, and in Reactions 3, 4, 5, and 10 in Table I. It is primarily with these delocalized carbanion systems that this review is concerned although saturated organolithium compounds are discussed briefly. 

Alkali-metal ate compounds are among the first organometallic compounds reported. Already in 1858 the formation of a crystalline material formulated as Na[Et3Zn] , obtaiued from the reaction of metallic sodium with EtaZn, was reported by Wanklyn . It then took almost a century before the first organomagnesiate was reported. In 1951 Wittig and coworkers realized that organometallic compounds with anionic formulations, for which he coined the term ate , could be made. In this paper the formation of LilPhsMg] and other ate -type compounds from its homometallic components was described (equation 4). 

Trialkylaluminum and alkylaluminum hydrides associate with alkyl or hydride bridges. Since there are no available lone-pair electrons with which to form bridges by standard two-center two-electron interactions, multicenter bonding is invoked in the same manner as for electron-deficient boranes (see Boron Hydrides), alkyllithium (see Alkali Metals Organometallic Chemistry), dialkylberyllium and dialkylmagnesium compounds (see Beryllium Magnesium Organometallic Chemistry). 

Recently some papers have appeared which deal with the related structures of the heavier alkali earth metal organometallic compounds. Cyclopentadienyl derivatives of calcium, strontium, and barium proved to possess sufficient stability to permit their synthesis and subsequent crystallization. These results are briefly included in this review (see Table 111). 

In recent years this simple picture has been completely transformed and it is now recognized that the alkali metals have a rich and extremely varied coordination chemistry which frequently transcends even that of the transition metals. The efflorescence is due to several factors such as the emerging molecular chemistry of lithium in particular, the imaginative use of bulky ligands, the burgeoning numbers of metal amides, alkoxides, enolates and organometallic compounds, and the exploitation of multidentate... 

Similar structural diversity has been established for the heavier alkali metals also but it is unnecessary to deal with this in detail. The sUTictural chemistry of the organometallic compounds in particular, and of related complexes, has been well reviewed. 

Some structural aspects of the organometallic compounds of the alkali metals have already been briefly mentioned in Section 4.3.6. The diagonal relation of Li with Mg (p. 76), coupled with the known synthetic utility of Grignard reagents (pp. 132-5), suggests that Li, and perhaps the other alkali metals, might afford synthetically... 

Organometallic compounds of the alkali metals (particularly LiMe and LiBu") are valuable synthetic reagents and have been increasingly used in industrial and laboratory-scale organic syntheses during the past 20 y,(86,94,95) annual produc-... 

Hexamethylphosphoric triamide (HMPT) is a high-boiling solvent particularly satisfactory for dissolving metals or organometallic compounds. It has been found to be an ideal solvent in which to conduct the reduction of a,jS-unsaturated ketones by alkali metals. 

Ge, P, As, Sb, and Bi, can also be prepared in this manner." Except for alkali metal alkyls and Grignard reagents, the reaction between RM and M X is the most conunon method for the preparation of organometallic compounds." ... 

Electronic Effects in Metallocenes and Certain Related Systems, 10, 79 Electronic Structure of Alkali Metal Adducts of Aromatic Hydrocarbons, 2, 115 Fast Exchange Reactions of Group I, II, and III Organometallic Compounds, 8,167 Fluorocarbon Derivatives of Metals, 1, 143 Heterocyclic Organoboranes, 2, 257... 

Smith, David J., Organometallic Compounds of the Heavier Alkali Metals. 43 267... 

Aryl Migrations in Organometallic Compounds of the Alkali Metals, 16, 167... 

Whatever the best explanation may be, an indication that allylic alkali metal compounds or allylic carbanions do in fact form the less stable of the two possible acids on neutralization is found in the results of the reduction of aromatic compounds by dissolving metals.376The detection of a paramagnetic intermediate in a similar system and polaro-graphic evidence indicate a one electron transfer in the rate and potential determining step.878 376 The mechanism therefore involves ions (or organometallic intermediates) like the following ... 

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