The Organosilyl Metal Compounds

The ability of an organosilicon atom to form a silicon-metal bond is differential. No such bond, with proven identity, has yet been reported for silver, gold, calcium, strontium, barium, vanadium, niobium or tantalum. 

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The stability of the compound depends on the solvent. Liquid ammonia [429], THF [430] and TMEDA [427] are especially suitable. The molality of a triphenylsilyl sodium solution in THF remained at 0.047 for l(X)h [430]. By contrast, the organosilyl metal solutions in benzene and toluene decompose very rapidly [431] (Eq. 3.226) ... 

Transition-metal catalyzed metathesis of carbon-halogen bonds with Si-Si bonds provides useful access to organosilicon compounds. Most of the reaction may involve initial oxidative addition of the carbon-halogen bond onto the transition-metal followed by activation of the Si-Si bond to give (organosilyl)(orga-no)palladium(II) complex, which undergoes reductive elimination of the carbon-silicon bond. 

The organosilyl alkali metal compounds are extremely sensitive to oxygen and moisture, and cannot be identified by means of boiling or melting point. Only trimethylsilyl lithium has been isolated in the form of crystalline complexes with the solvent [427, 428] (Eq. 3.224, 3.225) ... 

Chiral organosilanes have been shown to undergo stereospecific catalytic reactions leading to the preparation of optically active silyl-transition metal complexes. We first discuss the stereochemistry and mechanism of transition metal catalyzed reactions of organosilicon compounds. Then the stereochemistry of chiral organosilyl-transition metal complexes are described. The chemistry of optically active silyl- and germyl-transition metals has been the subject of a recent review (12), and we concentrate here on mechanistic implications, especially in the field of homogeneous catalytic reactions. 

Organosilyl magnesiums are synthesized via halo- or organohalosilanes with Mg metal. Disilanes are produced, suggesting that an intermediate silylmagnesium may be formed. The best results are obtained when chloroarylsilanes are reacted in tetrahydrofuran (THF). Chloroalkylsilanes, such as MejSiCl, react only under specific conditions. These reactions are only useful for disilanes (see also 5.2.3.4) Si—Mg bonded compounds are formed only as reactive intermediates. Older work is reviewed in ref. 1. newer work in refs. 2-6. 

Organosilyl germanium and tin derivatives are usually prepared from the corresponding alkali metals and halogen compounds (Eq. 3.242) ... 

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