Silylmercury compounds

Transmetalation of silylmercury compounds with lithium (equation 3) ... 

The silylmercury compounds are most conveniently available by reacting a chlorosilane with sodium amalgam. In contrast to the two methods mentioned above, which in most cases require polar, aprotic solvents such as THF, DME or HMPA, transmetalation reactions can be performed in nonpolar solvents and often result in better yields than when performed in ethereal solvents. 

Transmetallation of silylmercury compounds, which are most easily available via the reaction of a silane with (/-Bu)2llg, appears to be the most convenient method for the preparation of cyclic potassium oligosilyl compounds c-(MegSis)K (19)83c as well as c-(MenSi6)K (20)84 were obtained by Hengge and coworkers from the corresponding mercury compound by means of a Na/K alloy in THF (equation 33). 

Doubtless, in these reactions unstable intermediate silylmercury compounds such as [H2(CH3)Si]2Hg and [H(CH3)2Si]2Hg are first produced which then undergo decomposition. The formation of the trisilane and higher polysilanes from the reaction of (CH3)2SiHBr with Na/Hg may be rationalized by the insertion into [H(CH3)2Si]2Hg of dimethylsilylene, (CH3)2Si , which is probably produced during the reaction through decomposition of an unstable intermediate species (CH3)2SiHg, followed by decomposition of the adducts. The generation of dimethylsilylene and its insertion into the... 

Enantiomeric silylmercury compounds are obtained from reaction of diorganomercurys with an optically active hydrosilane [Eq. (6)] (76). The configuration is retained predominantly at silicon. These compounds, however, racemized readily when sublimed during purification. 

Several dimerization rates of alkyl-substituted silyl radicals were measured earlier [8]. However, the dimerization rates of silyl-substituted silicon-centered radicals have not previously been determined. In this study we have measured, using EPR spectroscopy, the rate constants for the recombination of four silyl radicals (lb, 2b, 3b, and 4b), to produce the corresponding disilane dimers of type a (i.e. la, 2a, 3a, and 4a respectively). This dimerization reaction is shown as the backward reaction of Eq. 2 in Scheme 1. Radicals lb, 2b, and 3b were generated photochemically fiom the corresponding disilane dimers of type a (Scheme 1, Eq. 2), while radical 4b was generated photochemically from the corresponding silylmercury compound 4c (Scheme 1, Eq. 1). 

The chemistry of mercury(II) is dominated by the stability of two-coordinated compounds but in silylmercury compounds three- and four-coordinated anions, [(R3Si)3Hg] and [(R3Si)4Hg] are formed. 

Most isolable silylmercury compounds have three organic groups bonded to silicon, but the formation of H3SiHg derivatives is achieved by ... 

A disadvantage of both methods is that the obtained silylanions are usually adducts of the donor solvents used for their synthesis. These donor molecules can sometimes cause problems in subsequent reactions. Base-free silylanions can be obtained by means of transmetalation from silylmercury compounds (eq. In this case, hydrocarbon solvents can be used to generate the... 

Silyllithium compounds may also be prepared by the transmetalation reaction between silylmercury and Li. The requisite silylmercury may be prepared from the corresponding chlorosilane or hydrosilane. The latter can be applied to the synthesis of polysilanyllithium. Equation (17) is an example. ... 

Most bis-silylmercurials are of the organo-(R3Si)2Hg type, but compounds with one to three Si—Cl bonds are known. They are thermally stable but sensitive to photodecomposition ... 

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