Tetra(t-butyldimethylsilyl)germasilene (8b) was synthesized using di(t-butyldimethylsilyl)hydridogermyllithium prepared by the germa-metallation of the corresponding dihydridogermane. Tetrasilylgermasilene 8b was obtained as single crystals by recrystallization from hexane at room temperature. The molecular structure of 8b is similar to those of the corresponding disilene 8a and digermene 8c but with an intermediate unsaturated bond length and twist angle between those of 8a and 8c. The reactions of 8b with methanol and 2,3-dimethylbutadiene gave the corresponding adducts. Equilibrium between 8b and the corresponding (trisilylsilyl)(silyl)germylene is suggested by the reaction of 8b with triethylsilane giving the germylene insertion product into the Si-H bond.

The proton abstraction (sila-metalation) of trialkylsilyl-substituted dihydridosilanes with t-BuLi or LDA in THF was found to be a convenient route to the corresponding silyllithiums (RR'SiHLi; 1a, R, R' = t-BuMe(2)Si; 1b, R, R' = Me(3)Si; 1c, R, R' = i-Pr(2)MeSi; 1d, R = t-BuMe(2)Si, R' = 4-methylphenyl). Hydridosilylithium 1a was isolated as air- and moisture-sensitive, but thermally stable, colorless crystals. X-ray analysis has shown that 1a is dimeric in the solid state, where two lithium atoms bridge between anionic silicon atoms forming a parallelogram, each lithium atom is coordinated by one THF molecule, and the Si-H hydrogen atoms are in the plane of the parallelogram. X-ray analysis has shown that (t-BuMe(2)Si)(2)GeHLi (5) has a dimeric structure similar to that of 1a.

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Organo-silicon compoundsOrgano-silicon compounds S 0060 Sila-metalation Route to Hydrido(trialkylsilyl)silyllithiums. -A convenient sila--metalation of trialkylsilyl-substituted dihydridosilanes is achieved for derivatives (I) using tBuLi. By addition of excess amounts of MeI to intermediate lithiated silanes such as (XIV), the corresponding methylated silanes are obtained. The scope and limitation of this reaction is determined by using other bases (LDA and BuLi), and silanes (IV) and (IX). Silyllithium (XIV) is dimeric in the solid state as is shown by X-ray analysis. A corresponding germyllithium compound (XVIII) is formed by the same method.-(IWAMOTO, T.; OKITA, J.; KABUTO, C.; KIRA*, M.; J.

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