Germyllithium compounds

In the reaction between (chlorodimesitylsilyl)diarylgermanes and t-BuLi in THF, new germyllithium compounds, resulting from an intramolecular hydrogermolysis of an intermediate silyllithium (Scheme 6), were characterized26. The silylated germylanion was characterized by deuteriolysis and alkylation. 

Starting from a metal-14 dihalide, selective monogermylation or complete germylation can be obtained by using germylpotassium or germyllithium compounds (equations 128 and 129)152. 

The configurational stability of germyllithium compounds has been studied by temperature variation of the proton NMR spectra. The selected system Ph(i-Pr)2GeLi possesses groups (methyl of the i-Pr groups) which are diastereotopic. The methyl non-equivalence was observed in diglyme up to 185 °C, which is the upper experimental limit. Assuming that rotation around the Ge—C bond was fast on the NMR time scale, the non-equivalence... 

It is interesting that the strnctural diversity of 58 M depends on the polarity of the solvating medium. Thus, in nonpolar hexane both silyl- and germyllithium derivatives 58a Li (E = Si) and 58b Li (E = Ge) adopt the nonsolvated monomeric strnctnres, in which the central anionic atom (Si or Ge) was nearly planar and E-Si bonds were appreciably shorter than those of the neutral compounds (r-Bn2MeSi)aEH... 

Most of the reactions of silicon or germanium organic compounds proceed photochemically via a radical mechanism or via a cycloaddition mechanism (Chapters 4 and 6). There are few examples of nucleophilic addition of RSi or RGe to Cgo [118,119]. Reaction of silyUithium derivatives RjSili or germyllithium derivatives RjGeLi with different alkyl- and aryl-substituents R yields mainly the 1,2-adduct 28 or the 1,16-adduct 29 1,4-addition and dimerization of two fullerene-units was also found as a minor pathway. One example is given in Scheme 3.15. 

Since the original preparation of optically active germyllithium by Brook and Peddle (31), these reagents have been found to undergo various stereospecific reactions. Carbonation and reaction with carbonyl compounds (eq. [12]) lead to retention of configuration at germanium (31). 

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