Synthesis, crystal structure and reactions of the dimeric organolithium compound [{[(MeO)Me2Si]3CLi}2]

Abstract

Treatment of the compound (Me₃Si)₃CCl with ICI followed by MeOH–Et₃N gave the methoxy-derivative [(MeO)Me₂Si]₃CCl. This reacted with LiBuⁿ at –78 °C to give [(MeO)Me₂Si]₃CLi 3, which was used to prepare the compounds SiMe₂X{C[SiMe₂(OMe)]₃}(X = H, Cl, OCOCF₃ or NCO) and SiPh₂H{C[SiMe₂(OMe)]₃}. An X-ray diffraction study has shown that in the solid state the lithium compound 3 is dimeric, with the carbanionic fragments bound by two oxygen atoms to one lithium and by carbon and the third oxygen to the other. The Li–C bond [2.401(9)Å] is longer than usual and the C–SiMe₂(OMe) bonds [mean 1.805(4)Å] are short.