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.