Organosilicon chemistry. Part XIII. Insertion reactions of 1,2,2-trifluoroethylidene into silicon–hydrogen and silicon–halogen bonds

Abstract

1,2,2-Trifluoroethylidene, generated by the pyrolysis of 1,1,2,2-tetrafluoroethyltrifluorosilane, inserts exclusively into the silicon–hydrogen bond of trialkylsilanes R₃SiH (R₃= Et₃, Et₂Me, or Me₃) or the silicon–deuterium bond of the silane Me₃SiD to afford the silanes CHF₂·CHF·SiR₃(98–99%) or CHF₂·CDF·SiMe₃(88%). With silanes X₃SiCl (X₃= Cl₃, Cl₂Me, ClMe₂, or Me₃) or Me₃SiBr insertion occurs into the silicon–halogen bond to give the silanes CHF₂·CFCl·SiX₃ or CHF₂·CFBr·SiMe₃(2–15%). The silane Me₂ClSiH reacts exclusively by Si–H insertion (96%) but both Si–H and Si–Cl insertion (total ca. 55%) are observed with the silanes Cl₃SiH and MeCl₂SiH. Reaction of the carbene with dimethylvinylsilane and allyldimethylsilane gives products (99%) resulting from both Si–H insertion and double-bond addition (ratios 93 : 7 and 67 : 33, respectively), but with trichlorovinylsilane only addition to the double bond takes place (66%).