Different fluoride anion sources and (trifluoromethyl)trimethylsilane: molecular structure of tris(dimethylamino)sulfonium bis(trifluoromethyl)trimethylsiliconate, the first isolated pentacoordinate silicon species with five Si–C bonds

Abstract

(Trifluoromethyl)trimethylsilane, CF₃SiMe₃ reacts with [(Me₂N)₃S]⁺[Me₃SiF₂]^–, Q⁺F^– and Q⁺[HF₂]^– (Q⁺ = Me₄N⁺, [(Me₂N)₃C]⁺, [(Me₂N)₄P]⁺) at –70 to 50 °C to afford the first hypervalent silicon species, [(CF₃)₂SiMe₃]^– with five Si–C bonds (stable in monoglyme up to –10 °C) as the main reactive species whose molecular structure was determined by X-ray crystallography.