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

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