Fluorination of dimethyl sulphide. Formation of the fluorodimethylsulphonium cation, [Me2SF]+, and dimethylsulphur difluoride, Me2SF2
The controlled reaction of dimethyl sulphide with xenon difluoride in a non-acidic medium gives rise via CH2FSMe to a product best formulated as [Me2SCH2SMe]+[F(HF)n]–. In HF solution at –23 °C, however, the reaction affords the fluorodimethylsulphonium cation, [Me2SF]+, solid derivatives of which have also been prepared by the reaction of XeF2 with Me2S·A (A = BF3 or AsF5); the species have been characterised by their 1H and 19F n.m.r. and vibrational spectra. With CDCl3 as a diluent, Me2S reacts with an excess of AgF2 at –23 °C to provide the first evidence of the thermally unstable dimethylsulphur difluoride, Me2SF2. The 1H and 19F n.m.r. spectra have served to characterise the new compound and to chart its decomposition (to CH2FSMe) and other reactions.