An improved preparation of substituted phosphoryl difluorides. Synthesis of trifluoromethylthiodifluorophosphine and trifluoromethylthiophosphoryl difluoride

Difluorobromophosphine reacts readily with bis(trifluoromethylthio)- mercury to yield the fluorophosphine CF₃SPF₂ in excellent yields. The resulting new phosphine is readily oxidized under very moderate conditions by ClF, Cl₂ and O₂ to give new chlorofluorophosphorane and fluorophosphoryl compounds which contain the CF₃S moiety. CF₃SPF₂Cl₂ and CF₃SPF₂Cl were not characterized because of their tendency to disproportionate. CF₃SP(O)F₂ has, however, been isolated and characterized. All the new compounds are relatively unstable and decompose with a fluoride shift from the methyl group to the phosphorus atom. A new synthetic route to the known difluorophosphoryl compounds OPF₂Cl, OPF₂Br, OPF₂NCS and OPF₂(CH₃)₂, by the direct oxidation of the respective difluorophosphine with oxygen, has been found.