Reactions of some phosphorus(III) halides with halogens in strongly acidic solvents

Abstract

The reactions of some phosphorus(III) halides with halogens in the strongly acidic solvents 25 oleum, HSFO₃, and 100% H₂SO₄ have been investigated by means of ³¹P n.m.r. spectroscopy. The compound PCl₃ and Br₂, and PBr₃and Cl₂, react to give complex mixtures of products containing tetrahalogenophosphonium ions [PBr_4–nCl_n]⁺, together with solvolysed species [PBr_3–nCl_n(OH)]⁺(25 oleum) or PF₃O(HSFO₃). No evidence has been found for halogenophosphonium ions [PX_nY_4–n]⁺ derived from PI₃, although the partially solvolysed species [Pl_nX_3–n(OH)]⁺(X = Cl or Br) have been identified in solution.