Redox Interchange Reactions of Halogenoplatinum(IV) Complexes. pH Dependence of the Hexabromoplatinate(IV)–Iodide Reactions

Abstract

Successive stages in the reaction of the complex [PtBr6]2− with iodide have been reexamined with particular attention to their pH dependence. A reassignment of two of the three stages is necessary although the intimate mechanism remains unchanged. Reoxidation of [PtBr4]2− produced by the slow reduction of [PtBr6]2− with iodide leads to a mixture of trans-[PtBr4I(OH2)]− and trans-[PtBr4I(OH)]2−. Rate constants for reaction of iodide with the aquo- and hydroxy-complexes have been determined, as well as a value of 3.7 for the pKa of the aquo complex.