Reduction of some platinum(IV) complexes by iodide and thiosulphate ions

Abstract

The kinetics of the reactions of trans-[Pt(AsEt₃)₂Cl₄], trans-[Pt(AsEt₃)₂Br₄], and trans-[Pt(PEt₃)₂Cl₄] with I^– and with S₂O₃^2– in methanol and in methanol containing 4·3% of water have been studied. In all the reactions, the platinum(IV) species is reduced by the anions to give, initially, trans-[PtL₂X₂](where L = AsEt₃ or PEt₃ and X = Cl or Br) which then sometimes undergoes further substitution. The kinetics of the reduction process are of the form: Rate =k₂[complex][Y^n–]. In all cases the chloro-complexes react more slowly than the bromoderivative, and the phosphine complex is a little more reactive than the arsine one.