Oxidative Addition of S-S Bonds to Dimethylplatinum(II) Complexes: Evidence for a Binuclear Mechanism

Oxidative addition of the S-S bond of S(2)py(2) (py = 2-pyridyl) to [Pt2Me4(mu-SMe2)(2)] occurs with displacement of Me2S to give [PtMe2(kappa(2)-S,N-Spy)(2)], 1. Oxidative addition of S2Ar2 (Ar = 2-pyridyl or Ph) to [PtMe2(NN)], NN = 2,2'-bipyridine or 1,10-phenanthroline, gives initially the binuclear Pt(III) complexes [{PtMe2(kappa(1)-S-SAr)(NN)}(2)], which react further with S2Ar2 to give [PtMe2(kappa(1)-S-SAr)(2)(NN)] and then, when Ar = 2-pyridyl, to give an equilibrium with free NN and complex 1. Evidence is presented that the S-S Oxidative addition to [Pt2Me4(mu-SMe2)(2)] occurs by a concerted mechanism whereas the reactions with [PtMe2(NN)] to give the binuclear complexes [{PtMe2(kappa(1)-S-SAr)(NN)}(2)] occur by a polar nonconcerted mechanism, involving a loosely bonded dimer [PtMe2(NN)](2).