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

Oxidative addition of the S−S bond of S2py2 (py = 2-pyridyl) to [Pt2Me4(μ-SMe2)2] occurs with displacement of Me2S to give [PtMe2(κ2-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(κ1-S-SAr)(NN)}2], which react further with S2Ar2 to give [PtMe2(κ1-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(μ-SMe2)2] occurs by a concerted mechanism whereas the reactions with [PtMe2(NN)] to give the binuclear complexes [{PtMe2(κ1-S-SAr)(NN)}2] occur by a polar nonconcerted mechanism, involving a loosely bonded dimer [PtMe2(NN)]2.