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 [Pt 2 Me 4 (μ-SMe 2 ) 2 ] occurs with displacement of Me 2 S to give [PtMe 2 (κ 2 - S,N -Spy) 2 ], 1 . Oxidative addition of S 2 Ar 2 (Ar = 2-pyridyl or Ph) to [PtMe 2 (NN)], NN = 2,2′-bipyridine or 1,10-phenanthroline, gives initially the binuclear Pt(III) complexes [{PtMe 2 (κ 1 - S -SAr)(NN)} 2 ], which react further with S 2 Ar 2 to give [PtMe 2 (κ 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 [Pt 2 Me 4 (μ-SMe 2 ) 2 ] occurs by a concerted mechanism whereas the reactions with [PtMe 2 (NN)] to give the binuclear complexes [{PtMe 2 (κ 1 - S -SAr)(NN)} 2 ] occur by a polar nonconcerted mechanism, involving a loosely bonded dimer [PtMe 2 (NN)] 2 .