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.

Cationic Rh(III) methyl complexes, [(η 5 -ligand)-Rh(CO) 2 Me] + (η 5 -ligand ) C 5 Me 5 , C 9 Me 7 , C 9 Me 3 H 4 ), undergo facile reactions with strained alkenes (e.g. norbornadiene) to give products resulting from insertion of the alkene into a Rh-acetyl bond. Kinetic, mechanistic, and structural results are presented, along with evidence of catalytic activity for CO/alkene copolymerization.

A study of the basis of selectivity of C−H bond activation of anisole by electrophilic methylplatinum(II) complexes is reported. Anisole reacts with [PtXMe-(NN)] in trifluoroethanol solvent to give methane and [PtXAr(NN)], Ar = 2-, 3-, and 4-anisyl, in 90:8:2 ratio when X = HOB(C 6 F 5 ) 3 and NN = (2-C 5 H 4 N) 2 CO (DPK) but not when NN = 2,2′-bipyridine. Similar results are obtained when X = triflate or when NN = (2-C 5 H 4 N) 2 NH. Competition between reaction of anisole and anisole-d 8 with [PtXMe(NN)], X = HOB(C 6 F 5 ) 3 and NN = DPK, in trifluoroethanol gave an isotope effect k H /k D = 3.6. Several 4-anisyl complexes, [PtClAr(NN)], [PtAr 2 (NN)], and [PtMeAr(NN)], NN = DPK, DPA, or bipy, were prepared and reacted with HX [X = Cl, OTf, or HOB(C 6 F 5 ) 3 ]. Reaction of [PtMeAr(NN)], NN = DPK or bipy, with HX gave a detectable hydride [PtXHMeAr(NN)] when X = Cl, followed by loss of methane to give [PtClAr(NN)], but only [Pt(OTf)Ar(NN)] was detected when X = OTf. Reaction with more HOTf gave anisole and [PtX 2 (NN)], X = OTf, and no isomerization of the 4-anisyl group to the more favored 2-anisyl group was observed at any stage. The similar reaction of [PtMeAr(NN)] and HOTf in CD 3 OD/CD 2 Cl 2 gave CH n D 4−n (n = 0−4) and mostly 4-MeOC 6 H 4 D. It is argued that the anisole C−H bond cleavage step in anisole activation, or the anisyl−H bond forming step in protonolysis, is responsible for the observed selectivity in these reactions.