The steric effect of o-tolyl ligand on the fluxionality behavior of some binuclear organoplatinum(II) complexes with bis(diphenylphosphino)methane as bridging ligand

Abstract

A series of binuclear organoplatinum(II) complexes of general formula cis, cis-[R 2Pt(μ-SMe 2)(μ-dppm)Pt( o-MeC 6H 4) 2], 3a– 3d, in which R = Ph, p-MeC 6H 4, m-MeC 6H 4 or p-MeOC 6H 4, were prepared by the reaction of monomeric precursors [Pt( o-MeC 6H 4) 2(dppm)] and cis-[PtR 2(SMe 2) 2]. The binuclear dialkyl analogs, in which R = Me ( 3e) or R 2 = {(CH 2) 4} ( 3f), were prepared by the reaction of cis-[Pt( o-MeC 6H 4) 2 (SMe 2) 2] and [PtR 2 (dppm)]. The complexes were fully characterized by multinuclear ( 1H, 13C, 31P, 195Pt) NMR spectroscopy each as a mixture of syn and anti isomers (depending on the relative orientations of Me substituents on o-tolyl ligands) and each isomer was shown to have a rigid structure. Other binuclear analogs cis , cis - [ R 2 Pt ( μ - SMe 2 ) ( μ - dppm ) PtR 2 ′ ] , 3g– 3j, in which R is a less steric demanding aryl groups m-MeC 6H 4 or p-MeOC 6H 4, and R′ = Me or R 2 ′ = { ( CH 2 ) 4 } , were prepared by the reaction of cis-[PtR 2(SMe 2) 2] and [ PtR 2 ′ ( dppm ) ] , and shown to have fluxional structures.