Cumulated double bond systems as ligands: VII. N,N′-diarylsulfurdiimine complexes of nickel(0) and platinum(0) of the type [(PPh 3) xM(RNSNR)] y and formation of a novel complex [ [formula omitted]HR′)(R)](PPh 3) 2] from [Pt 0(RNSNR)(PPh 3) 2], via an irreversible intramolecular rearragement involving NC(aryl) bond formation and NS bond breaking

Abstract

The complexes [Ni(PPh 3)(4-tolylNN-4-tolyl)] 2 and [Pt(PPh 3) 2(RNSNR)] (R = 4-tolyl, 4-Cl-phenyl and 3,5-xylyl) are reported. It is suggested that the Nicomplex is dimeric, and spectroscopic data indicate that the NSN units are bridging via a σ(NNi) and π((NS)Ni) bond. The platinum complexes are monomeric and occur in two isomeric forms: in CHCl 3 (at −30°C) the complex is probably three coordinated, with the RNSNR unit in the trans, trans configuration and linked to Pt via one of the N atoms. In CD 3NO 2 the complex is four-coordinated with the sulfurdiimine acting as a bidentate ligand coordinated to Pt via both N atoms. The three coordinated platinum complex is fluxional between −30 to +30°C, probably because of migration of the Pt atom from one N atom to the other. At +30°C a slow irreversible process occurs which leads to the formation of [ Pt[SN(1-N HR′)(R)](PPh 3) 2]. This compound has been characterized by X-ray crystallography and spectroscopic methods. A possible mechanism for the formation of this novel platinum(II) complex involves an initial intramolecular redox process, resulting in oxidation of platinum(0) to platinum(II), followed by concerted NS bond rupture, H-migration, and NC(aryl) bond formation.