Insertion of platinum and palladium into a sulfur(IV)–sulfur(II) bond of a sulfur-substituted sulfurane

Abstract

Transition metal complexes are known to react with disulfides and insert into the disulfide bond, but there has been no report on similar reactivity towards the hypervalent sulfur(IV)–sulfur(II) bond compound, a sulfur-substituted sulfurane, because of its instability. In this paper, we report the reactions of the sulfur-substituted sulfurane 1 with platinum and palladium complexes, in which the corresponding complexes 2 and 3 with an O,S,S′-ligand were obtained by bond cleavage of both the sulfur(IV)–sulfur(II) bond and the sulfur(IV)–oxygen bond. The structures of the complexes were characterized by NMR spectroscopic studies, elemental analysis, and X-ray crystallographic analysis. The palladium complex 3 underwent elimination of triphenylethylene episulfide when treated with dppe to give the dppe palladium complex 4 with an O,S-ligand, which was also obtained by the reaction of Pd(dba)₂ and dppe with the sulfurane 1. X-ray crystallographic analysis of complexes 2 and 4 revealed a square-planar structure around the platinum or palladium. The formation mechanisms of these complexes 2–4 are discussed.