Carbon–sulfur bond reductive coupling from a platinum(ii) thiolate complex

Abstract

The room temperature addition of electrophilic alkyl halide reagents (RX = MeI, EtI and PhCH₂Br) to complex [Pt(ppy)(η¹-S-Spy)(PPh₃)], 1a, in which ppyH = 2-phenylpyridine and pySH = pyridine-2-thiol, resulted in a rapid carbon–sulfur (C–S) bond reductive coupling to produce alkyl sulfides and corresponding halide complexes [Pt(ppy)(PPh₃)X], X = I (2a) and Br (2b). A mechanism for this C–S bond formation reaction was suggested based on ¹H and ³¹P {¹H} NMR spectroscopic analyses. In the suggested mechanism, the reaction proceeded through a binuclear intermediate complex [{Pt(ppy)(PPh₃)}₂(μ₂-Spy)]I, 3-I, which was separately synthesized by another counter anion (PF₆) and it was fully characterized by multinuclear NMR spectroscopy and single X-ray crystallography. Also, density functional theory (DFT) calculations were used to theoretically assess the structures of intermediates and transition states in this bond formation reaction.