Electrochemical S-C bond cleavage in dimolybdenum thiolate/thioether- and bis(thioether)-bridged complexes

Abstract

International audienceThe electrochemical behavior of complexes possessing bridging thioether ligands, [Mo2Cp2(CO)2(CO) 2(μ-SMe)(μ-SMe2)]+ and [Mo2Cp2(CO)2(μ-SMe2) 2]2+, is reported. Controlled-potential reduction of the dicarbonyl complexes leads to cleavage of the S-C bond(s) of the bridging thioether(s). The different electrochemical and chemical steps producing [Mo2Cp2(CO)2-(μ-SMe)2] are presented. The reactions of the dicarbonyl complexes with cyanide and isocyanide proceed via the substitution of these ligands for CO. In the case of [Mo2Cp2(CO)2(μ-SMe2) 2]2+, the reactions with 1 and 2 equiv. isocyanide produce the singly- and disubstituted derivatives, respectively. The electrochemical reduction of the cyanide analogs [Mo2Cp2(CO)(CN)(μ-SMe)(μ-SMe2)] and [Mo2Cp2(CO)(CN)(μ-SMe2)2] + also results in the cleavage of S-C bond(s). These reactions are faster, and occur at less negative potentials, for the cyanide complexes than for their dicarbonyl precursors, which shows that S-C bond cleavage in these types of complexes is promoted by an increase of the electron density on the Mo2S2 core. © CNRS-Gauthier-Villars