Electrochemical oxidation and protonation of a bridging amide ligand at a dinuclear metal-sulfur site

Abstract

International audienceThe electrochemical oxidation of the amide complex [Mo2(cp)2(μ-SMe)3(μ-NH2)] 1 (cp = η5-C5H5) has been investigated in tetrahydrofuran (thf) and MeCN electrolytes by cyclic voltammetry, controlled-potential electrolysis and coulometry. The two-electron oxidation of 1 leads to the release of a proton and to the formation of the imide derivative [Mo2(cp)2(μ-SMe)3(μ-NH)]+ 2. In MeCN, this reaction is reversible. The protonation of 1 has been shown to produce a complex in which a NH3 ligand is bound to a Mo centre; the protonated complex is stabilized by co-ordination of the anion of the acid, of the solvent or of a substrate to the neighbouring metal centre. The protonation performed in thf in the presence of chloride produces [Mo2(cp)2(μ-SMe)3(μ-Cl)] which is the precursor of the amide complex 1. The final protonation product formed in MeCN is [Mo2(cp)2(μ-SMe)3(MeCN)2]+, which also is a precursor of 1. Therefore, these experiments allow the construction of a hydrazine disproportionation cycle