ELECTROCHEMICAL OXIDATION AND PROTONATION OF A BRIDGING AMIDE LIGAND AT A DINUCLEAR METAL-SULFUR SITE

The electrochemical oxidation of the amide complex [Mo-2(cp)(2)(mu-SMe )(3)(mu-NH2)] 1 (cp = eta(5)-C5H5) has been investigated in tetrahydro furan (thf) and Me:CW electrolytes by cyclic voltammetry, controlled-p otential electrolysis and coulometry. The two-electron oxidation of 1 leads to the release of a proton and to the formation of the imide der ivative [Mo-2(cp)(2)(mu-SMe)(3)(mu-NH)](+) 2. In MeCN, this reaction i s 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 solve nt or of a substrate to the neighbouring metal centre. The protonation performed in thf in the presence of chloride produces [Mo-2(cp)(2)(mu -SMe)(3)(mu-Cl)] which is the precursor of the amide complex 1. The fi nal protonation product formed in MeCN is [Mo-2(cp)(2)(mu-SMe)(3)(MeCN )(2)](+), which also is a precursor of 1. Therefore, these experiments allow the construction of a hydrazine disproportionation cycle.