Electroreduction of the group VI metal hexacarbonyls in liquid ammonia

Abstract

The reduction of the group VI metal hexacarbonyls has been studied by cyclic voltammetry, chronoamperometry and controlled potential coulometry in liquid ammonia solutions. At either platinum or vitreous carbon the reduction proceeds with only slight differences in apparent heterogeneous charge transfer rates. The compounds are reduced and reoxidized in two electrons processes. The reduction process is irreversible in the time scale of C.V. experiment. The reduction of the compounds occurs with dimerization in an E iCE rC mechanism, the resulting dianion is oxidized at relatively positive potentials. Computer simulations of cyclic voltammetric data based on an E iCE rC mechanism well with the experimental data. The synthetic utility of the method has been demonstrated by the obtention of the potassium salts of K 2[M(CO) 5] with M  Cr, Mo, W in yields up to 80%.