Electrochemical properties of the catalyst precursor for the dinitrogen fixation cluster: [Mo 8Mg 2O 22(MeO) 6(MeOH) 4] 2−

Abstract

The X-ray characterized cluster [Mo 4Mo 4Mg 2O 22(MeO) 6(MeOH) 4] 2− (I), which is the precursor of a Shilov-type catalyst of amalgam and electrochemical dinitrogen fixation at ambient temperature and pressure, was studied in methanol by phase-sensitive ac voltammetry on the Hg electrode. Irreversible reduction of I is accompanied by a chemical reaction leading to a Mo III cluster which is active towards dinitrogen and shows reversible redox behaviour and strong adsorption combined with film formation. The effect of methoxide ion on the stability of cluster I and its reduced form is studied. In comparison with the reduced form, the sensitivity of I towards attack by methoxide, resulting in cluster decomposition, is increased. The ac responses of I and its reduced form confirm the existence of two different redox centres in both clusters.