Electrochemical behavior of heterometallic chalcogenide clusters

The electrochemical properties of sixteen tri- and tetranuclear chalcogenide-bridged heterometallic clusters in comparison with the tetrahedral clusters Cp′ 4 M 4 S 4 (M = Cr, V; Cp′ = CH 3 C 5 H 4 ) simulating ferredoxins were studied. For complexes with μ 4 -coordination of the chalcogen, only reduction processes involving the metal-heterometal bonds are reversible. For complexes with μ 3 -coordination of the chalcogen, the oxidation processes are reversible except for triiron-chalcogen-pnicogenide clusters having an easily and reversibly oxidizable E-Fe(CO) 2 C 5 H 4 Bu- t bond (E = Sb, Bi) at the pnicogen atom. The electron-compensating role of the lone pair at the bridging chalcogen atom in the stabilization of the oxidation products of the clusters is discussed.