Generation of substrate-binding sites by electrochemical reduction of cis-[Fe-2(cp)(2)(mu-SMe)(2)(MeCN)(L)](2+) (L = CO or MeCN). Reactivity of the sites toward CO and (BuNC)-Bu-t. Crystal structure of [Fe-2(cp)(2)(mu-SMe)(2)(CO)( MeCN)][BF4](2)center dot CH2Cl2

Iron complexes with the {Fe-2(cp)(2)(mu-SMe)(2)} core have been synthesized and their electrochemistry investigated. Electrochemical reduction of the acetonitrile-substituted complexes cis-[Fe-2(cp)(2)(mu-SMe)(2)(MeCN)(2)](2) and cis-[Fe-2(cp)(2)(mu-SMe)(2)(CO)(MeCN)](2+) labilizes the MeCN ligand( s) and generates vacant sites at which CO and isocyanide substrates can bin d. The mechanism of the electrochemical reduction of both complexes has bee n investigated in the presence of these substrates. A single-crystal X-ray analysis established that cis-[Fe-2(cp)(2)(mu-SMe)(2)(CO)(MeCN)][BF4](2) co ntains an unusual dication in which different ligands (CO, MeCN) occupy cor responding sites in the co-ordination polyhedra of the two iron centres of the Fe-2(mu-S)(2) ring. Aspects of the reactivity and electrochemistry of c omplexes with Fe-2(mu-SMe)(2) and Mo-2(mu-SR)(2) cores are compared.