Intervalence transfer of ferrocene moieties adsorbed on electrode surfaces by a conjugated linkage

Effective intervalence transfer occurred between the metal centers of ferrocene moieties that were adsorbed onto a ruthenium thin film surface by ruthenium–carbene π bonds, a direct verification of Hush’s four-decade-old prediction. Electrochemical measurements showed two pairs of voltammetric peaks where the separation of the formal potentials suggested a Class II behavior. Additionally, the potential spacing increased with increasing ferrocene surface coverage, most probably as a consequence of the enhanced contribution from through-space electronic interactions between the metal centers. In contrast, the incorporation of a sp3 carbon spacer into the ferrocene–ruthenium linkage led to the diminishment of interfacial electronic communication.