Electrochemical Studies of C₆₀−Triosmium Complexes:  First Evidence for a C₆₀-Mediated Electron Transfer to the Metal Center

Abstract

The C60-triosmium carbonyl complexes Os3(CO)11-n(PPh3)n(η2-C60) [n = 0 (1), n = 1 (2), n = 2 (3)] have been studied by both cyclic voltammetric and IR spectroelectrochemical methods in a dichloromethane−toluene (4:1) solution. Both results suggest that a C60-mediated electron transfer to the triosmium metal center takes place in these complexes. This is further confirmed by the synthesis and characterization of [NiCp‘2]+1- (Cp‘ = η5-C5Me5). The three sequential one-electron reduction potentials of 1−3 are in the order of 1 > 2 > 3, respectively, due to the donor effect of the PPh3 ligand. Reduction is accompanied by loss of the C60 moiety.