Joon T. Park, Jeong-Ju Cho, Hyunjoon Song, Chang-Soo Jun, Youngbae Son, and Juhyoun Kwak, "Electrochemical Studies of C60-Triosmium Complexes: The First Evidence for C60-Mediated Electron Transfer to the Metal Center," Inorg. Chem., 36 (13), 2698 - 2699 (1997.06.18.)

Abstract
The C60-triosmium carbonyl complexes Os3(CO)11-n(PPh3)n(h2-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' = h5-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.