Co(I)-Mediated Removal of Addends on the C60 Cage and Formation of the Monovalent Cobalt Complex CpCo(CO)(η2-C60).

The removal of addends on the fullerene C60 cage plays an important role in the final stage for synthesizing endohedral fullerenes by the molecular surgery method. We developed a cobalt-mediated reaction to regenerate C60 from N-substituted C60 derivatives (aziridinofullerene and azafulleroid). In these reactions, we found the formation of a green monovalent-cobalt complex of C60, and its structure was unambiguously determined by X-ray analysis. The characteristic electronic structure of this cobalt complex was studied by IR and UV-vis absorption spectroscopy and electrochemical analyses.