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.