Evidence of Oxygen Activation in the Reaction between an N‑Heterocyclic Carbene and M₃N@<i>I</i>_<i>h</i>(7)–C₈₀: An Unexpected Method of Steric Hindrance Release

We herein demonstrate for the first time the unexpected oxygen-involving reaction between M3N@Ih(7)–C80 (M = Sc, Lu) and 1,3-bis­(diisopropylphenyl)­imidazol-2-ylene (1). By introducing a tiny amount of oxygen into the reaction, unprecedented products (2a for Sc3N@C80 and 3a for Lu3N@C80) with the normal carbene center C2 singly bonded to a triple hexagonal junction (THJ) cage carbon together with an oxygen atom bridging the same THJ carbon atom and a neighboring carbon atom forming an epoxy structure are obtained. In situ mechanism study, in combination with theoretical calculations, reveals that the bond-breaking peroxidation facilitates the formation of the unexpected products 2a and 3a, providing new insight into fullerene chemistry.