Stabilizing a non-IPR C2(13333)-C74 cage with Lu2C2/Lu2O: the importance of encaged non-metallic elements

Abstract

A difference in encaged non-metallic element (i.e., C₂versus O) leads to a clear change of intramolecular interactions and shifts in redox potentials of Lu₂C₂@C₂(13333)-C₇₄ and Lu₂O@C₂(13333)-C₇₄, as a result of their distinct molecular orbital energy levels. Different from these two endoherals whose HOMOs are located on the cage, experimentally absent Lu₂@C₂(13333)-C₇₄ possesses a HOMO predominantly delocalized on the internal Lu–Lu bond, accompanied by a much smaller HOMO–LUMO gap, suggesting that the presence of a non-metallic unit broadens the electrochemical gaps and consequently improves the kinetic stability. These findings shed light on the role of non-metallic moieties in clusterfullerenes, providing valuable insights into the stability and properties of metallofullerenes.