Ln3@C80+ (Ln = lanthanide): a new class of stable metallofullerene cations with multicenter metal–metal bonding in the sub-nanometer confined space

Unstable tri-metallofullerenes Ln 3 @C 80 are greatly stabilized in their cationic form. The stability of Ln 3 @C80 + originates from a three-center two-electron metal–metal bond that compensates for the Coulomb repulsion between the metal ions.