Regioselective Bis-functionalization of Endohedral Dimetallofullerene, La2@C80: Extremal La–La Distance

Bis-functionalization of endohedral metallofullerene La2@C80 by carbene addition is reported herein. Adducts were characterized using spectroscopic and single-crystal X-ray structure analyses. Crystallographic data for bisadduct La2@C80(CClPh)Ad (3, Ad = adamantylidene) revealed that both carbene additions occur at the 6,6-bond junction on the C80 cage with ring cleavages and that La atoms are positioned collinearly with spiro carbons. It is noteworthy that the La–La distance in 3 is highly elongated by carbene bis-functionalization compared to the distance in pristine La2@C80 and reported functionalized derivatives. The metal positions were confirmed through density functional calculations.