Endohedral metallofullerenes (EMFs) with a composition of M₂C_2n may exist as di-EMFs, M₂@C_2n, or as carbide cluster metallofullerenes (CCMFs), M₂C₂@C_2n-2. Although metals with a small ionic radius such as scandium were found to form cluster EMFs and some have been incorrectly assigned as conventional EMFs.^[1-3] , Lu-containing EMFs remain largely unexplored in spite that lutecium has a similar ionic radius to that of scandium. In this work, we report the isolation and single-crystal X-ray crystallographic characterization of several unprecedented Lu- containing EMFs: Lu₂@C_2n (2n=82, 84, 86) EMFs. Theoretical results demonstrate that four electrons are transferred from the two divalent Lu ions onto the fullerene cages.

References：

(1) Lu, X.; Akasaka, T.; Nagase, S. Acc. Chem. Res. 2013, 46 (7), 1627.

(2) Lu, X.; Feng, L.; Akasaka, T.; Nagase, S. Chem. Soc. Rev. 2012, 41 (23), 7723.

(3) Popov, A.; Yang, S.; Dunsch, L. Chem. Rev. 2013, 113, 5989-6113.