Entrapped Planar Trimetallic Carbide in a Fullerene Cage: Synthesis, Isolation, and Spectroscopic Studies of Lu₃C₂@C₈₈

Abstract

We report the preparation, isolation, and spectroscopic characterizations of a novel endofullerene Lu3C2@C88, where a planar trimetallic carbide cluster Lu3C2 is encapsulated by D2-symmetric C88 cage. Meanwhile, the trimetallic nitride endofullerene Lu3N@C88 was also isolated and characterized for comparison. The results revealed that both metal carbide Lu3C2 and metal nitride Lu3N share the same D2-symmetric C88 cage. Theoretical studies revealed that the internal moieties supply the C88 cage with six electrons in both Lu3N@C88 and Lu3C2@C88 cases; however, Lu3N@C88 has a closed-shell electronic structure and Lu3C2@C88 owns an unpaired electron localized on the internal [Lu3C2]6+ moiety. The different molecular electronic structures of Lu3C2@C88 and Lu3N@C88 lead to distinct differences on both the UV−vis absorption spectral features and their electrochemical redox properties.