Atomically Precise Insights into Metal–Metal Bonds Using Comparable Endo-Units of Sc2 and Sc2C2

Abstract

The precise identification of metal–metal bonds is critical to fully understanding the nature of metal–metal bonding but remains a fundamental challenge. Herein, we show the essence of Sc–Sc bonds with a metal–metal distance of 3.36 Å in a C3v(8)-C82 fullerene cage using crystallography. To elucidate the metal–metal bond formation, a metallofullerene Sc2C2@C3v(8)-C82 with a Sc2C2 endo-unit encapsulated inside the same fullerene[82] cage was studied as a unique control molecule. Theoretical calculations reveal that each Sc atom donates one electron to the Sc–Sc bond. The existence of the Sc–Sc bond in Sc2@C3v(8)-C82 versus Sc2C2@C3v(8)-C82 is thoroughly investigated.