Scandium Tetrahedron Supported by H Anion and CN Pentaanion inside Fullerene C₈₀

Endohedral metallofullerenes have greatly expanded the range of the fullerene family due to their nesting structure and unusual encapsulated clusters protected by a fullerene cage. Herein, we report a metallofullerene Sc4CNH@Ih-C80, which has a scandium tetrahedron supported by H and CN anions inside fullerene C80. Sc4CNH@Ih-C80 has a rare multilayer nesting structure, and the internal Sc4CNH is the most complex endohedral cluster disclosed to date. Sc4CNH@Ih-C80 has so many bonding types (metal-carbide, metal-nitride, and metal-hydride), which weave a polyhedron of Sc4CNH clusters. This work shows that the endohedral metallofullerenes have the potential to build inorganic nesting polyhedra that have distinctive architectures and unique electronic properties. Sc4CNH@Ih-C80 was synthesized by means of the arc-discharge method using scandium and graphite under the mixed atmosphere of hydrogen, nitrogen, and helium. It is the first time to disclose an unprecedented metal-hydride bond in a fullerene cage. This result shows that the endohedral fullerenes bearing hydrogen species can be synthesized by the arc-discharge technique under an atmosphere of hydrogen. This work demonstrates that a fullerene cage can be an ample carrier to encapsulate unusual cluster moieties.