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@I-C₈₀, which has a scandium tetrahedron supported by H and CN anions inside fullerene C₈₀. Sc₄CNH@I-C₈₀ has a rare multilayer nesting structure, and the internal Sc₄CNH is the most complex endohedral cluster disclosed to date. Sc₄CNH@I-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@I-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.