ScC@D(14246)-C: A Missing Piece of the Clusterfullerene Puzzle.

Clusterfullerenes with variable carbon cages have been extensively studied in recent years. However, despite all these efforts, C cage-based clusterfullerene remains a missing piece of the puzzle. Herein, we show that single-crystal X-ray crystallographic analysis unambiguously assigns the previously reported dimetallofullerene Sc@C to a novel carbide clusterfullerene, ScC@D(14246)-C, the first experimentally proven clusterfullerene with a C cage. In addition, ScC@D(14246)-C was charaterized by mass spectrometry, ultraviolet-visible-near-infrared absorption spectroscopy, Sc nuclear magnetic resonance, and cyclic voltammetry. Comparative studies of the motion of the carbide cluster in ScC@D(14246)-C and ScC@C (n = 40-44) revealed that a combination of factors, involving both the shape and size of the cage, is crucial in dictating the cluster motion. Moreover, structural studies of D(14246)-C revealed that it can be easily converted to C(10528)-C and T(19151)-C cages via C desertion/insertion and Stone-Wales transformation. This suggests that D(14246)-C might play an important role in the growth pathway of clusterfullerenes.