Endohedrally stabilized C70 isomer with fused pentagons characterized by crystallography

Abstract

Besides the conventional D_5h(8149)-C₇₀ fullerene, there are a large number of C₇₀ isomers that violate the isolated pentagon rule (IPR). However, these non-IPR C₇₀ fullerenes have been less investigated owing to their low stabilities or high reactivities. In this study, we report for the first time the X-ray structure of an unconventional endohedral C₇₀ fullerene, Sc₂O@C₂(7892)-C₇₀. The combined study of geometrical analysis and computation further reveals the ionic and covalent interactions between the cluster and the cage, both of which contribute to the stabilization of this non-IPR C₇₀ fullerene. In addition, a close structural relationship between the non-IPR C₂(7892)-C₇₀ and the IPR D_5h(8149)-C₇₀ has been demonstrated, which might provide an alternative explanation of the formation of non-IPR fullerenes.