Endohedrally stabilized C-70 isomer with fused pentagons characterized by crystallography

摘要

Besides the conventional D-5h(8149)-C-70 fullerene, there are a large number of C-70 isomers that violate the isolated pentagon rule (IPR). However, these non-IPR C-70 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 C-70 fullerene, Sc2O@C-2(7892)-C-70. 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 C-70 fullerene. In addition, a close structural relationship between the non-IPR C-2(7892)-C-70 and the IPR D-5h(8149)-C-70 has been demonstrated, which might provide an alternative explanation of the formation of non-IPR fullerenes.