The saturated hydrides of C60:F5F6 PK F5F7 isomers

The carbon cages composed of pentagons and heptagons (F5F7 isomers) are the analogs of fullerenes composed of pentagons and hexagons (F5F6 isomers). To provide insight into the structures and stability of the hydrides of F5F6 and F5F7 isomers, systematical density functional theory calculations are performed on all the 1,812 F5F6-C60H60 and 56 F5F7-C60H60. The calculated results demonstrate that the isomer with lowest/highest energy has most/fewest fused pentagons for both F5F6 and F5F7 hydrides and the stability of these hydrides increase with the number of fused pentagons roughly. The lowest energy F5F6-C60H60 and F5F7-C60H60 are 237.1 and 152.5 kcal/mol lower in energy than the isolated pentagon rule (IPR) C60H60, respectively; however, these two parent cages are 529.6 and 660.0 kcal/mol higher in energy than the IPR C-60. The calculations suggest that heptagon-containing cages, not only those violating the IPR can be the candidate cages for fullerene derivatives and the possible repulsion between the added atoms may play an important role in determining the structures and stability of the hydrides of carbon cages.