Consecutive Trifluoromethylation of C88(7) Fullerene: A Theoretical Study

Abstract

AbstractThe trifluoromethylation of C88(7) fullerene has been systematically studied using an energy‐controlled consecutive CF3 addition approach. The thermodynamically favored C88(7)(CF3)2n isomers with 2n = 2–20 were predicted at the DFT B3LYP‐D3BJ/6–311G* level of theory for the first time, in harmony with the two experimentally characterized isomers C88(7)(CF3)12/16. It was found that these stable isomers are formed mainly by 1,4‐additions of CF3 groups, and meanwhile, there are a few stable isomers with isolated CF3 groups for 2n ≤ 12, with ortho addition for 2n > 12, and with triple‐hexagon‐junction addition for the highest degree of trifluoromethylation (2n ≥ 18). The addition patterns of CF3 groups were discussed in terms of the local structural motif of the pristine cage and the formation of stabilizing substructures of local aromaticity. The possible trifluoromethylation pathways of C88(7) were proposed on the basis of the relative Gibbs free energies. The results show that almost all the intermediate isomers for the thermodynamically most stable isomers of C88(7)(CF3)2n possess low relative Gibbs free energies (below 14 kJ·mol−1). Moreover, the hardness, chemical potential, electrophilicity index, electron affinity, HOMO and LUMO energies, and HOMO–LUMO gaps of the thermodynamically most stable C88(7)(CF3)2n isomers were also calculated.