Charging and equilibration of fullerene isomers

Variation of the total charge is shown to affect the computed relative stabilities of fullerene isomers. Within the QCFF/ce:simple-paraI model, the 80 kJ/mol pentagon-adjacency penalty in neutral C60 is reduced by a factor of ten in the dianion, and icosahedral C80 moves from least to most stable of the seven isolated-pentagon isomers of this fullerene as the charge varies from +2 to −4. The two experimentally isolable isomers of C84, however, remain almost isoenergetic in this model over the same charge range. Energy-charge isomerisation maps are presented for all isolated-pentagon isomers of C84. Implications for fullerene formation and annealing are discussed.