Structure, bonding, and energetics of C72- isomers

Several isomers of C-7(2-) were studied with electron correlation methods and augmented, correlation-consistent basis sets. All are thermodynamically stable with respect to dissociation into C-5(-) and C-2(-) anions. Isomerization energies are less than5 kcal/mol at the highest level of theory. Vertical and adiabatic electron detachment energies are positive for the D-3h form of C-7(2-). Linear, carbene, bridged-chain, and chain-ring isomers are considered as well. Feynman-Dyson amplitudes connecting dianionic and anionic states reveal extensive delocalization of the least bound electrons. (C) 1998 American Institute of Physics. [S0021-9606(98)30225-1].