Localization energies for graphite and fullerenes

Abstract

The localization energy (LE) for carbon atoms in a graphite sheet was estimated using Hosoya's hypothetical carbon molecules, benzenoid tori. The LE approaches 2.720 ∣β ∣ on going to higher members of the toroidal molecules. This value was used as an approximation of the LE for graphite. For all isolated-pentagon isomers of fullerenes but C₆₀(I_h), the minimum cation LE in a molecule (min cation LE) is smaller than the graphite value. It is noteworthy that all fullerene isomers have a very small minimum anion LE (min anion LE), which is much smaller than the min cation LE. Thus, fullerenes are predicted to be much more reactive than graphite. In fact, they are very susceptible to nucleophilic attack. C₆₀(I_h) has larger cation and anion LEs than the graph-theoretically defined polyene reference, which indicates that this molecule is not only energetically but also kinetically stabilized by cyclic conjugation.