Further test of the isolated pentagon rule: Thermodynamic and kinetic stabilities of C₈₄ fullerene isomers

Thermodynamic and kinetic stabilities of 73 C84 fullerene isomers were estimated from the MM3 heats of formation and the recently defined bond resonance energies (BREs), respectively. The BRE represents the contribution of a given π bond in a molecule to the topological resonance energy (TRE). All π bonds shared by two pentagons turned out to be highly reactive without exceptions. C84 fullerene isomers with such π bonds must be incapable of survival during harsh synthetic processes. Thus, the isolated pentagon rule (IPR) proved to be applicable to such large fullerene cages. For sufficiently large fullerenes like C84, some isolated-pentagon isomers are also predicted to be very unstable with highly antiaromatic π bonds.