SEMIEMPIRICAL CALCULATIONS OF C-60 DERIVATIVES - ADDITION TO DOUBLE-BONDS RADIATING FROM A 5-MEMBERED RING

The electronic structures of C60 derivatives with one to five atoms added at adjacent double bonds radiating from a five-membered ring have been calculated with the PM-3 parametrization of the MNDO Hamiltonian. The calculations were done for n = 1-4 with H, F, and Cl and for n - 5 with H. The stabilities of the C60 derivatives are predicted from the calculated energies. The isodesmic reactions of C60 with alkanes and perchloroalkanes are predicted to become more exothermic with increase in the number of substituents and the length of the alkyl chain. The reactions of C60 with perfluoroalkanes are not predicted to be exothermic due to the stable C-F bond in perfluoroalkanes. Valence bond structures are presented on the basis of the calculated geometries and spin densities. These results are compared to ESR measurements.