Quantum chemistry of hydrogenation and methylation of a fullerene molecule C₆₀

Abstract

The electronic structure of a fullerene molecule C₆₀ is calculated in the case of its hydrogenation and methylation with a varying number (from 1 to 12) of the covalent bonds being formed. The results of quantum-chemical analysis are compared with the optical experimental data on films of synthesized fullerene-containing starlike polystyrenes with a varying number of polymer chains covalently bound with fullerene. The dependences of the optical spectra of hydrogenated and methylated fullerenes on the isomeric composition are studied by the ΔSCF method, taking polarization into account. The energies of formation of isomers are calculated and used for depicting the optical spectra of a real isomer mixture formed upon chemical synthesis. Isomers with highest symmetry have the lowest energy, and their binding energies differ insignificantly if the saturated bonds are arranged as uniformly as possible over the fullerene surface. The type of arrangement of saturated bonds is reflected in the polarization dependences. According to the experimental results, the energy of optical transitions in the series of isomers with the highest binding energy increases with the number of saturated fullerene bonds.