Addition reaction of alkyl radical to C60 fullerene: Density functional theory study

Functionalized fullerenes are known as a high-performance molecules. In this study, the alkyl-functionalized fullerenes (denoted by R-C-60) have been investigated by means of the density functional theory (DFT) method to elucidate the effects of functionalization on the electronic states of fullerene. Also, the reaction mechanism of alkyl radicals with C-60 was investigated. The methyl, ethyl, propyl, and butyl radicals (denoted by n = 1-4, where n means the number of carbon atoms in the alkyl radical) were examined as alkyl radicals. The DFT calculation showed that the alkyl radical binds to the carbon atom of C-60 at the on-top site, and a strong C-C single bond is formed. The binding energies of alkyl radicals to C-60 were distributed in the range of 31.8-35.1 kcal mol(-1) at the CAM-B3LYP/6-311G(d, p) level. It was found that the activation barrier exists before alkyl addition, the barrier heights were calculated to be 2.1-2.8 kcal mol(-1). The electronic states of R-C-60 complexes were discussed on the basis of the theoretical results. (C) 2016 The Japan Society of Applied Physics