Equilibrium configurations of fluoromethyl-C60 radicals. An EPR and theoretical study of interactions with the C60 surface

The EPR spectra of CH2FC60 and CHF2C60 are presented, and the dominant conformer for each species identified. It is suggested that the equilibrium configurations of fluoromethyl-C60 radicals are determined not by steric effects, but by Coulombic interactions between highly polarizable fluorine atoms and the C60 surface. The dominant effect appears to be a preference for the conformation in which a fluorine atom lies over the pentagon adjacent to the point of attachment of the CHnF3-n (3≥n≥0) ligand. These effects are discussed on the basis of semi-empirical calculations of the equilibrium structures and charge distributions on the C60 surface.