Addition of alkyl radicals to C60. Part 3. The EPR spectra of R3C60 radicals and a theoretical study of HC60 and H3C60 radicals

Abstract

The EPR spectra of a series of C60 adducts of the type R3C60 are described and discussed. In every case, two of the three ligands are equivalent, leading to the conclusion that the R3C60 radicals have a plane of symmetry. The unpaired electron distributions in mono- and trisubstituted-C60 radicals are computed with the help of the QCFF/PI and MNDO Hamiltonians. It is shown that the hyperfine constants predicted on the basis of the calculated spin densities reproduce well the values observed and suggest a reassignment of framework 13C coupling constants in RC60.