Relative energies and entropies of fullerene triplet states in solution

A novel method was employed to measure the relative entropies as well as energies of triplet-state molecules in mixed solutions. In particular, the approach was applied to the fullerenes C60, (CH3)2C60, and C70 in toluene solution. It was found that the triplet energies of C60 and C70 are equal within 0.2 kJ mol-1, whereas that of (CH3)2C60 lies ca. 3.4 kJ mol-1 lower. Evidence found for a 3-fold orbital degeneracy in triplet C60 indicate only Jahn-Teller splitting. The entropy result for C70 indicates a nondegenerate lowest triplet state lying ca. 600 cm-1 below a doubly degenerate triplet.