EPR STUDY OF RADICAL-ANIONS OF C-60 AND C-70

Utilizing highly polar solvents for the stabilization of Fullerene anions, electrochemical and chemical reduction resulted in narrow single line EPR spectra for the monoanions of C-60 and C-70 being characterized by g = 2.0001(1), Delta B = 0.075 mT, g = 2.0019(1), Delta B = 0.016 mT, respectively. Apparently, the orbital degeneracy of the C-60 monoanion is lifted under these conditions to such an extent, that the abnormal large spin lattice relaxation rate believed to be responsible for the approximately 5 mT line width of the monoanion is sufficiently reduced. C-13 enrichment resulted in noticeable line broadening, allowing an estimate of the average C-13 hyperfine coupling constant a(ave) = 0.1 mT.