Electron spin resonance characterization of the anion radicals of singly, doubly, and triply reduced C60 in liquid solutions

Simultaneous electrochemical and electron paramagnetic resonance studies of fullerene anion radicals C 60 1− and C 60 3−

“…The broad line has been misleadingly identified so far as Clo [3][4][5][6][7][8]. The linewidth of these broad signals show strong temperature dependence [3,4] similar to our observations.…”

“…The electrochemical generation of C 91 for n = 1-6 has been well established [1] along with a growing EPR characterization of discrete fullerene ions [2][3][4][5][6][7][8]. Reduction of C60 to each C~' o level involves a one-electron transfer [1,3].…”

“…Samples were collected from freshly electrolyzed solutions and transferred into EPR tubes. The spectra of C6" 0 in both liquid and frozen solutions were often complex [2][3][4][5][6][7][8] making unambiguous assignment impossible. In a recent paper [8], broad, temperature dependent signals were ascribed to -1 and -3 anions in frozen solutions while the sharp spectra largely independent of temperature were assigned to as-yet unidentified species.…”

Discrete Fulleride Anions and Fullerenium Cations

“…60 G (see Figure 17). 53,106,116,117,123,125,132,146,179,[183][184][185][343][344][345][346][347][348][349] The most extensive investigations have been made by Eaton and co-workers, and the following general features have been identified. 338 Below about 80 K, there is no longer a substantial temperature dependence.…”

“…Room-temperature line widths have been reported in the range 10-54 G. 133 These features have led Eaton et al to conclude that electron-spin relaxation rates are the main determinant of the line width variation, but the whole problem of line width variation is made complex by the presence of low-lying excited states, 179 motional effects, 106,220 and environmentally induced distortions. 346 A more quantitative understanding of the broad, temperature-dependent signal is coming from pulsed EPR measurements of the traverse and longitudinal relaxation times of C 60 -in a tetraphenylphosphonium salt. 350 Its origin clearly lies in the dynamic nature of the small Jahn-Teller distortion associated with degeneracy of the (t 1u ) 1 ground state.…”