Reduction of C60 and C70 by primary amines: Optical and ESR studies

Radical anions C70- and C70 2- were obtained in vacuo by the reaction of I-amino3-propanol (AP) and 1,5-diaminopentane (DAP) with fullerene C70. The radical anions were identified by visible/near IR (X = I372 and I172 nm, respectively) and ESR spectroscopies. The temperature dependences of the ESR spectra were studied for the C₆₀-AP, C₇₀-AP, and C70-DAP systems. At low temperatures (I5-45 K), the ESR spectrum for C60 is close to that for species with axial symmetry of theg-factor (q_| = 2.000 and g, = I.995). The anisotropy of theg-factor is averaged, when the temperature increases. At T > I48 K the averaged line is broadened, and the sharp signal with g = 2.0001 overlaps this broad line. The intensity of the narrow line increases, when the temperature increases. The ESR spectrum observed in the C₇₀-AP system at I2.5 K may be tentatively described as a superposition of two ESR spectra, namely, the ESR spectra of a radical with g_| = 2.0042 and g, = 2.0015 (presumably a radical cation) and of C₇₀ ^– with q_| = 2.000 and g = I.994. The spectra of the sample in which C70 is present mainly as C₇₀ ^2– exhibit only a line with g = 2.0004.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. I, pp. 103–108, January, 1996.