The gamma-dose dependence of the absorbance of the electronic absorption bands in the near-m region of the anion radicals produced in MTHF solid solution containing C-60 at 77 K was investigated. The bands at lambda(max) = 1075 and 950 nm were ascribed to C-60(-) and C-60(2-) anion radicals, respectively. In the case of the solid solution containing [5,6]-bis(4-methoxyphenyl)methano[60]fullerene, which was used as a C-60 derivative, the bands at lambda(max) = 1075 and 1140 nm were ascribed to the mono-anion, and the band at lambda(max) = 1025 nm to the di-anion radical of the C-60 derivative. It is inferred that the unpaired electron density is delocalized on the C-60 moiety with a slight perturbation from the [5,6]-bis(4-methoxyphenyl)-methane functionality.