The studies of X-ray photoelectron spectra of a series of crystalline fulle
rene molecular complexes, (D)(x).(F).(R)(y), showed that in addition to the
main state of a heteroatom of donor, there are heteroatoms in higher oxida
tion states on a crystal surface. The causes for donor oxidation and the ap
pearance of heteroatoms in higher oxidation states are discussed.