Comparative EPR study of Cu@C60 and N@C60 endofullerenes.

A comparative study of C60-based endohedral fullerenes was performed. From an analysis of spin relaxation times of the recently characterized Cu@C60 metallo-endofullerene, it could be shown that the encased ion occupies a well-defined off-centre position even at room temperature. Localization on the timescale of an EPR experiment is combined with charge transfer of approximately two electrons, resulting in the EPR signature of a 3d9 copper ion.