EPR test of the resonating-valence-bond theory of superconductivity in ${\mathrm{C}}_{60}$${\mathrm{K}}_{\mathit{n}}$

EPR experiments on powder samples of ${\mathrm{C}}_{60}$${\mathrm{K}}_{\mathit{n}}$ are presented. The results contradict the basic assumption of a negative Hubbard U, which has been used to explain the superconductivity in fullerenes. The apparent orbital nondegeneracy of the observed state is explained in terms of a generalized dynamic Jahn-Teller effect.