NMR Probes of the Molecular Orientational Dynamics of the Endohedral Fullerene Sc$_{3}$N@C$_{80}$.

We report NMR lineshapes and spin-lattice relaxation times for both $^{13}$C and $^{45}$Sc in the endohedral fullerene Sc$_{3}$N@C$_{80}$. The data show rapid reorientation of the molecule with an activated temperature dependence for the motion over the observed temperature range (50 -- 350 K). The ratchet to rotator transition found in C$_{60}$ is not observed in Sc$_{3}$N@C$_{80}$. The measurements strongly suggest the motion of the encapsulated Sc$_{3}$N derives from the reorientational dynamics of the C$_{80}$ cage, however without the Sc$_{3}$N being fixed to the cage in the motional narrowing regime.