13 C NMR studies of polycrystalline C 60 •2S 8 are reported. At room temperature, the static 13 C NMR spectra are similar to the 13 C spectrum of polycrystalline C 60 , which suggests that C 60 molecules undergo fast reorientational motion within the solvate lattice as within pure crystalline C 60 . This observation seems to contradict previous x-ray results that were interpreted in terms of motionless C 60 molecules within the solvate lattice; however, it agrees with thermodynamic measurements according to which the enthalpy for the departure of sulfur from the solvate is nearly equal to that of pure sulfur sublimation. The evolution of the shielding tensor as a function of temperature is also reported: it exhibits a steep change near 150 K that corresponds to a slowing down of the C 60 rotational motion. Finally, according to the variation of the 13 C spin-lattice relaxation time T 1 vs temperature, the dynamics of C 60 molecules, which consists in jumps between symmetryequivalent orientations, can be considered as ruled by two activation energies, 15.3 and 24.8 kJ mol Ϫ1 .
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