Communication: Syndiotactic polystyrene clathrates hosting benzene-d(6) or toluene-d(8) molecules in the cavities of the delta crystalline form have been prepared and investigated by means of solid state H-2 NMR spectroscopy. Benzene-d(6) molecules were found to be involved in a fast rotation about the C-6 symmetry axis whereas the toluene-d(8) molecules exhibit a fast rotation of the methyl group about the symmetry axis passing through the C-1 and C-4 carbon atoms.