Selective inversion investigations of slow molecular motion in solid state deuteron NMR spectroscopy

Deuteron selective inversion experiments are reported for polycrystalline dimethyl sulfone-d6 as a function of temperature from 288 to 333 K. Double side-band modulation was used to achieve efficient off-resonance orientation-selective inversion. Fitting the selective inversion-recovery curves to two-site jump equations yields the motional rate. Temperature dependent jump rates, obtained from both selective inversion and deuteron quadrupole echo lineshapes, give an activation energy Ea = 86.5 +/- 1.4 kJ mol-1 and a frequency factor In(A) = 39.2 +/- 0.5. These values differ significantly from those of earlier 13C lineshape studies. At 298 K, variable power excitation was used to determine the underlying orientation dependent homogeneous linewidth, which is predominantly dipolar. The temperature dependence of the homogeneous linewidth is a sensitive indicator of large angle jump motion in the range 10(3)-10(4) s-1.