ROTATIONAL TUNNELING OF CD3 GROUPS IN THE HYDROQUINONE METHANOL CLATHRATE - SINGLE-CRYSTAL AND POWDER DEUTERIUM NMR-SPECTRA

The single-crystal and powder H-2 NMR spectra of the hydroquinone/CD3OH clathrate recorded at T < 13 K reveal features characteristic of rotational tunneling of the CD3 groups. The ground-state tunnel splitting nu-t is larger than 2 MHz. Satisfactory agreement between simulated and recorded spectra is obtained if the angle between the C3 axis of the CD3 group and the C-D bond directions is taken to be 2-degrees larger than the tetrahedral angle. The line intensities in the single-crystal spectra show an oscillatory dependence on the pulse separation of the quadrupolar echo sequence.