NMR Determination of Some Deuterium Quadrupole Coupling Constants in Nematic Solutions

Abstract

The analysis of the NMR spectra of suitable nematic liquid-crystal solutions appears to offer a convenient and desirable method for the determination of small nuclear quadrupole coupling constants for molecules in the liquid state. Nuclear quadrupole coupling constants have been determined for deuterium in the C–H bond of a number of small molecules. Assuming that the field gradient has axial symmetry, values of e2qQ/h along the bond axis are as follows: CH3CD3167± 18 kHzC3D6184± 20C2D2198± 7CH3C2D199.4± 2.0DCN199.0± 3.0. The results are discussed in terms of various theoretical calculations of the field gradient at the deuteron, and a compilation of some of the accurate experimentally determined deuterium coupling constants is presented.