Isotope effects on order in nematic solutions. Deuterium quadrupole coupling constants for CDH2I

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Abstract
In a previous publication [J. Chem. Phys. 66, 4226 (1977)] it was noted that dipolar coupling constants obtained from the NMR spectra of mixtures containing 13CH3I and 13CDH2I dissolved in nematic solvents revealed the presence of an isotope effect. In order to investigate this phenomenon quantitatively we have carried out vibrational averaging of the dipolar couplings, and derived the order parameters, Sαβ, for the two molecules. We also derived the quadrupole coupling constant, QD, for deuterium in 13CDH2I from the splitting observed in the deuterium spectrum and values of Sαβ obtained from vibrationally corrected dipolar couplings. The average value of QD was found to be 160.7±1.7 KHz if the asymmetry parameter, η, is assumed zero, and 153.9±1.6 KHz or 168.2±1.8 KHz for values of η=−0.04 and +0.04, respectively.