Spin–spin coupling in the HD molecule determined from 1H and 2H NMR experiments in the gas-phase

Abstract

The indirect spin–spin coupling of hydrogen deuteride, J(D,H), was determined from a series of 1H and 2H NMR spectra acquired at various densities of gaseous solvents (He, Ar, CO2, and N2O). The analysis of these spectra shows that accurate determination of J(D,H) from this experimental data requires careful examination of the effects of nuclear relaxation and of HD–solvent gas interactions on hydrogen deuteride line shapes. Particularly, it was found that the first-order corrections of the peak-to-peak separations between HD multiplet peaks due to weak van der Waals interactions are proportional to solvent gas density, while these corrections for nuclear relaxation of the proton and the deuteron are proportional to the second power of the inverse of the gas density. Analysis of the data indicates that J(D,H), obtained by correcting for the effects of nuclear relaxation and intermolecular interactions, is 43.136(7)Hz at 300K.