High resolution 2H NMR spectroscopy at the natural abundance level of deuterium

The relaxation time, T 1 , of deuterium nuclei in a few deuterated compounds, such as methanol- d 4 , benzene- d 6 , and dimethylsulfoxide- d 6 , is measured at higher temperatures in the range from 300 to 375 K. An almost linear increase in time, T 1 , over an increase in temperature is observed in all these cases, which confirms an increase in the mobility of molecules and a decrease in the correlation time. A T 1 value in the range from 2 to 3 s can be expected for deutrons in small organic molecules at temperatures above 350 K. Thus, a linewidth of about 0.1 Hz in 2 H NMR spectra can be obtained for a magnetic field inhomogeneity of about 0.5 Hz in 1H NMR spectra. Such high resolution 2 H NMR spectra provide information about chemical shifts and J (H-D) spin-spin coupling constants (or J (H-H) = (γ H /γ D ) J (H-D) when the isotope effects on the spin-spin coupling constants are neglected), including information about coupling constants between magnetically equivalent protons that can not be observed in 1 H NMR spectra. New or refined data on the coupling constants are obtained from the studied 2 H NMR spectra for ethanol, propanol, 1,2-dichloroethane, and 1,4-dioxane.