CORRELATION TIMES AND QUADRUPOLE COUPLING-CONSTANTS IN NEAT, LIQUID FORMAMIDE

Nuclear magnetic resonance longitudinal relaxation rates of the dipola r nuclei C-13 and N-15 were measured in the liquid phase over the temp erature range 261-395 K. Rotational correlation times were determined for the C-H and the N-H bonds and indicate that the motion is isotropi c in the neat liquid. Longitudinal relaxation measurements for the qua drupolar nuclei O-17, N-14, and H-2 provide values of four different q uadrupole coupling constants. The quadrupole coupling constants for th e two amide deuterons are temperature dependent and vary from 230 to 2 90 kHz. The quadrupole coupling constant for oxygen ranges from 8.7 to 9.4 MHz. The quadrupole coupling constant for oxygen ranges from 8.7 to 9.4 MHz. The quadrupole coupling constants for the formyl deuteron (170 kHz) and the nitrogen-14 (2.84 MHz) are essentially temperature i ndependent. Values for the quadrupole coupling constants provide infor mation about the strength of the hydrogen bonds at different sites in the formamide molecule and their change with temperature.