D. Wallach, W. Huntress
Feb 1, 1969
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Journal of Chemical Physics
Abstract
The anisotropy in the molecular rotation of N,N‐dimethylformamide (DMF) in the liquid is investigated by considering the NMR relaxation times of the 14N, 17O, and formyl deuteron nuclei in DMF, DMF17O, and DMF‐d1, respectively. Assuming that the molecular rotation is diffusional and that one principal diffusion axis (the z axis) is perpendicular to the molecular plane, a range of possible orientations for the diffusion axes in the plane and a corresponding range of values for each of the three diffusion constants are calculated. The range of possible orientations of the x diffusion axis, which varies little with temperature, extends over about 26°, from the direction of the x principal inertial axis toward and past the direction of the molecular dipole moment. At 280°K the diffusion constants are Dx = (2.0 ± 0.4) × 1011sec−1, Dy = (6 ± 3) × 109sec−1, and Dz = (2.9 ± 0.7) × 1010sec−1. At 390°K, Dx = (4.0 ± 0.7) × 1011sec−1, Dy = (10 ± 8) × 109sec−1 and Dz = (2.1 ± 0.7) × 1011sec−1. The ratio of the rotatio...