Deuteron and proton magnetic resonance studies of AlCl3⋅6D2O and AlCl3⋅6H2O

Abstract

The angular dependence of the deuteron magnetic resonance line splittings recorded in one plane of rotation of a single crystal of AlCl₃⋅6D₂O have been used to establish the quadrupole coupling tensor and determine the deuteron positional coordinates. These coordinates are found to be 0.073, 0.187, 0.143; 0.202, 0.204, and 0.087. Proton relaxation times in polycrystalline AlCl₃⋅6H₂O have been measured as a function of temperature to evaluate the dynamic parameters associated with molecular motion. Twofold motion of H₂O with an activation energy of 10.0±0.5 kcal/mole is found to dominate the relaxation process below 385 °K. A second motion with an activation energy of 17.0±1.0 kcal/mole appears above 385 °K and is likely to be translational diffusion of the water molecules.