Magnetic Resonance Studies of Anisotropic Molecular Rotation in Liquid Acetonitrile-d3

The magnetic relaxation times T1 for 14N and 2D in liquid CD3CN have been measured as functions of temperature and concentration of added ionic salts. With no model assumed for the reorientation process, the molecular rotation is demonstrated to be anisotropic. The further assumption of a rotational diffusion equation permits the determination of the rotational diffusion constants. At 25°C, D⊥=1.35×1011(sec)−1, and D∥=1.2×1012(sec)−1. The rotational diffusion tensor remains anisotropic over a wide range of temperatures. The addition of the perchlorates of silver, lithium, or sodium to CD3CN reduces D⊥ for bound CD3CN by a factor of 10, but leaves D∥ unchanged.