CARBON AND PHOSPHORUS RELAXATION IN SOME PHENYLPHOSPHORUS COMPOUNDS

Carbon and phosphorus relaxation times have been determined for several phenylphosphorus compounds. The relaxation time for the α carbon is dominated by the dipole-dipole mechanism at lower temperature and the spin-rotation mechanism at high temperature. All other carbons in these molecules are relaxed predominantly by the dipole-dipole mechanism, except that at the highest temperatures a spin-overall rotation mechanism becomes important for some. The importance of the spin-rotation mechanism is related to chemical shielding. The chemical shift anisotropy mechanism makes a significant contribution to phosphorus relaxation in most of these compounds. Spin-rotation is also a significant mechanism, while the dipole-dipole mechanism is apparently relatively unimportant in phenylphosphorus compounds. © 1979.