High-resolution phosphorus-31 N.M.R. studies of solid phosphorus pentachloride

The 31P N.M.R. bandshapes and spin-lattice relaxation times for solid PCl5 have been studied under conditions of magic-angle rotation, for both the phase II and phase III forms. Temperature and magnetic field were both varied. The influence of molecular motion on both bandshapes and T 1 is discussed. Second-order effects resulting from the dipolar coupling of 31P to the quadrupolar chlorine nuclei are found to cause splittings in the spectra under certain conditions. It is postulated that Zeeman/quadrupolar cross-relaxation influences T 1 for [PCl4]+ in phase II.