NMR-STUDY OF MOLECULAR-DYNAMICS IN HYDRAZINIUM PHOSPHATES

The proton spin-lattice relaxation time T1 (at 5.4, 10 and 15 MHz) and second moment M2 (at 9.8 MHz) were measured in the temperature range 77-300 K in hydrazinium dihydrogen phosphate N2H5H2PO4 and dihydrazinium hydrogen phosphate (N2H5)2HPO4. In N2H5H2PO4 a well-defined single proton T1, minimum and three M2 transitions have been observed. The T1 minimum has been interpreted in terms of the NH3 group reorientation with activation energy of 7.69 kcal mol-1, relaxing all protons by spin-diffusion. In (N2H5)2HPO4 a single T1 minimum and a small hysteresis behaviour have been observed in the temperature dependence of T1. Two M2 transitions were observed. The T1 minimum has been interpreted in terms of the NH3 group reorientation with an activation energy of 4.4 kcal mol-1. The M2 behaviour in both phosphates is explained in terms of NH3/NH2 motions. © 1990.