Nuclear magnetic resonance spin–lattice relaxation and barriers in ethylenediammonium chloride, bromide, iodide and sulphate

Abstract

N.m.r. T₁ has been studied as a function of temperature in the Cl^–, Br^–, I^– and SO₄^2– salts of the ethylenediammonium ion ⁺NH₃CH₂CH₂NH₃⁺. The chloride and sulphate show phase transitions at elevated temperatures. The T₁ minima of 21–22 ms (at 31 MHz) in all four salts may be interpreted in terms of —NH₃⁺ reorientation. The observed activation energies for this motion, which vary between 41.3 and 8.6 kJ mol^–1, have been related where possible to the nature of the group's environment.