A nuclear magnetic resonance study of molecular motion in solid diethylamine and in diethylamine clathrate deuterate

The proton magnetic resonance second moment and spin-lattice relaxation data are reported for the two solids namely pure diethylamine and diethylamine clathrate deuterate, over the temperature range 77 K to 270 K. The results indicate that in both materials the only motion which occurs at a rate great enough to affect the N.M.R. observables is methyl group reorientation and for such motion activation energies of (2·9₀±0·02) kcal mole^-1 and (2·3₄±0·02) kcal mole^-1 are obtained for pure diethylamine, and the deuterate, respectively. The strength of the dipolar interaction in the deuterate as estimated from both the second moment and the maximum in the temperature dependence of nuclear relaxation rate is consistent with a carbon-proton distance of 1·10 Å and a large degree of chemical exchange of the amine protons with the deuterons of D₂O.