Reorientational motions of NH2 groups in potassium amide

Rotational motions of NH2 groups have been observed in the three known solid phases of KNH2 by means of quasielastic neutron scattering. The observed intensities of the elastic and quasielastic components can be accounted for by various reorientational jump models between equivalent equilibrium orientations of the NH2 ion: 180° jumps about the molecular axis (monoclinic phase); 90° jumps about the fourfold crystal axis (tetragonal phase); most probably 120° jumps about the threefold axes (cubic phase). In some cases preliminary values of residence time have been obtained from lineshape fits.