High-Pressure Structural Studies of Hydroxides

Abstract

Hydrogen bonds involving hydroxyl groups appear to to be significantly different from the H-bonds found in molecular solids. High-pressure structural studies of hydroxides using neutron diffraction provide a means to explore the changes in geometry over a wide range of interatomic separations. The structure of NaOD-V is found to have a complex geometry which appears on the basis of bond-valence-sum calculations to be at most weakly H-bonded. KOD-VI is found not to be structurally related to NaOD-V as previously thought. Studies of ammonia monohydrate have provided the first full determination of the ambient pressure structure and have revealed phase transitions under pressure.