Study of the NMR Results in Some Crystalline Hydrates

The NMR results have been studied in 12 crystalline hydrates whose neutron-diffraction structures are available. The purpose of this study is to examine the validity of the Pake technique which may appear questionable in view of recent studies, and to try to propose a general method for calculating hydrogen positions using the NMR data and the positions of the heavy atoms in the unit cell. Comparison of the NMR results with the neutron-diffraction structures shows that the Pake technique, when applied without considering the influence of thermal motion on the resonance spectrum, gives fairly accurate results. The method proposed for calculating hydrogen positions is described and the assumptions made are discussed in detail. It is found that in the general case, the positions calculated by this method are in close agreement with the corresponding positions obtained by neutron diffraction.