Crystal structure of two [Ba(H2O)3](ClO4)2 phases and H2O ligands reorientational motions studied by X-ray single crystal, inelastic and quasielastic incoherent neutron scattering and proton magnetic resonance Original Research Article

XRSCD and NPD measurements indicated that the crystal space group (P63/m) is the same for high and low temperature phases. IINS spectra calculated by the DFT method are in a good agreement with the experimental data. The QENS peaks, registered at 225 and 175 K, (above and below the phase transition at View the MathML sourceTCh=211.3 K, respectively) do not show any broadening, what implies that the corresponding reorientational correlation times for 180° jumps of H2O ligands are longer than 10–11 s. The 1H NMR line absorption results indicate that above View the MathML sourceTCh, the ratio of the area under the narrow contribution of the line to the whole line is close to 1:3, what suggests that upon heating of the sample, activation of a much faster than 10−8 s rotational (of diffusive nature) motion of the only one of the three H2O ligands per one [Ba(H2O)3](ClO4)2 formula unit occurs.