The effect of hydrate number on the structural changes, thermal properties, and ionic (molecular) mobility character in NH_4ZrF_5 ⋅ H_2O, NH_4ZrF_5 ⋅ 0.75H_2O crystal hydrates have been investigated by the methods of IR, Raman, nuclear magnetic resonance (NMR) (^1H, ^19F, including ^19F MAS), and TG-DTA spectroscopy. Differences in crystal hydrate structures—anion structure, molecular state of water, and O–H⋅⋅⋅F, N–H⋅⋅⋅F hydrogen bond strengths—have been corroborated by IR and Raman spectroscopy data. Isotropic chemical shifts of magnetic inequivalent positions have been determined and attributed to crystal structures of the studied compounds by the method of ^19F MAS NMR. It has been established that the removal of water molecules from NH_4ZrF_5 ⋅ H_2O and NH_4ZrF_5 ⋅ 0.75H_2O results in the transformation of chain or layered structures accompanied by the increase of the number of bridge bonds while retaining or increasing the dimensionality of the anion structural motif. According to the ^1H NMR data, the NH $$_{4}^{ + }$$ cation diffusion in NH_4ZrF_5 occurs only in the temperature range of 370–520 K.

Методами дифференциального термического и термогравиметрического анализа (ДТА-ТГА), рентгенофазового анализа (РФА), колебательной спектроскопии исследованы строение и термическая устойчивость соединения Na5Zr2F13 на воздухе в интервале температур 20-800oС. Подтверждено наличие фазового перехода в высокотемпературную модификацию α-Na5Zr2F13 с динамически разупорядоченной структурой. Получены, систематизированы и обобщены данные инфракрасной спектроскопии (ИК), спектроскопии комбинационного рассеяния (КР) соединения β-Na5Zr2F13 и продуктов его разложения при нагревании. На основе результатов квантово-химических расчетов проведено отнесение полос в колебательных спектрах Na5Zr2F13. Ключевые слова: комплексные фториды циркония, фторидоцирконаты натрия, термогравиметрия, колебательная спектроскопия.

Crystalline hydrates of pentafluoridozirconic acid HZrF5∙3H2O, HZrF5∙2H2O and intermediate product of the thermal decomposition of acids ZrF4∙H2O were studied by vibrational spectroscopy and thermogravimetry. It is shown that the crystalline hydrates HZrF5∙nH2O (n=2, 3) are salts with complex H5O2+ and H7O3+ cations. Based on the results of quantum chemical calculations, the bands in the IR and Raman spectra were assigned.