Über basische Aluminiumsalze und ihre Lösungen. XIV. Zur Strukturellen Funktion des Wassers in basischen Aluminiumchloriden

Basic Aluminum Salts and their Solutions. XIV. Structural Function of Water in Basic Aluminum Chlorides The structural function of water in basic aluminum chlorides as intercalation compounds was examined by X-ray, thermoanalytical, and solid state ¹H-NMR investigations in connection with charging experiments in water vapor atmosphere. The basic salts were prepared by hydrothermal reaction of χ-Al₂O₃ with hydrochloric acid. It was shown, that the structural changes caused by loading with water vapor are reversible; the original state of the compounds may be recovered by a treatment in vacuum or by heating up to 130°C. The ¹H-NMR spectrum of the H₂O-loaded compounds consists of three components, caused by protons (a) of fixed coordination water or of OH^? ions, (b) of adsorbed water molecules with possibility of random motion, (c) of water molecules with hindered mobility. The development of spectra as a function of specimen temperature and of specimen treatment shows, that the third component is bound to intercalated water, located in voids, the dimensions of which are in the order of magnitude of water molecules.