Titanium³⁺ hexacyanometallates(II): Preparation and porous framework

The studied compounds were prepared by the precipitation method mixing Ti ⁺ in concentrated HCl with aqueous solution of [M(CN)6] where M = Fe, Ru, Os. The formed solids, Ti₃Cl[M(CN)₆]2·10H ₂O, were characterized by IR spectroscopy, X-ray diffraction, thermogravimetry, Mössbauer spectroscopy, energy-disperse X-ray spectroscopy, UV/Vis spectroscopy, adsorption data, and chemical analyses. Their crystal structures were solved and refined from the recorded X-ray powder patterns in the Fm3m space group. This series of compounds has a porous framework with a relatively high free volume, which is occupied by coordinated and hydrogen bonded water molecules. The charge balancing Cl^- ion was found coordinated to titanium atoms. This series of porous solids was studied in order to explore the hydrogen interaction with the titanium atoms found at the surface of the cavities. On the water removal by moderate heating their porous framework collapses as reveal the nitrogen, CO₂, and hydrogen adsorption but without complex salt decomposition. On the solids rehydration the porous framework is partially restored.