Synthesis, crystal structure, NMR data and thermogravimetrical properties of novel zirconium fluoride LiK 10Zr 6F 35·2H 2O

Abstract

The synthesis and study (single crystal X-ray diffraction, thermogravimetry, IR- and NMR-spectroscopy) of a novel fluorozirconate LiK 10Zr 6F 35·2H 2O was performed. The structure of the compound is built from infinite chains ∞[Zr 6F 35] 11−, in which Zr-polyhedra are linked to each other through common edges and vertices. The chains are surrounded by K and Li cations and H 2O molecules. The compound dehydration occurs in the temperature range 453–543 K with maximal rate at 528 K. It was established that zirconium polyhedra chain fragments underwent reorientational motion starting to influence 19F NMR spectra at temperatures higher than 270 and 180 K in LiK 10Zr 6F 35·2H 2O and LiK 10Zr 6F 35, respectively. Above 450–420 K all fluorine sites in both samples participate in fluorine translational diffusion by at least two diffusion paths. Isotropic 19F NMR chemical shifts from different site types were detected by MAS NMR in the range 125–171 ppm.