Structural Organization and Thermal Behavior of Compounds Rb3(SbF3)(Zr2F11)·0.5H2O and Rb3(SbF3)(Zr2F11)

Compound Rb3(SbF3)(Zr2F11)·0.5H2O and its dehydration product Rb3(SbF3)(Zr2F11) were synthesized and their structures were studied. It was found that compound Rb3(SbF3)(Zr2F11)·0.5H2O has a unique fluoride zirconate framework structure built of ring tetrameric fragments (Zr4F24) connected to each other at the vertices by bridging fluorine atoms. Inside the tetrameric fragments, ZrF8 polyhedra are connected to each other along common edges. The zirconium framework [Zr2F11]3– is bound by Zr–F–Sb fluoride bridges from the second coordination sphere of antimony atoms. The structure of the dehydrated compound Rb3(SbF3)(Zr2F11) is a three-dimensional framework consisting of infinite chains of composition [Zr2F11]3–. The chains are formed by ZrF7 polyhedra connected along edges and vertices and united with each other into a three-dimensional framework by fluoride bridges Zr–F–Sb from the second coordination sphere of antimony atoms. In Rb3(SbF3)(Zr2F11), in the temperature range 247–256 K, a reversible phase transition occurs from the partially disordered high-temperature phase α to the ordered low-temperature phase β. With the participation of fluorine atoms of the second coordination sphere and a lone pair of electrons around antimony atoms, coordination polyhedra are formed in the structures in the form of distorted (SbEF5) and single-capped (SbEF6) octahedra.