Ba5Cl4(H2O)8(VPO5)8: a novel three‐dimensional framework solid

The novel hydrothermally synthesized title compound, pentabarium tetrachloride octahydrate octakis(oxovanadium phosphate), Ba₅Cl₄(H₂O)₈(VPO₅)₈, crystallizes in the orthorhombic space group Cmca with a unit cell containing four formula units. Two Ba²⁺ cations, two Cl⁻ anions and the O atoms of four water molecules are situated on the (100) mirror plane, while the third independent Ba²⁺ cation is on the intersection of the (100) plane and the twofold axis parallel to a. Two phosphate P atoms are on twofold axes, while the remaining independent P atom and both V atoms are in general positions. The structure is characterized by two kinds of layers, namely anionic oxovanadium phosphate (VPO₅), composed of corner‐sharing VO₅ square pyramids and PO₄ tetrahedra, and cationic barium chloride hydrate clusters, Ba₅Cl₄(H₂O)₈, composed of three Ba²⁺ cations linked by bridging chloride anions. The layers are connected by Ba—O bonds to generate a three‐dimensional structure.