Pb2VO(VO4)(V2O7)0.5, a Novel Lead Vanadium III Vanadate Possessing Trivalent Vanadium Rutile-Like Chains: Relationship with Related Compounds

The crystal structure of the new Pb₂V₃O_8.5 has been determined and refined with final R₁ and wR₂ values 0.045 and 0.128, respectively, from 1063 independent single crystal reflections. It crystallizes with the P2/c space group, a=7.687(2) Å, b=5.996(2) Å, c=17.337(4) Å, and β=112.636(4)°. The structure consists of one-dimensional rutile-type chains of edge-sharing V^IIIO₆ octahedra parallel to the b axis. Bidentate V^VO₄ tetrahedra share corners with the chains to form one-dimensional columns. They are interconnected by divanadate V^V₂O₇ to form infinite layers. In the presented work, the Pb₂V₃O_8.5 crystal structure is compared to several closely related materials including Ba₂V₃O₉ and the mineral Vauquelinite Pb₂CuCrO₄PO₄OH. Special attention is given to the existence along the rutile chains of V-V pairs due to strong V-O bonds with O₂ bridging edges.