Pb2VIIIO(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 Pb2V3O8.5 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) ?, b=5.996(2) ?, c=17.337(4) ?, and BETA= 112.636(4)°. The structure consists of one-dimensional rutile-type chains of edge-sharing VIIIO6 octahedra parallel to the b axis. Bidentate VVO4 tetrahedra share corners with the chains to form one-dimensional columns. They are interconnected by divanadate VV2O7 to form infinite layers. In the presented work, the Pb2V3O8.5 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.