Synthesis and characterization of an organic–inorganic hybrid compound: [WO3 (2,2′-bipy)] (2,2′-bipy=2,2′-bipyridine)

Abstract

The hydrothermal synthesis and characterization of an organic–inorganic hybrid compound [WO₃(2,2′-bipy)] (2,2′-bipy=2,2′-bipyridine) is presented. This compound was characterized by various techniques including Raman and IR spectroscopy, XRD and thermogravimetric analysis. Structural analysis of the compound by Raman and IR data shows that it has a novel tungstate structure with 2,2′-bipy coordinated to tungsten. The X-ray powder diffraction data of the compound are indexed to a monoclinic cell with a=14.313(4), b=9.603(2), c=7.288(2) Å,β=102.07(2)°. The structure of [WO₃(2,2′-bip\y)] adopts a chain-like framework consisting of corner-shared distorted octahedra (WO₄N₂) with 2,2′-bipy acting as a bidentate ligand whose rings fan out from the chain. Upon heating, [WO₃(2,2′-bipy)] retains its structural integrity until 300 °C, followed by a gradual loss of 2,2′-bipy which leads to the formation of WO₃ at ca. 475°C. The thermal decomposition is observed to proceed through a transitional intermediate, [W₄O₁₂(2,2′-bipy)], the structure of which is proposed and discussed.