Hexatungstate subunit as building block in the hydrothermal synthesis of organic-inorganic hybrid materials:: synthesis, structure and optical properties of Co2(bPY)6 (W6O19)2 (bpy=4,4′-bipyridine)

A hydrothermal reaction of WO3, CoCl2 and 4,4'-bipyridine, yields a novel organic-inorganic hybrid compound, Co-2(bpy)(6)(W6O19)(2), at 170degreesC. X-ray single crystal structure determination reveals a two-dimensional covalent structure belonging to monoclinic crystal system, space group C2/c, with cell parameters a = 19.971(4)Angstrom, b = 11.523(2)Angstrom, c = 16.138(3)Angstrom, beta = 96.49(3)degrees, V = 3690.0Angstrom(3) and Z = 2. The hexatungstate, [W6O19](2-), acts as a building block in bidentate fashion to bridge the Co(II) centers in the crystal structure. The title compound is found to have an optical energy gap of 2.2 eV from UV-Vis-NIR reflectance spectra. (C) 2004 Elsevier Inc. All rights reserved.