Synthesis, characterization and crystal structure of an inorganic-organic composite metatungstate:: [Co(4,4′-bipy)2(H2O)4](4,4′-H2bipy)2[H2W12O40]•5.5H2O

A novel hybrid compound [Co(4,4'-bipy)(2)(H2O)(4)](4,4'- H(2)bipy)(2)[H2W12O40]center dot 5.5H(2)O has been synthesized from an acidified aqueous solution and characterized by elemental and thermal analyses, IR and UV spectroscopy, and single-crystal X-ray structure determination. Structure analysis indicates that the title compound is of monoclinic, space group C2/c, with a = 21.315(9), b = 15.303 (7), c = 24.139(10) angstrom, beta = 105.170(5)degrees, V = 7599(6) angstrom(3), M-r = 3706.99, Z = 4, F(000) = 6616, D-c = 3.231, mu = 18.395 mm(-1), R = 0.0652 and wR = 0.1594. X-ray crystallographic study shows that the title compound consists of one [Co(4,4'-bipy)(2)(H2O)(4)](2+) cation, two diprotonated 4,4'-bipyridine molecules, 5.5 water molecules of crystallization, and one metatungstate polyoxoanion [H2W12O40](6-), which approaches an effective T-d point symmetry. TG-DTA analysis indicates that the framework of the metatungstate polyoxoanion is collapsed at 587.0 degrees C.