Three organic-inorganic hybrid complexes based on the Wells-Dawson polyoxoanion

Three new organic-inorganic hybrid complexes based on the Wells-Dawson polyoxoanion, namely (H(2)bpp)[Ni-2(bpp)(2)(H2O)(4)(P2W18O62)]center dot H2O 1, [Cu-6(Hbpy)(6)(bpy)(3)(P2W18O62)(2)]center dot 2H(2)O 2 and (Him)(5)[Cu(im)(2)(P2W18O62)]center dot 4H(2)O 3 [bpp = 1,3-bis (4-pyridyl) propane, bpy = 4,4'-bipyridine, im = imidazole] have been synthesized and characterized. Complex 1 exhibits a three-dimensional (6, 3)-connected framework with anatase topology constructed from [alpha-P2W18O62](6-) clusters and [Ni(bpp)](2+) fragments. Each [alpha-P2W18O62](6-) anion links to six nickel atoms through six terminal oxygen atoms from four polar and two equatorial WO6 octahedra, which shows a novel coordination mode of a Wells-Dawson cluster with a transition-metal atom. Complex 2 displays an interesting one-dimensional double-chain structure built from [alpha-P2W18O62](6-) clusters and [Cu-2(bpy)(Hbpy)(2)](2+) fragments. To our knowledge, complex 2 represents the first double-chain organic-inorganic hybrid complex based on a Wells-Dawson-type cluster. Complex 3 possesses a one-dimensional zigzag chain structure constructed from [alpha-P2W18O62](6-) anions and [Cu(im)(2)](+) units through weak Cu center dot center dot center dot O interactions.