Keggin Type, The Synthesis And Characterization Of Tungsten Heteropoly Acid Salt Derivatives

Polyoxometalates(POMs) have aroused great interest due to the enormous structural variety and a multitude of interesting properties, and in this field the synthesis of new POMs has been the driving force of its development, especially the design and construction of new transition-metal (TM) clusters POMs and new inorganic-organic hybrids baseed on POMs building blocks and transition-metal coordination polymers have been the focus of recent research. In this paper, we successfully synthesized three new inorganic-organic hybrids baseed on Keggin-POMs and1,4-bis(imidazolyl)benzene (bib) by adjusting the reaction conditions, and two sandwich-type heteropolytungstates. All these compounds have been characterized by elemental analyses, IR and X-ray single crystal diffractions. The thermal stabilities and magnetic properties of some compounds have been also investigated.1. Three new inorganic-organic hybrids based on Keggin anion and1,4-bis(imidazolyl)benzene CuⅠ4(bib)4GeW12O40·2H2O (1) CuⅡ3Cl2(bib)3SiW12O40·7H2O (2) H4GeW12O40(C12H10N4)3(3) bib=1,4-bis(imidazolyl)benzeneIn compound1, the bib ligand acts as a bidentate ligand to CuⅠ ions to form wavelike {Cu-bib}n, polymer chains, which are further connected by terminal/bridging O atoms from the bidentate [GeW1204o]4-polyanions to construct1D ladder-like{CuⅠ4(bib)4GeW1204o}∞chain. It should be mentioned that there exist a sort of strong short contact interaction between CuⅠ and other O atom of [GeW1204o]4-polyanions, which plays an important role in constructing the3D crystal structur of1. Like1, all bib ligands in2act as a bidentate ligand to bridge two CuⅡ ions to form{Cu-bib}n polymer chains, however in2, three parallel chains are furthermore linked by two Cl" ions to form a1D polymeric tri-chains containing{CuⅡ3Cl2}4+units. The Keggin polyanions [SiW12O40]4-as bidentate ligands use its terminal O atom to coordinate two Cu2+ions of neighbour polymeric tri-chains to form a2D sheet with (4,4) topology, then built3D framework by Coulombic force and weak interactions. In compound3, there exist complex interactions among bib molecules and the polyanions, such as Coulombic force, C-H···O, N-H···O hydrogen bonds and C-H···π and π···π stacking among organic ligands. Magnetic measurements reveal that compound2presents ferromagnetic interactions among the three-nuclearity cluster{CuⅡ3Cl2}4+. The successful synthesis of the new three kinds of organic and inorganic hybrids based Keggin anion and1,4-bis(imidazolyl)benzene shows the diversity of polyoxometalates.2. Two sandwich-type tungstogermanates have been synthesized by adjusting counter ionsNa10H2[Cu4(H2O)2(geW9O34)2]·40H2O (4)Na7H5[Co4(H2O)2(GeW9O34)2]·21H2O (5)The sandwich structure of the polyanios in compounds4and5are well-known and consist of two [GeW9O34]10-moieties linked by a central [M4(H2O)2] unit, and the polyanios are further connected by Na-0salt bonds to form3D framework network structures...