Hydrothermal Synthesis, Crystal Structure And Characterization Of Copper-organonitrogen Coordinates -Polyoxotungstates

In this paper, seven unreported copper-organonitrogen-polyoxotungstates compounds have been synthesized by utilizing organic chelating ligand, 1, 10'-phenanthroline, or bridging ligand, 4,4'-bipy, as organic composition, polyoxoanions as inorganic composition and adjusting reaction conditions and reaction materials. These compounds have been structurally characterized by elemental analyses, UV-vis, IR, TG and single crystal X-ray diffractions. The magnetic properties and electrochemistry of compound 5 have been studied.1. Three novel polyoxometalates compounds have been hydrothermally synthesized and structurally characterized by using Keggin clusters as templates. {[Cu(bipy)2·(H2O)2]4}·[SiW12O40]2·[(bipy]4·8H2O (1) {Cu(bipy)2·(H2O)2}·{Cu(bipy)2}[SiW12O40]·20H2O (2), [Cu+(4,4'-bipy)]2·[H2SiW12O40]·2H2O (3); (bipy= 4,4'-bipyridine) Compounds 1 and 2 are novel examples of porous 3D coordination polymers assembled by the Keggin anions as templates,Keggin anions connect 2D metal-organic network through the hydrogen bonding, the anions and bipyridine molecules or water clusters lie in the pores alternately. The successful syntheses of 1 and 2 indicate a novel approach to assemble porous Keggin-based 3D coordination polymers. Because of the diversity of the 2D metal-organic networks and rich structures of POMs, a great number of porous Keggin-based 3D coordination polymers are expected by selecting proper POMs unit and 2D metal-organic network. Compound 3 is 1D chain structure similar to train-rail, namely metal-organic double chains connect the Keggin anions.2. Three supramolecular compounds based on iso- and hetero-polyoxotungstates are synthesized hydrothermally and characterized structurally: [Cu(phen)3][W6O19] (4) [Cu(phen)3]2[PW11VO40].2H2O (5) [Cu+(phen)2]4[SiW12O40] (6) (phen =1,10'-phenanthroline) Compound 4 shows 3D supramolecular architecture assembled by the Lindqvist isopolyoxometalates and transition metal complex through the hydrogen bonding interactions between them. Aromaticπ-πstacking interactions exist in the copper coordination complexes of compound 5, there exist hydrogen bonding interactions between the Keggin anions and transition metal complex, namely the hydrogen bonding interactions linked compound 5 into three-dimensional network consists of one-dimensional channels which accommodate free water molecules,the size of the channel is 10.4×10.4 ?2. Keggin anions of compound 6 exhibit orthorhombic face-centered close packing mode, which is similar to the array of chloric ions of NaCl ionic crystal, the coordination cations fill in the lacuna. The successful synthesis of three compounds demonstrates the possibility of constructing supramolecular arrays between POM and transition metal coordinates via hydrogen bonding interactions and may provide experimental data for supramolecular chemistry and interesting crystal engineering.3. A new organic-inorganic hybrid compound on the basis of Keggin type polyoxoanion cluster has been hydrothermally synthesized and structurally characterized: [{Cu(phen)2}2SiW12O40] (7) Compound 7 is a disupported compound, Keggin anion regarded as bi-dentate liagand simultaneously provides a terminal oxygen atom and a bridging oxygen atom from the opposite sides of the Keggin structure and coordinates to two {Cu(phen)2} fragments, Cu2+ are all five-coordinated, but show unusual coordination geometry configuration, Cu1 displays a distorted trigonal bipyramidal geometry, Cu2 displays square pyramidal geometry.