Synthesis And Characterization Of Complexes With Molybdenum Anion

Polyoxometalates (POMs) are a diverse class of inorganic compounds, formed by early-transition metal cations in their high-oxidation-state and bridged oxide anions, with fascinating structure and interesting electrochemical, catalytic, magnetic, medicinal and photophysical properties.Solvent thermal synthesis is an effective way to synthesis of polyoxometalates containing molybdenum/tungsten. These compounds synthesized by hydrothermal often contain solvent water molecules. Zero-dimensional, one-dimensional chain, two-dimensional water layer or three-dimensional network water clusters will be formed through hydrogen bond between water molecular and molybdate or between water molecules.My thesis mainly includes the following aspects:I Three compomds containing copper(II), nickel(II), manganese(IV) have been synthesized:[Cu(phen)(paba)2] (2-1), [Ni(phen)2Cl(H20)][Cl(Hpaba)(CH30H)0.5]-2H2O (2-2) and [Mn(phen)2Cl2](Hpaba) (2-3). As precursores, they have been used to modify the surface of hexamolybdate by imidization.Ⅱ By adjusting pH of reaction system with H3PO4, two tetra-nuclear copper complexes have been obtained:[Cu4(phen)4(OH)4(H2O)] [MoO4]·5H2O (3-1) and [Cu4(phen)4(OH)4(H2O)] [Mo04]·5H20 (3-2), which were based on Keggin-POMs and MoO42-, respectively. When the pH value is 7, we would obtain the compound 3-1. Bond valence sum calculations and XPS results show that in [Cu4(phen)g(PO4)]3- half of copper atoms were reduced from Cu2+ to Cu+. But if without H3PO4, we will get 3-2, four copper ions was connected by bridging hydroxyl. The study of catalytic activity shows that the compound 3-1 can weakly catalyze the reaction of cyclohexanone to adipic acid with H2O2 as oxidant.III there are three compounds containing water cluster, based on MoO42-, been synthesized: [Cu(phen)2(MoO3)(phen)(MoO4)]·8H2O (4-1), [Ni(phen)3][Mo2O7]·5H2O (4-2) and [Cu(phen)2(MoO4)]·5H2O (4-3). Single-crystal X-ray diffraction analysis reveals that compound 4-1 is in triclinic, space group P21, and two-dimensional layer are formed by hydrogen bond between water molecules and Oxygen atoms from MoO42-. The anion of compound 4-2 is the dimers molybdate, formatting a 3D framework by the interaction with water molecules, and [Ni(phen)3] was uniformly distributed in the 3D framework as a guest. In compond 4-3, the hydrogen bonds were formed among water molecules and oxygen atoms of molybdate to generate a 3D net structure. As the change of test temperature, irreversible changes in the crystalline phase due to the weak structure changes in the water cluster.