The Study Of The Derivatives Based On Keggin-type Polyoxometalates (I)

The aim of this thesis is the synthesis of new polyoxometalate compounds on the basis of bis(undecatungstophosphate) lanthanates and Keggin type polyoxoanion clusters, which are decorated or bridged by various transition metal compounds. The study on synthetic conditions and rules for these new compounds and the exploration of relationships between structures and properties for these new compounds are also carried out. With water solution synthesis methods and/or hydrothermal technique, we separated eight compounds and charactered their structures. Magnetic properties of partial conpounds have also studied and discussed.Compound (H₃O)[Fe(2,2′-bipy)3]2[FeW₁₂O₄₀]·7H₂O (1) is obtained under hydrothermal condition. It displays a 3D supramolecular framework based on the [FeW₁₂O₄₀]5-, [Fe(2,2′-bipy)3]2+ and lattice water molecules through extensive hydrogen bonding interactions andπ–πinteractions. Magnetic study reveals iron ions are mixed valence and counter- ions are diamagnetic.Compound {(H₃O)[CuI(4,4′-bipy)]₃[SiW₁₂O₄₀]}·1.5H₂O (2) is obtained from hydrothermal condition. It consists of 1D zigzag chains, in which each [SiW₁₂O₄₀]^4- polyoxoanion is supported by three parallel infinite [CuI(4,4′-bipy)]nn+ polymeric chains in a single W3O13 triplet. Zipper-like arrangement of adjacent zigzag chains by hydrogen interactions leads to a 2D layer andπ–πinteractions of 4,4′-bipy ligands from adjacent layers further result in the three-dimensional structure of 2.Five hybrid compounds have been synthesized on the basis of bis(undecatungsto- phosphate) lanthanates anions connected by dinuclear copperII–oxalate complexes:K₂H₇[{La(PW₁₁O₃₉)₂}{Cu₂(bpy)₂(μ-ox)}]·17H₂O (3)K₂H₇[{Pr(PW₁₁O₃₉)2}{Cu2 (bpy)2 (μ-ox)}]·18H₂O (4)K₂H₇[{Eu(PW₁₁O₃₉)₂}{Cu₂(bpy)₂(μ-ox)}]·16H₂O (5)K₂H₇[{Gd(PW₁₁O₃₉)₂}{Cu₂(bpy)₂(μ-ox)}]·22H₂O (6)K₂H₇[{Yb(PW₁₁O₃₉)₂}{Cu₂(bpy)₂(μ-ox)}]·19H₂O (7)K2H9[{K(PW₁₁O₃₉)₂}{Cu₂(bpy)₂(μ-ox)}]·20.5H₂O (8) has also been obtained in the absence of Ln3+. Compounds 3-8 consist of 1D chains,π–πinteractions lead to three-dimensional structures. Magnetic studies of 3, 4 and 5 showed that there were strong antiferromagnetic coupling in the oxolato–bridging CuII dimers, and the lanthanide cations slightly influence the magnetic properties of 4 and 5.