| In this thesis, we obtained three unprecedent isopolyniobates by precipitation-transformed method with A-8Nb6O19·nH2O (A = K or Na) as raw material. Meanwhile, polyoxometalates with Sandwich and saturated Keggin anion as building blocks have been synthesized by the normal techniques.(I) Using Cu2+ cation as template, we first synthesized three polyniobates, K(120Na4H23[ NaO8Cu24(Nb7O22)8]·106H2O (1), K16Na12H9[Cu25.5O8(Nb7O22)8]·73.5H2O (2) and K14 H22[KO8Cu25.5(Nb7O22)8]·45.5H2O (3), and characterized them by IR, ICP and the variable-temperature magnetic susceptibilities. The studies of magnetic properties of compound 1 show the presence of antiferromagnetic coupling between Cu2+ ions;(II) Two heteropolytungstates containing trivacant Keggin anion SbW9O339- have been obtained, [Na(H2O)]2H2[Mn2.5W1.5(H2O)10(β-B-SbW9O33)2]·28H2O (4) and Na-4H7[Na3 (H2O)6Mn3(Ac)2(α-B-SbW9O33)2]·20H2O (5). Compound 4 and 5 were charactered by element analysis and IR spectra. The results of IR spectra show the two anions still keep the backbone of trivacant Keggin-type anion;(III) Using plenary Keggin-type polyanion [CuW12O40]6-, [PMo12O40]3- and [BW12O40]5- as building block and using 2,2′-bpy and DMF as organic ligands, we have synthesized three organic-inorganic hybrid compounds and characterized them by IR, UV, and ESR spectroscopy, and studied by TG/DTA and CV, [Cu(2,2′-bpy)3]2H4[CuW12O40]·6H2O (6), {H[Ba(DMF)6PMo12O40]·(dma)}n (7) and [Ce(DMF)4(H2O)][α-BW12O40]·H2O·(HDMA)2 (8). The results of the single crystal X-ray diffraction analyses show these compounds present the structure of 0D, 1D zigzag linkage and 2D network, espectively. ESR spectra of powder of compound 7 after exposed to sunshine are typical of Mo5+. The results of cyclic voltammetry (CV) show that (a) [PMo12O40]3- and [BW12O40]5- anions are active centers for electrochemical redox reactions in solution, while corresponding cations have a small effect on the electrochemical properties; (b) pH value of the solution has great influence on the redox behavior of the polyanion of the...
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