吡啶配位的夹心型杂多阴离子{[Na(H2O)2]3[Ni(C5H5N)]3(AsW9O33)2}9-的结构及磁学性质

The pyridine coordinated sandwich-type heteropolytungstate Na7[Ni（H2O）6] { [Na（H2O）2]3[Ni（C5H5N）]3（AsW9O33）2}·28H2O was obtained by the reaction of Na2WO4·2H2O, NaAsO2 and pyridine with NiCl2·6H2O at pH =7.0 and characterized by elemental analysis, IR, UV-Vis,^1H NMR spectra and magnetic measurement. The structure of this heteropolytungstate was determined by X-ray diffraction analysis, which crystallized in triclinic system, space group P1 with a= 1.3153（9） nm, b= 1.7228（12） nm, c=2.6866（19） nm, a=74.130（11）°,β=78.032（12）°, γ = 73.179（12）° and Z= 2, R1 = 0.0604, wR2 = 0.0915 [I〉 2σ（I）]. Polyanion {[Na（H2O）2]3[Ni（C5H5N）]3（AsW9O33）2}^9- has approximately C3 symmetry, and three pyridine coordinated Ni（C5H5N）^2＋ and three Na（H2O）2^＋ are encapsulated between two AsW9O33^9- . Magnetic measurements show that central Ni3 unit in the polyanion exhibits ferromagnetic Ni-Ni exchange interactions （J=6.17 cm^-1）.