Syntheses And Properties Of Transition-metal Substituted Dawson-type Polyoxometalates And Its Extended Structure

Transition-metal-substituted polyoxometalates(TMSPs) are a remarkable class of inorganic metal oxide clusters formed from the reaction of lacunary polyoxometalates and transition metal ions. They have potential applications in the fields of magnetism, medicine, catalysis, and material chemistry due to their varieties of structures and rich electronic properties. In this paper, we choose the trivacant Dawson-type polyanion [P2W15O56]12-(abbreviated as {P2W15}) as the precursor, reacting with transition metal ions under the conventional solution conditions and under hydrothermal conditions respectively, and four compounds based on transition-metal-substituted Dawson-type POMs have been successfully obtained.Under conventional solution conditions, by using {P2W15} as the precursor, reacting with transition metals Co2+ and Ni2+, two {M3}cluster(M = Co/Ni) substituted γ*-Dawson-type polyoxotungstates have been obtained successfully:H12[P2W15O59{Co(OH2)}3]?14H2O(1) H12[P2W15O59{Ni(OH2)}3]?14H2O(2)They were characterized by powder and single-crystal X-ray diffraction, IR spectroscopy, thermogravimetric analysis and elemental analysis. The magnetic property and the electrochemistry of these two compounds have also been studied preliminary.Under hydrothermal conditions, by using {P2W15} as the precursor, reacting with transition metal Ni2+, yielding a new polyoxometalate which contains a planar {Ni6} cluster:[Ni0.5(H2O)3][{Ni6(μ3-OH)3en(H2O)10}(H2P2W15O56)]?10H2O(3)We also obtained the extended structure of 3 by introducing succinic acid into the system of 3.[Ni(dap)2]{[Ni1.5(dap)1.5(H2O)3][Ni6(μ3-OH)3(dap)2(en)(H2O){O2C(CH2)2CO2}0.5(CH3C OO)(P2W15O56)]}?15H2O(4).The synthetic conditions and the reaction rules of these two compounds have also been analyzed. In addition, the magnetic properties of both compounds were studied, and the selective adsorption performances of compound 4 have also been investigated.