Hydrothermal Syntheses, Structure Characteristics and Magnetic Properties of a Series of New Molybdenum Arsenates Based on {(As3O3)2(Mo6O18)(MO6)}(M = Ni, (1); Co, (2); Zn, (3))

Three new polyoxometalates K2[H2（As3O3）2（Mo6O18）（NiO6）]？H2O （1）, K2[H2-（As3O3）2（Mo6O18）（CoO6）]？H2O （2） and [Zn（H4,4？-bpy）2（H2O）4][（As3O3）2（Mo6O18）（ZnO6）]？4H2O （3） （4,4？-bpy = 4,4？-bipyridine） have been synthesized under hydrothermal conditions and characterized by IR, elemental analyses, XPS and single-crystal X-ray diffraction analyses, respectively. Compound 1 represents a new 3D framework structure constructed from polyoxoanion [（As3O3）2（Mo6O18）（NiO6）]4- via covalent bond. Compound 2 has an identical structure with 1. Compound 3 represents a new 2D layer structure constructed from transition metal coordination cations [Zn（H4,4？-bipy）2（H2O）4]4＋, lattice water molecules and polyoxoanions [（As3O3）2- （Mo6O18）（ZnO6）]4- via multi-point N–H？？？O and O–H？？？O hydrogen bonding interactions. Crystal data： for 1, cubic, space group Pa-3, a = 15.0022（8） ？, V = 3376.5（3） ？3, Z = 24; for 2, cubic space group Pa-3, a = 15.1596（10）, V = 3483.88 ？3, Z = 24; for 3, monoclinic, space group C2/m, a = 19.699（4）, b = 14.223（3）, c = 9.1455（18） ？, β = 106.80（3）o, V = 2453.0（9） ？3, Z = 8. In addition, the magnetic behaviors for compounds 1 and 2 have been investigated.