Synthesis,Characterization and Crystal Structure of a Three-dimensional Coordination Polymer {[Cd（1,5-nds）（Him）2（H2O）]·2H2O}n

A novel cadmium（Ⅱ） coordination polymer {Cd（1,5-nds）（Him）2（H2O）]·2H2O}n （1,5-nds = naphthalene-1,5-disulfonate and Him = imidazole） was synthesized based on the reaction of cadmium oxide and 1,5-naphthalenedisulfonic acid firstly, and then mixed with imidazole in methanol medium. Its structure was characterized by elemental analysis, IR and TGA, respectively. The crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group P1, with a = 8.5420（10）, b = 10.2570（10）, c = 13.361（2） A, α = 100.704 （2）, β = 100.195（2）, γ = 108.873（3）°, C16H20Cd N4O9S2, Mr= 588.91, V = 1.0524（2） nm^3, Dc = 1.858 g/cm^3, Z = 2, F（000） = 592, β^ = 1.294 mm-1, R = 0.0397 and wR = 0.1007 for 3180 observed reflections （Ⅰ〉 2σ（Ⅰ））. Structural analysis shows that the cadmiun atom is coordinated with four oxygen atoms from three 1,5-nds and one water molecule together with two nitrogen atoms from two imidazoles, giving a distorted octahedral coordination geometry. The molecules are linked to form a two-dimensional coordination polymer based on bridging ligands of naphthalene- 1,5-disulfonate anions, the sheets of which are then interacted via hydrogen bonds, leading to a three-dimensional network structure.