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 P,with a = 8.5420(10),b = 10.2570(10),c = 13.361(2) ,α = 100.704(2),β = 100.195(2),γ = 108.873(3)o,C16H20Cd N4O9S2,Mr = 588.91,V = 1.0524(2) nm3,Dc = 1.858 g/cm3,Z = 2,F(000) = 592,μ = 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.