Synthesis and Structural Characterization of Co（Ⅱ） Coordination Polymer [Co（-phth）(imi)2]n

A new cobalt(Ⅱ) complex [Co(-phth)(imi)2]n (phth = o-phthalato, imi = imidazole) has been synthesized by the reaction of CoCl2 with disodium o-phthalate and imidazole. The crystal structure of the compound has been determined by single-crystal X-ray diffraction. The crystal is of monoclinic system, space group Pn with a = 8.405(1), b = 9.995(1), c = 9.996(2) ? b = 104.479(2), V = 813.0(2) ?, Dc = 1.467 g/cm3, C14H12N4O4Co, Mr = 359.21, F(000) = 366, m = 1.079 mm-1, Z = 2, R = 0.0483 and wR = 0.1209 for 1583 observed reflections (I > 2s(I)). In the title complex, the Co(Ⅱ) ions are bridged by o-phthalate ligands in a bidentate mode, producing a zigzag infinite chain structure. Each four-coordinated cobalt(Ⅱ) center was coordinated by two oxygen atoms and two nitrogen atoms to give a distorted tetrahedral geometry. The chains are linked by hydrogen bonds between oxygen atoms belonging to carboxylate groups and hydrogen atoms of imidazole molecules, forming an unusual two-dimensional coordination polymer.