Synthesis and crystal structure of a novel two-dimensional layered polymer [Zn(μ-O2CCH=CHCO2)(C3H4N2)(H2O)]n

The title complex [Zn(mu-O2CCH=CHCO2)(C3H4N2)(H2O)](n) was prepared by the reaction of zinc carbonate with maleic acid and imidazole in an aqueous-alcohol solution at 333 K, and its crystal structure has been solved by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group Pc with a = 5.3858(7), b = 22.685(3), c 7.6782(1) Angstrom, beta = 92.261(2)degrees, V = 937.4(2) Angstrom(3), Z = 1, C14H16N4O10Zn2, M-r = 531.05, D-c = 1.882 g/cm(3), mu = 2.623 mm(-1), F(000) = 532, the final R = 0.0372 and wR = 0.0930 for 1926 observed reflections with I>2sigma(I). The central zinc atom is five-coordinated in a distorted square pyramidal environment to three oxygen atoms of two different maleate ligands, a nitrogen atom of the imidazole ligand and an oxygen atom of water. In the complex two carboxylate groups of the maleate ligands have two coordination modes. One acts as a bidentate chelate ligand and the other a monoatomic monodentate ligand to bridge two zinc centers. As a result, 1-D infinite polymeric chains are formed, which are linked together by pairs of O-(HO)-O-... hydrogen bonds between the coordination water OH groups and carboxylate oxygen atoms to construct a 2-D layered polymer, and the layer structure is stabilized by pi-pi stacking of the imidozel ligands.