Synthesis, Crystal Structure and Theoretical Calculations of a Three-dimensional Supramolecular Cadmium(II) Coordination Polymer

new metal-organic cadmium coordination polymer [Cd(pzdc)0.5(L)]n·nH2O (1, H2pzdc = pyrazine-2,3-dicarboxylic acid, HL = 3-(2-pyridyl)pyrazole) has been successfully synthesized under hydrothermal conditions. The structure has been determined by single-crystal X-ray diffraction analysis, elemental analyses, IR and fluorescence spectrum. Brown crystals crystallize in the orthorhombic system, space group Fdd2 with a = 11.2636(9), b = 38.296(3), c = 10.5795(8) ?, V = 4563.5(6) ?3, C11H9CdN4O3, Mr = 357.62, Dc = 2.082 g/cm3, μ(MoKα) = 1.924 mm-1, F(000) = 2800, Z = 16, the final R = 0.0169 and wR = 0.0443 for 2106 observed reflections (I > 2s(I)). It shows a two-dimensional network structure and extends into a three-dimensional supramolecular framework through π-π stacking interactions. Moreover, we analyzed Natural Bond Orbital (NBO) by using the PBE0/LANL2DZ method built in Gaussian 03 Program. The calculation results showed obvious covalent interaction between the coordinated atoms and Cd(II) ion.