A New Cd(Ⅱ) Coordination Polymer Constructed by 3-(2-Pyridyl)pyrazole and 5-Nitroisophthalic Acid:Synthesis,Crystal Structure and Theoretical Calculations

A new coordination polymer, Cd_2(NIPH)(L)_2(H_2O)]n(1, HL = 3-(2-pyridyl)pyrazole and H_2NIPH = 5-nitroisophthalic acid), has been synthesized. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, IR spectrum analysis, thermogravimetric analysis and fluorescence spectrum analysis. Complex 1 belongs to the triclinic system, space group P1 with a = 8.9539(6), b = 11.6252(8), c = 12.2472(8) ?, α = 80.011(2), β = 80.3850(10), γ = 86.773(2)°, V = 1237.37(14) ?~3, Z = 2, D_c = 1.987 g/cm~3, μ = 1.780 mm~(-1), M_r = 740.25, F(000) = 724, the final R = 0.0295 and wR = 0.1015 with I 2σ(I). Two H_2NIPH as monodentate and bidentate ligands and two L ligands link four Cd(Ⅱ) ions to form a tetranuclear subunit. Each pair of the tetranuclear subunits is bridged by NIPH ligands to yield a one-dimensional double-chain structure. Furthermore, the 1D chains are linked into a 3D supramolecular framework with hydrogen bonds and π-π interactions. In addition, we analyzed Natural Bond Orbital(NBO) in using the PBE0/LANL2DZ method built in Gaussian 03 Program. The calculation results indicated the obvious covalent interaction between the coordinated atoms and Cd(Ⅱ) ion.