Synthesis, Crystal Structure and Theoretical Calculations of a New Two-dimensional Co（II） Coordination Polymer Based on Oxalic Acid and Bis（imidazol） Ligands

A new Co(Ⅱ) coordination polymer has been successfully synthesized under hydrothermal conditions [Co(C2O4)(mbix)]n(1, H2C2O4 = oxalic acid, mbix = 1,3-bis(imidazol-1-ylmethyl)benzene). Its structure has been determined by elemental analyses, IR, UV spectroscopy and single-crystal X-ray diffraction analysis. Pink crystals crystallize in the triclinic system, space group P1 with a = 8.8666(7), b = 9.5859(8), c = 10.8537(9) , α = 67.6810(10), β = 66.1260(10), γ = 77.1300(10)°, V = 777.77(11), C16H14CoN4O4, Mr = 385.24, Dc = 1.645 g/cm3, F(000) = 394, Z = 2, μ(Mo Kα) = 1.134 mm-1, the final R = 0.0482 and w R = 0.1231 for 2968 observed reflections(Ⅰ 2σ(Ⅰ)). It shows a two-dimensional(2D) network structure. The intermolecular C–H···O hydrogen bonding and π-π stacking interactions extend complex 1 into a 3D supramolecular architecture andplay an important role in stabilizing 1. In addition, Natural Bond Orbital(NBO) analysis was performed by using the PBE0/LANL2 DZ method built in Gaussian 09 Program. The calculation results showed obvious covalent interaction between the coordinated atoms and Co(Ⅱ) ion.