Two Coordination Polymers Based on the Flexible N-Substituted 2,2'-Biimidazole Ligand: Solvothermal Synthesis, Crystal Structures and Characterizations

Two new supramolecular complexes, [Cu;（Pra;biim）;（H;O）;]×2 H;O（1） and [Mn（Pra;biim）(H;O);];（2）(H;Pra;biim = 1,1?-di（propionic acid）-2,2?-biimidazole) have been prepared and structurally characterized by thermogravimetric analysis, elemental analysis, IR spectra and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that complex 1 crystallizes in the triclinic, space group P1 with a = 8.403, b = 9.60970（10）, c = 10.5681（2） ?, V = 736.272（16） ?3, Z = 1, Dc = 1.695 g/cm3, F（000） = 386, GOOF = 1.156, R(I > 2σ（I）) = 0.0396 and w R(I > 2σ（I）) = 0.1060, and exhibits a dinuclear structure formed by the connection of Cu2+ ions with two bridging Pra2 biim2-ligands. Complex 2 crystallizes in the monoclinic, space group Pc with a = 9.058（4）, b = 5.2745（16）, c = 17.591（7） ?, V = 733.2（5） ?3, Z = 2, Dc = 1.663 g/cm3, F（000） = 378, GOOF = 1.060, R(I > 2σ（I）) = 0.0885 and w R(I > 2σ（I）) = 0.2199, and the Pra2 biim2-ligands link Mn2+ ions to a 63 2 D sheet structure. The Pra2 biim2-ligand shows two different types of coordination modes. Moreover, hydrogen bonds further stabilize the 3 D supramolecular architecture. The magnetic behavior in the temperature range（2～300 K） reveals weaker antiferromagnetic interactions between the Cu2+ ions in 1.