Synthesis, Structures and Magnetic Properties of CuIIand CoIICompounds Based on Asymmetric 5-(1H-Imidazole-1-yl)-3-pyridine Carboxylic Acid

Five coordination compounds [Cu-2(impc)(2)(mu(2)-OH)Cl](n)(1), [Cu-2(impc)(2)(mu(2)-OH)Br](n)(2), [Co(impc)(2)(H2O)(2)](n)(3), [Co-4(impc)(4)(SO4)(2)(H2O)](n)(4) and {[Co(impc)(H2O)(2)]center dot H2O} (5) based on asymmetric 5-(1H-imidazole-1-yl)-3-pyridinecarboxylic acid (Himpc) have been hydrothermally synthesized and structurally characterized.1and2are isostructural and consist of binuclear Cu(II)units and display two-dimensional (2D) framework, where1and2present a new {(4.6(2))(4(2).6(5).8(2).10)(4)} topology.3features a 1D chain structure. Polymer4, which also displays a new Schlafli symbol {(4(13).6(20).8(8).10(4))(4(3))(2)(4)}, contains tetranuclear Co(II)cluster and is a 2D structure. The planar-type tetranuclear Co(II)cluster with SO(4)(2-)bridge in4has not been reported. Compound5possesses a mononuclear structure. Magnetic susceptibility studies for1and2with Cu(2)units reveal the antiferromagnetic coupling withJ= -3.42 cm(-1)for1andJ= -3.83 cm(-1)for2. Contrary to the only example of class F2 ferromagneticVII,1and2(class F2) exhibit different antiferromagnetic behavior. Compounds3and5exhibit ferromagnetic behavior, and theirM(H)curve is consistent with the ferromagnetic nature. No peaks are observed in the out-of-phase (chi'') plots of3, suggesting no long-range order and no spin canting. For4with the Co(4)units, it also exhibits ferromagnetic behavior, and theM(H) curve is consistent with the ferromagnetic nature.