Synthesis, Structures and Magnetic Properties of Cu II and Co II Compounds Based on Asymmetric 5‐(1 H ‐Imidazole‐1‐yl)‐3‐pyridine Carboxylic Acid

Five coordination compounds [Cu 2 (impc) 2 (µ 2 ‐OH)Cl] n ( 1 ), [Cu 2 (impc) 2 (µ 2 ‐OH)Br] n ( 2 ), [Co(impc) 2 (H 2 O) 2 ] n ( 3 ), [Co 4 (impc) 4 (SO 4 ) 2 (H 2 O)] n ( 4 ) and {[Co(impc)(H 2 O) 2 ] · H 2 O} ( 5 ) based on asymmetric 5‐(1 H ‐imidazole‐1‐yl)‐3‐pyridinecarboxylic acid (Himpc) have been hydrothermally synthesized and structurally characterized. 1 and 2 are isostructural and consist of binuclear Cu II units and display two‐dimensional (2D) framework, where 1 and 2 present a new {(4.6 2 )(4 2 .6 5 .8 2 .10)(4)} topology. 3 features a 1D chain structure. Polymer 4 , which also displays a new Schläfli 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 in 4 has not been reported. Compound 5 possesses a mononuclear structure. Magnetic susceptibility studies for 1 and 2 with Cu 2 units reveal the antiferromagnetic coupling with J = –3.42 cm –1 for 1 and J = –3.83 cm –1 for 2 . Contrary to the only example of class F2 ferromagnetic VII , 1 and 2 (class F2) exhibit different antiferromagnetic behavior. Compounds 3 and 5 exhibit ferromagnetic behavior, and their M(H) curve is consistent with the ferromagnetic nature. No peaks are observed in the out‐of‐phase ( χ'' ) plots of 3 , suggesting no long‐range order and no spin canting. For 4 with the Co 4 units, it also exhibits ferromagnetic behavior, and the M ( H ) curve is consistent with the ferromagnetic nature.