Hydrothermal synthesis of two novel three-dimensional cobalt(II) metal–organic frameworks based on polycarboxylate and benzotriazole

The hydrothermal reactions of 1,4-H2BDC or 1,4-H2CDC, HBTA, with Co(NO3)2 · 6H2O in basified solvent gave rise to two coordination polymers, Co5(μ3-OH)2(1,4-BDC)3(BTA)2 (1), [Co(1,4-CDC)0.5(BTA)] (2) (1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,4-H2CDC = 1,4-cyclohexanedicarboxylic acid, HBTA = benzotriazole) and characterized by elemental analysis, IR, single-crystal X-ray diffraction and variable-temperature magnetic measurements. Complex 1 crystallizes in the triclinic system, P View the MathML source1¯ space group; the structure determination reveals that 1 has a scarcely reported 8-connected 3D self-penetrating structure based on pentanuclear cobalt clusters. Complex 2 is monoclinic system, P21/c space group, and the X-ray structural analysis shows that 2 has a 3D infinite network with (4.64.8)(42.62.82) topology. Complex 1 exhibits moderately antiferromagnetic coupling, while complex 2 indicating strong spin-orbit coupling.