New butane-1,2,3,4-tetracarboxylato bridged cobalt(II) complexes

Four butane-1,2,3,4-tetracarboxylato bridged supramolecular complexes [Co-2(H2O)(5)(BTC)]center dot 2H(2)O 1, [Co-2(H2O)(5)(BTC)]center dot 2H(2)O 2, [Co-2(H2O)(6)(bpy)(2)(BTC)]center dot 4H(2)O 3 and [Co-2(H2O)(2)(bpy)(2)(BTC)] 4, (H4BTC = butane-1,2,3,4-tetracarboxylic acid, 2,2-bpy = 2,2-bipydine) are synthesized and characterized by single-crystal X-ray diffraction. IR spectroscopy, TG-DTA analyses, elemental analyses, powder X-ray diffraction and magnetic measurements for 3 and 4 are carried out. The dinuclear Co unit in 2 is bridged by BTC4 anions into 2D layers, which are assembled via interlayer hydrogen bonds into a 3D (4(4).6(2))(4(5).6(5))(2)-(4(6) .6(8).8) topological supramolecular architecture. In 3, the [Co-2(H2O)(6)(bpy)(2)(BTC)] molecules are aggregated to 2D layers via pi-pi stacking interactions, the resulting layers are engaged in hydrogen bonding leading to a novel 3D supramolecular architecture with the schlafli symbol of (10(2).12)(2)(4.10(2))(2)-(4(2).10(2).12(2)). The Co atoms in 4 are linked by BTC4 anions into a 1D chain, then the hydrogen bonding and pi-pi stacking interactions result in formation of a 3D novel (4(3).6(2).8)(2)(4(6).6(6).8(3))(6(3))(2) topological networks. The variable temperature magnetic characterizations on 3 and 4 suggest weak antiferromagnetic or ferromagnetic coupling exchange via pi center dot center dot center dot pi stacking interactions (J = -0.03 cm (1) for 3, J = 0.11 cm (1) for 4). (C) 2010 Elsevier B.V. All rights reserved.