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RESEARCH PRODUCT

1,2,4,5‐Benzenetetracarboxylic Acid and 4,4′‐Bipyridine as Ligands in Designing Low‐Dimensional Coordination Polymers

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The combined use of 1,2,4,5-benzenetetracarboxylic acid (H4bta) and 4,4′-bipyridine (bpy) as ligands with MnII and CoII ions afforded two polymeric compounds with the formulae [Mn(Hbta)(Hbpy)(H2O)2] (1) and [H2bpy][Co(bta)(bpy)(H2O)2] (2). 1 and 2 were prepared under hydrothermal conditions (145 °C, 3 h) and characterized by elemental analysis, IR spectroscopy, TG-DTA analysis and single-crystal X-ray diffraction methods. 1 exhibits a novel double chain structure growing along the b axis where the manganese atoms are linked by tris-monodentate Hbta3− ligands. The values of the manganese···manganese intrachain separations are 7.627(2) A [Mn(1)···Mn(1c); c = −x + 1/2, y − 1/2, −z] and 9.274(4) A [Mn(1)···Mn(1d); d = x, y + 1, −z]. Adjacent double chains in 1 are further linked through hydrogen bonds between the NH fragment of the Hbpy+ cation and one of the carboxylate groups of the Hbta3− anion along the a axis, resulting in a sheetlike structure. 2 exhibits a rectangular grid arrangement of cobalt atoms bridged by bis-monodentate bta4− and bpy ligands in the bc plane, the cobalt···cobalt separations across them being 6.228(2) and 10.074 (2) A, respectively. The metal atoms in 1 and 2 are six-coordinate with two water molecules in trans positions (1 and 2), three (1)/two (2) carboxylate oxygen atoms and one (1)/two (2) pyridyl nitrogen atoms forming a distorted octahedral environment. The varying nature of the divalent metal ions [Mn 1 and Co 2] along with the differing degrees of protonation of the tetracaboxylate [Hbta3−1 and bta4−2] and bipyridyl [Hbpy+1 and bpy and H2bpy2+2] species account for the structural differences between 1 and 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)