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

Abstract

AbstractThe 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) Å [Mn(1)···Mn(1c); c = −x + 1/2, y − 1/2, −z] and 9.274(4) Å [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) Å, 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)