FULL PAPER 1,2,4,5-Benzenetetracarboxylic Acid and 4,4'-Bipyridine as Ligands in Designing Low-Dimensional Coordination Polymers Catalina Ruiz-Pe ´rez,* [a] Pablo Lorenzo-Luis, [b] Marı ´a Herna ´ndez-Molina, [a] M. Milagros Laz, [c] Fernando S. Delgado, [a] Pedro Gili, [b] and Miguel Julve [d] Keywords: Hydrothermal / 1,2,4,5-Benzenetetracarboxylic acid / 4,4'-Bipyridine / Low-dimensional polymers / Manganese / Cobalt The combined use of 1,2,4,5-benzenetetracarboxylic acid (H 4 bta) and 4,4'-bipyridine (bpy) as ligands with Mn II and Co II ions afforded two polymeric compounds with the formu- lae [Mn(Hbta)(Hbpy)(H 2 O) 2 ](1) and [H 2 bpy][Co(bta)(bpy)- (H 2 O) 2 ](2). 1 and 2 were prepared under hydrothermal con- ditions (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 Hbta 3- 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 Hbta 3- anion along the a axis, resulting in a Introduction The crystal engineering of supramolecular architectures or metal-organic coordination polymers is a growing field and it has attracted much attention in the past decades. [1-4] With the recent development of self-assembly supramolecu- lar chemistry, it is possible to rationally design and synthe- size supramolecular architectures or metal-organic coordi- nation polymers based on covalent or supramolecular con- tacts (such as forces resulting from intermolecular non- [a] Laboratorio de Rayos X y Materiales Moleculares, Dpto. de Fı ´sica Fundamental II, Avda, Astrofı ´sico Francisco Sa ´nchez s/ n. Facultad de Fı ´sica, Universidad de La Laguna, 38204, Tenerife, Spain E-mail: caruiz@ull.es [b] Dpto. de Quı ´mica Inorga ´nica (Facultad de Farmacia), Universidad de La Laguna, 38204, Tenerife, Spain [c] Laboratorio de Rayos X y Materiales Moleculares, Dpto. de Edafologı ´a y Geologı ´a, Universidad de La Laguna, 38204, Tenerife, Spain [d] Departament de Quı ´mica Inorga `nica/Instituto de Ciencia Molecular, Universitat de Vale `ncia, 46100 Burjassot, Vale `ncia, Spain Supporting information for this article is available on the WWW under http://www.eurjic.org or from the author. Eur. J. Inorg. Chem. 2004, 3873-3879 DOI: 10.1002/ejic.200400217  2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 3873 sheetlike structure. 2 exhibits a rectangular grid arrange- ment of cobalt atoms bridged by bis-monodentate bta 4- 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) carb- oxylate oxygen atoms and one (1)/two (2) pyridyl nitrogen atoms forming a distorted octahedral environment. The vary- ing nature of the divalent metal ions [Mn 1 and Co 2] along with the differing degrees of protonation of the tetracaboxyl- ate [Hbta 3- 1 and bta 4- 2] and bipyridyl [Hbpy + 1 and bpy and H 2 bpy 2+ 2] species account for the structural differences between 1 and 2. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) bonded, non-covalent electrostatic forces (due to static and oscillating fixed charge interactions) and dispersion forces (due to induced transient charge interactions). [5-7] How- ever, the assembly of molecular materials from organic li- gands and metal ion building blocks to generate new supra- molecular architectures is still a challenge. [8-10] Two main methods can be envisaged in order to construct open supra- molecular architectures on the basis of the different interac- tions between the building blocks: one takes advantage of the covalent bonds and the other focuses on the supramol- ecular contacts. [11] The use of covalent bonds to link metal ions and organic molecules such as polycarboxylic acids or 4,4'-bipyridine (bpy), has resulted in a large number of po- rous frameworks with different dimensionalities and topologies. [12-15] It is worth noting that the coordination ability of aro- matic polycarboxylic acids towards transition metal com- plexes has received considerable attention due to the variety of the bridging modes of the carboxylate group with re- gards to the formation of extended frameworks. [16,17] The goal in the search for organic porous frameworks is not simply to mimic inorganic materials by using different