Hydrogen Bonded Supramolecular Network from a Mixed Valence Cobalt System: Synthesis and Crystal Structure of [Co(H2O)(6)][Co(pydc)(2)(en)](2)center dot 14H(2)O

Abstract

The [Co(H2O)(6)][Co(pydc)(2)(en)](2)center dot 14H(2)O (1) compound (H(2)pydc = Pyridine-2,3-dicarboxylic acid and en = ethylenediamine) was synthesized and characterized by elemental analysis, magnetic and spectroscopic measurements (UV-Vis and IR spectra) and single crystal X-ray diffraction technique. There are two coordination spheres with different charges inside this aqueous compound of ionic character. The cationic part is composed of Co(II) encircled by six aqua ligand. Whereas the anionic part contains two anions complex unit each with -1 charge and have Co(III) ions in the centre. As a result different coordination spheres have cobalt ions with different states. The crystallographic analysis revealed that 1 consists of both discrete one-cationic and two-anionic entities, [Co(H2O)(6)](2+) and [Co(pydc)(2)(en)](2)(-) and fourteen crystal water molecules. Two water molecules within the water cluster act as hydrogen-bonding acceptors, whereas one water molecule acts as a hydrogen-bonding donor to form a discrete water trimer. These water molecules have stabilized the crystal structure by strong hydrogen bonding interactions.