Role of weak interactions in binding of aryldicarboxylate ion: Synthesis, spectroscopic characterization, single-crystal X-ray structure determination and packing analysis of [Co(phen)(2)CO3](2)(C8H4O4)center dot 15H(2)O

To explore the role of weak interactions in aryldicarboxylate binding, the hydrated complex salt, [Co(phen)(2)CO3](2)(C8H4O4)center dot 15H(2)O, 1, (C8H4O42- = terephthalate) was synthesized and characterized by elemental analyses, spectroscopic studies (IR, UV/Visible, H-1, C-13 and Co-59 NMR), physical measurements and single-crystal diffraction. Compound 1 crystallizes in space group Pi and the unit cell contains two complex cations, one terephthalate anion and fifteen water molecules. Two N,N-bidentate 1,10-phenanthroline ligands and one O,O-bidentate carbonate dianion lead to a distorted cis-CoO2N4 octahedral geometry for the metal ion. In the crystal, a supramolecular network built up from C-H center dot center dot center dot O-water/carboxylate (through second sphere interactions) and O-H center dot center dot center dot O-water/carboxylate pi-pi stacking and C-H center dot center dot center dot pi interactions besides electrostatic forces of attraction help to consolidate the packing. Interestingly a chain of water hexamers and tetramers running along the a-axis also have been observed which is trapped in between the complex cations and terephthalate anions framework. (C) 2010 Elsevier B.V. All rights reserved.