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Synthesis, characterization and crystal structure of novel supramolecular proton transfer compound frombenzene-1,2,4,5- tetracarboxylic acid, diethylenetriamine and cupper(ii) chloride

MehrnoushAhmadi, Samaneh Salkhordeh,Majid Esmhosseini

We have recently focused on the proton delivery from acids, which are considered to be suitable proton donors, to amines as proton acceptors. The results were the production of proton transfer ion pairs possessing some remaining donor sites applied for coordination to metal centers in the preparation of metal-organic compounds. A new proton transfer compound, [Cu(BTEC)(H2dn)(H4BTEC)0.5.3H2O]n was synthesized from the reaction of CuCl2.2H2O and (BTEC)(H2dn)2.2H2O,(BTEC) = benzene- 1,2,4,5-tetracarboxylato and (H2dn) = diethylene amine diammonium. The characterization was performed using IR spectroscopy and single crystal X-ray structure determination. The crystal structure of the title compound consists of one copper(II) cation, one diethylene amine diammonium cation, one benzene-1,2,4,5-tetracarboxylato anion, one half of free benzene- 1,2,4,5- tetracarboxylate and three water solvent molecule. The Cu(II) atom is four-coordinated in a distorted square-planer configuration by four O atoms from four benzene-1,2,4,5-tetracarboxylato ligand. The Cu-O bond lengths are 1.960(3), 1.963(3), 1.921(3) and 2.020(3)ºA. The chemical formula is [Cu(C4H15N3)(C10H2O8)(C10H6O8)0.5.3H2O]n. The title compound crystallizes in the Monoclinic system with unit-cell parameters a= 11.7356(6) Å, b= 17.4020(7) Å, and c= 11.7253(6)Å, and space groupP21/ c, Z= 4. Its structure has been determined from single-crystal X-ray diffraction data and refined to a conventional R=0.053 (Rù=0.119) for 3455 reflections with I>2ó(I). The intra and intermolecular N–H...O, O–H...O and C–H...O hydrogen bonds stabilize the crystal structure.