J. Iran. Chem. Soc., Vol. 8, No. 4 December 2011, pp.919~930.

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A Proton Transfer and a Nickel(II) Compound Including Pyridine-2,6-dicarboxylate and Phenylhydrazinium Ions: Synthesis, Characterization, Crystal Structure and Solution Study

M. Ghadermazia,*, F. Manteghib, S. Mehdizadeha, N. Kakaeia, A. Shokrollahic, Z. Malekhosseinic and M. Shamsipurd

aDepartment of Chemistry, Faculty of Science, University of Kurdistan, Sanandaj, Iran
bDepartment of Chemistry, Iran University of Science and Technology, Tehran, Iran
cDepartment of Chemistry, Yasouj University, Yasouj, Iran
dDepartment of Chemistry, Razi University, Kermanshah, Iran

The new compounds, (phhyH)2(pydc), 1 and (phhyH)[Ni(pydc)(pydcH)].3H2O, 2, phhy: phenylhydrazine, pydcH2: pyridine-2,6-dicarboxylic acid, were synthesized and characterized by IR, 1H NMR, 13C NMR and UV spectroscopy. The structure of 2 was determined by X-ray crystallography. In the crystal structure, the metal ion was six coordinated by two tridentate (pydc)2- and (pydcH)- groups and each anionic complex unit, [Ni(pydc)(pydcH)]- was accompanied by one (phhyH)+ as counter ion and two water molecules. In compound 2, a large number of O-H∙∙∙O, N-H∙∙∙O and C-H∙∙∙O hydrogen bonds were observed. These interactions as well as other noncovalent interactions such as ion pairing, C-O∙∙∙π and π-π stacking play an important role in the formation and stabilization of the crystal lattice. In the solution study, the equilibrium constants for the binary pydc-phhy proton transfer system, the stoichiometry and stability of complexation of this system with Ni2+ ion in aqueous solution were investigated using potentiometric pH titration method. The stoichiometry of the most abundant species in the solution was compared to the crystalline cited metal ion complexes.

Keywords: Pyridine-2,6-dicarboxylic acid, Phenylhydrazine, Nickel, Proton transfer, Crystal structure, Solution study

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