Copper(II) ion catalytic oxidation of o-phenylenediamine and characterization, X-ray crystal structure and solution studies of the final product [DAPH][H3O][Cu(dipic)(2)]center dot 3H(2)O

摘要

The complex [DAPH][H3O][Cu(dipic)2 center dot 3H(2)O, (I) (dipicH(2) = 2,6-pyridinedicarboxylic acid and DAP = 2,3-diaminophenazine) was prepared from the reaction of Cu(NO3)(2)center dot 2H(2)O with mixture of o-phenylenediamine (OPD) and 2,6-pyridinedicarboxylic acid in water. The complex was characterized by FTIR, elemental analysis, UV-Vis and the single-crystal X-ray diffraction. The crystal system is monoclinic with the space group P2(1)/c. This complex is stabilized in the solid state by an extensive network of hydrogen bonds between crystallized water, anionic and cationic fragments, which form a three-dimensional network. Furthermore, hydrogen bonds, pi center dot center dot center dot pi C-O center dot center dot center dot pi and C-O center dot center dot center dot pi stacking interactions seem to be effective in stabilizing the crystal structures. The protonation constants of dipic (L) and DAP (Q), the equilibrium constants for the dipic-DAP proton transfer system and the stoichiometry and stability constants of binary complexes including each of ligands (dipic, DAP) in presence Cu2+ ion, ternary complexes including, both of ligands (dipic-DAP) in presence of metal ion were calculated in aqueous solutions by potentiometric pH titration method using the Hyperquad2008 program. The stoichiometry of the most complexes species in solution was found to be very similar to the solid-state of cited metal ion complex. (C) 2015 Elsevier B.V. All rights reserved.