Potentiometric and spectrophotometric studies of the complexation of Schiff-base hydrazones containing the pyrimidine moiety

• Main Authors: Seleem H.S., El-Shetary B.A., Khalil S.M.E., Shebl M.
• Format: Article
• Language: English
• Published: Serbian Chemical Society 2003-01-01
• Series: Journal of the Serbian Chemical Society
• Subjects: stability constants; thermodynamic parameters; spectrophotometric determination of stability; schiff-base hydrazones containing the pyrimidine moiety
• Online Access: http://www.doiserbia.nb.rs/img/doi/0352-5139/2003/0352-51390310729S.pdf

Three Schiff-base hydrazones (ONN – donors) were prepared by condensation of 2-amino-4-hydrazino-6-methylpyrimidine with 2-hydroxyacetophenone 2-methoxybenzaldehyde and diacetyl to yield 2-OHAHP, 2-OMeBHPand DHP respectively. The structures of these ligands were elucidated by elemental analysis, UV, IR, 1H-NMR and mass spectra. The metal–ligand stability constants of Mn2+, Fe3+,Co2+,Ni2+,Cu2+, Zn2+,Cd2+,UO22+ and Th4+ chelates were determined potentiometrically in two different media (75%(v/v) dioxane–water and ethanol–water) at 283, 293, 303 and 313 K at an ionic strength of 0.05 M (KNO3). The thermodynamic parameters of the 1:1 and 1:2 complexes were evaluated and are discussed. The dissociation constants of 2-OHAHP, 2-OMeBHP and DHPligands and the stability constants of Co2+, Ni2 and Cu2+ with 2-OHAHP were determined spectrophotometrically in 75 % (v/v) dioxane–water.