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

• Published in: Journal of the Serbian Chemical Society Vol. 68; no. 10; pp. 729 - 749
• Main Authors: Seleem, H.S., El-Shetary, B.A., Khalil, S.M.E., Shebl, M.
• Format: Journal Article
• Language: English
• Published: Serbian Chemical Society 01.01.2003
• Subjects: Schiff-base hydrazones containing the pyrimidine moiety; spectrophotometric determination of stability; stability constants; thermodynamic parameters
• ISSN: 0352-5139; 1820-7421
• DOI: 10.2298/JSC0310729S

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. Tri hidrazona Sifovih baza (ONN - donori) dobijeni su kondenzovanjem 2-amino-4-hidrazino- 6-metilpirimidina sa 2-hidroksiacetofenonom 2-metiloksibenzaldehidom i diacetilom pri cemu su dobijeni 2-OHAHP 2-OMeBHP i DHP. Strukture ovih liganada odredjene su elementalnom analizom, UV IR, 1H-NMR i masenom spektrometrijom. Konstante stabilnosti helata Mn2 Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, UO22+ i Th4+, sa dobijenim ligandima odredjene su potenciometrijski u dva razlicita medija (75%(v/v) dioksan?voda i etanol?voda) na 283, 293, 303 i 313 K pri jonskoj jacini 0,05 M KNO3. Odredjeni su i diskutovani termodinamicki parametri 1:1 i 1:2 kompleksa. Konstante disocijacije 2-OHAHP, 2-OMeBHP i DHP kao liganada, kao i konstante stabilnosti njihovih kompleksa sa Co2+, Ni2+ i Cu2+ odredjene su spektrofotometrijski u smesi 75%(v/v) dioksan?voda.