Journal of the Serbian Chemical Society 2009 Volume 74, Issue 3, Pages: 269-277
https://doi.org/10.2298/JSC0903269D
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Acid-base equilibria of the Zn(II) and Fe(III) complexes with condensation products of 2-acetylpyridine and the dihydrazide of oxalic and malonic acid
Dražić Branka
(Farmaceutski fakultet, Beograd)
Popović Gordana
(Farmaceutski fakultet, Beograd)
Jelić Ratomir
(Prirodno-matematički fakultet, Kragujevac)
Sladić Dušan
(Hemijski fakultet, Beograd)
Mitić Dragana
(Hemijski fakultet, Beograd)
Anđelković Katarina (Hemijski fakultet, Beograd)
Tešić Živoslav
(Hemijski fakultet, Beograd)
Acid-base equilibria of Zn(II) and Fe(III) complexes with N',N'2-bis- [(1E)-1-(2-pyridyl)ethylidene]ethanedihydrazide (ligand L1) and N',N'2-bis[(1E)- -1-(2-pyridyl)ethylidene]propanedihydrazide (ligand L2), i.e., [Fe(L1)Cl2(H2O)], [Fe(L2)Cl(H2O)]2+, [Zn(L1)(H2O)3]+ and [Zn(L2)(H2O)2]2+, which expressed cytotoxic activity, were investigated in aqueous media. The equilibrium constants were determined potentiometrically at 25°C at a constant ionic strength of 0.10 mol/dm3 (Na2SO4). The results showed that at pH < 8 both the Fe(III) complexes studied here have three, while [Zn(L1)(H2O)3]+ and [Zn(L2)(H2O)2]2+ have one and two titratable protons, respectively. Based on the obtained values for the equilibrium constants, protonation schemes of the examined complexes are proposed.
Keywords: metal complexes, d-metals, hydrazone, acid-base equilibria, potentiometry