Abstract

Mamdouh S. Masoud, Ekram A. Khalil and Adel R. Youssef

The dissociation constants of 3-amino-4-(arylazo)-5~(1H) pyrazolones containing different Substituents are evaluated potentiometrically and spectrophotometrically. The data are explained in terms of the electronic character of the substituents. The pK values are increased by increasing the mole fraction of dioxane solvent. The electronic spectra were recorded in solvents of different polarities. The stability constants of CoII, NiII and CuII complexes were evaluated in 50% (v/v) dioxane-water media. The mechanism of complexation is favoured by metal ion - π electron back donation.

Dissociation; Solvent; Compounds

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