Thermodynamic Studies of 5-(P-Bromophenylazo)-3 Phenylrhodanine and Its Metal Complexes.

Document Type : Research Studies

Author

Physical & Mathmatics Science Department., Faculty of Engineering (Shoubra), Benha Branch., Zagazig University, Cairo., Egypt.

Abstract

The dissociation constant of 5-(p-bromophenylazo)-3-phenylrhodanine (HL) and metal-ligand stability constants of its complexes with bivalent (Mn2+, Co2+, Ni2+ and Cu2+) metal icons have been determined potentiometrically in 0.1 M KÇI and 40% (v/v) ethanol-water mixture. The order of the stability constants of the formed complexes was found to be Mn2+ <C02+ < Ni2+ < Cu2+. The effect of temperature was studied and the corresponding thermodynamic parameters (∆G, ∆H and ∆S) were derived and discussed. The dissociation process is nonspontaneous, endothermic and entropically unfavorable. The formation of the metal complexes has been found to be spontaneous, exothermic and entropically favorable. 

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