Polarographic Determination of Stability Constant Values of Thallium (I) Complexes with L-Threonine in Aqueous Nonaqueous Media

Author(s): Smita Agrawal and O. D. Gupta

Polarographic studies of stability constants of various species formed by Tl(I)-L-Threonine have been carried out in aqueous-nonaqueous mixture of 20% DMF and 20% ethanol under varying temperatures at 308 K and 318 K and potassium nitrate was used as supporting electrolyte. The reduction was found to be reversible and diffusion controlled involving one electron transfer and ligand have shown the formation of 1 : 1, 1 : 2 complexes. DeFord and Hume's method as modified by Inving has been applied for the determination of composition and stepwise formation constants of complex species and the mathematical Mihailov's method has been also applied for the comparison of stability constant values. The complexes with metal to ligand ratio as 1 : 1, 1 : 2 have been reported. The changes in thermodynamic parameters ΔH°, ΔG° and ΔS° have been evaluated.

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