Abstract

Ch. Venkata Ramana Reddy, Shivaraj, G. Seshikala and M. G. Ram Reddy

The formation constants of binary and ternary complexes of the type ML, ML2 and MAL where M(II) = Co (II), Ni (II) and Zn (II); L = ninhydrid (1, 2, 3-triketo hydrindane hydrate or 2, 2-dihydroxy-1,3-indandione) and A=alanine, valine , ethylenediamine, 2, 2-bipyridyl, oxilic acid and catechol have been determined potentiometrically at different temperatures (20,30,40,50 ± 10C) and at 0.1 M (KNO3) ionic strength in aqueous medium. The stabilities of various ternary complexes have been quantitatively compared with those of the corresponding binary complexes. The results are discussed in terms of Δ log K, (Δ log K=log β M MAL (log K M MA + log K M MA) ), nature of donor atoms, basicity of ligands, and charge neutralization. The thermodynamic parameters ΔH, ΔG and ΔS are found to be favourable for the formation of these metals chealtes.

Transition; Aqueous; Medium

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