Stability constants of ternary complexes of Ni(II) with 4-hydroxypicolinic acid N-oxide as a primary ligand & S,O; O,O; N, O & N, N donor ligands as secondary ligands

Abstract

The equilibria involved in the formation of ternary chelates of Ni(II) with different ligands in the presence of O,O donating ligand(4-OH picolinic acid N-oxide) have been studied by <em>p</em>H-titration technique at 30°± 1°C and μ = 0.1 M(KNO₃) in aqueous medium. The ligands used are (i) thioglycolic acid (S,O donor); (ii) catechol, oxalic acid, salicylic acid (N,O donors); (iii) glycine, alanine, proline (N,O donors); (iv) ethylenediamine, 1,10-phenanthroline,2,2'- bipyridyl (N, N donor). The overall stability constants of ternary chelates are discussed in the light of basicity of ligands, nature of donor atoms, metal-ligand dπ-pπ, and dπ-dπ interactions, denticity, stereochemical interactions etc.