Formation constants of binary and ternary complexes of Cu(II) with ninhydrin and some O,O; N, and N, N donor ligands in aqueous medium

Abstract

The formation constants of 1:1 and 1:2 binary chelates of Cu(II) with ninhydrin (1,2,3-triketohydrindene hydrate or 2,2-dihydroxy-1,3-indamedione) and the corresponding 1: 1: 1 ternary chelates involving oxalic acid, catechol, α-alanine, valine, ethylenediamine and 2,2-bipyridyl as primary Iigands have been determined <i>p</i>H metrically at 20°, 30°, 40°· and 50°C at 0.1 <i>M </i> (KNO₃) ionic strength. The effect of change in ionic strength has also been studied at 30°C. The order of stabilities of, ternary complexes has been discussed in terms of ∆ log <i>K, </i> basicity of the Iigands, nature of donor sites and thermodynamic parameters.