Potentiometric Formation of Binary and Ternary Complex of Cu(II) with Tridentate Schiff Base and Dipeptide as Primary and Secondary Ligand

The stability of 1:1:1 ternary chelates of bivalent Cu(II) metal ion with Schiff base ligand 4-hydroxy-3(1-{2-[(4-chlorobenzylideneamino) o-phenylimino) ethyl)-6methyl- 2H-pyran2one- as primary ligand (L 1 ) and DL- Alanyl Glycyl (R 1 ), Glycyl- DL-Valine (R 2 ) as secondary ligand (R1) have been carried out in 60% (v/v) THF-Water medium pH metrically at 30° C and 0.1 M NaClO 4 ionic strength. The stability constants of ternary complexes ML and MR are also determined under similar experimental conditions. The stability constants of ternary complexes are evaluated and their relative stabilities compared to the corresponding binary complexes are evaluated and their relative stabilities compared to the corresponding binary complexes are expressed in terms of statistical parameter Δ logk, K R ,K L and K r values. The species distribution curves are used to explain the variation in concentration of these as function of pH. The pH have been discussed by Irving-Rossotti technique and evaluated by using the computer SCOGS program.