IJSRP, Volume 4, Issue 7, July 2014 Edition [ISSN 2250-3153]
Sridarala Ramu, Mesineni Anand Rao
The metal mediated intramolecular interactions and their stabilities have been established for the ternary complexes of metal ions (copper, nickel, zinc and cobalt) with beta-hydroxy ketone (BHK) derivatives (O-O donor atoms) and benzotriazole (BTAZ) derivatives (N-N and N-O donor atoms) in 50% water + 50% dioxane medium in 0.1 M KNO3 ionic strength at 25oC using potentiometric pH titrations. The intramolecular interactions and the stabilities of these complexes are quantified in terms of Δ log K values, intra-molecular equilibrium constants and percentage of stacking interaction in the ternary systems. The observed positive Δ log K values suggest that the flexible side chain in BHK ligand having butyl and phenyl ring overlaps with the fixed aromatic moiety of BTAZ ligand in the ternary complex, which results in the enhanced stabilities for the ternary complexes. Based on the experimental data we conclude that, (i) the flexible side chains of BHK ligand having butyl and phenyl ring interacts with the heterocyclic ring of BTAZ ligand in the ternary metal-ligand complex, but not with aniline ring, (ii) ternary complexes with BTAZ having N-N donor atoms form more stable complexes over the BTAZ having N-O donor atoms and (iii) ternary complexes with copper forms more stable complexes, which is followed by zinc ion complexes with the ligands, and both nickel and cobalt form complexes with similar stabilities.