Equilibrium studies of CoII and NiII ternary complexes with anthranilic acid derivatives and N,N-donor ligands

Department of Chemistry, K. U. College of Engineering, Kothagudem-507 101, Andhra Pradesh, India Department of Chemistry, Nizam College, Osmania University, Hyderabad-500 001, India Department of Chemistry, Chaitanya Bharathi Institute of Technology, Gandipet, Hyderabad-500 075, India E-mail : vrr9@yahoo.com Manuscript received 29 January 2008, accepted 12 June 2008 Equilibrium studies of (1 : 1 : 1) ternary, MAL complexes where, M = CuII and NiII, L = N-methyl anthranilic acid (NMAA), N-butyl anthranilic acid (NBAA) and N-phenyl anthranilic acid (NPAA) and A = 2,2-bipyridyl (bipy) and 1,10- phenanthroline (phen) were carried out pH-metrically at 30 ºC and 0.1 M (KNO3) ionic strength in aqueous-ethanol (50% v/v) medium. The formation constants of the binary (ML) and ternary complexes were determined under identical conditions for better correlation. The relative stabilities of the ternary complexes are quantified in terms of the parameter, Δ log K. The stabilities of the complexes with respect to the ligand, L follow the order, NBAA > NMAA > NPAA. Various factors influencing the formation and stability of the complexes are discussed