Speciation studies of binary complexes of nickel(II) with L-arginine and L-histidine in micellar medium

School of Chemistry, Andhra University, Visakhapatnam-530 003, India

E-mail : gollapalli@yahoo.com

Department of Chemistry, Dr. L. B. College, Visakhapatnam, India

Department of Chemistry, Anil Neerukonda Institute of Technology & Sciences, Sangivalasa,

Visakhapatnam-531 162, India

Manuscript received 24 August 2004, revised 22 February 2005, accepted 11 April 2005 

A computer assisted investigation has been made on the nature of complexes of nickel(II) with L-arginine and L-histidine. The formation constants have been determined experimentally by monitoring hydrogen ion concentration. The distribution of the metal ion amongst the complexes formed with the above amino acids has also been computed. The formation constants have been refined with the computer program, MINIQUAD75 using the primary alkalimetric data. The distribution pattern of different species varies with the relative concentrations of the metal ion and the ligand. Influence of the micelles on the speciation is discussed based on the dielectric constant of the medium and distribution of various species in the Stern layer and in the bulk solvent. The probable structures of the complexes are also given.