pH Metric Studies on the Mixed Ligand Complexes of Ruthenium(III) with DL-2-Amino-3-Hydroxy Butanoic Acid and Nitrilotriacetic Acid in Aqueous Media

Abstract

The stability constants of the mixed ligand complexes of
ruthenium(III) with DL-2-amino-3-hydroxy butanoic acid (DL-threonine)
as secondary ligand and nitrilotriacetic acid (NTA) as
primary ligand have been determined by employing well known
Irving- Rossotti method as modified by Chidambaram and Bhattacharya
under varying conditions of temperature and ionic strength.
It has also been found that values of stability constants for Ru(III)DL-
2-amino-3-hydroxy butanoic acid-nitrilotriacetic acid mixed
ligand metal complex is significantly less as compared to the first
formation constant value for Ru(III)-DL-2-amino-3-hydroxy
butanoic acid binary metal complex which has been explained on
the basis of factors involving properties like coulombic interaction
between various ligand anion species present and steric hindrance
caused by the bulky NTA molecule. Thermodynamic parameters
have also been evaluated.