Polarographic Study of Mixed Ligand Complexes in Aqueous Medium: Lead(II)-Thiourea-Glutamate System

Abstract

The mixed ligand complexes of thiourea (tu) and glutamate (glu) ions withPb(II) have been studied polarographically in aqueous medium at 25 ± 0.5^oCand  μ = 1.0 M (NaClO₄),  Four mixed ligand complexes, viz.,[Pb(tu)(glu)]⁺, [Pb(tu)₂(glu)]⁺,  [Pb(tu)(glu)₂] and [Pb(tu)₂(glu)₂] with theirrespective stability constants log   β₁₁ = 4.79, log  β₂₁ = 5.78, log  β₁₂ = 8.76 andlog  β₂₂ = 9.01 respectively were detected. The values of mixed ligand complexesare compared with the stability constants of the simple mono- andbis-complexes of the binary systems. The statistical factors in the complexationconstants were evaluated by following the procedure suggested by Walters. Thesimultaneous   π-bonding between the metal ion and ligand was inferred from thedeviation observed in the relationship of log K_N and (N - 1) where N representsthe coordination number as suggested by Van Panthaleion Van Eck.