Polaigraphically Determination of Stability Constants of Mixed Ligand complexes of Cadmium(II) with Pyridine and Some Amino Acids

Abstract

The mixed ligand complexes of pyridine and lysine and metheonine with Cd(II) have been studied polarographically at constant ionic strength, μ = 1.5M (NaNO₃) and pH 8.2 at 25.4 ± 0.1°C. The reduction of the complexes at d.m.e. is reversible and diffusion-controlled. Two mixed complexes [Cd(lys)(pyr)]⁺, and [Cd (lys)₂(pyr)] are formed in Cd(II)––lysine-pyridine system with the stability constants log b₁₁ = 5.230 and log b₂₁ = 8.602. Three mixed complexes [Cd(meth)(pyr)]⁺, [Cd(meth)(pyr)₂]⁺ and [Cd(meth)₂(pyr)] are formed in Cd(II)-metheonine-pyridine system with the stability constants log b₁₁ = 5.322, log b₁₂ = 6.518 and log b₂₁ = 9.113 respectively.