Thermodynamics and Solution Studies on Some Quaternary Metal Complexes and their Comparison with Binary and Ternary Complexes

Abstract

Equilibrium studies on quaternary metal complexes of type M₁M₂AB where M₁ and M₂ are Cu(II) and Ni(II) or Cd(II) or Co(II) or Pb(II), L₁ = o-phenylenediamine and L₂ = salicylic acid were carried out using Irving Rossotti titration technique at 30 ± 0.1, 40 ± 0.1 and 50 ± 0.1 ºC at fixed ionic strength, μ = 0.2 mol dm^-3 (NaClO₄). The separation of titration curves demonstrate the formation of mixed metal mixed ligand complexes of stoichiometry M₁M₂L₁L₂. All metal ion formation constant of the complexes, M₁M₂L₁L₂ in addition to M₁L₁L₂, M₂L₁L₂, M₁(L₁)₂, M₁(L₂)₂, M₂(L₁)₂ and M₂(L₂)₂ type of complexes for all metal ions were evaluated using for the Fortran IV computer program and the complex formation equilibrium data were pruned with the aid of speciation curves plotted with aid of Fortran IV computer program SPEPLOT. The stability order of metal complexes and solution structure of heterobinuclear M₁M₂L₁L₂ complexes have been discussed on the basis of basicity of ligands and coordination sphere of complexation.