Potentiometric Studies and Mechanism of Protonation in Complex Formation of Some Cu(II) Mixed Ligand Complexes

Abstract

Modified form of Irving-Rossotti titration technique is used to
determine the formation constants for Cu(II) mixed ligand complexes
at 1 : 1 : 1 optimum molar concentration of metal, primary
ligand (A) and secondary ligand (L). The formation constant values
of binary complexes are compared with ternary complexes. The
Δlog K_T values are negative suggests favourable formation of ternary
complexes. The variation of   Δlog K_T values has been explained
in terms of M  → Lπ interaction, size of chelate ring and
steric factors. Stability Constants have been evaluated and discussed
in terms of basicity of ligand, statistical and stereochemical phenomenon.
A mechanism of protonation in complex formation is
suggested.