Mixed-Ligand Complexes of Cadmium(Ii) With Phthalate and Some Amino Acids

Sudesh Kumar Singh and C. P. Singh Chandel*

Department of Chemistry, University of Rajasthan, Jaipur- 302 004 (India)

The reduction of cadmium(II) in the presence of phthalate and some amino acids (Isoleucine, Valine, Threonine and Serine) has been carried out electrochemically. The reduction of all the systems has been found to be reversible and diffusion controlled, involving two electrons. The stability constants of mixed-ligand complexes MXY, MXY2 and MX2Y have been evaluated by the method of Schaap and McMasters. The statistical and electrostatic effect have also been discussed by using these stability constants. For the comparison of the simple and mixed complexes, the mixing constants (Km) and the stabilization constants (Ks) are measured. The positive values of the mixing constants and stabilization constants show that the ternary complexes are more stable than the binary complexes. For the comparison of the stability Dlog K are measured. The Dlog K values are higher than statistical values which again proves that the ternary complexes are more stable than expected from statistical reasons.

Stability constant; mixed-ligand complexes; polarography