Thermodynamics of Complex Formation between Neodymium(III) and Carboxymethylthiosuccinic Acid and Equilibrium Study of Mixed Complexes with Simple and Substituted Dicarboxylic Acids

Department of Chemistry, Marathwada University, Aurangabad-431 004

Manuscript received 25 October 1983, accepted 17 June 1984

Complexiog of neodymium ion with carboxymethylthiosuccinic and dicarboxylic acids have been studied in aqueous solution potentiometrically and the relevant stability constants have been evaluated using computer technique. Carboxymethylthiosuccinic acid has been shown to form 1 : 2 complexes more readily than other dicarboxylic acids. The thermodynamics of the complex formation have been evaluated by potentiometric equilibrium data and the relationship between the site of coordination. and the thermodynamic quantities has been discussed. The results of mixed complexes are explained in terms of
substituent influences upon the chelation of malonic and succinic dianions to N^III-  CMTSA
systems and the relationship between stabilization parameter ( \(\bigtriangleup\) logK) and the ligand basicity.