Formation constants of lanthanide metal ion chelates with some substituted sulfonic acids

R.S. SONONE* and G.H. MURHEKAR

Department of Chemistry, Govt. Vidarbha Institute of Science and Humanities, Amravati- 444 604 (India).

Received on December 22, 2009 and accepted on January 28, 2010

ABSTRACT

The pKa and logK values of some substituted sulfonic acid in 70% (v/v) dioxane-water mixture have been determined using pH metric measurements. The stability constant of complexes of Gd (III), Tb (III) and Ho (III) with p-aminobenzenesulfonic (L1) and p-sulfophthalic acid (L2), 2-amino-5-chloro benzenesulfonic acid (L3) and trifluoromethanesulfonic acid (L4) have been determined at 0.1M ionic strength at 28±0.1 0C pH metrically. It is observed that both the metal ions formed 1:1 & 1:2 complexes with all the ligands.

Keywords : Stability constant, chelates, and sulfonic acids.