Reaction Rates and Mechanisms of the Formation of Gallium(III), Indium(III), and Thallium(III) Complexes with Semi-Xylenol Orange in Aqueous Solutions

Publisher Website
Google Scholar
Abstract
The kinetics for the complex formation of Ga(III), In(III), and Tl(III) with Semi-Xylenol Orange (SXO) in acid solutions were studied by stopped-flow technique. Kinetic results are interpreted in terms of a two-step mechanism involving pre-equilibrium. The increase in the reaction rate with decreasing hydrogen ion concentration is interpreted as the sum of several parallel pathways including monohydroxo metal ions and a few charge types of the ligand. The mechanisms and the rates of the three different d10-system metal ions are discussed. The phenomena of the slower increase in absorbance of Ga(III)-SXO complex after the rapid increase and the slow color fading of Tl(III)-SXO complex are also discussed.