Interconnection between mechanistic and kinetic investigations of organometallic complex formation in palladium detection.

The main goal of this work was to explain the mechanism of organometallic complex formation during the process of palladium determination. The azo dye tropaeolin OO and Pd(II) ions in various media (H2O, acetate buffer, ethanol) were used as a model system to predict the mechanism. The changes occurring during complex formation were monitored spectrophotometrically. Based on the obtained spectra evolution, at selected wavelengths kinetic curves were constructed. Rate constants for formation of the intermediate and final products were determined by fitting equations to the kinetic curves. The changes in the spectra were correlated with changes in the complex structure based on TD-DFT calculations and further confirmed using NMR spectra. The collected data provides a comprehensive overview of the organometallic complex formation pathway, pointing to a consecutive reaction mechanism. Furthermore, to support the proposed models (A→B→C and A→B&C), kinetic simulations were performed using Berkeley Madonna software. A thorough understanding of the kinetics and reaction mechanism underlying complex formation is essential for advancing the analytical applications of these complexes in palladium and other precious metal detection.