Abstract: The complexation of Cr³⁺ with F^- undergoes a multistep reversible process. An approach to research the involved equilibria and kinetics using suitable chemometrics methods to the online measured UV-Vis spectra is proposed. By investigating the equilibrium spectra of the complexes at different molar ratios of M to L(metal to ligand) and 50 ℃, the result of Principal Component Analysis(PCA) shows that three complexes, ML, ML₂ and ML₃, can be formed under the research conditions. The spectrum of each complex was then analyzed and the accumulated equilibrium constants were calculated by applying Target Testing Factor Analysis(TTFA). Meanwhile, a reactive intermediate was observed before the formation of ML_x during the specific kinetic study at 15 ℃. The equilibrium constant and spectrum of the intermediate as well as the rate constants were all resolved by using TTFA.

Key words: Metal complexation, Kinetics, Equilibrium, Reactive intermediate