Experimental and Theoretical Study on the Complexation of the Thallium Cation with Dibenzo-18-crown-6

摘要

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Tl~+(aq) + 1-Na~+(nb) <=> 1·Tl~+(nb) + Na~+(aq) taking place in the two-phase water-nitrobenzene system (1 = dibenzo-18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K_(ex)(Tl~+, 1·Na~+) = 2.1. Further, the stability constant of the complex 1·Tl~+ in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β_(nb) (1·Tl~+) = 6.6. Finally, by using quantum mechanical DFT calculations, the most probable structure of the resulting complex 1·Tl~+ was solved.