Extraction and DFT Study on the Complexation of the Sodium Cation with Dibenzo-18-crown-6.

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Na+(aq) + A-(aq) + 1(nb) left arrow over right arrow 1•Na+(nb) + A-(nb) taking place in the two-phase water-nitrobenzene system (A- = picrate, 1 = dibenzo-18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as was log Kex (1•Na+, A-) = 1.7 ± 0.1. Further, the stability constant of the complex 1•Na+ in nitrobenzene saturated with water calculated for a temperature of 25 °C: log βnb (1•Na+) = 6.9 ± 0.1. Finally, by using quantum mechanical DFT calculations, the most probable structures of the resulting complex were solved.