[en] Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of diphenyl-N-butylcarbamoylmethyl phosphine oxide (DPBCMPO, L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL₂⁺, ML₂³⁺, ML₃³⁺ and ML₄³⁺ (M³⁺ = Eu³⁺, Am³⁺) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It has been found that the stability constants of the corresponding complexes EuL_n³⁺ and AmL_n³⁺, where n = 2, 3, 4 and L is DPBCMPO, in water saturated nitrobenzene are comparable. (author)

[en] Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of tetraisopropyl methylene diphosphonate [T(iPr)MDP, L] has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL₂⁺, ML₂³⁺, ML₃³⁺ and ML₄³⁺ (M³⁺ = Eu³⁺, Am³⁺) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It was found that the stability constants of the corresponding complexes EuL_n³⁺ and AmL_n³⁺, where n = 2, 3, 4 and L is T(iPr)MDP, in water-saturated nitrobenzene are comparable. (author)

[en] Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of tetraisopropyl methylene diphosphonate [T(iPr)MDP, L] has been investigated. The equilibrium data have been explained assuming that the species HL⁺, HL₂⁺ , ML₂²⁺ and ML₃²⁺ (M²⁺ = Ca²⁺, Sr²⁺) are extracted into the organic phase. The values of extraction and stability constants of the cationic complexes in nitrobenzene saturated with water have been determined. In the considered nitrobenzene medium, it was found that the stability constants of the CaL_n²⁺ complexes, where n = 2, 3 and L is T(iPr)MDP, are somewhat higher than those of the corresponding complex species SrL_n²⁺. (author)

[en] From extraction experiments and γ-activity measurements, the extraction constants corresponding to the general equilibrium M⁺(aq) + 1 · Cs⁺(nb) ↔ 1 · M⁺(nb) + Cs⁺(aq) taking part in the two-phase water-nitrobenzene system (1 = hexaarylbenzene-based receptor; M⁺ = H₃O⁺, NH₄⁺, Ag⁺, K⁺, Rb⁺, Tl⁺; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML⁺ complex species in nitrobenzene saturated with water were calculated; they were found to increase in the series of Rb⁺ < K⁺ < Ag⁺, Tl⁺ < H₃O⁺, NH₄⁺. (author)

[en] Highlights: ► Nitro compounds poses a challenging problem not only for experiment, but also for theory. ► Calculation of enthalpies of formation of nitromethane and nitrobenzene by G4 method using isodesmic reactions. ► New measurements of enthalpy of formation of nitrobenzene would be extremely valuable. -- Abstract: Enthalpies of formation of gaseous nitromethane and nitrobenzene are calculated by Gaussian-4 method with the use of isogyric and isodesmic reactions. Of the two widely-used experimental values for nitromethane (−74.5 and −81.0 kJ · mol⁻¹), the calculations provide strong support for the first one. The cited experimental values of enthalpy of formation of nitrobenzene (67.5 and 68.5 kJ · mol⁻¹) are based on the only calorimetric investigation; the both these values look to be a somewhat overestimated when compared with the average result (62.8 kJ · mol⁻¹) obtained from 95 isogyric and isodesmic reactions with 26 reference nitro compounds involved. The purpose of the present work is to attract attention of experimentalists to new experimental investigation of nitrobenzene, and probably nitromethane as well

[en] From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M²⁺(aq) + SrL²⁺ (nb ↔ ML²⁺(nb) + Sr²⁺ (aq) taking place in the two-phase water-nitrobenzene system (M²⁺ = Ca²⁺, Ba²⁺, Pb²⁺, Cd²⁺; L = hexaethyl calix[6]arene hexaacetate; aq = aqueous phase, nb nitrobenzene phase) were evaluated. Moreover, the stability constants of the ML²⁺ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following order: Cd²⁺ < Ca²⁺ < Sr²⁺ < Pb²⁺ < Ba²⁺. (author)

[en] From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium taking place in the two-phase water-nitrobenzene system (A^- = picrate, 1 = dibenzo-21-crown-7; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K_ex (1 x Cs⁺, A^-) = 4.4 ± 0.1. Further, the stability constant of the 1 x Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 deg C: log β_nb (1 x Cs⁺) = 6.3 ± 0.1. Finally, by using quantum mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1 x Cs⁺ was solved. (author)

[en] Extraction of microamounts of strontium and barium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of polyethylene glycol PEG 1000 (L) has been investigated. The equilibrium data have been explained assuming that the complexes H2L2+, ML2+ and MHL3+ (M2+ = Sr2+, Ba2+) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It was found that in water-saturated nitrobenzene the stability constant of the BaL2+ cationic complex species is somewhat higher than that of the complex SrL2+. (author)

[en] Extraction of microamounts of cesium by nitrobenzene solutions of sodium dicarbollylcobaltate (Na⁺B^-), potassium dicarbollylcobaltate (K⁺B^-) and rubidium dicarbollylcobaltate (Rb⁺B^-) in the presence of polypropylene glycol PPG 425 (L) has been investigated. The equilibrium data have been explained assuming that the complex species ML⁺ (M⁺ = Na⁺, K⁺, Rb⁺, Cs⁺; L = PPG 425) are present in the organic phase. The stability constants of the cationic complex species ML⁺ (M⁺ = Na⁺, K⁺, Rb⁺) in nitrobenzene saturated with water have been determined; they were found to increase in the series of Rb⁺ < K⁺ < Na⁺. (author)

[en] From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺ (aq) + NaL⁺ (nb) ↔ ML⁺ (nb) + Na⁺ (aq) taking place in the two-phase water-nitrobenzene system (M⁺ = H₃O⁺, NH₄⁺, Ag⁺, Tl⁺; L hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML⁺ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following order: Ag⁺ < NH₄⁺ < H₃O⁺ < Na⁺ < Tl⁺. (author)