I. M. Gusev

Effect of the oxidation state of copper on the solution-solid phase equilibria in CuClx-MCl-H2O systems

The effect of the oxidation state of the metal on the solubility was analyzed using the example of CuClx-MCl-H2O (x = 1, 2; M = Li-Cs, NH4) ternary systems. The prevalence of acido complex formation is responsible for an essential similarity of the solubility isotherms: the presence of crystallization branches of complex salts and salting-in (or weak salting-out) of copper(I) and (II) chlorides, that increases in the order LiCl < NaCl < KCl < CsCl. The different stability of copper(I) and (II) chloride complexes results in that the chemical individuality of alkali metal cations is differently reflected in the shape of the solubility isotherms: The stronger complex formation in copper(I) systems results in leveling of this effect and the weaker complex formation with copper(II), in its differentiation.

Solution-solid phase equilibrium in the systems MgBr2-NR4Br-H2O at 25°C (R = Me, Et, Bu)

Solubility in the ternary systems MgBr2-NR4Br-H2O (R = Me, Et, Bu) at 25°C was determined by the isothermal saturation method. A comparative analysis of phase diagrams was fulfilled. The results obtained were interpreted in the context of competition between hydration and association processes in water-salt systems. The structure of double salts NMe4Br·MgBr2·6H2O and NEt4Br·MgBr2·8H2O was determined, and the possibility for predicting compositions of crystallizing double salts on the basis of crystallographic characteristics of ions was analyzed.

Structure of complex bromides crystallizing in MBr2-NEt4Br-H2O systems (M = Cd, Cu, Co) at 25°C

The crystalline structures of four tetraethylammonium salts, [Et4N]CdBrP3, [Et4N]Cd2Br5, [Et4N]2CoBr4, and [Et4N]2CuBr4 were determined by X-ray analysis of their single crystals. The CdBrx2 − x anions in the examined salts are linked to polymeric chains, and the coordination number of cadmium ion is 5 or 6. The d-metal ion in the copper and cobalt complexes has tetrahedral configuration, and the corresponding anions are discrete.

Structure of NR4BR-H2O and CoBr2-NR4BR-H2O solutions according to electronic and IR spectroscopy data

Absorption spectra of NR4Br-H2O and CoBr2-NR4Br-H2O (R = Et, Bu) aqueous solutions were measured within the range of 1000–25000 cm−1, and the influence of tetraalkylammonium cations on the equilibrium between cobalt octahedral and tetrahedral complexes was revealed. The specificity of hydration interactions in solutions under study in various concentration ranges and resulting from them difference in spectral characteristics were analyzed. Variously directed changes in positions of bands in the region of stretching vibrations, a composite frequency of 5200 cm−1, and the first water overtone occurring due to the concentration variation were found.

Formation of complex and double salts in systems MX2-NR4X-H2O [M = Cd(II), Cu(II), Co(II), Mg(II); X = Cl, Br; R = Me, Et, Bu] at 25°C

Results of an experimental research of phase equilibrium in ternary systems MX2-NR4X-H2O [M = Cd(II), Cu(II), Co(II), Mg(II); X = Cl, Br; R = Me, Et, Bu] at 25°C were reported. A comparative analysis of compositions of solid compounds and regions of their crystallization, which are equilibrium with liquid phase, was conducted. An effect of hydration, association of salts of quaternary ammonium and acido complexation of ions of d-elements on the formation of the complex and double salts in the systems was presented.

Solution-solid phase equilibrium in the systems MBr2-NR4Br-H2O (M = Cd, Cu, Co; R = Me, Et, Bu) at 25°C

The solubility diagrams in ternary MBr2-NR4Br-H2O systems (M = Cd, Co; R = Me, Et, Bu) at 25°C were determined by isothermal saturation. The composition and crystallization range of solid compounds occurring in equilibrium with the liquid phase were found. The effects of ion hydration, association of tetraalkylammonium salts, and complex formation with d-elements on the solution-solid phase equilibrium were estimated.

Anion influence on the solution-solid phase equilibria in the MX2-NEt4X-H2O systems (M = Cd, Cu, Co; X = Cl, Br) at 25°C

Solubility of the ternary systems M-NEt4Cl-H2O (M = Cd, Cu, Co) at 25°C was determined by the method of isothermal saturation. Compositions and fields of crystallization of solid compounds in equilibrium with a liquid phase were determined. Changes in the processes of hydration, association of tetraethyl ammonium salts, and acido-complex formation of d-element ions on the replacement of a halide anion affect the solution-solid phase equilibria in the studied systems.

Comparative analysis of the solubility in the systems CuBr2-NR4Br-H2O at 25°C

The solubility in the CuBr2-NR4Br-H2O (R = Me, Et, n-Bu) ternary systems at 25°C was determined by the isothermal saturation method. Comparative analysis of the phase equilibria diagrams was done. The results obtained were interpreted in terms of the competition of two processes, association of tetraalkylammonium salts and copper(II) complex formation in water-salt systems.