I. P. Alimarin

Chloride complexes of rhodium (III) in aqueous solutions

1. The process of complex formation of rhodium with the chloride ion in aqueous solutions is stepwise and reversible. 2. On the basis of the spectrophotometric data, using perchlorate solutions of rhodium, we calculated the total and stepwise stability constants of rhodium chloride complexes.

Amperometric determination of chromium (III) in the presence of chromate, using ethylendiaminetetraacetic acid

1. The formation of less inert complexes of chromium (III) with acetate or bicarbonate ions substantially accelerates the complex formation of chromium with EDTA, which permits an amperometric determination of chromium in the titration of an excess of the reagent with a solution of copper salt. TABLE 2. Determination of Chromium (III) in the Pres-ence of Chromate (n=3; α=0.95). RatioCr3+/Cr (VI) Amount of Cr3+, mg. taken found taken found taken found 1:0 1,14 1,15±0,06 1,71 1,72±0,09 3,50 3,48±0,07 1:50 1,71 1,72±0,04 2,86 2,86±0,08 3,50 3,50±0,04 1:100 1,71 1,69±0,05 2,86 2,85±0,04 3,50 3,52±0,10 2. The method permits the determination of 1–3 mg chromium (III) in 10 ml of a solution with an error of less than 1%. The determination is not hindered by hundredfold amounts of chromate.

Extraction of cerium N-benzoylphenylhydroxylaminate

1. Cerium (III) and cerium (IV) are quantitatively extracted by a benzene solution of N-benzoyl-phenylhydroxylamine. Regardless of the initial oxidation state of cerium, a complex compound of Ce (IV) with ratio of the components Ce∶BPHA=1∶4 is present in the extract. 2. The yellow-colored extract of cerium (III) N-benzoylphenylhydroxylaminate, possessing no absorption bands in the visible region of the spectrum, can be obtained only under conditions preventing its oxidation, namely, in the extraction of Ce (III) in an atmosphere of argon or in the extraction of Ce (III) and Ce (IV) in the presence of a reducing agent.

Distribution of the components of the water-organic solvent-mineral acid system between the phase of the cation exchange resin KU-2 and the external solution

1. The distribution of the components of the ternary system: water-organic solvent-mineral acid between the phase of the cation exchange resin KU-2 and the external solution of the components was studied in methanol, propanol, acetone, dioxane, and dimethylformamide solutions of hydrochloric and nitric acids and in dioxane and dimethylformamide solutions of sulfuric acid. 2. With increasing acid concentration, the selective sorption of water is reduced, while the absorption of the organic component is increased. 3. The sorption of the organic component depends on the thermodynamic and structural properties of the solutions. 4. With increasing concentration of the organic solvent, the selective sorption of water is increased. 5. The presence of a small amount of water causes a sharp asymmetry of the distribution curves.

Influence of certain complexing substances on the rate of extraction of chromium (III) 8-hydroxyquinolate

1. A mechanism explaining the rate of extraction when the catalyst is introduced directly before the beginning of the process was proposed. It is suggested that the acceleration of extraction in this case is due to the formation of an activated complex, including both the ligand-catalyst and the reagent, i.e., the complex in which the coordination number of the central ion of the metal is equal to 8. 2. The existence of a relationship between the position of the ligands in the spectrochemical series and their catalytic action on the extraction of chromium (III) 8-hydroxyquinolate was noted.

Investigation of the kinetics of the extraction of chromium (III) by 8-hydroxyquinoline

1. The extraction of Cr(III) with solutions of 8-hydroxyquinoline in organic solvents practically cannot be accomplished even at increased temperature as a result of the “inertness” of aquo-complexes of chromium and on account of the formation of incompletely substituted or hydrated hydroxyquinolinates. 2. The rate of extraction and the amount of chromium extracted increases sharply in the presence of salts of formic or acetic acid when the temperature is raised to 50–80°. The significance of the presence of these salts in the aqueous phase is determined by the formation of more labile complexes of Cr(III). 3. Oxygen-containing organic solvents (alcohols) extract chromium more rapidly and completely than “inert” solvents (of the type of chloroform and benzene) for two reasons: in the first place, on account of the lower distribution constant of the reagent in the system water-organic solvent, and in the second place, on account of the possibility of the formation of solvents of the chromium hydroxyquinolate to be extracted.

Effect of cationic composition on complexation of ruthenium(IV) by chloride and bromide

Substitution of water in the ruthenium(IV) aquacomplex by chloride and bromide in media of various compositions is studied spectrophotometrically. Changing the supporting electrolyte in the series Na-Li-H shifts the equilibrium for formation of the chloro- and bromocomplexes toward species more coordinatively saturated with halide.

Mixed chloro-bromo complexes of ruthenium(IV)

Using spectrophotometry the authors have investigated complexing in the system Ru(IV)-Cl−-Br−. They have identified the formation of mixed-ligand chloro-bromo complexes of Ru(IV) and determined the equilibrium constants of reactions of formation of the complexes [Ru2OCl7Br-(H2O)2]2− and [Ru2OBr7Cl(H2O)2]2−.

Catalytic effect of ruthenium compounds on the oxidation of bromide and chloride ions by sodium perchlorate

1. When chloro and bromo complexes of ruthenium(III) and ruthenium(IV) are heated, oxidation of iodide ions by sodium perchlorate is catalyzed. 2. The optimal conditions for the reaction have been found and a kinetic method for determination of Ru(III) and Ru(IV) is proposed.

The state of osmium(IV) in hydrochloric acid solutions

1. Using spectrophotometry the authors have investigated the state of Os(IV) in hydrochloric acid solutions without maintenance of a constant ionic strength. At 90°C, aquation, hydrolysis, and apparently reduction of Os(IV) to Os(III) take place in the solutions, depending on the HC1 concentration and heating time. Equilibrium is not attained for 400 h. 2. Photochemical aquation and hydrolysis occur in hydrochloric acid solutions of potassium hexachloroosmate. It is shown that aquation of the hexachloroosmate anion takes place in stages and is reversible; successive formation of two thermodynamically stable monoand diaquo complex forms has been established.