A. V. Belyaev

Technological Problems of Platinum Metals in Nuclear Fuel Waste Disposal

This paper discusses waste disposal of nuclear fuel from atomic power plants (APPs). The state of fragmentation platinum metals (ruthenium, palladium, and rhodium) and their distribution in waste disposal processes are analyzed. The state of fundamental research on the coordination chemistry of these metals in nitrite and nitrate solvents is characterized for technological design of methods for the separation of valuable components.

103Rh and 17O NMR study of oligomer rhodium(III) sulfates in aqueous solutions

By virtue of 103Rh-, 17O-NMR, electrophoresis in agarose gel, and pH-metry, we report on the formation of rhodium(III) sulfate complexes in aqueous solutions. At higher concentrations of sulfuric acid (above 3 M), more than 90% of metal was found to stay in the state of symmetric polynuclear complexes containing magnetically equivalent rhodium atoms. We also labeled the 103Rh-NMR chemical shifts for the complexes with 3, 4 and 6 metal atoms in the spectra.

Tetrabutylammonium Salts of Ruthenium(II) Nitroso Complexes

The paper describes synthesis of (n‐Bu4N)2[RuNOCl5](I), (n‐Bu4N)2[RuNOCl4OH](II), (n‐Bu4N)2×[RuNOCl4OH]·6H2O (III), and (n‐Bu4N)2[RuNOCl5]· 2(n‐Bu4N)2[RuNOCl4(H2O)]·2H2O (IV). The complexes were studied by IR spectroscopy and powder X‐ray and crystal X‐ray analyses. The structures are built up of [RuNOCl5]2- (I, IV), [RuNOCl4OH]2- (II, III), and [RuNOCl4(H2O)]- (IV) complex anions, (n‐Bu4N)+ cations, and crystal water molecules (III, IV). The substances are moderately soluble in water; highly soluble in polar organic solvents, such as acetone, ethanol, chloroform, methylene chloride; and almost insoluble in carbon tetrachloride and toluene. Under storage in light, the compounds decompose from the surface; in darkness I and II are stable, whereas III and IV can lose part of the crystal water.

State of Radiorhodium in High-Level Liquid Waste from Regeneration of Spent Nuclear Fuel

The state of radiorhodium in liquid waste from processing of spent nuclear fuel was analyzed in detail by ESR and NMR spectroscopy on several nuclei. The most probable oxidation state of rhodium in nitric acid solutions is +3. Three procedures for preparing nitric acid solutions of rhodium were studied. The composition of Rh(III) complexes in these solutions is similar but not identical. The method for identifying the ionic composition of similar objects was proposed. The speciation of rhodium in nitric acid solutions with the acid concentration ranging from 2×10-2 to 15 M was studied. Polynuclear oligomers with (μ-ONO2)2 bridges, mainly tetramers, are formed in solutions with CRh > 2 M, [NO3-] ≥ 8 M, and [H+] ≥ 0.7 M. At CRh = (1-2)×10-2, [NO3-] = 1-4 M, and [H+] = 0.4-4 M, the (μ-OH, μ-ONO2) dimer and trimer prevail; at [NO3-] < 1 M and [H+] < 0.2 M, the (μ-OH, μ-ONO2) dimer dominates. No Rh(III) aqua ion and no monomeric nitrate complexes were detected in the quasiequilibrium system at any concentrations of the components. In nitrate-nitrite solutions, both “subnitrated” (μ-OH, μ-ONO2) Rh(III) oligomers and mononuclear Rh(III) nitroaqua complexes exist. The equilibrium between these species is attained very slowly and depends on the equilibrium concentration of nitrite anion. Forecast was given on isolation of rhodium from nitric acid solutions of SNF by extraction, ion-exchange, electrolytic, and precipitation procedures.

Synthesis and Crystal Structure of Nitrosoruthenium Triammino Complex [RuNO(NH3)3Cl(H2O)]Cl2

This paper reports on a procedure for the synthesis of the compound [RuNO(NH3)3Cl(H2O)]Cl2. The complex was studied by IR spectroscopy and X-ray phase and X-ray diffraction analyses. Crystal data for RuCl3N4O2H11: a = 13.151(2), b = 6.852(1), c = 10.361(1) Å, V = 933.6(2) Å2, space group Pna21, Z = 4, dcalc = 2.181 g/cm3, dexp = 2.178 g/cm3. The structure consists of the [RuNO(NH3)3Cl(H2O)]2+ complex cations and Cl– anions. The compound crystallizes as small orange red isometric orthorhombic crystals well soluble in water and insoluble in concentrated hydrochloric acid and organic solvents and is stable when stored in air.

A multinuclear magnetic resonance study of transformations of ruthenium(II) nitrosyl chloride complexes in aqueous solutions

Aqueous solutions of ruthenium nitrosyl chloride complexes have been studied by14N, 15N, 17O, 99Ru, and 35Cl NMR. Individual complex species have been identified and the corresponding chemical shifts have been determined. The primary aquation product of the pentachloronitrosylruthenate ion is the cis-[RuNO(H2O)Cl4]− complex, which subsequently undergoes isomerization. The equilibrium constants of interconversions of ruthenium nitrosyl chloride complexes in an aqueous solution at room temperature have been estimated.

Crystal structures of rhodium(III) aqua ion with tetrahedral anions

The crystal structures of compounds of the composition [Rh(H2O)6]2(SO4)3·5H2O (I) and [Rh(H2O)6]PO4 (II) are determined. Crystallographic data for I: a = 7.272(9) Å, b = 27.047(1) Å, c = 12.464(9) Å, β = 97.038(10)°, P21 space group, Z = 4, dx = 2.184 g/cm3; for II: a = 9.746(6)Å, b = 6.877(7) Å, c = 23.623(6) Å, β = 100.601(10)°, C2/c space group, Z = 8, dx = 2.611 g/cm3. Compounds are analyzed by IR spectroscopy and powder XRD. Crystalline phase I is well soluble in water, whereas II is almost insoluble.

Platinum(IV) complexation with the nitrate ion in aqueous solutions according to 195Pt, 15N, 14N, and 17O NMR data

Solutions of platinum(IV) nitrate were studied by 195Pt, 15N, 14N, and 17O NMR and IR and Raman spectroscopy. It was found that in nitric acid, two interrelated systems of nitrate complexes, mono- and polynuclear ones, coexist. The complexes predominating in concentrated solutions are [Pt2(μ-OH)(μ-NO3)(NO3)2(H2O)6 − x(OH)x](4 − x)+, [Pt4(μ-OH)3(μ-NO3)3(NO3)3(H2O)9 − x(OH)x](7 − x)+, [Pt4(μ-OH)4(μ-NO3)2(NO3)4(H2O)8 − x(OH)x](6 − x)+, and [Pt4(μ-OH)6(NO3)3(H2O)16 − x(OH)x](7 − x)+.

Formation of a Dimer with a Double Hydroxo Bridge in Nitric Acid Solutions of the Nitrosotetranitrohydroxo Complex of Ruthenium(II). Crystal Structure of K2[RuNO(NO2)3(μ-OH)]2

AbstractFine yellowish orange crystals of the binuclear complex K2[RuNO(NO2)3(μ-OH)]2 were obtained by the reaction of K2[RuNO(NO2)4OH] with a stoichiometric amount of 0.8 M nitric acid at room temperature. The compound was investigated by IR spectroscopy, X-ray phase analysis (DRON-3M, CuKα radiation), and X-ray diffraction analysis (Nonius CAD-4, MoKα radiation, graphite monochromator, ω scan mode, 1406 reflections). The crystals are poorly soluble in water and practically insoluble in ethanol and acetone; the compound is stable when stored in air. Crystal data for H2K2N8O16Ru2 are: a = 8.596(2), b = 10.111(1), c = 9.537(1) Å, β = 104.42(1)°, V = 802.8(2) Å3, space group