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1.
Radiochemistry - The structures of three new Np(V) complexes [(NpO2)2(phen)2(C7H5O2)2] (I), [(NpO2)2(phen)2. (o-C7H4FO2)2] (II), and [(NpO2)2(phen)2(p-C7H4FO2)2] (III), where phen =... 相似文献
2.
Radiochemistry - Structure of two new molybdate complexes of Np(V) with composition of Cs2[(NpO2)2(MoO4)2(H2O)]·H2O (I) and Cs3[(NpO2)(MoO4)2] (II) has been studied. In structure I, two... 相似文献
3.
Neptunium(V) at its relatively high concentrations in oxalate solutions forms, along with the mono-and bioxalate complexes, the intermediate binuclear anion (NpO 2) 2(C 2O 4) 3 4? . This anion gradually crystallizes from cold aqueous-ethanol solutions in the form of the compound Na 4(NpO 2) 2(C 2O 4) 3 · 6H 2O, and from hot aqueous-ethanol solutions, in the form of a lower hydrate, Na 4(NpO 2) 2(C 2O 4) 3 · 2H 2O. Both compounds were characterized by powder X-ray diffraction and by electronic absorption and IR spectra. The thermal behavior of the hexahydrate in air was studied. Attempts to prepare the related crystalline compounds M 4(NpO 2) 2(C 2O 4) 3 · nH 2O with M = Li or NH 4 failed. 相似文献
4.
Heteroligand compounds AnO 2(bipy)OOCC 6H 5 (An = Np, Pu; bipy = α,α-bipyridine, C 10H 8N 2) were synthesized and studied. It follows from powder X-ray patterns that these compounds are isostructural. Their unit cell parameters, determined by indexing of the powder X-ray patterns, are as follows: a = 9.2162 (7), b = 10.2339(8), c = 17.4083(17) Å, and β = 96.48(1)° for Np and a = 9.1983(18), b = 10.2052(18), c = 17.370(3) Å and β = 96.51(1)° for Pu. The compounds crystallize in the monoclinic system space group P2 1/ n, Z = 4. The electronic absorption spectra of crystalline compounds suggest pentagonal-bipyramidal surrounding of the central atom and the prescence of cation-cation bonds with AnO 2 + ions acting as monodentate ligands with respect to each other. The IR spectra of the compounds were recorded, and their thermal behavior in air was studied. 相似文献
5.
Complexes of 1,10-phenanthroline (phen) with Np(V) and Pu(V) benzoates of the compositions NpO 2(phen)(OOCC 6H 5) and PuO 2(phen)(OOCC 6H 5) were synthesized. A powder X-ray diffraction study showed that these compounds, depending on the preparation conditions, exist in the form of two phases having essentially the same composition but different powder patterns. The phases isolated from hot (70–100°C) solutions are isostructural with the previously described complexes AnO 2(bipy)(OOCC 6H 5) (An = Np and Pu, bipy = 2,2′-bipyridine), i.e., in their structure there are dimeric (AnO 2) 2 2+ cations formed by mutual coordination of two AnO 2 + ions via “yl” oxygen atoms. The compounds AnO 2(phen)(OOCC 6H 5) prepared by slow crystallization in the cold or at weak (up to 45°C) heating are isostructural with each other but appreciably differ in the structure from the high-temperature phases. The electronic absorption spectra of the compounds and their thermal behavior were examined. 相似文献
6.
Double Pu(V) and Np(V) acetates of the compositions BaPuO 2Ac 3·2H 2O and SrAnO 2Ac 3·3H 2O with An = Pu and Np were synthesized in a well-crystallized form. In the dry state the compounds are stable in prolonged storage and are not hygroscopic. The plutonyl(V) and neptunyl(V) salts of the similar composition are isostructural. The IR spectra of the compounds were measured, and their behavior in heating was studied. 相似文献
7.
A spectrophotometric study showed that ozone in concentrated carbonate solutions forms complexes with CO 3 2? ions, which inhibits the ozone decomposition. Free ozone oxidizes Np(V) at high rate. The bound ozone reacts with Np(V) at moderate rate. Np(IV) reacts with O 3 slowly, with Np(VI) formed in NaHCO 3 solution and only Np(V) formed in Na 2CO 3 solution. 相似文献
8.
It was shown that Np(V) forms complexes with anions of orthosilicic acid and other silicate ions at pH higher than 8–8.5. At pH < 9.5, the reaction is mainly described by the equation NpO
2
+
+ OSi(OH)
3
−
⇄ NpO 2OSi(OH) 3; the stability constant of the NpO 2OSi(OH) 3 complex is equal to log β 1 = 2.1 ± 0.3. Thus, interaction is weak and hardly significant under real conditions. Carbonate ions in equilibrium with air at pH > 8.5 are the substantially stronger ligands for NpO
2
+
, and in their presence it is impossible to reveal Np(V) complexation with silicate ions.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 39–43.Original Russian Text Copyright © 2005 by Yusov, Fedoseev, Isakova, Delegard. 相似文献
9.
Crystalline NpO 2OOCH·C 10H 8N 2· nH 2O and NpO 2OOCCH 3·C 10H 8N 2·H 2O were synthesized by the addition of a small excess of α,α′-bipyridine to neutral Np(V) formate and acetate solutions. In the wet state and after drying in air, these compounds have essentially different powder X-ray patterns. In the dry state, these compounds are monohydrates. In formate solutions with addition of α,α′-bipyridine, Pu(V) behaves similarly, whereas attempts to prepare the related Pu(V) acetate complexes failed. The Np(V) and Pu(V) compounds AnO 2OOCCH 3·C 10H 8N 2· nH 2O are isostructural. According to the results of spectrophotometric studies, the coordination polyhedron of the central atom in all the compounds studied is a pentagonal bipyramid. The IR spectra were recorded and the thermal behavior of the compounds was studied. 相似文献
10.
The kinetics of the transformation of Np(V) into Np(IV) in 0.1 M potassium biphthalate solutions containing 5–74 mM sodium 1,2-cyclohexanediaminetetraacetate (Na 2CHDTA) or in a 96–97 mM Na 2CHDTA solution at 25–45°С was studied. The reaction rate at Na 2CHDTA concentrations in the range 5–60 mM and pH 3.5–5.9 is described by the equation V = k[Np(V)] 1.4[CHDTA], and at Na 2CHDTA concentrations in the range 70–100 mM and pH 4.1–5.2, by the equation V = k A[Np(V)] 1.4. Neptunium(V) forms with the CHDTA ion an activated complex in which Np(V) is reduced to Np(IV). The dimer {Np(V)} 2 forming another activated complex with the CHDTA ion is formed concurrently. The latter complex decomposes along the disproportionation pathway to give Np(IV) and Np(VI). Np(VI) is reduced with the CHDTA ion to Np(V). 相似文献
11.
The crystal structure of a dioxalate complex Co(NH 3) 6NpO 2(C 2O 4) 2·1.5H 2O was studied. The structure consists of centrosymmetrical dimeric anions [NpO 2(C 2O 4) 2]
2
6−
, [Co(NH 3) 6] 3+ cations, and water molecules of crystallization. The NpO
2
+
dioxocations have close Np-O bond lengths (average 1.824 Å) and are noticeably bent (ONpO angle 175.6°). Each dioxocation
in the [NpO 2(C 2O 4) 2]
2
6−
anion is surrounded by five oxygen atoms of three C 2O
4
2−
anions; the Np coordination polyhedra are pentagonal bipyramids sharing a common edge.
__________
Translated from Radiokhimiya, Vol. 47, No. 6, 2005, pp. 495–499.
Original Russian Text Copyright ? 2005 by Charushnikova, Krot, Polyakova. 相似文献
12.
Radiochemistry - Phenylacetates [AnO2(C6H5CH2COO)2], where An = U (I), Np (II), or Pu (III), were synthesized and studied by single crystal X-ray diffraction. Compounds I–III are... 相似文献
13.
Interaction of actinides(IV) with hydroxyisobutyric acid (HHIB) in aqueous solutions and in the course of crystallization of solid compounds was studied. The complexes ML n (4-n)+ (M = U, Np, Pu; L ? is hydroxyisobutyrate anion; n = 1, 2, 3) exist in solution. Their apparent stepwise stability constants K?? i were measured, and the overall concentration stability constants ?? 3 of the complexes ML 3 + were calculated. For U(IV) and Np(IV), log?? 3 is close to 13.3?C13.4, and for Pu(IV), log?? 3 = 14.5 ± 0.9 (ionic strength I = 0.1?C0.3). In the course of crystallization in air, complexes of U(IV) with hydroxyisobutyric acid, as well as those with citric acid, undergo oxidative degradation, which can be accompanied by complete oxidation of U(IV). The crystalline compounds formed in the process are oxalates of U(IV) or U(VI). The complexation of Np(V) with HHIB was studied. NpO 2 + forms with HHIB the complexes NpO 2L and NpO 2L 2 ? . Their concentration stability constants are log K 1 = 2.04 ± 0.15 and log K 2 = 0.71 ± 0.10 ( I = 0.4), i.e., log?? 2 = 2.75 ± 0.25. 相似文献
14.
Two new Np(V) malonates, LiNpO 2L·2H 2O and KNpO 2L, where L = CH 2(COO) 2, were synthesized, and their characteristics were studied. Similar to their chemical analogs with Na +, NH 4
+, and Cs + ions in the outer sphere, these compounds transform into well crystallized neptunyl(V) compounds of the MNpO 2CO 3· nH 2O type on heating in sealed ampules beneath the layer of the corresponding alkali metal or ammonium malonate solution at a temperature higher than 140°C. Under hydrothermal conditions (NpO 2) 2L·4H 2O is not converted to lower hydrates, and above 135°C it decomposes to form a dark gray amorphous product. 相似文献
15.
The compounds NH4[AnO2(C6H4FCOO3], where An = U (I), Np (II), or Pu (III), CgH4COO? is the 2-fluorobenzoate anion, were synthesized and studied by single crystal X-ray diffraction. Compounds I–III are isostructural and crystallize in the cubic system, space group P213, Z = 4. The main structural units of I–III are mononuclear complexes [AnO2(C6H4COO)3]? belonging to crystal-chemical group AB31 (A = AnO22+, B01 = C6H4FCOO?). The actinide contraction in the structures of I–III is manifested in a regular decrease in the lengths of the An=0 bonds in the AnO22+ cations and in the volumes of the Voronoi-Dirichlet polyhedra (VDPs) of the An atoms in the series U-Np-Pu. The intermolecular interactions in crystal structures of I–III were analyzed by the method of molecular VDPs. 相似文献
16.
The rate of Np(V) reduction with phenylhydrazine in a perchloric acid solution is described by the equation d[Np(IV)/d t = k
1[Np(V)][C 6H 5N 2H 4
+] + k
3[Np(V)][C 6H 5N 2H 4
+][H +] 2 + k
2[Np(V)][Np(IV)], where k
1 = 1.27 × 10 -
3, 2.81 × 10 -
3, and 5.86 × 10 -
3 l mol -
1min -
1; k
3 = 2.32 × 10 -
3, 1.21 × 10 -
2, and 5.75 × 10 -
2 l 3 mol -
3 min -
1; and k
2 = 1.1, 8.3, and 50 l mol -
1 min -
1 at the ionic strength = 4 and 40, 60, and 80°C, respectively. The activation energies of three reaction pathways are E
1 = 35±7, E
3 = 74±17, and E
2 = 88±1 kJ mol -
1. The reaction is self-accelerated owing to formation of the reactive intermediate, hydroquinone. Its concentration in the reaction mixture is proportional to the concentration of the final product, Np(IV) ion. Probable slow stages of two main and autocatalytic pathways of the reaction are discussed. 相似文献
17.
The Np(V) reduction with hydroxyethylhydrazine is described by the equation −d[Np(V)]/d t = k
1[Np(V)][HOC 2H 4N 2H
4
+
] + k
2[Np(V)][Np(IV][H +] 1.8, reflecting its main and autocatalytic pathways. The rate constants are k
1 = 0.31±0.04 l mol −1 min −1 and k
2 = 4.04±0.11 l 2.8 mol −2.8 min −1 at 80°C and ionic strength μ = 4. The activation energies are E
1 = 90±6 and E
2 = 116±4 kJ mol −1, respectively. The autocatalytic pathway is limited by the reaction between hydroxyethyldiazenium ions, HOC 2H 4N 2H
2
+
and protonated Np(V) ions.
__________
Translated from Radiokhimiya, Vol. 47, No. 2, 2005, pp. 150–153.
Original Russian Text Copyright ? 2005 by V. Koltunov, Baranov, G. Koltunov. 相似文献
18.
Oxidation of U(IV) with Np(V) in bicarbonate-carbonic acid solutions and the nature and reactivity of actinide(IV) compounds formed in these media were studied spectrophotometrically. 相似文献
19.
Neptunium(VI) and plutonium(VI) monophthalates were prepared and characterized. The complexes AnO 2 (COO) 2C 6H 4 2H 2O were isolated from cold solutions, and AnO 2 (COO) 2C 6H 4 1.33H 2O, from hot solutions. NpO 2 (COO) 2C 6H 4 b. 2H 2O and PuO 2 (COO) 2C 6H 4 2H 2O crystalize in the triclinic and monoclinic systems, respectively. The complexes AnO 2(COO) 2C 6H 4 1.33H 2O are isostructural and crystallize in the rhombohedral system. The thermal behavior of these complexes was studied. Their IR and electronic absorption spectra were recorded. The properties of these complexes were compared to those of known U(VI) monophthalates.Translated from Radiokhimiya, Vol. 46, No. 5, 2004, pp. 389–395.Original Russian Text Copyright © 2004 by Krot, Bessonov, Grigorev, Charushnikova, Makarenkov. 相似文献
20.
Sorption of neptunium with fibrous complexing sorbents containing amidoxime and hydrazidine groups was studied. The influence of solution pH and the nature and concentration of salts on sorption of neptunium was examined; the sorption kinetics and the exchange capacity of the sorbents were evaluated. The sorbents are suitable for recovery and concentration of neptunium from aqueous solutions to solve production and environmental problems at the Mayak Production Association. 相似文献
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