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1.
The analysis of reported data on the interaction of ozone with alkaline solutions of PuVI leads to the conclusion that the process of ozonation involves reactions O3 + OH → HO 2 - + O2, O3 + + HO 2 - + OH → O 3 - + O 2 - + H2O and O3 + O 2 - → O 3 - + O2. The O 3 - radical ion oxidizes PuVI, the HO 2 - and O 2 - anions reduce PuVII and PuVI and react with O 3 - . Using persulfate instead of O3 in aerated solution at 80—95 °C results in thermal decomposition of the S2O 8 2- anion into radical ions of SO 4 - , oxidizing OH to the O ion, which in reaction with O2 forms O 3 - . The oxidation of PuVI proceeds via the formation of an activated complex with O 3 - . where charge transfer occurs with the simultaneous elimination of two H+ ions. A similar mechanism is operating in reactions of PuVI with BrO, Fe(CN) 6 3– , AmVI, and AmVII. Upon the γ-radiolysis of alkaline solutions of PuVI saturated with N2O or containing S2O 8 2– , e aq is converted into O and then into O 3 - ; F2 and XeF2 in alkaline solutions are decomposed with the formation of H2O2, which prevents producing PuVII.  相似文献   

2.
The energies and structural and spectroscopic characteristics of endohedral (MO4©B20O 30 n? ) and exohedral (MO4 · B20O 30 n? ) isomers of oxoborate complexes with MO 4 n? tetraoxo anions with 32 valence electrons located in the inner and outer spheres of the B20O30 cluster have been calculated by the density functional theory method (B3LYP). It has been demonstrated that, among the endohedral MO4©B20O 30 n? clusters with strong multiply charged anions (VO 4 3? , CrO 4 2? , PO 4 3? , SO 4 2? , AsO 4 3? , SeO 4 2? , etc.), the isomer in which a “guest” tetrahedron MO4 is located at the center of the B20O30 cage and bonded to it through internal oxygen bridges M-O*-B is the most favorable one. Among the exohedral analogues MO4 · B20O 30 n? , two most favorable isomers contain the “capping” MO4 tetrahedron bonded to the B20O30 cage through two and three external M-O-B bridges. For the complexes with doubly charged SO 4 2? and SeO 4 2? anions, the third exohedral isomer in which the sulfite or selenite group MO3 is bidentately coordinated to the oxidized B20O29(OO) cage with one peroxide bridge turns out to be close in energy to the above two isomers. For the systems with high negative charge n, the exohedral isomers are much more favorable than the endohedral isomer; however, with decreasing charge, the difference in energy between them decreases to ~10–18 kcal/mol, so that the exo–endo transition between them can require moderate energy inputs. For the endohedral complexes with singly charged ClO 4 ? and BrO 4 ? anions, two isomers with close energies are preferable in which the central atoms of the guest tetrahedra are reduced to the state of singly charged ions, while the oxoborate cage is oxidized to B20O26(OO)4 with four peroxide groups B-O-O-B and retains its closed (closo) structure. In the most favorable isomer of the complexes with multicharged ortho-anions BO 4 5? , CO 4 4? , and NO 4 3? , the outersphere anion is reduced to, respectively, borate, carbonate, and nitrate bidentately coordinated to the oxidized B20O29(O)2 cage with an open structure and two strongly elongated terminal B-O bonds. The results are compared with the data of previous calculations of endohedral and exohedral vanadate complexes MO4©V20O 50 n? and MO4 · V20O 50 n? with the same guest anions MO 4 n? .  相似文献   

3.
The emission spectra of hydrogen-oxygen and hydrogen-air flames at 0.1–1 atm exhibit a system of bands between 852 and 880 nm, which is assigned to the H2O2 molecule vibrationally excited into the overtone region. This molecule results from the reaction HO 2 · + HO 2 · → H2O 2 v + O2. The overtone region also contains bands at 670 and 846 nm, which are assigned to the vibrationally excited HO 2 · radical. This radical results from the reaction between H and O2. The HO 2 · radicals resulting from H2 or D2 combustion inhibited by small amounts of propylene are initially in vibrationally excited states. The role of vibrational deactivation is discussed.  相似文献   

4.
Peroxocarbonate ions HCO 4 ? and CO 4 2? , which are formed in the H2O2/NH4HCO3/HO? system, react with 4-nitrophenyl diethyl phosphonate (I) through a nucleophilic mechanism with rate constants \(k_{HCO_4^ - } = 0.008\) and \(k_{CO_4^{2 - } } = 0.13 L/mol \cdot s\). Comparison of these constants with the corresponding constants of other inorganic anions in their reaction with I in the framework of the Brönsted equation indicates that HCO 4 ? and CO 4 2? are typical α-nucleophiles.  相似文献   

5.
Ionic liquids with N-decylpyridinium cation and inorganic anions SO 4 2– , NO 3 , SCN, NO 2 , BF 4 were synthesized. The structure and composition of the synthesized compounds was proved by elemental analysis and IR spectroscopy. Electroconductivity of aqueous solutions of new ionic liquids was studied, critical concentrations of micelle formation was determined, and thermal stability in air in the temperature range 25–500°С was investigated.  相似文献   

6.
MALDI-TOF was used to study molybdenum dioxide (MoO2) containing a nanosized fraction. The composition of cationic clusters of nonstoichiometric lower molybdenum oxides in the gas phase was determined, and the thermodynamic stabilities and configurations of isomers were calculated for selected symmetric molecular structures and for cations MoSO 8 + and Mo5O 9 + . Molecular orbital analysis was performed for two trigonal-bipyramidal clusters Mo5O8 and Mo5O9. Changes in molybdenum–molybdenum interatomic distances in going from MoO 8 + and Mo5O 9 + cations to neutral clusters are discussed.  相似文献   

7.
Structural parameters and vibrational frequencies of the clusters (Td)–Nb4O10, (C3v)-TaNb3O10, (D2d)-Nb4O 10 , and (Cs)-TaNb3O 10 were calculated. According to the (U)DFT/SDD calculations with BLYP, B3LYP, and PBE0 functionals magnetization of the anion (D2d)-Nb4O 10 is distributed equally among four niobium atoms. In the anion (Cs)-TaNb3O 10 unpaired electron presumably occupies niobium atoms. The distinction in contributions from Nb atoms in the magnetization of the tantalum-containing cluster grows with the exchange component of the DFT functional in the series of functionals BLYP < B3LYP < PBE0 < UHF.  相似文献   

8.
The interaction of AgCN molecules and Ag(CN)2?, Ag(CN)32?, Ag(CN)43? ions with the silver surface is studied based on the cluster model of the metal surface by quantum chemistry methods. The geometrical and energy parameters of the interaction of these species with the metal surface are assessed. As regards the strength of their chemical bond with the surface, these compounds form the following series: Ag(CN)2? < Ag(CN)32? < AgCN < Ag(CN)43?. The surface activity of silver-containing species is compared with regard to the solvent effect. It is found that Ag(CN)2? and Ag(CN)32? anions exhibit close adsorbabilities on silver. Molecules AgCN are not accumulated on the surface because of their very low content in solution. The adsorption of Ag(CN)43? is hindered due to a considerable value of degradation energy of this three-charged ion. In the adsorbed state, the ions Ag(CN)2? and Ag(CN)32? represent stable compounds displaying no surface dissociation to yield compounds with the smaller coordination numbers.  相似文献   

9.
Substitution of chloride ions in AuCl 4 ? with ethylenediamine (en) and propylenediamine (tn) is studied by capillary zone electrophoresis at I = 0.05 M and T = 25°C. The substitution constants are determined: AuenCl 2 + + en = Auen 2 3+ + 2Cl, logK2 = 10.4; AuCl 4 ? + tn = AutnCl 2 + + 2Cl, logK1 = 16.1; AutnCl 2 + + tn = Autn3+2 + 2Cl, logK2 = 12.0.  相似文献   

10.
The single crystals of Rb2[(UO2)2(C2O4)2(SeO4)] · 1.33H2O were synthesized and studied by X-ray diffraction. The crystals are monoclinic, space group P21/m, Z= 2, the unit cell parameters: a = 5.6537(8), b = 18.736(3), c = 9.4535(15) Å, β = 98.440(5)°, V = 990.6(3) Å3, R 1 = 0.0506. The main structural units of the crystal are infinite layers of [(UO2)2(C2O4)2(SeO4)]2?, corresponding to the crystal chemical group A2K 2 02 B2 (A = UO 2 2+ , K02 = C2O 4 2? , B2 = SeO 4 2? ) of uranyl complexes. The uranium-containing layers are united into a three-dimensional framework through the electrostatic interactions with the outer-sphere rubidium ions and the hydrogen bonding system involving the outer-sphere water molecules.  相似文献   

11.
12.
The total limiting molar electrical conductivities of ions and triads of ions and the association constants of ions with the formation of ion pairs and triads of ions were calculated from the concentration dependences of the electrical conductivity of solutions of lithium and sodium perchlorates in tetrahydrofuran at 278.15–318.15 K with the use of the method specially developed earlier. The experimental total limiting electrical conductivities were used to calculate the limiting molar electrical conductivities and attraction friction factors of separate ions (Li+, Na+, ClO 4 ? , Li2ClO 4 + , Na2ClO 4 + , Li(ClO4) 2 ? , and Na(ClO4) 2 ? ). The constants of ion association into ion pairs were used to calculate the Gibbs energy of non-Coulomb interionic interaction (ΔG*+?), and the constants of association into triads of ions, to determine the a 3 distance parameter between the centers of the ion and the dipole of the ion pair. Positive ΔG*+?), values and deviations of the experimental a 3 value from the distance parameter calculated theoretically (a 3 0 ) for the triad of ions (Δa 3 = a 3 ? a 3 0 ) were related to non-Coulomb repulsion in the region of overlap of the solvation shells of ions and the influence of temperature and ion charge density on this repulsion.  相似文献   

13.
The activation energy and rate constant of the reaction between the nitroxyl radical and N-alkoxyamine as a concerted abstraction–fragmentation reaction have been calculated using the intersecting parabolas model. This reaction proceeds fairly rapidly and leads to nitroxyl radical autoregeneration as a result of the following consecutive reactions:AmO? + AmOR → AmOH + >C=O + Am?, RO 2 ? + AmOH → ROOH + AmO?, Am?+ O2 → Am 2 ? , and 2AmO 2 ? → 2AmO? + O2. Thus, the nitroxyl radical is an effective radical catalyst for its own regeneration from N-alkoxyamine. The rates of regeneration of the nitroxyl radical from its N-alkoxyamine under the action of alkyl, alkoxyl, peroxyl, nitroxyl, and hydroperoxyl radicals under conditions of polypropylene oxidation inhibited by the nitroxyl radical are compared. It is demonstrated that only peroxyl, hydroperoxyl, and nitroxyl radicals are involved in AmO? regeneration from AmOR.  相似文献   

14.
The vaporization of the NaI-PrI3 quasi-binary system was studied by high-temperature mass spectrometry over the whole concentration range. At 623–994 K, saturated vapor contained not only (NaI) n and (PrI3) n molecules (n = 1, 2) and Na+(NaI) n (n = 0–4) and I?(PrI3) n (n = 1–2) ions but also mixed molecular and ionic associates recorded for the first time (NaPrI4, Na2PrI5, NaPrI 3 + , Na2PrI 4 + , Na3PrI 5 + , Na4PrI 6 + , NaPrI 5 ? , and NaPr2I 8 ? ). The partial vapor pressures of molecules were calculated, and the equilibrium constants of the dissociation of neutral and charged associates were measured. The enthalpies of molecular and ion-molecular reactions were determined, and the enthalpies of formation of gaseous molecules and ions were obtained.  相似文献   

15.
Relativistic quantum chemistry investigations are carried out to tackle the puzzling oxidation state problem in a series of MO_3~- trioxide anions of all d- and f-block elements with five valence electrons. We have shown here that while the oxidation states of V, Nb, Ta, Db, Pa are, as usual, all +V with divalent oxygen O(-II) in MO_3~- anions, the lanthanide elements Pr and Gd cannot adopt such high +V oxidation state in similar trioxide anions. Instead, lanthanide element Gd retains its usual +III oxidation state, while Pr retains a +IV oxidation state, thus forcing oxygen into a non-innocent ligand with an uncommon monovalent radical(O~·) of oxidation state -I. A unique Pr·- ·(O)_3 biradical with highly delocalized unpairing electron density on Pr(IV) and three O atoms is found to be responsible for stabilizing the monovalent-oxygen species in PrO_3~- ion, while GdO_3~- ion is in fact an OGd~+(O_2~(2-)) complex with Gd(III). These results show that a na?ve assignment of oxidation state of a chemical element without electronic structure analysis can lead to erroneous conclusions.  相似文献   

16.
The substitution equilibria AuCl 2 ? + iNH 4 + = Au(NH3)iCl2 ? i + iCl? + iH+, β i * . were studied pH-metrically at 25°C and I = 1 mol/L (NaCl) in aqueous solution. It was found that logβ 1 * = ?5.10±0.15 and logβ 2 * = ?10.25±0.10. For equilibrium AuNH3Clsolid = AuNH3Cl, log K s = ?3.1±0.3. Taking into account the protonation constants of ammonia (log K H = 9.40), the obtained results show that for equilibria AuCl 2 ? + iNH3 = Au(NH3)iCl2 ? i + iCl?, logβ1 = 4.3±0.2, and logβ2 = 8.55±0.15. The standard potentials E 0 1/0 of AuNH3Cl0 and Au(NH3) 2 + species are equal to 0.90±0.02 and 0.64±0.01 V, respectively.  相似文献   

17.
The structure of aqueous lithium tetraborate solutions was investigated by species distribution calculation and synchrotron X-ray scattering. It shows that the dominant species in supersaturated solution at 298.15 K is B4O5(OH) 4 2? and the minor species are B3O3(OH) 5 2? , B3O3(OH) 4 ? and B(OH)3. The ‘intramolecular’ structural parameters of B4O5(OH) 4 2? , such as bond length and coordination number, were gives out using density function theory calculation. X-ray scattering study shows that the distance Li–O(H2O)I of [Li(H2O)4]+ is about 0.1983 nm with the coordination number(CN) 4 in tetrahedral configuration. The B–O(H2O) distance in hydrated anion B4O5(OH)4(OH2) 8 2? is 0.3662 nm with the CN 12. The Li+–B distance is about 0.3364 nm with a coordination number ~1.0. The temperature effect on solution structure was also discussed.  相似文献   

18.
The molecular and ionic sublimation of polycrystals and single crystals under Knudsen effusion and Langmuir evaporation conditions is reported. In both sublimation regimes, the sublimation product at 780–1050 K contains neodymium tribromide monomer and dimer molecules, as well as the negative ions NdBr 4 ? , Nd2Br 7 ? , and Br?. The dimer-to-monomer flux ratio j(Nd2Br6)/j(NdBr3)is larger in the molecular beam coming out of the effusion hole, while the ratio of the sublimation fluxes of the negative ions, j(Nd2Br 7 ? )/j(NdBr 4 ? ), is independent of the sublimation conditions. The partial pressures of the neutral components of the vapor have been determined, and the enthalpies and activation energies of sublimation of neodymium tribromide as monomer and dimer molecules and NdBr 4 ? and Nd2Br 7 ? ions have been calculated. The equilibrium constants of ion-molecule reactions have been measured, and the enthalpies of these reactions have been determined. Based on these data, values of the thermodynamic properties Δ s H 0(298.15) and Δ f H 0(298.15) are recommended for the monomer and dimer molecules and the NdBr 4 ? and Nd2Br 7 ? ions.  相似文献   

19.
Anion chromatography with ANIEKS-N selective ion exchanger and redox photometry with an antimony(V) ionic associate as selective oxidizing agent were suggested for determination of low concentrations of toxic (F?, Br?, NO 2 ? , NO 3 ? ) and biogenic (SeO 3 2? , I?) ions in some potable waters available from central water supply systems and mineral water springs.  相似文献   

20.
The paper presents the results of a theoretical study of the dynamics of nonadiabatic transitions between the ion-pair states E0 g + and D0 u + of the I2 molecule induced by collisions with the I2 molecule in the ground electronic state X0 g + . The potential energy surfaces and diabatic coupling matrix elements of electronic states were obtained using a model based on the diatomics-in-molecule approximation. Special perturbation theory for intermolecular interaction was used to show that the large transition dipole moment between the E0 g + and D0 u + states caused the appearance of additional long-range corrections, an electrostatic dipole-quadrupole correction to the diabatic coupling matrix elements and induction dipole-dipole correction to the potential energy surface. The influence of these corrections on nonadiabatic dynamics was studied at the level of the semiclassical approximation. The electrostatic correction was found to sharply increase the contribution of resonance (accompanied by minimum kinetic energy changes) vibronic transitions at large distances between the colliding molecules. The induction correction had the opposite effect because of the high transition probability at short distances. The results obtained were in qualitative agreement with experimental data. The conclusion was drawn that obtaining quantitative agreement required a more balanced inclusion of interactions at short and long distances.  相似文献   

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