Oxonitrates VO(NO<Subscript>3</Subscript>)<Subscript>3</Subscript> and MoO<Subscript>2</Subscript>(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> and nitronium and nitrosonium nitratometallates as nitrating agents

Dissolution of vanadium in anhydrous HNO₃ followed by exposure of the solution in a dessicator over P₂O₅ gave liquid vanadyl trinitrate (I). The X-ray diffraction analysis of I was carried out for a single crystal grown on cooling the liquid in a sealed capillary. The structure is composed of VO(NO)₃ molecules in which the V atom has an unusually high C.N. 7; it coordinates the terminal O atom and three bidentate nitrate groups to form a distorted pentagonal bipyramid as the coordination polyhedron with the terminal O atom occupying one axial vertex. Using the GAMESS program package, ab initio calculation of the structure of VO (NO₃)₃ in the liquid phase was carried out. It was shown that in all three physical states, vanadyl trinitrate retains its molecular structure almost invariable. Toluene and naphthalene nitration using I and (NO₂)[Fe(NO₃)₄], NO[Cu(NO₃)₃], (NO)_3/4(NO₂)_1/4[Zr(NO₃)₅], and MoO₂(NO₃)₂ proceeds at high rates at low temperatures to give an unusually high para-nitrotoluene percentage in the products as compared with the ortho-isomer. The activity of the studied compounds in the nitration of naphthalene decreases in the series VO(NO₃)₃ > (NO)_3/4(NO₂)_1/4[Zr(NO₃)₅] > MoO₂(NO₃)₂.     

Synthesis and X-ray investigation of Rb<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>] and Cs<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>]

Powder and single crystal X-ray diffraction studies have been performed for anhydrous nitrate complexes Rb₂[Pd(NO₃)₄] (I) and Cs₂[Pd(NO₃)₄] (II). Crystal data for I: a = 7.843(1) Å, b = 7.970(1) Å, c = 9.725(1) Å; β = 100.39(1)°, V = 597.9(1) Å ³, space group P2₁/c, Z = 2, d _calc = 2.918 g/cm³; for II: a = 10.309(2) Å, b = 10.426(2) Å, c = 11.839(2) Å; β = 108.17(3)°, V = 1209.0(4) ų, space group P2₁/c, Z = 4, d ^calc = 3.408 g/cm³. The structures are formed by isolated [Pd(NO₃)₄]^2? complex anions and alkali metal cations. The plane-square environment of the Pd atom is formed from the oxygen atoms of the monodentate nitrate groups. The geometrical characteristics of the complex anions are analyzed. Compound II has a short contact Pd...Cs 3.252 Å.     

Interactions in the system Mn(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-HCONH<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

Solubilities and solid phases in the system Mn(NO₃)₂-HCONH₂-H₂O were studied by an isothermal method at 25°C. The congruently saturating compound Mn(NO₃)₂ · 2HCONH₂ · 2H₂O was isolated; the concentration conditions for its crystallization in the system were determined. The solid phases of the system were characterized by physicochemical methods (X-ray powder diffraction, differential thermal analysis, IR spectroscopy, and crystal-optical analysis).     

Supramolecular 2D structure of [Co(2-Me-Pyz)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

The complex [Co(2-Me-Pyz)₂(H₂O)₄](NO₃)₂ is synthesized and its structure is determined. The crystals are monoclinic: space group P2₁/n, a = 10.685(2) Å, b = 6.837(1), c = 12.515(3) Å, β = 91.84(3)°, V = 913.8(3) ų, ρ_calcd = 1.042 g/cm ³, Z = 2. The Co²⁺ ion (in the inversion center) is coordinated at the vertices of the distorted octahedron by two nitrogen atoms of methylpyrazine and four oxygen atoms of the water molecules (Co(1)–N(1) 2.180(3), average Co(1)–O(w) 2.079(3) Å, angles at the Co atom 87.9(1)–92.1(1)°). Supramolecular pseudometallocycles are formed in the structure through the O(w)–H…N(1) hydrogen bonds between the coordinated H₂O molecules and the terminal nitrogen atoms of the 2-methylpyrazine molecules. Their interaction results in the formation of supramolecular layers joined by the NO₃ groups into a three-dimensional framework.     

Thermal behaviour of [Ca(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

Motor gasoline must present characteristics that guarantee its quality and the good performance of internal combustion engines without harming the environment. The contamination of gasoline by solvents can seriously adulterate its physical-chemical properties and affect its volatility and detonation capacity. To investigate organic solvent adulteration in gasoline samples, thermal analysis technique (TG/DTG) can be used as an auxiliary tool in the study of the thermal behavior of liquid fuels, as demonstrated by the present work involving a comparative analysis of kerosene-free and doped gasoline.     

Thermal decomposition of [Cd(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

Thermal decomposition of [Cd(NH₃)₆](NO₃)₂ was studied by thermogravimetry (TG) with simultaneous differential thermal analysis (SDTA) for two samples and at two different sets of measurement parameters. The gaseous products of the decomposition were on-line identified by evolved gas analysis (EGA) with a quadruple mass spectrometer (QMS). The decomposition of the title compound proceeds, for both cases, in the three main stages. In the first stage, deammination of [Cd(NH₃)₆](NO₃)₂ to [Cd(NH₃)](NO₃)₂ undergoes by three steps and 5/6 of all NH₃ molecules are liberated. At second stage the liberation of residual 1/6NH₃ molecules and the formation of Cd(NO₃)₂ undergoes. However, during this process simultaneously a two-step oxidation of a part of ammonia molecules also takes place. In a first step as a result a mixture of ammonia, water vapour and nitrogen is formatted. At the second step, subsequent oxidation of a next part of NH₃ molecules undergoes. As a result, a mixture of nitrogen oxide, nitrogen and water vapour is formatted, what for these both steps clearly indicates the EGA analysis. The third stage of the thermal decomposition is connected with the melting and subsequent decomposition of residual Cd(NO₃)₂ to oxygen, nitrogen dioxide and solid CdO. Additionally, third sample was measured by differential scanning calorimetry (DSC) and the results are fully consistent with those obtained by TG.     

Thermal behaviour of [Mg(DMSO)<Subscript>6</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

Polymorphism and thermal decomposition of [Mg(DMSO)₆](NO₃)₂, where DMSO =(CH₃)₂SO, were studied by differential scanning calorimetry (DSC) and thermogravimetry (TG). The gaseous products of the decomposition were on-line identified by a quadruple mass spectrometer (QMS). Three phase transitions have been detected for this compound in the temperature range of 95–370 K between the following solid phases: stable KIb↔stable KIa at T _C3=195 K, metastable KII↔supercooled K0 at T _C2=230 K and stable KIa→stable K0 at T _C1=337 K. Thermal decomposition of the title compound proceeds in three main stages. In the first stage, which starts just above ca. 380 K, and is continued up to ca. 540 K, the compound loses in two steps four DMSO molecules per one formula unit and undergoes into [Mg(DMSO)₂](NO₃)₂. The second stage starts just immediately after liberating four DMSO ligands and is connected with the decomposition of [Mg(DMSO)₂](NO₃)₂ and the formation of a mixture of solid anhydrous magnesium sulfate, magnesium nitrate and magnesium oxide and also a mixture of gaseous products of the DMSO and Mg(NO₃)₂ decomposition. The third and the last stage corresponds to the decomposition of not decomposed yet magnesium nitrate and formation of magnesium oxide, nitrogen oxides and oxygen.     

Phase formation in the LiCl-LiNO<Subscript>3</Subscript>-KCl-Sr(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> system

The LiCl-LiNO₃-KCl-Sr(NO₃)₂ four-component system was studied for the first time by a complex of physicochemical analysis methods, including differential thermal analysis, X-ray diffraction, visual-polythermal, and projection thermographic methods. Eutectic and peritectic invariant point characteristics were determined, and the phase diagram of the system was constructed.     

Reactions of Cr atoms with NO,N<Subscript>2</Subscript>O,CO<Subscript>2</Subscript>, NO<Subscript>2</Subscript>, and SO<Subscript>2</Subscript> molecules

Experimental results on the interaction of Cr atoms with various oxygen-containing molecules (NO, N₂O, CO₂, NO₂, and SO₂) at high temperatures (>1000 K) are presented. It is demonstrated that activation barrier for spin-forbidden reactions is higher, all other things being equal. For the reaction of Cr atoms with N₂O, an interpolated temperature dependence of the rate constant, based on the high-temperature measurements conducted in the present work and the published low-temperature data, is proposed.     

Glass formation in the Al<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>-Al(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

Glass formation boundaries in the Al₂(SO₄)₃-Al(NO₃)₃-H₂O system were determined. IR spectra were studied. Schemes of structural rearrangements within the boundaries of a second glass formation region in the Al(NO₃)₃-H₂O binary subsystem are suggested. A structure is suggested for glassy Al(NO₃)₃H₂O.     

Conversion of neodymium oxide with N<Subscript>2</Subscript>O<Subscript>4</Subscript> into nitrate followed by supercritical fluid extraction of nitrate

A novel method that spent nuclear fuel is converted into nitrates with N₂O₄, and then nitrates are extracted with TBP in supercritical CO₂ (SC-CO₂), has been developed for reprocessing of spent nuclear fuel, which has a potential prospect because of its potential to decrease generation of the secondary liquid waste. In this paper, conversion of Nd₂O₃ with N₂O₄ into its nitrate under various conditions and extraction of the conversion product with TBP in SC-CO₂ were investigated. When temperature was 60–120 °C, the molar ratio of H₂O to Nd₂O₃ was from 1 to 6, and molar ratio of N₂O₄ to Nd₂O₃ was above 8, complete conversion of Nd₂O₃ into its nitrate was achieved. The conversion product was characterized by thermal analysis (TG-DTA), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and Raman spectroscopy. Quantitative extraction of the conversion product with TBP in supercritical CO₂ was also achieved under experimental conditions.     

Behavior of silver sulfide in the system Ag<Subscript>2</Subscript>S-Fe(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>-HNO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O

Behavior of silver sulfide in the system Ag₂S-Fe(NO₃)₃-HNO₃-H₂O was studied at 25, 55, and 80°C using the method of the simplex-lattice experiment design. The quantitative dependences of Ag₂S oxidation on the concentrations of the acid and Fe³⁺ were determined. The isoconcentration diagrams were obtained.     

LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> and LiCoO<Subscript>2</Subscript> composite cathode materials obtained by mechanical activation

New composite cathode materials xLiMn₂O₄/(1 ? x) LiCoO₂(x = 0.7, 0.6, 0.5 и 0.4) were obtained by mechanical activation. According to scanning electron microscopy data, the process was accompanied by pronounced dispersion and fine mixing of the initial components. In the course of the preparation and electrochemical cycling of the composites, LiMn₂O₄ and LiCoO₂ partially reacted, leading to the replacement of manganese with cobalt in the structure of spinel, which was detected by powder X-ray diffraction (XRD), IR and X-ray photoelectron spectroscopy (XPS), and cyclic chronopotentiometry. The specific discharge capacity of composites was ～100 mAh/g.     

Electrophilic addition to norbornene derivatives containing CF<Subscript>3</Subscript> and NO<Subscript>2</Subscript> groups

Electrophilic sulfenylation, selenenation, and halogenation of bicyclo[2.2.1]heptenes containing CF₃ or NO₂ group in position endo-5 were studied. The sulfenylation and selenenation were accomplished by arylsulfene- and arylselenenamides activated by POHal₃ (Hal = Br, Cl), and iodination was performed by KICl₂. The reactions are regiospecific and involve an exo-attack of the electrophilic fragment (arylthio or arylseleno group or iodine) on the C=C bond atom located closer to the CF₃ or NO₂ group. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1445–1448, June, 2005.     

Radical–molecule reaction CH<Subscript>2</Subscript>Cl + NO<Subscript>2</Subscript>: a mechanistic study

The radical–molecule reaction mechanism of CH₂Cl with NO₂ has been explored theoretically at the B3LYP/6–311G(d,p) and MC–QCISD (single-point) levels of theory. Our results indicate that the title reaction proceeds mostly through singlet pathways, less go through triplet pathways. The initial association between CH₂Cl and NO₂ is found to be the carbon-to-nitrogen attack forming the adduct a H₂ClCNO₂ with no barrier, followed by isomerization to b ₁ H₂ClCONO-trans which can easily convert to b ₂ H₂ClCONO-cis. Subsequently, the most feasible pathway is the C–Cl and O–N bonds cleavage along with the N–Cl bond formation of b (b ₁ , b ₂ ) leading to product P ₁ CH₂O + ClNO, which can further dissociate to give P ₅ CH₂O + Cl + NO. The second competitive pathway is the 1,3-H-shift associated with O–N bond rupture of b ₁ to form P ₂ CHClO + HNO. Because the intermediates and transition states involved in the above two favorable channels all lie below the reactants, the CH₂Cl+NO₂ reaction is expected to be rapid, as is confirmed by experiment. The present results can lead us to understand deeply the mechanism of the title reaction and may be helpful for further experimental investigation of the reaction.     

Thermal analysis of binary system Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SnO<Subscript>2</Subscript> obtained by sol-gel technique

Summary A series of Al₂O₃-SnO₂ catalysts with Al₂O₃ to SnO₂ molar ratio of 1:1, 1:0.5, 1:0.2 and 1:0.1 were synthesized by sol-gel technique and characterized by thermal analysis and FTIR. In the case of binary gels - addition of tin component leads to better crosslinking than in pure alumina gel and as a result to a much uniform texture structure.     

Crystal and molecular structure of ammonium trinitratouranylate NH<Subscript>4</Subscript>[UO<Subscript>2</Subscript>(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>]

Ammonium trinitratouranylate NH₄[UO₂(NO₃)₃] (I) single crystals have been synthesized by the reaction of aqueous solutions of diaquadinitratouranyl tetrahydrate and ammonium nitrate in the presence of nitric acid. The structure of the complex has been studied by X-ray diffraction analysis: space group \(R\bar 3c\), a = 9.361(2), c = 18.883(4) Å; V = 1433.0(5) ų, and Z = 6. The structural units of the NH₄[UO₂(NO₃)₃] crystal—NH ₄ ⁺ cations and [UO₂(NO₃)₃]^? complex anions with three bidentate cyclic nitrato groups—are on crystallographic axes \(\bar 3\). A complex three-dimensional packing arranged by the electrostatic attraction forces between counterions and the N-H...O hydrogen bonds between ammonium cations and trinitratouranylate anions is realized in the structure. X-ray diffraction analysis results are confirmed by IR spectra of NH₄[UO₂(NO₃)₃].