Russian Journal of Inorganic Chemistry最新文献

The variable-composition compounds Bi(Al_1–xFe_x)₃(PO₄)₂(OH)₆ with an alunite-type structure were obtained by hydrothermal synthesis in the Bi₂O₃–Al₂O₃–Fe₂O₃–P₂O₅–H₂O system. Using experimental data on the miscibility limits of components in (1–x)BiAl₃(PO₄)₂(OH)₆–xBiFe₃(PO₄)₂(OH)₆, parameters of the subregular solution model were determined (Q₁ = 6.395, Q₂ = 8.987 kJ/mol) and the curves for spinodal and binodal decomposition of solid solutions with alunite-type structure were calculated. According to thermodynamic calculations, the compounds BiAl₃(PO₄)₂(OH)₆ and BiFe₃(PO₄)₂(OH)₆ can be formed at temperatures above 122 and 170°C, respectively, which is consistent with the experimental data obtained in the present study, indicating the absence of compounds with alunite-type structure at 160°C in the 0.8 < x ≤ 1 range.

The structure of ZnZrF₆·6H₂O and ZnZrF₆·5H₂O (high- and low-temperature forms) crystal hydrates and products of their thermal destruction ZnZrF₆·4H₂O, ZnZrF₆·2H₂O, ZnZrF₆, and ZnZr₂F₁₀·2H₂O have been studied. With the exception of ZnZr₂F₁₀·2H₂O, compounds of ZnZrF₆·nH₂O (n = 6, 5, 4, 2, 0) are isostructural to their formula analogs NiZrF₆·6H₂O, α- and β-MgZrF₆·5H₂O, CuZrF₆·4H₂O, MgZrF₆·2H₂O, and MgZrF₆, respectively. The structure of ZnZr₂F₁₀·2H₂O is built of unique infinite network anionic layers (_{infty }^{2})[Zr₂F₁₀]^2–, in which ZrF₈ square antiprisms are formed tetranuclear cycles and are shared six of their vertices with four neighboring Zr-polyhedra according to the law “…–edge–edge–vertex–vertex–…”; ZnF₄(H₂O)₂-octahedra link Zr-layers to each other into a framework.

The dependence of the microstructural properties of copper nanowires on temperature (110, 120, and 130°C) and time (4 and 8 h) has been studied for the hydrothermal synthesis of copper nanowires using oleylamine and dextrose. The change in diameter of the Cu nanowires formed was monitored by spectrophotometry in the visible range. X-ray powder diffraction was used to confirm the target crystal structure and the absence of copper oxide impurities, as well as to show the nonlinear dependence of the average size of the coherent scattering region on the temperature and duration of the synthesis process. The scanning electron microscopy results showed that, in general, increasing the temperature and duration of the synthesis process leads to an increase in the length of the formed copper nanowires from 45 to 150 μm, i.e. under certain conditions, ultra-long structures are obtained. As a result, the aspect ratio varies from 782 to 2358 by altering the synthesis conditions. Transmission electron microscopy shows that the sample obtained at 110°C (4 h) differs from the others by the presence of particles up to 10 nm in size on the surface of the nanowires. The microstructural parameters of the obtained materials were also studied by atomic force microscopy, and the values of the electronic work function of the individual copper nanowire surface in ambient atmosphere were determined by Kelvin probe force microscopy.

Successive abstraction of H₂ from the [ZnMg(BH₄)₄·4NH₃] and [Zn₂Mg₂(BH₄)₈·8NH₃] complexes has been modeled within the framework of the cluster approach using the 6-31G* basis set and the hybrid density functional (B3LYP). It has been found that to start the dehydrogenation process, it is necessary to overcome the energy barrier of ~1.25 eV, then the process proceeds with energy release until about 70% of the available H₂ is extracted; for a higher degree of conversion, additional energy input is required. The cleavage of H₂ molecules occurs through several intermediate structures with significant participation of metal cations to form chain fragments based on B–N bonds containing N–H and B–H bonds, which can be detected by IR spectroscopy, when dehydrogenation is stopped.

Molybdenum(V) porphyrin complexes O=Mo(X)P (P is substituted porphin, X is singly charged anionic ligand) show affinity for practically significant organic bases in organic solvents and produce spectral response accessible for recording in the UV-visible region. Therefore, these compounds may be promising for the selection of optimal structures to be studied as active components of sensor devices. In order to achieve high sensing characteristics, the effect of the composition of the coordination sphere of O=Mo(X)P on these characteristics was analyzed by varying the axial ligand X and the substituent in the equatorial macrocyclic ligand. For this purpose, a complete kinetic description of the reaction with pyridine (Py, a classical example of highly volatile organic compound (VOCs)), proceeding as two consecutive two-way reactions, was developed in relation to (ethoxy)(oxo)[5,10,15,20-tetraphenylporphinato]molybdenum(V) (O=Mo(OEt)TPP) in toluene. The intermediates and final products were identified by UV-Vis, ¹H NMR, and IR spectroscopy and mass spectrometry, and sensing activity parameters (time, numerical spectral response to the presence of Py, and the lower limit of Py determination) were studied. Using similar data for O=Mo(OH)TPP, O=Mo(OEt)TTP, and O=Mo(OEt)T^tBuPP (TTP and T^tBuPP are tetra-4-methyl- and tetra-4-tert-butyl-substituted TPP dianions, respectively), it was shown that targeted design of the coordination sphere can be used for fine tuning of the sensing properties and that the O=Mo(OEt)TPP complex is most effective for this purpose.

Abstract—The LiCl–LiBr–Li₂SO₄ system was studied by differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Phase assemblage analysis showed that system’s liquidus surface consists of L-i₂SO₄ and LiCl_xBr_{1 – x} continuous solid solutions (CSS) crystallization fields. The composition of the minimum point M 457 in equivalent percent (equiv %) was determined as LiCl, 18; LiBr, 42; Li₂SO₄, 40. The crystallization temperature is 457°C, and the specific enthalpy of phase transition is 248.1 ± 7.5 J/g. A 3D model of the system was designed, and a disassemblable model of the phase crystallization volumes was designed in order to identify phase reactions occurring in the LiCl–LiBr–Li₂SO₄ system. A mass balance diagram of the coexisting equilibrium phases was designed for an arbitrarily selected figurative point of the system to demonstrate the power of the 3D model. The melting temperatures and eutectic compositions of lower-dimension boundary elements and polythermal sections of the LiCl–LiBr–Li₂SO₄ three–component system used to design the model in the COMPAS-3D program were experimentally studied in the work.

Cobalt(II) complexation with azaheterocyclic ligands L (L = 2,2'-bipyridyl, 1,10-phenanthroline, and 2,2'-bipyridylamine) in the presence of a monohydroxy-substituted derivative of the closo-dodecaborate anion [B₁₂H₁₁OH]^2– has been studied. Depending on the nature of the organic ligand and the synthesis conditions, coordination compounds [Co^III(Bipy)₂Cl₂]₂[B₁₂H₁₁OH], [Co^II(Phen)₃][B₁₂H₁₁OH] and [Co^II(Bipy)₃][B₁₂H₁₁OH] with the boron cluster anion as a counterion, as well as the mixed-ligand complex [Co^II(BPA)₂Cl₂] of a known structure, have been isolated and characterized by X-ray diffraction. For the first time, a redox reaction leading to the formation of a cobalt(III) complex in air has been observed for a system containing cobalt(II) and a substituted derivative of the boron cluster anion without the introduction of additional oxidizing agents.

Using the nonempirical relativistic augmented cylindrical wave method, the electronic structure of single-walled (n₁, n₂) BN nanotubes with n₁ = 7 and 6 ≥ n₂ ≥ 1 has been calculated as a function of chirality and spin. All nanotubes are wide-bandgap semiconductors with optical gaps within 3.6–4.6 eV and spin–orbit splittings of the valence band top and the conduction band minimum of 0.15–0.004 meV. The spin splitting energies in right- and left-handed nanotubes coincide, and the spin directions are opposite. The (7, 1) nanotube is most suitable for selective spin transport of electrons, which can find application in spintronics elements.

A phase equilibrium analysis was carried out for the Ni–Mn–Ga–Sb and Ni–Mn–In–Sb systems in the absence of melt. Using topological modeling based on concentration diagrams of the ternary systems Ni–Mn–Sb, Ni–Mn–Ga, Ni–Mn–In, Ni–Ga–Sb, Ni–In–Sb, Mn–Ga–Sb, Mn–In–Sb, and fragmentary experimental data on phase equilibria involving Heusler intermetallics Ni₂Mn_1+x(Ga,Sb)_1–x and Ni₂Mn_1+x(In,Sb)_1–x, isobaric-isothermal subsolidus concentration diagrams of the quaternary systems Ni–Mn–Ga–Sb and Ni–Mn–In–Sb were constructed. The key differences between them are demonstrated.

The products of the reaction between hydrogen and the body-centered cubic modification of the Ta_0.33V_0.67 alloy with partial substitution of its components by titanium and niobium were studied by X-ray powder diffraction. It was found that during hydrogenation of such alloys, hydride samples with different phase compositions and different lattice types are formed. Varying the amount of titanium and niobium in the Ta_0.33V_0.67 alloy affects the transition of the crystal lattice from body-centered cubic to face-centered. Hydrogenation of the Ta_0.33V_0.67 alloy with partial substitution of components by titanium and niobium leads to the formation of stable hydrides.