Том 58, № 5 (2017)

Structural, dynamic, and thermodynamic features of double hydrates of xenon and nitrous oxide are calculated. Thermodynamic stability regions of these hydrates are found. At the atmospheric pressure the xenon hydrate is in the equilibrium with the gas phase at temperatures up to 263 K, whereas at these pressures the nitrous oxide hydrate decomposes already at 218 K. A strong dependence of the equilibrium temperatures and pressures of the formation/decomposition of double nitrous oxide and xenon hydrates on the composition of their mixture in the gas phase is shown.

The electronic structure of calix[4]arene phosphine oxides (CPO) and thiacalix[4]arene phosphine oxides (TCPO) is studied by X-ray photoelectron and emission spectroscopy and quantum chemical methods. The electron density distribution over atoms contained in CPO and TCPO is analyzed. The structure of higher occupied molecular orbitals (HOMO) is examined. It is shown that HOMOs of these compounds mainly consist of contributions of oxygen 2p atomic orbitals (AOs) of phosphoryl and hydroxyl moieties and also bridging sulfur 3p AOs, which indicates the bifunctionality of the considered extractant molecules. The mutual effect of the lower and upper rims of CPOs and TCPOs as well as the effect of their structures on the electron density distribution over calixarene molecules is investigated.

An attempt is made to explain the causes of coloration of LiB₃O₅ crystals after their long-term operation as laser elements. By EPR and optical spectroscopy the impurity and radiation centers are studied in as-grown LiB₃O₅ crystals and in the crystals whose color appeared after the long-term operation as laser elements. In a number of as-grown crystals a copper impurity is detected. EPR spectral parameters and the structural positions of Cu²⁺ ions are found. Defect formation features in electron irradiated as-grown LiB₃O₅ crystals and in the most colored regions of crystals of spent laser elements are analyzed. It is shown that in both growth crystals and crystals after long-term operation as laser elements the same set of radiation defects is observed: oxygen O^– in the interstitial position, an O^– hole center in the crystal structure, and the B²⁺ electron center due to the removal of an oxygen atom near the lithium vacancy. The only distinction is that the concentration of these radiation defects in crystals long used as laser elements is higher than that in growth ones by an order of magnitude. The results obtained enable the conclusion that the cause of coloration of LiB₃O₅ crystals is photo-induced diffusion of lithium atoms and their capture by cation vacancies in the dark part of the crystal, which provides the formation and accumulation of lithium vacancies in the region where the laser beam passes.

In the paper results of the investigation of the thermal decomposition process of double complex salt [Pt(NH₃)₄][OsCl₆] by x-ray absorption (XAFS) and photoelectron (XPS) spectroscopies have been presented. The data obtained allows a mechanism of the thermal decomposition to be refined. An influence of size effect and nanoalloy formation on chemical shift of Pt and Os is discussed.

Iron(II) dicyanamide and isothiocyanate compounds with 2-(2-tert-butyltetrazol-5-yl)pyridine (L) of the composition [FeL₂(C₂N₃)₂]•2H₂O (I) and [FeL₂(NCS)₂]H₂O (II) are synthesized and studied. The compounds are examined using powder and single crystal XRD (for I), electron (diffuse reflectance spectra) and IR spectroscopy, static magnetic susceptibility. The analysis of the dependence μ_eff(Т) indicates that the exchange interactions of antiferromagnetic nature appear between the iron(II) ions at temperatures below 50 K.

Impurity-free RBaCo₄O_7+x (R = Y, Lu) crystals are grown and the evolution of their structure with varying oxygen concentration in the range 0 ≤ x ≤ 1.3 is studied. The structural features of the studied samples required to develop an extended strategy of the X-ray crystallographic experiment, which made it possible to obtain more accurate data on unit cell parameters and additional information on the features of superstructure modulation and diffuse scattering, along with the phase composition of crystalline samples. A crystal chemical analysis of the known structural models of RBaCo₄O_7+x is performed and suggestions are made about possible structural changes occurring when the oxygen concentration increases up to the limit.

The crystallogenesis of three groups of structures of fluoride-orthoborates (and their analogs) with large cations is studied from the point of view of the current cation-framework representations. Their cation frameworks are sterically templated by rigid borate anions and are built as antizeolite structures. Cavities of channel or layered types are filled with components different their composition and configuration with the main function as charge compensators. An example of different functionalities of the identical anions are Ba₃(BO₃)₂ and La₃Ca₃(BO₃)₅ structures. In these structures, two (BO₃) types generate a cation framework, and the third type stabilizes it in ready channels (!).

The tris-chelate complex of vanadium(IV) (Bu₄N)₂[V(dmit)₃] is prepared from VCl₃ and (Bu₄N)₂[Zn(dmit)₂] (dmit = isotrithionedithiolate C₃S₅^2–) and characterized by single crystal XRD and mass spectrometry. The complex crystallizes in the space group Pna2₁ and has a distorted octahedral environment of vanadium. The complex is paramagnetic and gives a characteristic EPR spectrum in both solution and solid phase. The g factors and hyperfine interaction constants are determined.

Single crystal X-ray diffraction is used to study the nitrosoruthenium mer-trinitrato complex [RuNO(NH₃)₂(NO₃)₃]. The crystallographic data for H₆N₆O₁₀Ru are as follows: a = 7.6477(1) Å, b = 10.8404(2) Å, c = 24.0168(6) Å, α = β = γ = 90°, V = 1991.09(7) ų, Z = 8, d_calc = 2/338 g/cm³, space group P2₁2₁2₁. The structure is formed of two structurally non-equivalent uncharged mer-[RuNO(NH₃)₂(NO₃)₃] complexes. The complex crystallizes as yellow needles or orange powder belonging to the orthorhombic system. The substance is poorly soluble in water, ethanol, and acetone, stable in dark storage. The comparisons with the EXAFS data for this complex and the theoretical DFT calculations with different functionals are performed.

A cluster complex of the composition [CsK₂(μ₃-DMF)₂(μ-DMF)₃(DMF)₄][{Re₆(μ₃-Se)₈}Br₆] is obtained by the reaction of K₄[{Re₆(μ₃-Se)₈}(OH)₆]·8H₂O with hydrobromic acid in the presence of CsBr and its subsequent crystallization by diethyl ether diffusion in a dimethylformamide solution. The compound crystallizes in the triclinic space group P1̅, with the following unit cell parameters: a = 13.6169(3) Å, b = 14.7584(4) Å, c = 18.1573(4) Å, α = 103.332(1)°, β = 108.250(1)°, γ = 97.371(1)°, V = 3286.55(14) ų, Z = 2, d_calc = 3.130 g/cm³. The crystal structure is built of [{Re₆Se₈}Br₆]^3– anionic cluster complexes and complex [CsK₂(μ₃-DMF)₂(μ-DMF)₃(DMF)₄]³⁺ cations.

Palladium(II) and copper(II) complexes with 2-(2,2-dimethylhydrazone) pentanone-4 are synthesized for the first time. The compounds are characterized by IR and NMR spectroscopy, elemental and single crystal X-ray diffraction analyses. The palladium complex crystallizes in the space group I4₁/a; the copper complex crystallizes in the space group P1̅. Both compounds are molecular; the palladium chelate core has a distorted square geometry and that of copper has a distorted tetrahedral geometry. The average M–O and M–N bond lengths are respectively 1.9808(15) Å and 2.0427(17) Å for M = Pd, 1.915(8) Å and 1.97(1) Å for M = Cu. The chelate O–M–N angles are 88.32(7)-91.67(7)° for M = Pd, 93.37(4)-99.02(5)° for M = Cu.

A low-temperature plasma enhanced chemical vapor deposition procedure is developed for hexagonaloro boron nitride nanowalls that are an array of sheets vertically aligned relative to the Si(100) substrate. A triethylaminoborane and ammonia gas phase was used for the first time to form h-BN nanowalls. Nanowall sizes are 50–250 nm long and 10–25 nm thick. Grazing incidence X-ray diffraction and high-resolution transmission electron microscopy techniques are employed to study the structures of boron nitridex nanowalls. The effect of synthesis parameters (film deposition temperature and growth time) on the chemical and phase compositions, surface morphology, film structure, and their optical properties are analyzed.

Stable colloidal dispersions with a 2 mM TiS₃ concentration (300 mg/l) are obtained by ultrasonic treatment of TiS₃ in acetonitrile and isopropyl alcohol and characterized by physicochemical methods. The electrical double layers for the particles in dispersions are estimated from the measured ζ-potentials, and the energies of interparticle interactions are calculated based on the Derjaguin–Landau–Verwey–Overbeek theory. The structural and spectroscopic identity of the particles and crystalline TiS₃ is demonstrated for the solid phases obtained from the dispersions.

Three new metal-organic coordination polymers (H₂NMe₂)₂[Li₃(btc)(Hbtc)(DMF)₄] (1), [Li₅(DMF)₆(btc)(Hbtc)]·2DMF (2), and [Li₆(DMF)₈(bdc)(Hbtc)] (3) (H₃btc is trimesic acid, H₂bdc is terephthalic acid) are prepared by heating LiOH with different aromatic carboxylic acids in dimethyl formamide (or its mixture with water). The crystal structures and composition of the compounds are determined by single crystal X-ray diffraction. Compound 1 has a layered structure; compounds 2 and 3 have a framework structure.