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New methylsulfate complex (Bu4N)2[Мо6I8(O3SOCH3)6] (I) is synthesized by the reaction of (Bu4N)2[Mo6I8(C≡C–C(O)OCH3)6] with dimethyl sulfate (CH3)2SO4. According to the XRD data, the molybdenum atoms are coordinated by the monodentate methylsulfate ligands. In a DMSO solution, the complex undergoes solvolysis accompanied by the complete substitution of the methylsulfate ligands by the solvent molecules. A powder sample of cluster I luminesces (phosphorescence) with the emission maximum at a wavelength of 620 nm (77 K). Increasing temperature to 300 K results in the shift of the emission maximum to 650 nm and a decrease in the integral intensity by 1.6 times. [ABSTRACT FROM AUTHOR]

The possibility of the formation of supramolecular hybrids based on two photosensitizers, an octahedral molybdenum(II) iodide cluster with six terminal isonicotinate ligands (Bu4N)2[{Mo6I8}(OOC–C5H4N)6] (PyMoC, C) and A4-type zinc(II) porphyrin (ZnTPP, P), has been demonstrated. Spectrophotometric and NMR titration methods have shown that the formation of CPn complexes (n = 1–6) occurs in solutions of noncoordinating chlorinated solvents due to the formation of metal–N-ligand coordination bonds between the components. The use of an octahedral cluster as a hexatopic N-ligand and the lability of the Zn···NPy bonds together lead to the formation of a series of CPn complexes (n = 1–6), which are in dynamic equilibrium in solution. Nevertheless, conditions have been selected to isolate single crystals of individual forms CP4 + 2 and CP6 + 2, and their structures have been determined by X-ray diffraction analysis. The PyMoC cluster turns out to coordinate four or six ZnTPP molecules, respectively, while both structures contain two "extramolecules" of zinc(II) porphyrin bound to the cluster via hydrogen bonds involving the oxygen atoms of the isonicotinate groups and protons of water axially coordinated to the porphyrin metal center. [ABSTRACT FROM AUTHOR]

Two new luminescent cluster complexes (Bu4N)2[Mo6X8(N3C2H2)6]·n(H2O) (1) (X = Br, n = 4) and (2) (X = I, n = 5) are obtained by the reaction of (Bu4N)2[Mo6X8(OOCCH3)6] (X = Br, I) with 1-trimethylsilyl-1,2,4-triazole Me3Si–N3C2H2. Their crystal structures are determined and the luminescent properties of powder samples are studied. According to single crystal X-ray diffraction data, molybdenum atoms are monodentate coordinated by N1 atoms of triazolate ligands at Mo–N distances of 2.154(9)-2.185(9) Å (1) and 2.158(13)-2.21(13) Å (2). The complexes are characterized by electrospray mass spectrometry, proton magnetic resonance, elemental analysis, and IR spectroscopy data. [ABSTRACT FROM AUTHOR]

Extracting the reaction product of Ta, Br2, and LiBr (720 °C, 48 h, mole ratio 1.5:1.75:1.0) with diglyme yields crystals of complex [Li(diglyme)2]2[Ta6Br18] whose structure is determined by XRD. [ABSTRACT FROM AUTHOR]

The first iodide cluster of molybdenum with the metal cage in the form of a tetragonal pyramid (Bu4N)[Mo5OI13]·THF (I) and cocrystallizate (Bu4N){[Mo5OI13]0.9[Mo6I14]·THF (II) are synthesized for the first time by heating a LiI–I2–Mo mixture in a temperature range of 300–400°С followed by the extraction of the product. Complexes I and II are studied by X-ray diffraction analysis (CIF files CCDC nos. 2063029 (I) and 2063030 (II)). The molybdenum atoms in [Mo5OI13]– form a square pyramid with Mo–Mo distances of 2.67 Å between the basal molybdenum atoms and the Mo–Mo distances equal to 2.72 Å between the apical and basal molybdenum atoms. The oxygen atom is coordinated to the pyramid base (Mo–μ4-O 2.10 Å). The cluster anion [Mo5OI13]– can be presented as the octahedral cluster anion [Mo6I14]2– in which the position of the {MoI}– fragment (d0, 6e) is occupied by the isoelectronic oxygen atom (s2p4, 6e). In the structure of compound II, the [Mo5OI13]– and [Mo6I14]2– cluster anions occupy close atomic positions. [ABSTRACT FROM AUTHOR]

Large crystallite mesoporous MFI (ZSM-5) zeolite was synthesized by using carbon nano-powder as a secondary template. The surface properties, morphological and phase composition of the synthesized material and of the commercial ZSM-5 (Zeolyst) zeolite were studied by nitrogen porosimetry, XRD and scanning electron microscopy. The results showed that the volume of mesopores volume increases with development of a secondary mesoporosity in the structure of zeolite. The obtained zeolite supports were used to prepare molybdenum-containing catalysts for the methane aromatization by solid phase preparation technique. Based on the XPS data, molybdenum particles in these catalysts are characterized by more uniform size distribution. The formation of a secondary pore structure restrains the carbon deposit formation as well as increases the methane conversion and the yield of the aromatic compounds. [ABSTRACT FROM AUTHOR]

MFI zeolite materials (ZSM-5) with crystal sizes in the range from 0.10 to 1.70 μm have been synthesized. Acidic and surface properties, phase and morphological composition of the prepared zeolites have been studied by the IR sprectroscopy, nitrogen porosimetry, XRD, and scanning electron microscopy. Increasing crystal size was shown to decrease the general acidity of the zeolite. Synthesized zeolites served as supports for molybden-containing catalysts for methane aromatization prepared by using the solid phase synthesis approach. Diffuse reflectance IR spectroscopy, thermoprogrammed desoption of ammonia and 27Al NMR spectroscopy were used to characterize the physicochemical properties of the catalysts. An increase in the crystallite size of the zeolite favors a decrease in the acidity of the catalysts and inhibits the formation of alumina molybdate during the catalyst preparation. As a result, a tendency to coke formation is suppressed and the performance of the catalysts in methane aromatization improved: methane conversion and aromatic hydrocarbon yield increase. [ABSTRACT FROM AUTHOR]

Investigations for the development of a SLZhS-32 BR promising rhenium-free heat-resistant nickel alloy for single-crystal turbine blades are carried out. The chemical composition of the experimental promising alloy is calculated and substantiated, and a pilot batch (10 kg) of the alloy is smelted. According to analytical results of the investigation, the long-term strength of the developed alloy is 248 MPa at 1000°C and 100 h. [ABSTRACT FROM AUTHOR]

Microstructural investigations of the new economically doped alloy SLZhS32 BR are carried out, and workpieces of single-crystal specimens are cast for mechanical tests. Thermal processing conditions are developed, workpieces are processed, specimens are made for mechanical and metallographic investigations, and metallographic investigations and strength tests are carried out. The produced alloy has creep-rupture strength σ= 238-248 MPa at a density of 8.87 g/cm. [ABSTRACT FROM AUTHOR]

The fundamental components of the Earth's rotation parameters play an important role in solving the problems of navigation and control of spacecraft motion. Mathematical models of the Earth's pole motion and dUT1 mismatch of the UT1 and UTC time scales adequate to the observation and measurement data of the International Earth Rotation and Reference Systems Service are considered. It is shown that the proposed models provide sufficient autonomy to form parameters of the Earth's rotation onboard the spacecraft. It is necessary to account for these parameters in real time onboard the spacecraft to solve problems of navigational support. The graphs of the daily forecast errors of the GLONASS navigation satellite orbits that are caused by the pole displacement, are presented. A comparative analysis of the graphs shows that disturbances of navigation satellite orbits are comparable with the gravitational influence of the Moon and the Sun and disturbances caused by the anomalous part of the Earth's gravitational field. It is found that a significant increase in forecast accuracy for satellite ephemerides is achieved taking into account of the Earth's rotational and vibrational motion in equations of spacecraft motion. [ABSTRACT FROM AUTHOR]

The results of an investigation of the short-time mechanical properties of two batches of experimental ferrite-martensite alloys with 12% chromium content are presented. The chemical composition of the alloys was calculated with a neural-net model developed using data from tests performed on samples of EI-852, EP-450, EP-823, and EP-900 steels. Analysis showed that one of the melted alloys has a high yield stress in the test temperature range 20-720°C. A second version of the neural net model was developed using test data obtained for experimental samples with elevated manganese content. [ABSTRACT FROM AUTHOR]