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1.
G. V. Girichev N. V. Tverdova S. A. Shlykov V. V. Rybkin N. P. Kuzmina A. Yu. Rogachev 《Journal of Structural Chemistry》2006,47(6):1071-1077
In a mass spectrometric study, it was found that the saturated vapor over gadolinium tris-hexafluoroacetylacetonate Gd(C5O2HF6)3 contains molecular forms with a mass exceeding the mass of the dimer. The vapor overheated to 250–300°C contains only the monomer form. Simultaneous electron diffraction and mass spectrometric experiment aimed at investigating the structure of the Gd(hfa)3 monomer molecule was carried out at 284(5)°C. The Gd(hfa)3 molecule was found to have the symmetry of the equilibrium D 3 configuration. The basic structural parameters are r h1(Gd-O) = 2.291(10) Å, r h1(O-C) = 1.257(10) Å, r h1(C-Cr) = 1.404(6) Å, r h1(CF-F)av = 1.341(3) Å, ∠OGdO = 72.8(0.4)°. The GdO6 coordination polyhedron has the structure of a distorted antiprism. The rotation angle of the O-O-O trigonal faces relative to their position in a regular prism is 18.7(0.9)°. Quantum chemical calculations (HF/SBK, 6-31G*) generally reproduce the experimental structure, but the Gd-O internuclear distance is exaggerated by 0.04 Å. 相似文献
2.
M. A. Dzubina G. N. Kuzmina N. N. Lebedenko Yu. V. Korshak O. P. Parenago 《Journal of Thermal Analysis and Calorimetry》1992,38(5):1103-1112
The structure transition temperature, monomer melting point and critical temperatures of polymerization and decomposition of 2,2,6,6-tetramethyl-4-oxy-4-ethynylpiperidin-1-oxyl were determined by means of thermal analysis. Some features of the polymerization of the acetylenic monomer were studied via thermal analysis, and IR and ESR spectroscopy.It was shown that, during non-isothermal temperature increase, the mass loss of the sample associated with the exothermic effect of polymerization occurred at the expense of the monoacetylene sublimation process (42%), a reagent explosion and decomposition of the reaction products formed (15%).
Zusammenfassung Mittels Thermoanalyse wurde die Strukturumwandlungstemperatur, der Monomerschmelzpunkt und die kritischen Temperaturen für Polymerisierung und Zersetzung von 2,2,6,6-Tetramethyl-4-oxy-4-ethynylpiperidin-1-oxyl bestimmt. Mit Hilfe von Thermo-analyse, IR- und ESR-Spektroskopie wurden einige Eigenschaften der Polymerisierung des Acethylen-Monomers untersucht.Es wurde gezeigt, daß bei einem nichtisothermen Temperaturanstieg der Massenverlust der Probe zunimmt, verbunden mit einem exothermen Effekt der eingetretenen Polymerisierung auf Kosten des Monoacetylen-Sublimierungsprozesses [42%], der Explosion und der Zersetzung der gebildeten Reaktionsprodukte [15%].相似文献
3.
C. T. Simmons S. L. Molodtsov S. I. Fedoseenko J. C. Allman C. Laubschat G. Kaindl S. V. Moshikin M. A. Kuzmina M. U. Vlasov O. F. Vyvenko 《Zeitschrift für Physik B Condensed Matter》1992,87(3):271-273
The results of a high-resolution photoemission study using synchrotron radiation of two single crystals of Bi2Sr2CaCu2O8+, with different critical temperaturesT
c
due to a variation in oxygen stoichiometry are reported. Within experimental accuracy, the energy gap 2 is found to scale withT
c
, amounting to a reduced gap parameter of 2/k
BTc7.4. Employing resonant photoemission at the O–2s and Cu–3p thresholds, two spectral peaks at binding energies of 180 meV and 320 meV were identified as predominantly O–2p-and Cu–3d 4s-derived states, respectively. 相似文献
4.
5.
I. A. Martynova D. M. Tsymbarenko A. A. Kamenev S. N. Mudretsova A. N. Streletsky A. L. Vasiliev N. P. Kuzmina A. R. Kaul 《Russian Chemical Bulletin》2013,62(6):1454-1458
A series of (Y(AcO)3·4H2O—Q—Solv) solutions (Q is monoethanolamine (MEA), diethanolamine (DEA), en, dien; Solv = MeOH, EtOH, PriOH, BuOH) was studied to choose the metal-organic precursor for surface smoothing treatment of metallic tapes by chemical deposition of nanocrystalline yttria films. Based on the results of viscosity, wetting angle, and thermal stability measurements, a solution (Y(AcO)3·4H2O—dien—PriOH) was proposed as a new metal-organic precursor. After chemical deposition of nanocrystalline yttria films about 300 nm thick on a Hastelloy C-276 metallic tape the surface roughness was reduced by a factor of 11 (from 9.0 to 0.8 nm on a surface area of 5×5 μm2). 相似文献
6.
Dr. Andrey Y. Khalimon Prof. Dr. Stanislav K. Ignatov Andrey I. Okhapkin Dipl.‐Ing. Razvan Simionescu Prof. Dr. Lyudmila G. Kuzmina Prof. Dr. Judith A. K. Howard Dr. Georgii I. Nikonov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8573-8590
The reactions of bis(borohydride) complexes [(RN?)Mo(BH4)2(PMe3)2] ( 4 : R=2,6‐Me2C6H3; 5 : R=2,6‐iPr2C6H3) with hydrosilanes afford new silyl hydride derivatives [(RN?)Mo(H)(SiR′3)(PMe3)3] ( 3 : R=Ar, R′3=H2Ph; 8 : R=Ar′, R′3=H2Ph; 9 : R=Ar, R′3=(OEt)3; 10 : R=Ar, R′3=HMePh). These compounds can also be conveniently prepared by reacting [(RN?)Mo(H)(Cl)(PMe3)3] with one equivalent of LiBH4 in the presence of a silane. Complex 3 undergoes intramolecular and intermolecular phosphine exchange, as well as exchange between the silyl ligand and the free silane. Kinetic and DFT studies show that the intermolecular phosphine exchange occurs through the predissociation of a PMe3 group, which, surprisingly, is facilitated by the silane. The intramolecular exchange proceeds through a new non‐Bailar‐twist pathway. The silyl/silane exchange proceeds through an unusual MoVI intermediate, [(ArN?)Mo(H)2(SiH2Ph)2(PMe3)2] ( 19 ). Complex 3 was found to be the catalyst of a variety of hydrosilylation reactions of carbonyl compounds (aldehydes and ketones) and nitriles, as well as of silane alcoholysis. Stoichiometric mechanistic studies of the hydrosilylation of acetone, supported by DFT calculations, suggest the operation of an unexpected mechanism, in that the silyl ligand of compound 3 plays an unusual role as a spectator ligand. The addition of acetone to compound 3 leads to the formation of [trans‐(ArN)Mo(OiPr)(SiH2Ph)(PMe3)2] ( 18 ). This latter species does not undergo the elimination of a Si? O group (which corresponds to the conventional Ojima′s mechanism of hydrosilylation). Rather, complex 18 undergoes unusual reversible β‐CH activation of the isopropoxy ligand. In the hydrosilylation of benzaldehyde, the reaction proceeds through the formation of a new intermediate bis(benzaldehyde) adduct, [(ArN?)Mo(η2‐PhC(O)H)2(PMe3)], which reacts further with hydrosilane through a η1‐silane complex, as studied by DFT calculations. 相似文献
7.
Journal of Analytical Chemistry - We studied a possibility of determining fluorine in rocks by the X-ray fluorescence spectrometry using pressed pellets as emitters. The most important factors... 相似文献
8.
M. Dubničková E. A. Kuzmina V. N. Chausov I. Ravnachka A. V. Boreyko E. A. Krasavin 《Physics of Particles and Nuclei Letters》2016,13(2):274-278
The modulatory effects of lipid A (diphosphoryl lipid A (DLA) and monophosphoryl lipid A (MLA)) on apoptosis induction and DNA structure damage (single and double-strand breaks (SSBs and DSBs, respectively)) in peripheral human blood lymphocytes are studied for 60Co gamma-irradiation. It is shown that in the presence of these agents the amount of apoptotic cells increases compared with the irradiated control samples. The effect is most strongly pronounced for DLA. In its presence, a significant increase is observed in the number of radiation-induced DNA SSBs and DSBs. Possible mechanisms are discussed of the modifying influence of the used agents on radiation-induced cell reactions 相似文献
9.
A. A. Loshmanov M. A. Chernysheva V. A. Trunov A. I. Kurbakov Yu. V. Shaldin N. L. Sizova I. P. Kuzmina V. R. Regel 《Crystal Research and Technology》1984,19(1):73-78
It has been carried out the investigation of the mosaic structure of ZnO crystals by two methods providing the information on mosaic structure and inner stresses (γ-ray diffraction and conoscopic method). It has been observed a certain correlation between the results obtained by the two methods. 相似文献
10.
The Debye-Waller factors and the mean-square dynamics displacements of the Be and O ions in beryllium oxide are obtained from X-ray diffraction powder data over the temperature range from 10 to 720 K for different crystallographic directions. The observed anisotropy of these mean-square displacements is discussed. 相似文献