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41.
T. S. Pokidova E. T. Denisov A. F. Shestakov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(3):375-382
The experimental data on the molecular decomposition of olefins ( 1 -pentens) of various structures to two olefins in a gas phase were analyzed by means of the parabola intersection method. The enthalpies and kinetic parameters characterizing such decomposition were calculated for eighteen reactions. Decomposition of olefins representing two-centered concerted re action was found to be characterized by a very high classic potential barrier of thermoneutral reaction (197.4 kJ/mol). The kinetic parameters (activation energy and velocity constant) of fifteen reverse reactions of formation of olefins from two alkenes were calculated using the parabola-intersection method. The factors affect ing the activation energy of the reactions of olefin decomposition and formation are discussed. Quantum chemical calculations of the transition state energy and geometry for six reactions of olefin decomposition were performed. 相似文献
42.
The mass spectra of the dissociative electron-impact ionization products of telomers formed upon the radiation-chemical telomerization
of tetrafluoroethylene in acetone were measured over the range of m/z from 1 to 204. The most intense bands at m/z = 43, 51, and 57 were attributed to the CH3CO+, CF2H+ and CH3COCH2+ cations—the main dissociation products of the H(C2F4)
n
CH2COCH3 telomers. The telomer composition was consistent with a radical telomerization mechanism, in which chain growth and chain
transfer are due to the formation of the CH3COCH2· radical. Based on published data supplemented with quantum-chemical calculations, the enthalpies of formation of the radicals
R(CF2)
n
(n = 2–8; R = H, CH3, CH3CO, and CH3COCH2) were tabulated. The formation of telomers with the same terminal groups is consistent with thermodynamic data and a polymerization
mechanism in which the chain growth reaction is diffusion-limited and the chain transfer reaction is activated hydrogen-atom
transfer. 相似文献
43.
L. A. Syrtsova N. A. Sanina A. F. Shestakov N. I. Shkondina T. N. Rudneva N. S. Emel’yanova A. I. Kotel’nikov S. M. Aldoshin 《Russian Chemical Bulletin》2010,59(12):2203-2214
The hydrolysis of the iron nitrosyl complex [Fe2(μ2-SC4H3N2)2(NO)4](C4H3N2S? is pyrimidine-2-thiolate) in the presence of hemoglobin (Hb) is accompanied by the NO release into a solution. In the absence of Hb, the starting complex is oxidized by nitric oxide that is released into a solution, which leads to further transformations of NO, nitric oxide being present in the solution only partially. The effective rate constant for the decomposition of the complex is high and depends on its concentration. On the one hand, in the presence of Hb, NO molecules rapidly and irreversibly bind to Hb to form HbNO, which is the intermediate in the nitric oxide metabolism. On the other hand, the reversible binding of the iron nitrosyl complex to the surface functional groups of Hb leads to a decrease in its concentration in a solution and deceleration of the formation of NO. Therefore, Hb can ensure the complete and more prolonged assimilation of NO. 相似文献
44.
N. A. Sanina N. S. Emel’yanova A. N. Chekhlov A. F. Shestakov I. V. Sulimenkov S. M. Aldoshin 《Russian Chemical Bulletin》2010,59(6):1126-1136
Dinuclear iron tetranitrosyl complex with the composition [Fe2(SPh)2(NO)4] (1) was synthesized and its single crystals and polycrystals were studied by X-ray diffraction, IR spectroscopy, and elemental
analysis. The decomposition products of complex 1 were investigated by electrochemical method and mass spectrometry. The mass spectrum of a solution of complex 1 shows two groups of ions: the primary decomposition products of 1 in solution (the complex ions [Fe(SPh)(NO)2(NO2)]−, [Fe(SPh)2(NO)]−, and [Fe(SPh)2(NO)2]−) and a series of the ions [FeO2 + n(NO)]− and [FeO3 + n(NO)]− (n = 0–4), which are formed in secondary reactions. The structures of the complexes, which were formed through the Fe-NO bond
dissociation and the replacement of the NO ligand by aqua and oxygen ligands in complex 1, and the structure of the complex [FeO3]− were studied by quantum chemical modeling. 相似文献
45.
V. A. Shestakov I. R. Shelpakova V. I. Kosyakov A. R. Tsygankova 《Journal of Analytical Chemistry》2009,64(10):1072-1075
The physicochemical modeling of the behavior of impurities in the course of their preconcentration by the chemical distillation
of the sample matrix consisting of granules of a solid solution of impurities in bismuth oxide was carried out. It was supposed
that the distillation process is conducted in a kinetic mode. The results of calculations by the model are compared with the
earlier results of modeling of the behavior of impurities in distilling a heterophase sample consisting of matrix (bismuth
oxide) granules and granules of impurity oxides. The experimental data and results of calculations by the model agree well. 相似文献
46.
Quadratic alternative superalgebras are introduced and their super-identities and central functions on one odd generator are described. As a corollary, all multilinear skew-symmetric identities and central polynomials of octonions are classified. 相似文献
47.
48.
D. K. Shestakov I. K. Gainullin I. F. Urazgil’din 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(1):33-37
The electron exchange under grazing scattering of a negative hydrogen ion from a thin Al disk is analyzed via the wave packet propagation method that does not use the perturbation theory. The probability of H? ion fraction formation is calculated as a function of the ion velocity component (v‖) parallel to the surface. It is shown that the yield of negative hydrogen ions has a bell-like dependence on the value of v‖ under grazing scattering from a thin disk. The negative ion yield under grazing scattering from a disk is very close to the H? ion yield under scattering from a film. The maximum of the probability of H? fraction formation calculated for a thin disk is shifted to smaller values of v‖ with respect to the maximum of the probability of H? formation for a thin film. 相似文献
49.
It is shown that axially symmetric two-dimensional nonuniform states can exist in easy-axis and cubic antiferromagnets lacking
inversion symmetry, in the form of two-dimensional spatially modulated structures (magnetic vortex lattices) and isolated
two-dimensional structures (vortices). The structure and equilibrium dimensions of the lattices and vortices have been determined
by numerical solution of differential equations.
Fiz. Tverd. Tela (St. Petersburg) 40, 1486–1493 (August 1998) 相似文献
50.
One gives the structure of a locally compact pro-solvable group, the set of noncompact subgroups of which forms a distributive lattice.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, Nos. 7 and 8, pp. 1108–1111, July–August, 1991. 相似文献