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221.
222.
The preparation of new nitrogen derivatives of benzanthrone is described. X-ray diffraction structural data are given for 3-N-pyrrolidinobenzanthrone. 相似文献
223.
I. V. Kravtsov S. V. Baranin P. A. Belyakov V. A. Dorokhov 《Russian Chemical Bulletin》2011,60(10):2027-2029
O-Methyllactims react at the methyl group of difluoroboron complexes of aroylacetones with the formation of condensation products, novel difluoroboron chelates of 1-aryl-4-(piperi-din-2-ylidene)butane-1,3-diones and 1-aryl-4-(azepan-2-ylidene)butane-1,3-diones, which upon the action of concentrated HCl in ethanol are transformed into the corresponding quino-lizin-2-one and pyrido[1,2-a]azepin-2-one derivatives. 相似文献
224.
A. V. Belyakov A. A. Baskakov V. N. Naraev A. N. Rykov H. Oberhammer I. Arnason S. O. Wallevik 《Russian Journal of General Chemistry》2011,81(11):2257-2261
The molecular structure of axial and equatorial conformer of the 1-chloro-1-silacyclohexane molecule, CH2(CH2CH2)2SiH-Cl, as well as thermodynamic equilibrium between these species were investigated by means of gas-phase electron diffraction
and quantum chemistry on the MP2(full)/AUG-cc-PVTZ level of theory. According to electron diffraction data, the compound exists
in the gas-phase as a mixture of conformers possessing the chair conformation of the six-membered ring and Cs symmetry and differing in the axial and equatorial position of the Si-Cl bond
at 352 K. NBO analysis revealed that axial conformer of 1-chloro-1-silacyclohexane molecule is an example of the stabilization
of the form that is unfavorable from the point of view steric effects and effects of conjugations and that stabilization is
achieved due to electrostatic interactions. 相似文献
225.
E. Silina S. Belyakov J. Ashaks A. Tokmakov L. Pech D. Zaruma 《Chemistry of Heterocyclic Compounds》2011,47(3):302-308
Di(2-phenyl-8-quinolyl) diselenide [2-(C6H5)C9H5NSe]2 and zinc bis[(2-phenyl-9-quinolyl)selenolate], Zn [2-(C6H5)C9H5NSe]2, have been synthesized. The molecular and crystal structure of the compounds were determined by X-ray structural analysis.
The structures of the 2-phenyl-8-quinolylselenol ligand in the molecules of di(2-phenyl-8-quinolyl) diselenide and in the
intracomplex compound of zinc are compared. The effect of the phenyl group in position 2 of the quinoline nucleus on the formation
of the molecules and their packing in the crystal structure is discussed. 相似文献
226.
Pavel K. ElkinVitalij V. Levin Alexander D. Dilman Marina I. StruchkovaPavel A. Belyakov Dmitry E. ArkhipovAlexander A. Korlyukov Vladimir A. Tartakovsky 《Tetrahedron letters》2011,52(41):5259-5263
Boranes substituted with a CF3-group can be generated from methyl boronic esters RB(OMe)2 and Me3SiCF3/KF followed by treatment with Me3SiCl. These boranes are stable only in coordinating solvents, and due to the increased Lewis acidity of boron, react rapidly with α-diazocarbonyl compounds to give the products of transfer of the organic group from boron. Alkyl, aryl, vinyl, and alkynyl boronic esters can be used in this reaction. 相似文献
227.
The crystal structure of Sr(H2O)4[(C12H11O14)B] · 3H2O (I) has been restudied and determined with a higher accuracy. The crystals are monoclinic, space group P21/n, a = 11.405(1) Å, b = 18.814(1) Å, c = 11.987(1) Å, β = 110.79(1)°; Z = 4. The structure was refined by full matrix least-squares calculation to R = 0.0547 on 5343 unique reflections with R int = 0.0419. The structural units of crystal I are the Sr2+ cation, seven water molecules, and doubly charged dicitratoborate anion, which is not equivalent to the singly charged complex dicitratoborate anion identified previously in the crystal structures of complexes of boric and citric acids. The coordination polyhedron of the Sr2+ cation is a distorted dodecahedron composed of four O atoms of coordinated water molecules and four O atoms of two complex anions. The crystal packing of I is layered. Thirteen independent O-H…O and O-H…, O′ contacts form an intricate system of hydrogen bonds. 相似文献
228.
229.
V. A. Belyakov A. A. Konakov N. V. Kurova K. V. Sidorenko V. A. Burdov 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(8):1070-1072
It is found that the radiative recombination rate rises when silicon nanocrystals are doped with donors. This rise turns out
to be stronger when a nanocrystal surface contains abundant defects capable of capturing electrons emitted by donors. 相似文献
230.
An analytic approach to the theory of optical defect modes in chiral liquid crystals (CLCs) is developed. The analytic study
is facilitated by the choice of the problem parameters. Specifically, an isotropic layer (with the dielectric susceptibility
equal to the average CLC dielectric susceptibility) sandwiched between two CLC layers is studied. The chosen model allows
eliminating the polarization mixing and reducing the corresponding equations to the equations for light of diffracting polarization
only. The dispersion equation relating the defect mode (DM) frequency to the isotropic layer thickness and an analytic expression
for the field distribution in the DM structure are obtained and the corresponding dependences are plotted for some values
of the DM structure parameters. Analytic expressions for the transmission and reflection coefficients of the DM structure
(CLC-defect layer-CLC) are presented and analyzed for nonabsorbing, absorbing, and amplifying CLCs. The anomalously strong
light absorption effect at the DM frequency is revealed. The limit case of infinitely thick CLC layers is considered in detail.
It is shown that for distributed feedback lasing in a defect structure, adjusting the lasing frequency to the DM frequency
results in a significant decrease in the lasing threshold. The DM dispersion equations are solved numerically for typical
values of the relevant parameters. Our approach helps clarify the physics of the optical DMs in CLCs and completely agrees
with the corresponding results of the previous numerical investigations. 相似文献