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2009 year, number 1
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D. V. Suetin, I. R. Shein, A. L. Ivanovskii
Keywords: tungsten carbonitrides WC1-xNx, electronic properties, FLAPW-GGA, simulation
Pages: 7-15
Abstract >>
A full potential FLAPW-GGA method is used for the first time to study the electronic structure of hexagonal solid solutions of tungsten carbonitrides WC1-xNx (0 ≤ x ≤ 0.5) and to calculate their equilibrium structural parameters, density, cohesion energy, and coefficients of low-temperature heat capacity and Pauli paramagnetic susceptibility. They are discussed in comparison with similar values for initial binary phases: WC and WN and also hypothetical solid solutions WB0.5C0.5 and WB0.5N0.5.
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L. A. Gribov, V. I. Baranov
Keywords: chemical transformations, quasi-resonance, wave packet
Pages: 16-23
Abstract >>
We consider the transformation process of one molecular subsystem into another (for example, structural isomer-isomer transformation) under the condition of a group of close levels in the first subsystem that have the energy on average coincident with the mean energy of the second subsystem (quasi-degeneration). It is shown that, similar to the previously discussed resonance between two levels of two subsystems, it is also possible in this case to compose an oscillating wave packet leading to a resonant transition from one subsystem to another. The calculation procedure is described that can be applied to atomic ensembles of any complexity with any number of quasi-resonant levels.
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N. M. Vitkovskaya, V. B. Kobychev, E. Y. Larionova, I. L. Zaitseva, B. A. Trofimov
Keywords: alkali metals, hydroxides, cations, hydroxide ion, dimethyl sulfoxide, acetylene, coordination, solvation, ab initio calculations
Pages: 24-32
Abstract >>
Within the ab initio approach and with the use of density functional theory the formation of solvation shells of nondissociated alkali metals hydroxides of the corresponding cations and the hydroxide ion in dimethyl sulfoxide (DMSO) is studied. Complexes in which the alkali metal environment contains the coordinated acetylene molecule along with solvent molecules are considered. The coordination number of the hydroxide ion in DMSO is shown to be 4. It is demonstrated that solvated cations of alkali metals cannot form π-complexes with the acetylene molecule, whereas the introduction of molecular acetylene into the solvation sphere of nondissociated NaOH and KOH is possible.
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E. Y. Larionova, N. M. Vitkovskaya, V. B. Kobychev, N. V. Kaempf, A. D. Skitnevskaya, B. A. Trofimov
Keywords: ethynide ion, ethynylation, reaction mechanism, quantum chemical calculation, superbasic media
Pages: 33-39
Abstract >>
The reaction mechanism of the formation of alkali metal ethynides
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X.-H. Li, Z.-X. Tang, X.-Z. Zhang
Keywords: density functional theory, bond dissociation enthalpy, substituent effect, substituted chlorobenzene compounds
Pages: 40-46
Abstract >>
Quantum chemical calculations were used to estimate the bond dissociation energies (BDEs) for 13 substituted chlorobenzene compounds. These compounds were studied by employing the hybrid density functional theory methods (B3LYP, B3PW91, B3P86) with 6-31G** and
6-311G** basis sets. It was demonstrated that B3P86/6-311G** method is the best method for computing the reliable BDEs for substituted chlorobenzene compounds which contain the
C-Cl bond. It was found that the C-Cl BDE depends strongly on a computational method and basis set used. Substitution effect on the C-Cl BDE of substituted chlorobenzene compounds is further discussed. It is shown that the effects of substitution on the C-Cl BDE of substituted chlorobenzene compounds are very insignificant. Frontier orbital energy gap of studied compounds was also investigated. From the data on frontier orbital energies gap, we estimated the relative thermal stability of substituted chlorobenzene compounds.
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M. V. Korolevich, S. G. Kirillova, V. N. Piottukh-peletskii, V. M. Andrianov
Keywords: epoxysaccharides, IR spectroscopy, analysis of normal vibrations, absolute IR intensities, interpretation of IR spectra
Pages: 47-57
Abstract >>
A detailed assignment of absorption bands in IR spectra of methyl 3,4-anhydro-α-D-talo-hexapyranoside and methyl 2,3-anhydro-4-deoxy-α-D-ribo-hexapyranoside is first made based on the complete calculation of frequencies and absolute intensities of normal vibrations of molecules and their comparison with the corresponding experimental values. The effect of the epoxy group on the bands characteristic of the pyranose ring is analyzed. The charactericity of spectral features of oxymethyl substitution for the hydroxyl group and the oxirane ring is studied.
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N. I. Giricheva, G. V. Girichev, N. P. Kuzmina, Y. S. Medvedeva, A. Y. Rogachev
Keywords: structure, Schiff bases, CuO2N2C16H14, Cu(salen), electron diffraction, quantum chemical calculations
Pages: 58-65
Abstract >>
In the framework of synchronous gas-phase electron diffraction and mass spectrometry experiment, the saturated vapor of N,N'-ethylenebis(salicylaldiminate) copper(II) CuO2N2C16H14 is studied at a temperature T 574(5) K. It is found that evaporation is congruent and the saturated vapor consists of monomeric molecules. Electron diffraction data are proved to correspond to the geometric model for the CuO2N2C16H14 molecule of
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E. I. Voit, A. E. Panasenko, L. A. Zemnukhova
Keywords: antimony(III) oxide, DFT, IR, Raman, vibrational spectroscopy
Pages: 66-72
Abstract >>
IR and Raman spectroscopy are used to study cubic and orthorhombic modifications of Sb2O3. Vibrational spectra are calculated in the approximation of density functional theory; the bands are assigned. Based on the assignment made, vibrational spectra of the α-Sb3O2F5 compound are analyzed.
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M. Monajjemi, B. Honarparvar, S.M. Nasseri, M. Khaleghian
Keywords: nuclear magnetic resonance, nuclear quadrupole resonance, hydrogen bonding interactions, ab initio, density functional theory, DFT
Pages: 73-78
Abstract >>
In this paper extensive systematic computational study has been carried out to justify hydrogen bonding interactions and its influence on the oxygen, nitrogen and hydrogen NQR and NMR parameters of the anhydrous and monohydrated guanine crystal structures at two different levels, B3LYP and MP2, using 6-311++G** and D95** basis sets. These theoretical data have been compared with experimental NMR and NQR measurements. For further investigation, results of cluster calculations have been compared with that of a single molecule. Our theoretical NQR and NMR parameters of 17O, 15N and 2H atoms of anhydrous and monohydrated guanine exhibited extreme sensitivity to electron distribution around mentioned nuclei caused by cooperative influences of various types of hydrogen bonding interactions. Fortunately, our calculated isotropic shielding values and CS tensors for the 17O and 15N nuclei as well as obtained 14N-NQR parameters are in excellent agreement with experimental data. Therefore, we can undoubtedly conclude that for anhydrous and monohydrated guanine tetrameric clusters including intermolecular interactions, our theoretical estimates are in better agreement with observed experimental values than those in which these interactions have been ignored.
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V. P. Voloshin, Y. I. Naberukhin
Keywords: computer water simulation, hydrogen bonds, hydrogen bond lifetime
Pages: 84-95
Abstract >>
Various hydrogen bond lifetime distribution functions, used to describe the breaking and formation dynamics of these bonds in a computer experiment, are examined and relationships between them are found. The procedures for calculating these functions by the molecular dynamics method are described and the results for water models of 3456 molecules at 310 K are reported. The peak of short-lived spurious H-bonds, which results from short-time violations of hydrogen bonding criteria induced by dynamic intermolecular vibrations of molecules, prevails in the types of distributions most often referred to in the literature. A special distribution that appears to have not been used before is proposed. Along with short-lived bonds, it manifests long-lived ones whose lifetime is determined by the genuine, or random, hydrogen bond breaking rather than by dynamic. A technique to exclude dynamic effects and reveal the genuine H-bond breaking is proposed. This allows the evaluation of the average lifetime of "true" H-bonds that turns out to exceed 3 ps.
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G. N. Ten, V. I. Baranov
Keywords: thymine, 5-chlorouracil, tautomers, lifetime, calculation
Pages: 96-102
Abstract >>
The lifetime of zwitterionic, neutral, oxo, and hydroxy tautomeric forms of thymine and 5-chlorouracil is calculated with regard to intermolecular proton transfer in dimers. Time characteristics of picosecond spectra of aqueous solutions at different
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L. I. Men'shikov, P. O. Fedichev
Keywords: polar liquid, hydrophobic surface, ferroelectric, long-range order
Pages: 103-107
Abstract >>
The phenomenological vector model of water is used to clarify the nature of the percolation phase transition in hydration water films around the surface of immersed bodies, which is found in molecular dynamic calculations. The transition is explained by the emergence of ordering in the directions of projections of water dipole moments on the body surface at the lower critical temperature, i.e. by the formation of ferroelectric water film. The evaluation of this temperature is given, which is consistent with numerical calculations.
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B. V. Beznosikov, K. S. Aleksandrov
Keywords: crystal, structural family of delafossite, predictions of new compounds
Pages: 108-113
Abstract >>
This paper reports the results of our crystal-chemical analysis of structures from the delafossite family
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A. N. Nadeev, S. V. Tsybulya, E. Y. Gerasimov, L. A. Isupova
Keywords: perovskite, high-temperature X-ray diffractometry, phase transition
Pages: 114-120
Abstract >>
Phase transformations in a sample from the series La1-xSrxFeO3-
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I. I. Zviedre, S. V. Belyakov
Keywords: boron coordination compounds, dicitratoborates, X-ray diffraction analysis
Pages: 121-125
Abstract >>
Triethylammonium dicitratoborate monohydrate (C2H5)3NH×[(C6H6O7)2B]⋅H2O (I) was synthesized for the first time. Its crystal structure was solved from single crystal X-ray diffraction data (a = 9.7821(2) Å, b =
23.2196(4) Å, c = 10.0705(2) Å; β = 90.97(1)
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S. A. Martynova, K. V. Yusenko, I. V. Korolkov, I. A. Baidina, S. V. Korenev
Keywords: X-ray diffractometry, crystal chemistry, ruthenium, rhenium, binary complex salts
Pages: 126-132
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Binary complex salts [Ru(NH3)5Cl][ReCl6] and [Ru(NH3)5Cl]2[ReCl6]Cl2 were synthesized and characterized. An X-ray diffraction analysis showed that they were isostructural with the previously obtained isoformula salts [Rh(NH3)5Cl]×[OsCl6] and [Ir(NH3)5Cl]2[PtCl6]Cl2, respectively. Thermolysis of these compounds under hydrogen and helium was studied. According to X-ray phase analysis data, bimetallic solid solutions Ru0.67Re0.33 and Ru0.50Re0.50 were the final products of thermolysis. Their unit cell parameters correspond to the characteristics of alloys with similar compositions.
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I. Y. Bagryanskaya, E. V. Bartashevich, D. K. Nikulov, Y. V. Gatilov, A. V. Zibarev
Keywords: heterocyclic compounds, intermolecular interactions, crystal packings, molecular conformations, topological analysis of electron density
Pages: 133-143
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The intermolecular interactions and structural dichotomy in 1,3,2,4-benzodithiadiazine crystals (1) (the heterocycle is planar for one derivative, but bent for another) were studied in terms of topological analysis of electron density (ED) using QTAIM theory and crystal packing modeling in an OPiX approximation. The intermolecular interactions in crystals 1 can be detected and quantified by means of the critical points (CPs) of ED with (3, -1). The total value of ED at all CPs of a molecule can be correlated with the torsion angle that defines the bending of its heterocycle; the larger the total ED at intermolecular CPs, the smaller the bending of the heterocycle. Thus, under the conditions of weak intermolecular interactions in crystal, molecules 1 preserve the bent conformations typical of the gas phase; strong intermolecular interactions lead to planar conformations.
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A. V. Virovets, E. V. Peresypkina, E. V. Cherkasova, T. G. Cherkasova, N. V. Podberezskaya
Keywords: lanthanum, praseodymium, europium, gadolinium, terbium, Оµ-caprolactam, crystal structure, phase transition, twinning, thermochromism
Pages: 144-155
Abstract >>
The compounds [LnL8][Cr(NCS)6] (Ln = La3+, Pr3+, Eu3+, Gd3+, Tb3+, Yb3+, L = ε-C6H11NO) were obtained from aqueous solutions containing LnCl3, K3[Cr(NCS)6], and ε-caprolactam at
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B. V. Bukvetskii, T. V. Sedakova, A. G. Mirochnik
Keywords: crystal structure, antimony(III), aniline, luminescence
Pages: 156-159
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Y. S. Ezhov, S. A. Komarov, E. P. Simonenko, R. G. Pavelko, V. G. Sevast'yanov, N. T. Kuznetsov
Keywords: gas phase electron diffraction, quantum chemistry, tetrakis(trichlorosilyl)methane, molecule structure, internal rotation
Pages: 160-164
Abstract >>
Methods of quantum chemistry and gas phase electron diffraction (at a temperature of 303
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A. D. Vasiliev, N. N. Golovnev, I. A. Baidina
Keywords: fluoroquinolone, ciprofloxacin, sulfuric acid, crystal structure, hydrogen bonds
Pages: 165-168
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A new compound of C17H20FN3O⋅2HSO⋅H2O [ciprofloxacindi-um bis(hydrosulfate) monohydrate], C17H18FN3O3 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid (CfH, ciprofloxacin) is obtained and its crystal structure is determined. The crystal contains CfH and HSO ions and crystallization water molecules. Hydrogen (
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P. ??. Abramov, М. N. Sokolov, А. V. Virovets, V. P. Fedin
Keywords: rhodium, selenium, clusters, hydrothermal synthesis, X-ray analysis
Pages: 169-172
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The crystal structure of [(C5Me4Et)3Rh3(μ3-Se)2](PF6)2 and [(C5Me4Et)2Rh2(μ2-Cl)3]PF6, obtained in the reaction of [(C5Me4Et)Rh(C6H6)](PF6)2 with ZnSe in 4
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S. P. Khranenko, I. A. Baidina, N. V. Kuratieva, S. A. Gromilov
Keywords: palladium(II), nitrato complexes, X-ray powder diffraction, X-ray analysis, crystal chemistry
Pages: 173-176
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E. B. Miminoshvili, K. E. Miminoshvili, L. A. Beridze
Keywords: complex compounds, synthesis, X-ray diffraction analysis, Mn(II), Mg(II), ethazol, sulfamides
Pages: 177-182
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X-ray phase and X-ray spectral analyses are performed for newly synthesized M(Aet)2⋅11H2O compounds, where M(II) = Mn, Mg, and Mg0.5Mn0.5, (Aet)- = (C10H11N4O2S2)-, the anion of ethazol (2-(para-aminobenzene sulfanilamide)-5-ethyl-1,3,4-thiadiazole). It is found that these compounds are isostructural. In the third compound, Mg and Mn statistically substitute for each other and the substitution takes place at any ratio of these metals. The structure of crystals of the [Mn(OH2)6](Aet)2⋅5H2O compound is studied:
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M. S. Salakhov, B. T. Bagmanov, O. T. Grechkina
Keywords: theoretical information indices, cis- and trans-4-cyclohexene-1, 2-dicarboxylic acids, ionization constant
Pages: 183-187
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Theoretical information indices of cis- and trans-4-cyclohexene-1,2-dicarboxylic acids and their methyl and dimethyl substituted derivatives are calculated. Correlations between the indices and physicochemical properties of these compounds are analyzed.
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M. Botoshanskii, P. N. Bourosh, M. D. Revenko, I. D. Korzha, Y. A. Simonov, T. Panfilie
Keywords: quinoline-8-aldehyde S-methyl thiosemicarbazone, tautomerism, configuration, crystal structure
Pages: 188-191
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It is established that in quinoline-8-aldehyde S-methyl thiosemicarbazone dihydrochloride the thiosemicarbazide fragment has cis-configuration of terminal nitrogen atoms, similarly to that found in its coordination compounds with copper(II) and palladium(II).
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Z.M. Jin, L.L. Ma, W.X. Wei, C.S. Lin, W.Z. Li
Keywords: Clarithromycin, ethanol solvate, supramolecular complex, crystal structure
Pages: 192-196
Abstract >>
6-O-Methylerythromycin A (clarithromycin) ethanol solvate, C38H69NO13⋅0.5(C2H5OH), crystallizes in orthorhombic space group P212121 with a = 8.8459(14), b = 14.616(2), c =
= 38.787(8) Å, V = 5014.9(15) Å3, Z = 4. The conformation of clarithromycin in the title compound is essentially the same as that in previously studied clarithromycin unsolvated crystal and its methanol solvate. However, the crystal structure of the title compound differs from the previously studied structures due to differences in hydrogen bonding which lead to different molecular packing arrangements. The lactone carbonyl oxygen atom is not involved in hydrogen bonding, which is consistent with IR data.
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Z.M. Jin, L.L. Ma, W.X. Wei, Y.Q. Li
Keywords: Matrine, trans-matrine, absolute configuration, Sophora flavescens, IR spectroscopy
Pages: 197-200
Abstract >>
The title compound crystallizes in the monoclinic space group P21 with a = 7.804(1), b =
= 13.597(2), c = 9.093(1) Å, β = 108.41(1)
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