42 results on '"L. A. Khristenko"'
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2. Using the Method of Rare Combinations in the Interpretation of Electrical Prospecting Data
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Ju. I. Stepanov and L. A. Khristenko
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Prospecting ,Geophysics ,Geology ,Interpretation (model theory) - Published
- 2021
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3. Joint use of inverse gravity problem methods to increase interpretation informativity
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T. Balk, L. A. Khristenko, A. S. Dolgal, and P. Balk
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gravimetry ,magnetometry ,return problem ,an assembly method ,the guaranteed approach ,localization function ,field sourсe ,Mathematical optimization ,Computer science ,media_common.quotation_subject ,Scalar (physics) ,Inverse ,Quality (business) ,Pairwise comparison ,Inverse problem ,Representation (mathematics) ,Equivalence (measure theory) ,Interpretation (model theory) ,media_common - Abstract
This paper offers classification of information types that may be contained in the results of solving inverse gravity and magnetometry problems. There is argued that in terms of this classification most of the known algorithms for quantitative interpretation potential fields are substantially equivalent — none of them can guarantee a higher quality of solution results of the inverse problem. It is proved that the main reasons of such equivalence are scalar criteria of pairwise comparison of admissible solutions of the inverse problem in order to select the best of them. Several new approaches to the solution of inverse problems have been proposed, based on alternative mathematical forms of representation of the results of interpretation and oriented to objective assessment of opportunities of geophysical methods in the concrete interpretation conditions.
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- 2017
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4. Minimax approach to inverse problems of geophysics
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P. I. Balk, A. S. Dolgal, L. A. Khristenko, and T. V. Balk
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Mathematical optimization ,010504 meteorology & atmospheric sciences ,Hierarchy (mathematics) ,Geophysics ,Inverse problem ,010502 geochemistry & geophysics ,Minimax ,01 natural sciences ,Object (philosophy) ,Field (geography) ,Interpretation (model theory) ,General Earth and Planetary Sciences ,A priori and a posteriori ,Game theory ,0105 earth and related environmental sciences ,General Environmental Science ,Mathematics - Abstract
A new approach is suggested for solving the inverse problems that arise in the different fields of applied geophysics (gravity, magnetic, and electrical prospecting, geothermy) and require assessing the spatial region occupied by the anomaly-generating masses in the presence of different types of a priori information. The interpretation which provides the maximum guaranteed proximity of the model field sources to the real perturbing object is treated as the best interpretation. In some fields of science (game theory, economics, operations research), the decision-making principle that lies in minimizing the probable losses which cannot be prevented if the situation develops by the worst-case scenario is referred to as minimax. The minimax criterion of choice is interesting as, instead of being confined to the indirect (and sometimes doubtful) signs of the “optimal” solution, it relies on the actual properties of the information in the results of a particular interpretation. In the hierarchy of the approaches to the solution of the inverse problems of geophysics ordered by the volume and quality of the retrieved information about the sources of the field, the minimax approach should take special place.
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- 2016
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5. Using of Probabilistic-Statistical Characteristics in the Interpretation of Electrical Survey Monitoring Observations
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Ju. I. Stepanov, L. A. Khristenko, K. N. Shiryaev, E. I. Parshakov, A. A. Tainickiy, and A. V. Kichigin
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Amplitude ,Trace (linear algebra) ,Field (physics) ,Sliding window protocol ,Line (geometry) ,Probabilistic logic ,Algorithm ,Mathematics ,Power (physics) ,Interpretation (model theory) - Abstract
It is within the Verkhnekamsk salt deposit, on the potentially dangerous sections of the mine fields the geologic-geophysical monitoring, which includes the electroprospecting researches by the methods NF and SEP on three spans of the power line AB is carried out regularly. The analysis of statistical characteristics of values of potentials of the natural field and apparent resistance by means of the theory of estimates allows to increase significantly the volume of useful information and more accurately to trace the features of a geological structure which are implicitly expressed in the observed fields. For a more distinct allocation of the hidden regularities of change of amplitude of the apparent resistance (AR) field, a fast wavelet-transformation (FWT) of discrete values of AR by means of the HAAR_2 program was executed previously. The statistical characteristics of SEP values and potential of NF were calculated by various methods realized in the COSCAD 2D software package (in the sliding window, in one-dimensional and two-dimensional dynamic windows), and with different sizes of windows. The statistical characteristics of values of NF potential were combined in turn with the statistics of AR obtained at AB 100, 200 and 400 m, i.e. three multi-attribute spaces were formed. Their structure was analyzed by means of various methods of non-standard classification. The using of procedures of non-standard classification allowed to break the analyzed sets on homogeneous, by formal mathematical criteria, the classes spatially answering to sites of possible engineering-geological complications, that it is extremely difficult by results of only the qualitative analysis of field observations.
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- 2019
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6. Conformational composition of meta- and ortho-fluoro(trifluoromethoxy)benzene as studied by vibrational spectroscopy
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L. V. Khristenko, Anna L. Vilkova, Boris V. Lokshin, Igor F. Shishkov, and Vladimir M. Senyavin
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Infrared spectroscopy ,Condensed Matter Physics ,Photochemistry ,Amorphous solid ,Crystal ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Normal mode ,Phase (matter) ,symbols ,Physical chemistry ,Physical and Theoretical Chemistry ,Benzene ,Raman spectroscopy ,Conformational isomerism - Abstract
The IR spectra of o- and m-F-C6H4OCF3 in the gas, liquid, and solid (glass and crystal) phases were analyzed along with the Raman spectra of these compounds in the liquid and solid (glass and crystal) phases. This investigation includes both experimental and theoretical studies of the spectra. Vibrational frequencies and normal modes for all possible stable conformers of m- and o-fluoro(trifluoromethoxy)benzene were calculated using B3LYP/cc-pVTZ harmonic quantum-chemical force fields. It was found that m-F-C6H4OCF3 exists as a mixture of the orthogonal and two planar conformers in the gas, liquid, and amorphous solid (glass) phases and as one orthogonal conformer in the crystal state, while o-F-C6H4OCF3 exhibits only one orthogonal conformer in every phase.
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- 2013
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7. The structure and conformations of piracetam (2-oxo-1-pyrrolidineacetamide): Gas-phase electron diffraction and quantum chemical calculations
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Igor F. Shishkov, L. V. Khristenko, Lev V. Vilkov, Denis N. Ksenafontov, Natalia F. Moiseeva, and Nikolai M. Karasev
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Gas electron diffraction ,Hydrogen bond ,Chemistry ,Organic Chemistry ,Ab initio ,Ring (chemistry) ,Analytical Chemistry ,Inorganic Chemistry ,Crystallography ,Electron diffraction ,Intramolecular force ,Atom ,Molecule ,Spectroscopy - Abstract
The geometric structure of piracetam was studied by quantum chemical calculations (DFT and ab initio), gas electron diffraction (GED), and FTIR spectroscopy. Two stable mirror symmetric isomers of piracetam were found. The conformation of pyrrolidine ring is an envelope in which the C4 atom deviates from the ring plane, the angle between the planes (C3 C4 C5) and (C2 C3 C5) is 154.1°. The direction of the deviation is the same as that of the side acetamide group. The piracetam molecule is stabilized in the gas phase by an intramolecular hydrogen bond between the N9H2 group and the oxygen O6, bonded to C2. The principal structural parameters (re, A and ∠ e, degrees; uncertainties are 3σLS values) were found to be: r(С3 С4) = 1.533(1), r(C4 C5) = 1.540(1), r(N1 C5) = 1.456(1), r(C2 C3) = 1.520(1), r(N1 C7) = 1.452(1), r(C7 C8) = 1.537(1), r(N1 C2) = 1.365(2), r(C8 N9) = 1.360(2), r(C2 O6) = 1.229(1), r(C8 O10) = 1.221(1), ∠ C2 N1 C5 = 113.4(6), ∠ N1 C2 C3 = 106.9(6), ∠ N1 C7 C8 = 111.9(6), ∠ C7 C8 N9 = 112.5(6), ∠ N1 C2 O6 = 123.0(4), ∠ C3 N1 C7 = 120.4(4), ∠ C7 C8 O10 = 120.2(4), ∠ C5 N1 C2 O6 = 170(6), ∠ C3 C2 N1 C7 = 178(6), ∠ C2 N1 C7 C8 = 84.2, ∠ N1 C7 C8 O10 = 111.9. Download : Download full-size image
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- 2010
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8. Structure and conformation of (trifluoromethyl)thiobenzene, C6H5SCF3: Gas electron diffraction and quantum chemical calculations
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Nina I. Giricheva, Georgiy V. Girichev, Lev V. Vilkov, Igor F. Shishkov, L. V. Khristenko, Anatolii N. Rykov, Heinz Oberhammer, and Sergey A. Shlykov
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Trifluoromethyl ,Gas electron diffraction ,Organic Chemistry ,Thioanisole ,Bond order ,Analytical Chemistry ,Inorganic Chemistry ,Bond length ,chemistry.chemical_compound ,Crystallography ,chemistry ,Computational chemistry ,Single bond ,Lone pair ,Spectroscopy ,Natural bond orbital - Abstract
The geometric structure and conformation of (trifluoromethyl)thiobenzene, C 6 H 5 SCF 3 , has been determined by two independent gas electron diffraction (GED) studies at the Universities of Moscow and Ivanovo and by quantum chemical calculations. Both experimental studies result in perpendicular orientation of the S CF 3 bond relative to the benzene plane. This result is confirmed by several quantum chemical calculations (HF/6-31G(d), B3LYP/cc-pVTZ, MP2/6-31G(d), MP2/6-311+G(d,p) and MP2/cc-pVTZ) which predict single-minimum potential functions for internal rotation around the C(sp 2 ) S bond. A double-minimum potential function predicted by the B3LYP/6-31G(d) calculation is not compatible with the experiment. B3LYP and MP2 calculations with large basis sets (6-311+G(d,p) and cc-pVTZ) predict barriers to internal rotation around the C(sp 2 ) S bond between 2.4 and 2.6 kcal/mol. The geometric parameters of both experimental studies agree with each other within the experimental uncertainties, except for the C F bond distance. The effect of fluorination of the methyl group in thioanisole, C 6 H 5 SCH 3 , i.e., conformational change from planar orientation of the S CH 3 bond to perpendicular orientation of the S CF 3 bond, is rationalized on the basis of a natural bond orbital (NBO) analysis. The predominant effect is loss of conjugation between the p-shaped sulfur lone pair and the π system of the ring upon fluorination.
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- 2008
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9. Structure and conformation of thioanisole: Gas electron diffraction and contradicting quantum chemical calculations
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L. V. Khristenko, Igor F. Shishkov, Heinz Oberhammer, Lev V. Vilkov, and Nikolai M. Karasev
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Gas electron diffraction ,Chemistry ,Organic Chemistry ,Thioanisole ,Molecular physics ,Analytical Chemistry ,Inorganic Chemistry ,Orientation (vector space) ,Crystallography ,Planar ,Electron diffraction ,Perpendicular ,Molecule ,Conformational isomerism ,Spectroscopy - Abstract
The geometric structure and conformational properties of thioanisole, C6H5SCH3, have been studied by gas-phase electron diffraction (GED) and quantum chemical calculations. The GED intensities are fitted very well with a single conformer with planar orientation of the S–CH3 bond (φ(C–S) = 0°). The experimental potential function for internal rotation around the C(sp2)–S bond derived with a dynamic model possesses a single minimum for planar conformation, but a second shallow minimum for perpendicular orientation cannot be excluded. Calculated potential functions depend strongly on the computational method. The MP2 approximation with small basis sets (6-31G(d)) predict a single minimum for perpendicular orientation, (φ(C–S) = 90°), with intermediate basis sets (6-311G(d,p)) an additional shallow minimum for planar orientation and with large basis sets (cc-pVTZ) the global minimum for planar orientation and an additional shallow minimum at φ(C–S) = 90°. The B3LYP/cc-pVTZ calculations result in a single minimum for planar orientation, in agreement with the GED experiment. The experimental and calculated barrier to internal rotation is about 1 kcal/mol. The following geometric parameters (ra and ∠h1 with 3σ uncertainties) were derived: r(C–C)av = 1.395(3) A, r(C(sp2)–S) = 1.775(4) A, r(S–CH3) = 1.813(4) A, ∠CSC = 104.5(5), ∠C2C1C6 = 119.3(3), ∠C1C2C3 = 120.2(4)°.
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- 2008
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10. The molecular structure of fluoromalononitrile as determined by gas-phase electron diffraction and ab initio calculations
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L. V. Khristenko, E. G. Atavin, Lev V. Vilkov, and Marwan Dakkouri
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Chemistry ,Molecular Conformation ,Normal Distribution ,Electrons ,Models, Theoretical ,Molecular physics ,Carbon ,Malonates ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry ,Gas phase ,Halogens ,Models, Chemical ,Electron diffraction ,Ab initio quantum chemistry methods ,Nitriles ,Quantum Theory ,Physical chemistry ,Molecule ,Gases ,Instrumentation ,Quantum ,Spectroscopy ,Fluoromalononitrile - Abstract
The molecular structure of fluoromalononitrile was studied by means of gas-phase electron diffraction and quantum mechanical methods using HF/6-31G(d), MP2/6-311++G(2df,2pd) and DFT/B3LYP/6-31G(d), B3PW91/6-31G(d), B3LYP/6-311++G(2df,2pd) and B3PW91/6-311++G(2df,2pd). The r(g) and angle(alpha) structural parameters we obtained from the present analysis are: CC=1.487(5) A, CN=1.157(3) A, CF=1.386(5) A, CH=1.096 A (ass.), angleCCC=106.7(1.0) degrees , angleCCF=108.0(0.7) degrees , angleCCN=177.6(2.0) degrees . Uncertainties in parenthesis are 3sigma.
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- 2005
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11. Gas-phase electron diffraction, vibrational spectroscopy, and quantum chemical studies of the molecular structure of 3,3-dimethyl-3-silathiane
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Lev V. Vilkov, Boris V. Lokshin, E. G. Atavin, Svein Samdal, S. V. Kirpichenko, and L. V. Khristenko
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Electron density ,Solid-state physics ,Chemistry ,Gas electron diffraction ,Infrared spectroscopy ,Overtone band ,Molecular physics ,Inorganic Chemistry ,Electron diffraction ,Physics::Atomic and Molecular Clusters ,Materials Chemistry ,Molecule ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Ionization energy - Abstract
The 3,3-dimethyl-3-silathiane molecule was studied by gas-phase electron diffraction and vibrational spectroscopy. The initial geometrical parameters and the force field were calculated by the B3LYP/6-311+G** method; the vibrational amplitudes of atomic pairs and vibrational corrections were calculated using the scaled B3LYP/6-311+G** force field. The molecular conformation was found to be a distorted chair with structural parameters close to the expected ones.
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- 2005
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12. Structure and Conformation of 4-Fluoro(trifluoromethoxy)benzene: Gas Electron Diffraction and Quantum Chemical Calculations
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L. V. Khristenko, Heinz Oberhammer, Igor F. Shishkov, and Lev V. Vilkov
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Quantitative Biology::Biomolecules ,Gas electron diffraction ,Chemistry ,Infrared spectroscopy ,Ring (chemistry) ,Crystallography ,chemistry.chemical_compound ,Electron diffraction ,Computational chemistry ,Perpendicular ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Adiabatic process ,Benzene ,Conformational isomerism - Abstract
The geometric structure and conformational properties of 4-fluoro(trifluoromethoxy)benzene, 4-F-C 6 H 4 OCF 3 , were investigated independently in two laboratories (Moscow State University and Universitat Tubingen) usinggas electron diffraction (GED), quantum chemical calculations, and matrix infrared spectroscopy. Both experimental GED studies result in a perpendicular conformation (C-O-C plane perpendicular to the benzene ring). Analyses of the GED intensities with a simple two-conformer model cannot exclude a small contribution of up to 25% (Moscow) or 13% (Tubingen) of a planar conformer. Quantum chemical calculations lead to rather different potenial functions for internal rotation around the C(sp 2 )-O bond. HF, MP2, and B3LYP methods with 6-31G* basis sets predict potential functions with a single minimum for perpendicular orientation. The planar structure is predicted to correspond to a transition state, 0.6-1.8 kcal/mol higher in energy. B3LYP/ cc-pVTZ calculations predict an additional very shallow minimum for the planar conformer, about 0.6 kcal/ mol higher than that for the perpendicular structure. Infrared spectra demonstrate the presence of a single conformer in a Ne matrix at 15 K and no second conformer is expected to be present in the gas phase, assuming an adiabatic cooling process.
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- 2004
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13. Electron diffraction study of meta- and para-fluoronitrobenzene using results from quantum chemical calculations. Trends in the carbon–halogen bond length found in ortho-, meta- and para-halonitrobenzenes (Halo=F, Cl, Br, I)
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Igor F. Shishkov, Snefrid Gundersen, Lev V. Vilkov, L. V. Khristenko, Svein Samdal, and Hans V. Volden
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Halogen bond ,Chemistry ,Stereochemistry ,Gas electron diffraction ,Organic Chemistry ,chemistry.chemical_element ,Analytical Chemistry ,Inorganic Chemistry ,Bond length ,Crystallography ,Molecular geometry ,Electron diffraction ,Molecule ,Halo ,Carbon ,Spectroscopy - Abstract
The molecular geometry of meta - and para -fluoronitrobenzene has been determined by gas electron diffraction and quantum chemical calculations using HF, MP2 and DFT, and 6-311G**, 6-311++G** and cc-pVTZ basis sets. The obtained geometrical parameters ( r g , in A, ∠ α in degrees) for meta -fluoronitrobenzene are: r (C–C) av =1.397(4), r (N–O) av =1.227(3), r (C–N)=1.484(3), r (C–F)=1.333(8), r (C–H) av =1.107(16), ∠C1C2N=118.3(6), ∠C5C6F=120.6(24), ∠ONO=125.3(37), ∠C1C2C3=122.9(24), ∠C3C4C5=119.2(18) and ϕ (C–N)=0 (fixed) and for para-fluoronitrobenzene: r (C–C) av =1.393(2), r (N–O) av =1.232(3), r (C–N)=1.479 (dependent), r (C–F)=1.338(12), r (C–H) av =1.124(27), ∠C6C4F=118.7 (fixed), ∠ONO=124.2(23), ∠C4C5C6=123.8(17), ∠C3C2N=119.1 (fixed) and ϕ (C–N)=0 (fixed). Estimated error limits are three standard deviations from least-squares refinement using a diagonal weight matrix. B3LYP/6-311G** has been used to calculate the molecular structure for all sixteen different molecules XC 6 H 5 (X=F, Cl, Br, I) and ortho -, meta - and para -XC 6 H 4 NO 2 (X=F, Cl, Br, I). These general trends are predicted by the calculations: the C–X bond in XC 6 H 5 is longer than the C–X bond in ortho -XC 6 H 4 NO 2 , the C–X bond in ortho -XC 6 H 4 NO 2 , is shorter than the C–X bond in meta -XC 6 H 4 NO 2 , the C–X bond in meta -XC 6 H 4 NO 2 is slightly longer than the C–X bond in para -XC 6 H 4 NO 2 , the variation in the C–X bond length is approximately the same for X=F and Cl, smaller for X=Br and smallest for X=I. These trends are essentially also found experimentally. The C–X bond lengths are all calculated too long compared to experimental values.
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- 2004
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14. Molecular Structure of Silatrane Determined by Gas Electron Diffraction and Quantum-Mechanical Calculations
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Igor F. Shishkov, Svein Samdal, Galina S. Zaitseva, Sergey S. Karlov, F. M. Rudakov, L. V. Khristenko, A. B. Golubinskii, and Lev V. Vilkov
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Bond length ,Molecular geometry ,Chemistry ,Ab initio quantum chemistry methods ,Gas electron diffraction ,Perpendicular ,Ab initio ,Infrared spectroscopy ,Molecule ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Molecular physics - Abstract
The geometry of silatrane HSi(OCH2CH2)3N has been determined by gas electron diffraction, ab initio calculations, and vibrational spectroscopy of crystal. Using the scaled force field from DFT calculations the amplitudes and perpendicular corrections were calculated. It was assumed that the silatrane molecule has C 3 symmetry. The following values (r g bond lengths in A and ∠ a bond angles in deg. with three standard deviations from the least-squared refinements using a diagonal weight matrix) are: SiN 2.406(27); NC 1.443(7); OC 1.399(11); SiO 1.648(3); CC 1.504(15); NSiO 78.8(21); SiOC 128.1(11); SiNC 105.4(14); CCO 117.0(26); CCN 108.2(30); CNC 113.2(17); OSiO 116.3(13). The 5-membered rings are flattened. The sum of its bond angles is equal to 537.5(42). It is shown that a very large difference is found for Si—N distance from ab initio and DFT calculating.
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- 2004
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15. [Untitled]
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L. V. Khristenko, Igor F. Shishkov, Snefrid Gundersen, Svein Samdal, and Lev V. Vilkov
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Amplitude ,Molecular geometry ,Electron diffraction ,Gas electron diffraction ,Ab initio quantum chemistry methods ,Chemistry ,Ab initio ,Molecule ,Physical and Theoretical Chemistry ,Dihedral angle ,Condensed Matter Physics ,Molecular physics - Abstract
The molecular structure of ortho-fluoronitrobenzene (o-FNB) has been investigated by gas-phase electron diffraction and ab initio MO calculations. The geometrical parameters and force fields of o-FNB were calculated by ab initio and DFT methods. The obtained force fields were used to calculate vibrational amplitudes required as input parameters in an electron diffraction analysis. Within the experimental error limits, the geometrical parameters obtained from the gas-phase electron diffraction analysis are mostly in agreement with the results obtained from the ab initio calculations. The main results are: the molecular geometry of o-FNB is nonplanar with a dihedral angle about C–N of 38(3)°. The r g (C–F) bond is shortened to 1.307(13) A in comparison with r g (C–F) = 1.356(4) A in C6H5F.
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- 2003
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16. [Untitled]
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M.V. Popik, L. V. Khristenko, E. G. Atavin, Lev V. Vilkov, A. V. Golubinskii, Yu. A. Ustynyuk, A. A. Salgalov, and Igor P. Gloriozov
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Quantum chemical ,chemistry.chemical_compound ,Crystallography ,Electron density ,chemistry ,Electron diffraction ,Molecule ,Density functional theory ,General Chemistry ,Molecular physics ,Flattening ,Fulvene ,Gas phase - Abstract
The molecular structure of 6-(N,N-dimethylamino)fulvene was studied by gas-phase electron diffraction and quantum-chemical methods (HF/6-31G(d), MP2/3Z, MP2/4Z, density functional theory with the B3LYP/6-31G(d) and PBE/3Z functionals). Pronounced flattening of the nitrogen atom and equalization of the intracyclic C—C bonds were found to be a consequence of the electron delocalization in the molecule.
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- 2003
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17. The molecular structure of boratrane determined by gas electron diffraction and quantum mechanical calculations
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Sergey S. Karlov, F. M. Rudakov, Igor F. Shishkov, L. V. Khristenko, Svein Samdal, Galina S. Zaitseva, and Lev V. Vilkov
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Gas electron diffraction ,Chemistry ,Organic Chemistry ,Ab initio ,Infrared spectroscopy ,Molecular physics ,Analytical Chemistry ,Inorganic Chemistry ,Bond length ,Crystallography ,Molecular geometry ,Ab initio quantum chemistry methods ,Perpendicular ,Molecule ,Spectroscopy - Abstract
The geometry of silatrane HSi(OCH2CH2)3N has been determined by gas electron diffraction, ab initio calculations, and vibrational spectroscopy of crystal. Using the scaled force field from DFT calculations the amplitudes and perpendicular corrections were calculated. It was assumed that the silatrane molecule has C3 symmetry. The following values (rg bond lengths in A and ∠a bond angles in deg. with three standard deviations from the least-squared refinements using a diagonal weight matrix) are: SiN 2.406(27); NC 1.443(7); OC 1.399(11); SiO 1.648(3); CC 1.504(15); NSiO 78.8(21); SiOC 128.1(11); SiNC 105.4(14); CCO 117.0(26); CCN 108.2(30); CNC 113.2(17); OSiO 116.3(13). The 5-membered rings are flattened. The sum of its bond angles is equal to 537.5(42). It is shown that a very large difference is found for Si—N distance from ab initio and DFT calculating.
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- 2002
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18. A reinvestigation of the molecular structure of dimethyl- N -nitramine by gas electron diffraction, ab initio calculations of the molecular geometry and the force field and vibrational spectra
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Svein Samdal, Snefrid Gundersen, L. V. Khristenko, V.A. Sipachev, Lev V. Vilkov, Igor F. Shishkov, and Mauricio Alcolea Palafox
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Chemistry ,Gas electron diffraction ,Organic Chemistry ,Ab initio ,Analytical Chemistry ,Inorganic Chemistry ,Bond length ,Crystallography ,Molecular geometry ,Electron diffraction ,Ab initio quantum chemistry methods ,Molecule ,Amine gas treating ,Spectroscopy - Abstract
The molecular structure of dimethyl- N -nitramine was reinvestigated with gas-phase electron diffraction (ED) and ab initio calculations. Ab initio calculations using different basis sets and HF, MP2 and DFT all predict a molecule with C s symmetry and a pyramidal amine N bond configuration. The vibrational spectra were interpreted from the scaling of the harmonic force field, and vibrational amplitudes required for the ED analysis were calculated from this scaled force field. The following values ( r g bond lengths in A and ∠ α angles in degrees with errors equal to three standard deviations) were found for the main parameters: r (N–O)=1.232(3), r (N–N)=1.387(3), r (N–C)=1.466(3), r (C–H) ave =1.114(9), ∠CCN=116.1(6), ∠CNC=122.4(27), ∠ONO=127.6(12), ∠NCH ave =109.9(18). The sum of the bond angles around the amine N atom is 354.6(28)°. The geometrical parameters obtained from the ED analysis are in agreement with the ab initio calculations except that a more pyramidal amine N bond configuration is predicted by ab initio.
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- 1999
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19. The molecular structure of methyl(vinyl)-N-nitroamine reinvestigated by gas phase electron diffraction and ab initio MO calculations
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Per N. Skancke, Lev V. Vilkov, L. V. Khristenko, and Igor F. Shishkov
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Chemistry ,Organic Chemistry ,Ab initio ,Analytical Chemistry ,Inorganic Chemistry ,Bond length ,Crystallography ,chemistry.chemical_compound ,Molecular geometry ,Electron diffraction ,Ab initio quantum chemistry methods ,Nitroamine ,Molecule ,Physics::Chemical Physics ,Conformational isomerism ,Spectroscopy - Abstract
The molecular structure of methyl(vinyl)- N -nitroamine has been reinvestigated by gas-phase electron diffraction and ab initio MO calculations. The methyl(vinyl)- N -nitroamine has been found from ab initio MO calculations to exist as a mixture of two conformers: an anti- and a syn-form, the former being more stable. The energy difference is predicted to be 3.3 kcal mol −1 . The results obtained by the calculation were used to evaluate vibrational amplitudes required for further electron diffraction analysis. In the electron diffraction analysis some bond length and bond angle differences found by ab initio calculations were assumed. The vapour was assumed to consist only of the anti-form. The torsional angle around the NC vinyl and NN bonds were refined. It has been found that the amine group is planar. The vinyl group is out of the molecular plane by 19° ( r a -structure).
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- 1997
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20. Vibrational spectra and rotational isomerism of bis(N-2-chloroethyl)nitramine
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L. V. Khristenko, Lev V. Vilkov, E. Yu. Ivanova, L. F. Shishkov, N. F. Pyatakov, Svein Samdal, and Yu. A. Pentin
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Quantitative Biology::Biomolecules ,Solid-state physics ,Chemistry ,Ab initio ,Spectral line ,Inorganic Chemistry ,Crystal ,symbols.namesake ,Crystallography ,Computational chemistry ,Materials Chemistry ,symbols ,Polar ,Molecule ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Conformational isomerism - Abstract
The IR and Raman spectra of bis(N-2-chloroethyl)nitramine (BCENA) in the liquid and crystalline states and in CCl4 and CH3CN solutions are studied. The spectra are compared, and it is concluded that BCENA exists as a mixture of conformers of different polarities in the liquid state and as one less polar conformer in the crystalline state. To determine the conformations corresponding to the total electron energy minima and interpret the vibrational spectrum of BCENA, we performed an ab initio quantum chemical calculation of the BCENA molecule in the Hartree-Fock approximation using the 3–21G* and 6–31G* basis sets. Out of twelve possible conformations five are stable; the most stable conformer is C2(GG). The frequencies and forms of normal vibrations of stable conformers are calculated using scaled quantum chemical force fields. The calculated and experimental frequencies are compared, and the relations between the frequencies of skeletal stretching and bending vibrations are analyzed. It is concluded that the BCENA crystal is formed by the C2 (GG) conformer. The vibrational spectrum is interpreted, and the frequencies are assigned to vibrations of conformers differing in form.
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- 1997
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21. The molecular structure of 2-chloroacrolein studied by gas electron diffraction, vibrational spectroscopy and ab initio MO calculations
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Per N. Skancke, L. V. Khristenko, Lev V. Vilkov, and Igor F. Shishkov
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Gas electron diffraction ,Chemistry ,Organic Chemistry ,Ab initio ,Dihedral angle ,Molecular physics ,Analytical Chemistry ,Inorganic Chemistry ,Bond length ,Crystallography ,Molecular geometry ,Electron diffraction ,Ab initio quantum chemistry methods ,Conformational isomerism ,Spectroscopy - Abstract
The molecular structure of 2-chloroacrolein was reinvestigated by means of gas-phase electron diffraction, ab initio MO calculations and vibrational analysis. From the MO calculations ( MP 2 6–31 G ∗ ), the molecule was found to exist as two conformers: an anti form which is more stable than its syn counterpart by 0.3 kcal mol −1 . The corresponding populations at room temperature are 70% and 30%, respectively. An analysis of the experimental vibrational spectra was carried out. The ab initio force field was scaled to fit the experimental spectra. The data obtained were used to calculate vibrational amplitudes and perpendicular corrections required for further electron diffraction analysis. In the electron diffraction analysis, the bond length and bond angle differences predicted by ab initio calculations of the conformers were assumed. The vapour was assumed to consist of two conformers: exact anti form and another close to syn form. The torsional angle of rotation about the CC bond in the latter was refined in two ways: the first refinement with perpendicular corrections and fixed amplitudes gave a dihedral angle in the range 160–180; the second, including both geometrical parameters and some amplitudes, resulted in a value of 160 for the dihedral angle. Conformational composition and geometrical parameters obtained from the electron diffraction analysis are in agreement with the results from ab initio calculations.
- Published
- 1996
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22. ChemInform Abstract: Vibrational Spectra and Conformation of Some Dinitramines, Alkyl- and Chloroalkyl Nitramines
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L. V. Khristenko, E. Yu. Ivanova, Yu. A. Pentin, and N. G. Sidorenko
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chemistry.chemical_classification ,chemistry ,Computational chemistry ,Stereochemistry ,General Medicine ,Alkyl ,Vibrational spectra - Published
- 2010
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23. Molecular structure of 1-methoxymethylaziridine and methoxymethyldimethylamine and anomeric effects
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Pavel E. Dormov, Igor F. Shishkov, L. V. Khristenko, Marwan Dakkouri, Lev V. Vilkov, Gulnara K. Kadorkina, and Remir G. Kostyanovsky
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Crystallography ,Anomer ,Chemistry ,Molecule ,General Chemistry ,Conformational isomerism - Abstract
For 1-methoxymethylaziridine 1 it is proved experimentally (GED) and theoretically that the equilibrium conformers are stabilised by the anomeric effects n(N) → σ*(C–O) and n(O) → σ*(C–N), whereas in the case of methoxymethyldimethylamine 2 the calculations predict the existence of a conformer appropriate to the n(N) → σ*(C–O) effect.
- Published
- 2000
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24. Molecular structure and conformation of nitrobenzene reinvestigated by combined analysis of gas-phase electron diffraction, rotational constants, and theoretical calculations
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Lev V. Vilkov, S. V. Krasnoshchekov, L. V. Khristenko, Natalja Vogt, István Hargittai, Igor F. Shishkov, Olga V. Dorofeeva, Yuriy V. Vishnevskiy, and Jürgen Vogt
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Chemistry ,Anharmonicity ,Internal rotation ,Analytical chemistry ,Condensed Matter Physics ,Gas phase ,Isotopomers ,Nitrobenzene ,chemistry.chemical_compound ,Electron diffraction ,Computational chemistry ,Molecule ,Rotational spectroscopy ,Physical and Theoretical Chemistry - Abstract
The molecular structure and conformation of nitrobenzene has been reinvestigated by gas-phase electron diffraction (GED), combined analysis of GED and microwave (MW) spectroscopic data, and quantum chemical calculations. The equilibrium r e structure of nitrobenzene was determined by a joint analysis of the GED data and rotational constants taken from the literature. The necessary anharmonic vibrational corrections to the internuclear distances (r e − r a) and to rotational constants (B e (i) − B 0 (i) ) were calculated from the B3LYP/cc-pVTZ quadratic and cubic force fields. A combined analysis of GED and MW data led to following structural parameters (r e) of planar nitrobenzene (the total estimated uncertainties are in parentheses): r(C–C)av = 1.391(3) A, r(C–N) = 1.468(4) A, r(N–O) = 1.223(2) A, r(C–H)av = 1.071(3) A, $${\angle}$$ C2–C1–C6 = 123.5(6)°, $${\angle}$$ C1–C2–C3 = 117.8(3)°, $${\angle}$$ C2–C3–C4 = 120.3(3)°, $${\angle}$$ C3–C4–C5 = 120.5(6)°, $${\angle}$$ C–C–N = 118.2(3)°, $${\angle}$$ C–N–O = 117.9(2)°, $${\angle}$$ O–N–O = 124.2(4)°, $${\angle}$$ (C–C–H)av = 120.6(20)°. These structural parameters reproduce the experimental B 0 (i) values within 0.05 MHz. The experimental results are in good agreement with the theoretical calculations. The barrier height to internal rotation of nitro group, 4.1±1.0 kcal/mol, was estimated from the GED analysis using a dynamic model. The equilibrium structure was also calculated using the experimental rotational constants for nitrobenzene isotopomers and theoretical rotation–vibration interaction constants.
- Published
- 2007
25. Vibrational spectra and confirmations of bis(N-ethy)nitramine molecule
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Lev V. Vilkov, Yu. A. Pentin, L. V. Khristenko, C. Van Alsenoy, K. Franckaerts, A. I. Fishman, Igor F. Shishkov, N. F. Pyatakov, and S.F. Mironov
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Chemistry ,Infrared ,Organic Chemistry ,Ab initio ,Infrared spectroscopy ,Analytical Chemistry ,Inorganic Chemistry ,Crystal ,Crystallography ,symbols.namesake ,Computational chemistry ,Ab initio quantum chemistry methods ,symbols ,Molecule ,Raman spectroscopy ,Conformational isomerism ,Spectroscopy - Abstract
The Raman (50–3200 cm−1) and infrared (50–3200 cm−1) spectra of bis(N-ethyl)nitramine, (CH3CH2)2NNO2, in the liquid and crystal states have been recorded. Optimized geometries and conformational stabilities have been obtained from ab initio calculations utilizing the RHF/6-31G∗∗ level. This compound was shown to have two stable conformations with a planar nitramine fragment and the CH3 groups orthogonal to it and located either on the same or on the different sides of it. The computed energy difference between two conformers is 0.57 kcal/mol. (CH3CH2)2NNO2 exists as a mixture of the two conformations in the liquid state, while only the most stable one, with the CH3 groups located on the different sides of the nitramine fragment, remains in crystal state. The vibrational frequencies have been calculated using ab initio scaled force fields, and the vibrational spectra have been interpreted in detail.
- Published
- 1999
26. Molecular Structure of Silatrane Determined by Gas Electron Diffraction and Quantum-Mechanical Calculations.
- Author
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I. F. Shishkov, L. V. Khristenko, F. M. Rudakov, A. B. Golubinskii, L. V. Vilkov, and S.
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PARTICLES (Nuclear physics) ,ELECTRON diffraction ,MOLECULAR structure ,CHEMICAL structure - Abstract
The geometry of silatrane HSi(OCH
2 CH2 )3 N has been determined by gas electron diffraction, ab initio calculations, and vibrational spectroscopy of crystal. Using the scaled force field from DFT calculations the amplitudes and perpendicular corrections were calculated. It was assumed that the silatrane molecule has C3 symmetry. The following values (rg bond lengths in Å and ∠a bond angles in deg. with three standard deviations from the least-squared refinements using a diagonal weight matrix) are: SiN 2.406(27); NC 1.443(7); OC 1.399(11); SiO 1.648(3); CC 1.504(15); NSiO 78.8(21); SiOC 128.1(11); SiNC 105.4(14); CCO 117.0(26); CCN 108.2(30); CNC 113.2(17); OSiO 116.3(13). The 5-membered rings are flattened. The sum of its bond angles is equal to 537.5(42). It is shown that a very large difference is found for Simath>N distance from ab initio and DFT calculating. [ABSTRACT FROM AUTHOR]- Published
- 2004
27. Molecular structure of 6-(N,N-dimethylamino)fulvene from a joint gas-phase electron diffraction and quantum-chemical study.
- Author
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E. G. Atavin, A. V. Golubinskii, M. V. Popik, L. V. Khristenko, I. P. Gloriozov, and A. A
- Abstract
The molecular structure of 6-(N,N-dimethylamino)fulvene was studied by gas-phase electron diffraction and quantum-chemical methods (HF/6-31G(d), MP2/3Z, MP2/4Z, density functional theory with the B3LYP/6-31G(d) and PBE/3Z functionals). Pronounced flattening of the nitrogen atom and equalization of the intracyclic CC bonds were found to be a consequence of the electron delocalization in the molecule. [ABSTRACT FROM AUTHOR]
- Published
- 2003
28. IR and Raman spectra of 1-sila-2-oxa-3,5-cyclohexadienes
- Author
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L. V. Khristenko, V. P. Anosov, Yu. A. Pentin, M. O. Labartkava, V. V. Stepanov, E. A. Chernyshev, T. L. Krasnova, and A. N. Kurskii
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symbols.namesake ,Chemistry ,Cyclohexadienes ,symbols ,Condensed Matter Physics ,Raman spectroscopy ,Photochemistry ,Spectroscopy - Published
- 1978
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29. Calculation of the reduced moment of inertia and estimation of the potential function for the hindered internal rotation in various methyl- and chloro-substituted vinylsilanes
- Author
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L. V. Khristenko, V. I. Tyulin, Yu. A. Pentin, and A. A. Zenkin
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Inorganic Chemistry ,Classical mechanics ,Materials science ,Solid-state physics ,Internal rotation ,Materials Chemistry ,Rotary inertia ,Function (mathematics) ,Physical and Theoretical Chemistry ,Moment of inertia ,Rotational energy - Published
- 1980
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30. An ab initio calculation of the structure and scaled quantum mechanical harmonic force field of nitromethane
- Author
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Charles W. Bock, L. V. Khristenko, Yu. N. Panchenko, S.V. Krasnoshchiokov, and Yu. A. Pentin
- Subjects
Electronic correlation ,Nitromethane ,Chemistry ,Ab initio ,Infrared spectroscopy ,Staggered conformation ,Condensed Matter Physics ,Biochemistry ,Molecular physics ,Isotopomers ,chemistry.chemical_compound ,Ab initio quantum chemistry methods ,Quantum mechanics ,Physical and Theoretical Chemistry ,Conformational isomerism - Abstract
A complete optimization of the nitromethane geometry at the HF/6-31G and HF/ 6-31G* (5D) levels for staggered (one CH bond situated in a plane perpendicular to the plane of the heavy atoms) and eclipsed conformations is reported. The geometrical parameters obtained for the staggered conformation are in quite good agreement with the microwave structure (ref. 1). The effect of electron correlation on the energy difference between the two conformers is estimated using single point MP4SDQ/6-31G* calculations at the 6-31G geometry. The harmonic force field for both conformers are calculated at the HF/6-31G//HF/6-31G level. Taking into account the known overestimation of the vibrational frequencies by ∼20% in ab initio calculations, the experimental frequency assignment is confirmed. The six scale factors for the force field were evaluated using the experimental frequencies of nitromethane and nitromethane-d 3 (ref. 2). The vibrational frequencies for the five isotopomers of staggered nitromethane are determined with the scaled quantum mechanical force field (SQMFF). A detailed interpretation of conformational effects in the IR spectrum of crystalline CHD 2 NO 2 is proposed.
- Published
- 1987
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31. Vibrational spectra and conformational composition of ethylene glycol dinitrate in solid phases
- Author
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S. V. Krasnoshchekov, L. V. Khristenko, Yu. A. Pentin, and G. A. Beresneva
- Subjects
Crystal ,Crystallography ,chemistry.chemical_compound ,Chemistry ,Metastability ,Excited state ,Ethylene glycol dinitrate ,Infrared spectroscopy ,Condensed Matter Physics ,Supercooling ,Conformational isomerism ,MINDO ,Spectroscopy - Abstract
8. J. A. Barltrop and J. D. Coyle, Excited States in Organic Chemistry [Russian transla- tion], Moscow (1978), pp. 67"70. 9. I. S. Ioffe and V. F. Otten, Zh. Organ. Khim., 32, No. 4, 1196-1201 (1962). i0. I. S. Ioffe and V. F Otten, Zh. Organ. Khim., i, No. 2, 343-346 (1965). ii. Yu. Yu. Lur'e, Handbook on Analytical Chemistry [in Russian], Moscow (1979), p. 322. 12. B. Stevens, N. Conneily, and P. Suppan, Spectrochim. Acta, 2-2, No. 12, 2121-2122 (1966). 13. Sharma Ashutash and M. K. Machwe, Curr. Sci. (India), 5_~i, No. 13, 657-659 (1982). 14. M. D. Galanin, A. A. Kut'enkov, V. N. Smorchkov, et al., Opt. Spektrosk., 53, No. 4, 683-689 (1982). 15. V. Ya. Artyukhov, R. T. Kuznetsova, and R. M. Fofonova, Zh. Prikl. Spektrosk., 37, No. 4, 576-580 (1982). 16. F. V. Schaefer (ed.), Dye Lasers, Springer, New York (1977). VIBRATIONAL SPECTRA AND CONFORMATIONAL C~9OSITION OF ETHYLENE GLYCOL DINITRATE IN SOLID PHASES G. A. Beresneva, L. V. Khristenko, UDC 539.194.01 S. V. Krasnoshchekov, and Yu. A. Pentin The authors of [i] studied the vibrational spectra of ethylene glycol dinitrate (EGDN) and showed that in the liquid state this compound consists of a mixture of conformers, while in the crystalline state it exists in the form of two modifications: a metastable one (crystal II), obtained by intense supercooling the liquid, and a stable modification (crystal I) obtained by either slowly cooling the liquid, or by heating the metastable modification to a temperature of -50~ If we assume that in a restrained internal rotation around the C--C and C--O bonds, the "staggered" conformations will be stable, while the --C-~NO= groups are planar, then EGDN can exist in the form of ten different nuclear equilibrium configurations. Figure i shows these possible conformations of EGDN. The authors of [i] suggested that each of the solid modifications is formed by only one of the ten possible conformers, which were identified from the data of rotation isomerism of ethyl nitrate [2] and the results of vibrational calculation carried out in [3], using force constants obtained by the MINDO/2 method. In this present work, the IR spectra of crystals I and II were recorded on a Bruker Fourier-type spectrometer with a higher,resolution than that obtained in [i], including the region below 400 cm -I, in which the IR spectra of crystals have not yet been studied. Figure 2 shows the IR spectra of a vitreous EGDN and two of its crystalline modifications (I and II). In the spectrum of crystal II in the 100-900 cm -I region, a region of skeletal stretch- ing and deformational vibrations, which are most sensitive to rotation isomerism, the number of bands exceeds that required for one nuclear configuration at equilibrium. On crystal II § crystal I transition, the bands at 213, 390, 588, 662, 715, 862, 928, i036,'1237, 1392, 1431, 1460, and 1646 cm -i disappear. Bands at 364, 405, 581, 656, 680, 937, 1044, 1232, 1309, 1396, 1422, 1449, and 1666 cm -~, with a low intensity in the spectrum of crystal II, become markedly more intense, and the number of bands in the spectrum of crystal I in the 100-900 cm -i region corresponds to the number of bands for one Conformer. These facts indicate that crystal II is formed by at least two conformers, and crystal I by one conformer, and the conformer forming crystal I is also included in the composition of crystal II. For a more reliable identification of the conformers forming crystals I and II, we calculated the frequencies and forms of normal vibrations of all the ten possible conformers of EGDN. The calculations were carried out in an independent system of local symmetry co- ordinates, by a standard method [4]. The natural coordinates introduced, which are repre- Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 48, No. 6, pp. 946-952, June, 1988. Original article submitted April 8, 1987. 614 0021-9037/88/4806-0614512.50 9 1988 Plenum Publishing Corporation
- Published
- 1988
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32. Structure of the 3,3-dimethyl-3-silathietane molecule according to data from gas-phase electron diffraction analysis with consideration of vibrational effects
- Author
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L. V. Khristenko, S. V. Kirpichenko, S. A. Strelkov, M. G. Voronkov, S. V. Krasnoshchekov, Lev V. Vilkov, Yu. A. Pentin, Vladimir S. Mastryukov, E. N. Suslova, and A. V. Golubinskii
- Subjects
Inorganic Chemistry ,Physics ,Crystallography ,Electron density ,Reflection high-energy electron diffraction ,Electron diffraction ,Gas electron diffraction ,Materials Chemistry ,Physical and Theoretical Chemistry ,Selected area diffraction ,Ring (chemistry) ,Powder diffraction ,Electron backscatter diffraction - Abstract
The 3,3-dimethyl-3-silathietane molecule has been investigated by gas-phase electron diffraction analysis with consideration of the vibrational effects. The following geometric parameters were obtained (the distances ra, the angles L~, the errors in the form of 3o in parentheses, for ~ 50): S-C 1.853(4), Si-C m 1.870(5) (m stands for methyl), Si-C r 1.916(3) (r stands for ring), C-H 1.086(3) ~, L(C-Si-C) m = 106.9(7), L(C-Si-C) r = 86.1(3), LSi-C-S = 90.5(5), and LC-S-C = 89.5(4) ~ The fourmembered ring is nonplanar; the angle 9 between the CSiC and CSC planes equals 2 0 . 3 ( 2 0 ) ~
- Published
- 1988
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33. Vibrational spectra of rotational isomers of vinyldichlorosilane
- Author
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L. V. Khristenko, Y. A. Pentin, and T. M. Il'enko
- Subjects
Materials science ,Rotational–vibrational spectroscopy ,Condensed Matter Physics ,Molecular physics ,Spectroscopy ,Vinyldichlorosilane ,Vibrational spectra - Published
- 1976
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34. Vibrational spectra and rotational isomerism of dimethylvinylmethoxysilane
- Author
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A. E. Chernyshev, Yu. A. Pentin, L. V. Khristenko, and A. N. Kurskii
- Subjects
Materials science ,Rotational–vibrational spectroscopy ,Condensed Matter Physics ,Molecular physics ,Spectroscopy ,Vibrational spectra - Published
- 1977
- Full Text
- View/download PDF
35. Ab initio analysis of structure and vibrational spectrum of methyl nitrate
- Author
-
Ch.W. Bock, S.V. Krasnoshchiokov, L. V. Khristenko, Yu. N. Panchenko, and Yu. A. Pentin
- Subjects
Force constant ,chemistry.chemical_compound ,chemistry ,Computational chemistry ,Ab initio quantum chemistry methods ,Ab initio ,General Physics and Astronomy ,Physical chemistry ,Molecule ,Physical and Theoretical Chemistry ,Vibrational spectrum ,Methyl nitrate - Abstract
Ab initio calculations of the structure and harmonic force field of methyl nitrate have been computed at the HF/6-31G//HF/6-31G level. The assignment of the experimental frequencies of the CH 3 ONO 2 and CD 3 ONO 2 molecules were made using the unscaled quantum-mechanical force constants, which suggest a reassignment of the δ(NO 2 ) and ϱ r (NO 2 ) vibrations of CD 3 ONO 2 . Taking into account these new vibrational assignments, a refined harmonic force field for methyl nitrate is computed using a least-squares technique.
- Published
- 1986
- Full Text
- View/download PDF
36. Vibrational spectrum of 1,1-dimethyl-1-sila-3-thiocyclobutane
- Author
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Yu. A. Pentin, L. V. Khristenko, V. K. Matveev, and O. I. Kolobova
- Subjects
Materials science ,Overtone band ,Vibrational spectrum ,Condensed Matter Physics ,Molecular physics ,Spectroscopy - Published
- 1987
- Full Text
- View/download PDF
37. Investigations on derivatives of 5′-O-tosyladenosine
- Author
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N. A. Preobrazhenskii, I. P. Rudakova, L. V. Khristenko, A. A. Amagaeva, I. M. Kustanovich, and A. M. Yurkevich
- Subjects
Acylation ,Substitution reaction ,chemistry.chemical_compound ,Acetic anhydride ,Deoxyadenosine ,Chemistry ,Lithium bromide ,Nucleophilic substitution ,Organic chemistry ,lipids (amino acids, peptides, and proteins) ,Plant Science ,General Chemistry ,General Biochemistry, Genetics and Molecular Biology - Abstract
Acylation and nucleophilic substitution reactions in a number of derivatives of 5′-O-tosyladenosine have been described.
- Published
- 1968
- Full Text
- View/download PDF
38. [Methods for the quantitative determination of streptomycin]
- Author
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L A, Khristenko, I M, Pertsev, and D P, Salo
- Subjects
Immunodiffusion ,Dose-Response Relationship, Drug ,Microbial Sensitivity Tests ,Buffers ,Hydrogen-Ion Concentration ,Solutions ,Nephelometry and Turbidimetry ,Streptomycin ,Autoradiography ,Colorimetry ,Indicators and Reagents ,Spectrophotometry, Ultraviolet ,Carbon Radioisotopes ,Dialysis ,Polarography - Published
- 1975
39. [Possibility of using cellulose derivatives as a protector of the endothelium in a cataract operation]
- Author
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M A, Pen'kov, I M, Pertsev, Z I, Butkevich, L A, Khristenko, and N M, Avrushchenko
- Subjects
Cornea ,Carboxymethylcellulose Sodium ,Drug Evaluation, Preclinical ,Animals ,Drug Evaluation ,Humans ,Cataract Extraction ,Endothelium ,Postoperative Period ,Rabbits ,Methylcellulose ,Ophthalmic Solutions - Published
- 1984
40. [Photoelectrocolorimetric method of determining streptomycin sulfate in the blood after absorption from ointments prepared on various ointment bases]
- Author
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L A, Khristenko, V I, Chueshov, I M, Pertsev, and D P, Salo
- Subjects
Ointments ,Photometry ,Ointment Bases ,Skin Absorption ,Electrochemistry ,Pharmaceutic Aids ,Streptomycin ,Animals ,Colorimetry ,Rabbits - Published
- 1975
41. [Study of arenarin eye ointments]
- Author
-
L A, Khristenko, A K, Negrash, I M, Pertsev, D P, Salo, and M A, Trunova
- Subjects
Diffusion ,Ointments ,Ointment Bases ,Plants, Medicinal ,Temperature ,Hydrogen-Ion Concentration ,Ophthalmic Solutions ,Anti-Bacterial Agents - Published
- 1978
42. [Ophthalmic drug films in the treatment of inflammatory diseases of the eyeball]
- Author
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M A, Pen'kov, N M, Avrushchenko, and L A, Khristenko
- Subjects
Adult ,Clinical Trials as Topic ,Endophthalmitis ,Mydriatics ,Plants, Medicinal ,Adolescent ,Hydrocortisone ,Administration, Topical ,Erythromycin Ethylsuccinate ,Anti-Inflammatory Agents ,Drug Evaluation, Preclinical ,Middle Aged ,Anti-Bacterial Agents ,Desensitization, Immunologic ,Animals ,Drug Evaluation ,Humans ,Drug Therapy, Combination ,Rabbits ,Ophthalmic Solutions ,Child ,Aged - Published
- 1978
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