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61.
Vokin A. I. Shulunova A. M. Aksamentova T. N. Es'kova L. A. Elokhina V. N. Lopyrev V. A. Turchaninov V. K. 《Russian Journal of General Chemistry》2001,71(1):137-142
The effect of nonspecific solvation on the long-wave absorption band in the UV spectra of isomeric nitropyrazoles was studied. The aprotic inert and aprotic protophilic solvents exert different spectroscopic effects. In the former solvents, the solvatochromism is mainly governed by orientation interactions, and in the latter solvents, along with the orientation interactions, the UV spectrum is appreciably influenced by the induction, polarization, and dispersion interactions, which is due to the presence of readily polarizable nonbonding electron pairs and/or a pi-electron system in molecules of such solvents. 相似文献
62.
The equilibrium torsion angles of 2-arylpyrroles in the liquid and solid phases were estimated by UV spectroscopy. In solution,
compounds containing no substituents in positions 1, 3, and 2′ possess an average torsion angle of 24°, those containing one
substituent have an angle of 29°, and in the case of two and three substituents, the angles are 53° and 65°, respectively.
Phase transitions lead to flattening of the molecules in almost all cases. The average torsion angles in the compounds with
no substituents in positions 1, 3, and 2′ decrease by ≈5° on passing from the gas to the liquid state and by ≈25° on going
from the liquid to the solid state. The geometric parameters of 2-arylpyrroles with one or two substituents in positions 1,
3, and 2′ are less sensitive to phase transitions, while trisubstituted derivatives even retain their equilibrium conformations
upon phase transitions.
Deceased.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1472–1479, August, 1997. 相似文献
63.
Turchaninov V. K. Vokin A. I. Gavrilova G. A. Aksamentova T. N. Chipanina N. N. Kanitskaya L. V. Fedorov S. V. Shulunova A. M. Trofimova O. M. Voronkov M. G. 《Russian Journal of General Chemistry》2004,74(4):559-566
(4-Nitrobenzoyloxymethyl)trifluorosilane containing a five-coordinate silicon atom ( = OSi) is specifically solvated in a protophilic medium to form a complex in which the solvent molecule donates an electron pair and the coordination number of the silicon atom increases to six. Formation of such solvation complexes gives rise to a pronounced positive specific solvatochromic effect in the UV spectra. According to dielectrometric, 19F NMR, and IR data, and also to ab initio calculations (HF/6-31G*), the solvent molecule occupies an equatorial position. 相似文献
64.
65.
I. V. Sterkhova A. I. Vokin L. P. Oznobikhina N. N. Chipanina B. A. Shainyan V. K. Turchaninov 《Russian Journal of General Chemistry》2007,77(2):264-273
For a series of H-complexes of ethers with N-methyltrifluoromethanesulfonamide CF3SO2NHMe, a proportionality between the spectral shift (ΔvNH) and the enthalpy of complex formation (ΔH) was found. Comparison with hydroxyl-containing H-bond donors revealed the following contradiction: ΔH increases in the order CF3SO2NHMe < MeOH < PhOH, whereas ΔvXH increases in the order MeOH < CF3SO2NHMe ~ PhOH. The absence of a single Badger-Bauer relationship ΔvXH ~ f(ΔH) is due to the contribution of universal interactions into the enthalpy of H-complex formation. The account for these interactions allowed calculation of the energy of an intermolecular hydrogen bond, which varies in parallel with the spectral shift: MeOH < CF3SO2NHMe ~ PhOH. 相似文献
66.
A. I. Vokin V. A. Lopyrev A. M. Shulunova T. N. Komarova V. K. Turchaninov 《Russian Chemical Bulletin》1997,46(4):834-836
The dependence of the energies of intramolecular charge-transfer electron transitions in 1,3,5-trimethyl-4-nitropyrazole,
4-nitropyrazole, and its anion on the dielectric and acidbase properties of solvents was analyzed. The dipole moments of these
species in the excited state are larger than those in the ground state. The nonspecific solvation is accomplished through
dipole-dipole interactions. 4-Nitropyrazole, which possesses acidic properties, is also solvated by the mechanism of hydrogen
bonding with the solvent, which acts as a base. The strength of the hydrogen bond increases on going from the ground to the
electron-excited state. The 4-nitropyrazole anion is a base, and its hydrogen bonds with the solvent are stronger in the ground
state. The mechanism of specific solvation of the molecule and the anion of 4-nitropyrazole during electronic excitation is
discussed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 867–869, April, 1997. 相似文献
67.
N. N. Chipanina L. V. Sherstyannikova V. K. Turchaninov B. A. Shainyan 《Russian Journal of General Chemistry》2004,74(10):1538-1542
IR spectroscopy and quantum-chemical calculations (B3LYP/6-31G*) were used to show that N-methyltrifluoromethanesulfonamide in the gas phase and in a low-polarity inert solvent (CCl4) exists as an equilibrium mixture of monomers and cyclic dimers. In a more polar solvent (CH2Cl2), highly polar open-chain dimers are stabilized.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1659–1664.Original Russian Text Copyright © 2004 by Chipanina, Sherstyannikova, Turchaninov, Shainyan.This revised version was published online in April 2005 with a corrected cover date. 相似文献
68.
A. I. Vokin A. M. Shulunova T. N. Aksamentova G. V. Bozhenkov V. K. Turchaninov 《Russian Journal of General Chemistry》2006,76(4):596-614
Examination of the UV spectra of a large series of solvatochromic indicators of the general formula 1-X-4-NO2-C6H4 in aprotic solvents confirmed the proportionality between the dipole moments of these compounds in the ground (μg) and first electronically excited (1 A 1, μe) states: μe = r μμg. The coefficient r μ was determined by applying the equation of the Bakhshiev-Bilot-Kawski solvatochromism theory both to nonspecifically solvated molecules and to their H complexes with aprotic protophilic solvents. An anisotropy of the electron redistribution was revealed for low-symmetry 1-substituted 2,4-dinitrobenzenes. The r μ value obtained allowed the calculation of the Kamlet-Taft empirical solvatochromic parameter π* on the basis of generalized characteristics of the solvent. 相似文献
69.
70.
T. N. Aksamentova N. N. Chipanina M. G. Voronkov O. M. Trofimova E. A. Zelbst V. K. Turchaninov 《Russian Journal of General Chemistry》2009,79(11):2328-2338
According to the data of X-ray diffraction analysis and quantum chemical calculations, in the hypervalent silicon compounds
where the coordination cycle is closed by the C=O→Si-F fragment, the O→Si interatomic distance is governed by the orientation
of the silicon atom determined by the C=O→Si angle. This is an indication of a directivity of the coordination bond O→Si;
a regular variation in the nature of the latter is reflected in the observed dependence of the O→Si distance on the C=O→Si
angle. 相似文献