Solvatochromism of Heteroaromatic Compounds: XXVI. Solvent Effect on the Solvatochromic Parameters of IR Bands of <Emphasis Type="Italic">N</Emphasis>-Methylanilines and Related Hydrogen Bond Donors

Formation of a hydrogen bond between molecules of a proton donor (phenol, pyrrole, N-methylanilines) and a solvent decreases the sensitivity of the XH stretching frequency to the polarity/polarizability of solvents. A change in the bond configuration in the amine moiety of N-methylaniline and related compounds upon formation of a solvation H complex is manifested in that the absolute terms of the solvatochromic equations for inert and protophilic media are different. The spectroscopic effect from the geometric reorganization of molecules is determined by their structure and the capability to act as hydrogen bond donors. Multicentered hydrogen bond with π bases affects the geometry of the amine fragment of N-substituted anilines to a lesser extent than does two-centered H bond with onium bases.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 642–649.Original Russian Text Copyright © 2005 by Vokin, Oznobikhina, Shulunova, Ustinov, Bozhenkov, Levkovskaya, Turchaninov.For communication XXV, see [1].     

Spectroscopic Study of Reaction of Propargyl Bromide with Pyridine

Pyridine was reacted with propargyl bromide to obtain the dibromide [C₅H₅NCH = CHCH = CHCH = CHC₅H₅N]^{2 +} 2Br^-. The effect of the vinyl group on its UV spectrum is qualitatively interpreted using the results of nonempirical quantum-chemical calculations (basis HF/6-31G^*).     

AM1 studies of photoelectron spectra

Five ionization potentials for thesp,ac andsp, sp conformers of (acetylthiomethyl)trifluorosilane MeC(O)SCH₂SiE₃ and six ionization potentials for the same conformers of (benzoylthiomethyl)trifluorosilane PhC(O)CH₂SiF₃ were calculated by the semiempirical AM1 method. The resulting values are in good agreement with the data of photoelectron spectroscopy only for thesp.ac conformers. The structure of the preferred conformer of (acetylthiomethyl)trifluorosilane was confirmed by measurement of its dipole moment in the gas phase. The influence of the long-range inductive effect (field effect) on the energy of nonbonding electrons of the carbonyl oxygen atom in the series of acetic acid derivatives was observed. For Part 9, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 236–241, February, 1998.     

AM1 study of photoelectron spectra.

The -orbital structure of the monomeric form of the 2,2,4,6-tetrachloro-2,2-dihydro-1,5,2-diazaphosphorinine has been studied by photoelectron spectroscopy and using quantum-chemical calculations by the semiempirical AM1 method. It has been concluded that the electronic and energy characteristics of four higher -MOs (frontier and three next orbitals) of this compound may be interpreted in terms of semipolar bonds formed by three atoms (C, P, and N). For describing two low-lying -MOs of the ⁴,⁵-phosphorine studied, it is necessary to take into account the --interaction.For Part 8, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 827–831, April, 1996.     

Strong intramolecular hydrogen bond N—H...O in 2-(2-acyl-1-phenylethenyl)-5-phenylpyrroles

The molecular structure of 2-(2-benzoyl-1-phenylethenyl)-5-phenylpyrrole and 2-(2-furoyl-1-phenylethenyl)-5-phenylpyrrole was studied by X-ray diffraction analysis at 110 K and quantum chemistry methods (B3LYP/6-31G*). In the crystalline state, both compounds have cyclic structures closed by strong intramolecular hydrogen bond N—H...O. Canonic zwitterionic structure contributes largely to the ground state of the molecules. This is probably due to synergism of the H-bonding and -electron interactions.     

Excited Π states of divinyl chalcogenides and chalcophenes

Electron transitions in divinyl chalcogenides (CH₂=CHXCH=CH₂, where X is S, Se, or Te) have been analyzed using UV absorption spectra of dialkyl and alkyl vinyl chalcogenides. The following relations for the orbital energies are found: ^* < ^* < ^* < ^* for Te and ^* < ^* < ^* < ^* for S and Se. For chalcophenes, a correlation between the energy of the excited state (E ^*) of specific symmetry, the ionization potential (I) and the electron affinity (EA) is obtained:E ^*=const+(I+EA)/2. The electron affinity of divinyl chalcogenides is estimated. The correlation between the excited ^* states of divinyl chalcogenides and chalcophenes is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 831–835, May, 1994.     

UV spectra of vinyl chalcogenides: Correlation with the photoelectron spectra

The electron absorption spectra of alkylvinyl chalcogenides (CH₂=CHEAlk, E = S, Se, Te) were analyzed with consideration of the photoelectron spectroscopic data. The following sequence of electronic transitions was found in their UV spectra:

Molecular structures of β-amino-α-bromovinyl trifluoromethyl ketones

The molecular structures of β-amino-α-bromovinyl trifluoromethyl ketones was studied by UV, IR, ¹H, ¹³C, and ¹⁵N NMR spectroscopy and using the density functional (B3LYP/6-31G(d,p) and PBE/QZ3P) and ab initio riMP2/cc-pVTZm quantum-chemical calculations. Factors affecting stabilization of the EZE-conformation of the molecules, which is atypical of analogous unsubstituted amino enones, are considered.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 102–106, January, 2005.     

Reaction of 1-vinylpyrazoles with tetracyanoethylene

It was shown that in the reaction of tetracyanoethylene with 1-vinylpyrazoles in aprotic solvents, one of the first stages involves the formation of - complexes. The final products of the reaction are 1-(2,2,3,3-tetracyano-1-cyclobutyl)pyrazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 924–926, July, 1989.