An approach to estimate the energy and strength of the intramolecular hydrogen bond in different conformers of 4‐methylamino‐3‐penten‐2‐one

The molecular structure and intramolecular hydrogen bond energy of 32 conformers of 4‐methylamino‐3‐penten‐2‐one were investigated at MP2 and B3LYP levels of theory using the standard 6–31G** basis set and AIM analyses. Furthermore, calculations for all the possible conformations of 4‐methylamino‐3‐penten‐2‐one in water solution were also carried out at B3LYP/6–31G** level of theory. The calculated geometrical parameters and conformational analyses in gas phase and water solution show that the ketoamine conformers of this compound are more stable than the other conformers (i.e., enolimine and ketoimine). This stability is mainly due to the formation of a strong N? H···O intramolecular hydrogen bond, which is assisted by π‐electrons resonance. Hydrogen bond energies for all conformers of 4‐methylamino‐3‐penten‐2‐one were obtained from the related rotamers method. The nature of intramolecular hydrogen bond existing within 4‐methylamino‐3‐penten‐2‐one has been investigated by means of the Bader theory of atoms in molecules, which is based on topological properties of the electron density. The results of these calculations support the results which obtained by related rotamers method. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Structure and photochromism of 2-(<Emphasis Type="Italic">N</Emphasis>-acyl-<Emphasis Type="Italic">N</Emphasis>-arylaminomethylene)benzo[<Emphasis Type="Italic">b</Emphasis>]thiophen-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004.     

A simple route to dinuclear complexes containing unusual μ-Nsulfonamido bridges

We report here the straightforward synthesis of some dimeric transition metal complexes of three Schiff base ligands, which were obtained by condensation of 2-tosylaminomethylaniline with 2,3-dihydroxybenzaldehyde (H₂L¹), 2,4-dihydroxybenzaldehyde (H₂L²), and 4-formyl-3-hydroxybenzoic acid (H₂L³), respectively. Both ligands and complexes were characterized by a combination of ¹H NMR, infrared and mass spectrometries, and elemental analyses. Furthermore, the crystal structures of H₂L² and Pd₂L²₂·2MeOH were elucidated by X-ray diffraction. The crystal structure of Pd₂L²₂·2MeOH has instead of typical μ-O_phenoxo bridges, repeating units held together by unusual μ-N_sulfonamido bridges. This complex is chiral, although it crystallizes as a racemate, with C_2v symmetry, where the two bridging nitrogens are asymmetric centers with identical handedness.     

Inverse photochromic systems based on ketoenamine derivatives

The results of studies into inverse photochromic systems (systems with negative photochromism) based on ketoenamines and ketoenehydrazines of benzo [b]annelated heterocycles and their acylated derivatives carried out at the Institute of Physical and Organic Chemistry at the Rostov State University in the last two decades are summarized.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 506–517, March, 2005.