34920-89-3Relevant academic research and scientific papers
Substituent cross-interaction effects on the electronic character of the C=N bridging group in substituted benzylidene anilines - Models for molecular cores of mesogenic compounds. A 13C NMR study and comparison with theoretical results
Neuvonen, Helmi,Neuvonen, Kari,Fueloep, Ferenc
, p. 3141 - 3148 (2007/10/03)
13C NMR chemical shifts δc(C=N) were measured in CDCl 3 for a wide set of mesogenic molecule model compounds, viz. the substituted benzylidene anilines P-X-C6H4CH=NC 6H4-p-Y (X = NO2, CN, CF3, F, Cl, H, Me, MeO, or NMe2; Y = NO2, CN, F, Cl, H, Me, MeO, or NMe2). The substituent dependence of δc(C=N) was used as a tool to study electronic substituent effects on the azomethine unit. The benzylidene substituents X have a reverse effect on δc(C=N): electron-withdrawing substituents cause shielding, while electron-donating ones behave oppositely, the inductive effects clearly predominating over the resonance effects. In contrast, the aniline substituents Y exert normal effects: electron-withdrawing substituents cause deshielding, while electron-donating ones cause shielding of the C=N carbon, the strengths of the inductive and resonance effects being closely similar. Additionally, the presence of a specific cross-interaction between X and Y could be verified. The electronic effects of the neighboring aromatic ring substituents systematically modify the sensitivity of the C=N group to the electronic effects of the benzylidene or aniline ring substituents. Electron-withdrawing substituents on the aniline ring decrease the sensitivity of δc(C=N) to the substitution on the benzylidine ring, while electron-donating substituents have the opposite effect. In contrast, electron-withdrawing substituents on the benzylidene ring increase the sensitivity of δc(C=N) to the substituent on the aniline ring, while electron-donating substituents act in the opposite way. These results can be rationalized in terms of the substituent-sensitive balance of the electron delocalization (mesomeric effects). The present NMR characteristics are discussed as regards the computational literature data. Valuable information has been obtained on the effects of the substituents on the molecular core of the mesogenic model compounds.
Reactions of [Cp(CO)2Fe=CHAr]+ (Ar = p-C6H4OMe) with O=N-Ar′ (Ar′ = C6H5, p-C6H4NMe2) and PhN=NPh
Peng, Wei-Jun,Gamble,Templeton,Brookhart
, p. 463 - 467 (2008/10/08)
Organometallic products formed from the reaction of an electrophilic iron carbene complex with nitrosoarenes or azobenzene reflect net insertion of the ArN=X moiety into the Fe=CHAr bond. Cp(CO)2Fe-O-N(Ar′)=CHAr+ and Cp(CO)2FeN(Ph)-N-(Ph)=CHAr+ (Ar = p-C6H4OMe, Ar′ = p-C6H4NMe2) have been isolated and spectroscopically characterized; the crystal structure of Cp(CO)2Fe-O-N(Ph)=CHAr+ is reported. Exposure of acetone solutions of Cp(CO)2Fe-O-N(Ar′)=CHAr+ or Cp(CO)2FeN(Ph)-N(Ph)=CHAr+ to light yields imine products Ar′N=CHAr or PhN=CHAr, respectively. We have no evidence to support the formation of the simple stoichiometric iron-containing products of these reactions, the oxo and nitrene complexes Cp(CO)2Fe=O+ and Cp(CO)2Fe=NPh+. Hydrolysis of the nitrone complexes Cp(CO)2Fe-O-N(Ar′)=CHAr+ in aqueous acetone yields aldehyde products Ar′CHO.
ELECTRONIC ABSORPTION SPECTRA OF AROMATIC SCHIFF BASES. PART III. p-PHENYLENEDIAMINE DERIVATIVES
Gawinecki, Ryszard,Muzalewski, Feliks
, p. 1091 - 1098 (2007/10/02)
The effect of para substituents in the benzylidene-p-dimethylaminoaniline and dibenzylidene-p-phenylenediamine molecules on their UV-VIS spectra has been studied.A linear relationship has been found between position of the most long-wavelength absorption
