INFRARED SPECTRA AND AM1 CALCULATIONS OF N-BENZYLIDENEANILINES

ABSTRACT

The molecular structure and conformation of nine substituted N-benzylideneaniline R1C₆H₄CH=NC₆H₄R2 where R1=H, R2=OCH₃, CH₃ or Cl; R1=OCH₃, CH₃, Cl or NO₂; R2=H; R1=NO₂ R2=OCH₃ and R1=OCH₃ R2=Cl have been studied experimentally by FTIR spectroscopy and theoretically using the AM1 semi-empirical quantum-mechanical method. From IR data of substitued N-benzylideneaniline, a decrease in the C=N stretching frequencies were observed. There is a correlation between C=N stretching frequencies and the Hammett σ _R constant of substituents. The calculated values of torsional angle (θ _N) between the H-C=N plane and the N-phenyl ring of the compounds show that the stronger the electron withdrawing properties of the substituent, the larger the angle. There is also relationship between θ _N and Hammett σ _R constant of substituents. The dipole moments, bond order and electron density values of studied compounds have also calculated using semiemprical AM1 method.

Keywords:

• N-benzylideneaniline
• Substituted N-benzylideneaniline
• IR spectra
• AM1

ACKNOWLEDGMENTS

This work was supported by the Scientific and Technical Research Council of Turkey (project No: TBAG-1690).