Molecular structure and vibrational spectra of 2- and 5-methylbenzimidazole molecules by density functional theory

Crystal Structure, Raman Spectroscopy and Dielectric Properties of New Semiorganic Crystals Based on 2-Methylbenzimidazole

“…There were 12 modes detected in both spectra that has been confirmed the noncentrosymmetric structure of the MBI crystal. Raman spectrum of the MBI single crystal obtained in our work (Figure 8) is similar to that of [44]. The positions of the 10 strongest lines coincide with accuracy of 2 cm -1 .…”

“…Another reason may be the effect of imidazole ring protonation [43]. Raman spectrum of the MBI single crystal obtained in our work (Figure 8) is similar to that of [44]. The positions of the 10 strongest lines coincide with accuracy of 2 cm −1 .…”

“…Experimentally, we observed 42 lines. Among them there were lines which were observed in Raman and FTIR spectra in [44], and also seven lines which were predicted theoretically but not observed experimentally before. In Table 2 these lines are marked by *.…”

“…There were 32 of oscillation modes related to in-plane (labelled as A) and 16 to out-of-plane (A) deformations of molecule. From the predicted 48 modes, 32 were detected experimentally in [44], among them 25 in Raman and 19 modes in FTIR spectra. There were 12 modes detected in both spectra that has been confirmed the noncentrosymmetric structure of the MBI crystal.…”

“…Experimental Raman and Fourier-transform infrared (FTIR) spectra of MBI crystal powder and their interpretation have been presented in [44]. Theoretical analysis based on density functional theory (DFT) method has shown that the vibration spectrum of MBI molecule (C S (m) symmetry) consists of 48 modes corresponding, in particular, to the stretching vibrations of carbon-hydrogen valence bonds with frequencies of about 3000 cm −1 , carbon-nitrogen, and carbon-carbon valence bonds in the region of 600-1700 cm −1 , bendings of the benzene and imidazole rings in the region of 100-1200 cm −1 and others.…”