Crystallographic, spectroscopic (FT-IR/FT-Raman) and computational (DFT/B3LYP) studies on 4,4′-diethyl-2,2′-[methylazanediylbis(methylene)]diphenol

• Crystal structure of the titled compound (EMD) was measured at 100 K and 296 K.
• Conformational analysis of EMD was carried out.
• FT-IR and FT-Raman spectra from experimental and theoretical methods were reported.
• Vibrational modes together with PED values of EMD were assigned.

Quantum mechanical calculations on geometries and vibrational wavenumbers of 4,4′-diethyl-2,2′-[methylazanediylbis(methylene)]diphenol denoted as EMD were performed by density functional theory (DFT/B3LYP) methods with the various basis sets, namely, 6-311G(d), 6-311G(d,p) and 6-311 + G(d,p). X-ray crystal structure of the EMD compound was measured at low temperature (100 K) and room temperature (296 K). It was found that no structural change was observed for the temperatures studied. The geometrical parameters from theoretical calculation were in good agreement with the ones from X-ray analysis. Both the theoretical and experimental structures confirmed the presence of the remarkably asymmetric intramolecular hydrogen bonding within the molecule of the EMD compound. Conformational analysis was carried out to calculate energy barrier of breaking the intramolecular hydrogen bond. Moreover, the theoretical IR and Raman spectra have been constructed to make a comparative study with the experimental FT-IR and FT-Raman spectra. The results revealed that the deviation of the theoretical wavenumbers from the experimental values were very small. Besides, the detailed vibrational assignments were conducted and the PED values were reported by VEDA4f program.

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