DFT and experimental study of the structure and vibrational spectra of 2-(benzylthio)-N-{pyridinylmethylidene}anilines

2-(Benzylthio)-N {pyridine-4-ylmethylidene}aniline was prepared by reaction of S-benzyl ortho-aminothiophenol with 4-pyridine carboxaldehyde and characterized by NMR, IR and Raman spectroscopy and mass spectrometry. The structure and the vibrational analysis of the series of 2-, 3-, and 4-pyridine derivatives was performed based on a comparative computational methodology study with the density functionals B3LYP and B3PW91 and the basis sets LanZ2DZ and 6-31++G(d,p). Comparison of computational results with single crystal X-ray diffraction results of 2-(benzylthio)-N {pyridine-3-ylmethylidene}aniline allowed the evaluation of structure predictions and confirmed B3PW91/6-31++G(d,p) as most accurate for structure determination of the four investigated levels of theories. B3LYP and B3PW91 with the LanL2DZ basis set consistently outperformed calculations for IR and Raman vibrational estimations when compared to level of theories using the 6-31++G(d,p) basis set. Application of scaling factors for IR and Raman frequency predictions showed excellent agreement with experimental values and supported the assignment of the major contributors of the vibration modes of the three pyridine pendant compounds. Overall, B3PW91/LanL2DZ level of theory showed best performance in accuracy and low computational cost for structural and vibrational analysis for the series of 2-(benzylthio)-N-{pyridinylmethylidene}anilines.