Spectroscopic Identification of Hydrogen Bond Vibrations and Quasi-Isostructural Polymorphism in N-Salicylideneaniline

The ortho-hydroxy aryl Schiff base 2-[(E)-(phenylimino)methyl]phenol and its deutero-derivative have been studied by the inelastic incoherent neutron scattering (IINS), infrared (IR) Raman experimental methods, as well Density Functional Theory (DFT) Density-Functional Perturbation (DFPT) simulations. assignments of vibrational modes within 3500–50 cm?1 spectral region made it possible to state that strong hydrogen bond in compound can be classified so-called quasi-aromatic bond. isotopic substitution supplemented results DFT calculations allowed us identify bands associated with all five major vibrations. Quasi-isostructural polymorphism (SA) 2-[(E)-(phenyl-D5-imino)methyl]phenol (SA-C6D5) has powder X-ray diffraction 20–320 K temperature range.