title: Pyridine N-oxide/trichloroacetic acid complex in acetonitrile: FTIR spectra, anharmonic calculations and computations of 1-3D potential surfaces of O-H vibrations.
abstract: FTIR spectra of pyridine N-oxide and trichloroacetic acid H-bonded complex in acetonitrile were studied at 20 and 50°C. The calculations of equilibrium configurations of the complex and their IR spectra in harmonic- and anharmonic approximations were carried out at the level of B3LYP/cc-pVTZ/PCM. However both approximations turned out to be incompetent determining the frequency of the O-Н stretching vibration. In order to reveal the causes of essential discrepancies between calculated and experimental data one-, two- and three-dimensional potential energy surfaces (PES) of the O-H…O bridge proton motion in the frame of fixed other atoms in the complex were calculated. The frequencies of O-H…O stretching and bending vibrations were calculated by numerical solution of the Schrödinger equation. It is shown that only the approach of proton motion on the 3D PES allows obtaining a good agreement between the calculated and the experimental values of the frequencies of the О-Н stretching vibrations.
authors.affiliation: Belarusian State University, Minsk, Belarus. Electronic address: pitsevich@bsu.by.
authors.forename: G
authors.initials: G
authors.lastname: Pitsevich
authors.affiliation: Belarusian State University, Minsk, Belarus.
authors.forename: A
authors.initials: A
authors.lastname: Malevich
authors.affiliation: National Taras Shevchenko University, Kyiv, Ukraine.
authors.forename: I
authors.initials: I
authors.lastname: Doroshenko
authors.affiliation: Belarusian State University, Minsk, Belarus.
authors.forename: E
authors.initials: E
authors.lastname: Kozlovskaya
authors.affiliation: National Taras Shevchenko University, Kyiv, Ukraine.
authors.forename: V
authors.initials: V
authors.lastname: Pogorelov
authors.affiliation: Vilnius University, Vilnius, Lithuania.
authors.forename: V
authors.initials: V
authors.lastname: Sablinskas
authors.affiliation: Vilnius University, Vilnius, Lithuania.
authors.forename: V
authors.initials: V
authors.lastname: Balevicius
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D008958:Models, Molecular; D011725:Pyridines / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014238:Trichloroacetic Acid / Q000737:chemistry*
chemical_list: D000097:Acetonitriles; D011725:Pyridines; D014238:Trichloroacetic Acid; C013229:pyridine N-oxide; C032159:acetonitrile
keywords: 3D PES; Anharmonic DFT calculations; Conformational analysis; FTIR spectra; H-bond