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Spectres de Vibration et Transition de Phase des Complexes Formés Entre l'Acide Oxalique et la Pyridine
Author(s) -
Belabbes Y.,
Lautié A.
Publication year - 1993
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250240410
Subject(s) - hydrogen bond , chemistry , pyridinium , raman spectroscopy , crystallography , moiety , pyridine , oxalic acid , infrared spectroscopy , ion , phase transition , stereochemistry , inorganic chemistry , molecule , medicinal chemistry , physics , organic chemistry , quantum mechanics , optics
Raman and infrared spectra (4000–20 cm −1 ) of polycrystalline pyridine–oxalic acid complexes were investigated between 80 and 300 K and an assignment in term of group frequencies is given. The 2:2 and 2:3 compounds are spectroscopically identified and the OH…O and NH…O hydrogen bonds characterized. The spectroscopic results are consistent with crystallographic data. With the deuterated oxalic acid, only one 1:1 complex is obtained and its crystalline structure is different. From spectroscopic analysis, it is found to be built of infinite chains of hydrogenoxalate ions with strong OD…O hydrogen bonds (νOD about 1300 cm −1 and estimated R o…o = 2.53 Å). The pyridinium moiety (C 5 H 5 ND + ) forms ND…O hydrogen bonds characterized by a νND frequency of 2130 cm −1 and an N…O distance of 2.75 Å. Further, in this compound, one second‐order phase transition is observed at 235 K and the structural modifications are discussed.