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Crystal structure and polarized vibrational spectra of 2‐bromo‐4‐nitropyridine N ‐oxide single crystal
Author(s) -
Hanuza J.,
Michalski J.,
Ma̧czka M.,
Waśkowska A.,
Talik Z.,
van der Maas J. H.
Publication year - 2002
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.839
Subject(s) - chemistry , crystallography , orthorhombic crystal system , molecule , raman spectroscopy , van der waals force , crystal structure , hydrogen bond , intermolecular force , single crystal , crystal (programming language) , ring (chemistry) , infrared spectroscopy , oxide , spectral line , physics , programming language , organic chemistry , astronomy , computer science , optics
2‐Bromo‐4‐nitropyridine N ‐oxide is orthorhombic, space group Pbca , with eight molecules per unit cell of dimensions a = 5.979(1), b = 9.899(1), c = 23.249(5) Å. The Br ion is nearly coplanar with the pyridine ring, while the two oxygen atoms of the nitro group are displaced above and below the ring by (−0.214 Å) and (+0.053 Å). The hydrogen bond of the type C—H···O links the molecules into pairs around centers of symmetry. These dimers, arranged into layers related by glide planes, are held together solely by contacts of the van der Waals type. The polarized Fourier transform IR and Raman spectra, measured in the regions 30–3500 and 80–3500 cm −1 , respectively, are correlated with x‐ray structural data. Comparison of the spectrum of the dissolved sample with the spectra obtained from the polycrystalline sample and single crystals shows the attractive character of the intermolecular C—H···O contacts for these molecules. The temperature‐dependent IR spectra suggest the presence of orientational disorder at higher temperatures. Copyright © 2002 John Wiley & Sons, Ltd.