J. Hanuza, M. Ma̧czka, A. Waśkowska
Mar 1, 1997
Citations
0
Influential Citations
20
Citations
Journal
Vibrational Spectroscopy
Abstract
Abstract The X-ray crystal structure determination of 3-chloro-2,6-dimethyl-4-nitropyridine N-oxide (ClDMNPNO) and 3-bromo-2,6-dimethyl-4-nitropyridine N-oxide (BrDMNPNO) shows that the two pyridine derivatives are isomorphic with monoclinic space group P21/c, and four formula units in a cell with the following dimensions: a=7.933(1), b=9.721(1), c=11.419(1) A, β=107.70(1)° and a=7.981(1), b=9.817(2), c=11.515(1) A, β=106.54(1)° for ClDMNPNO and BrDMNPNO, respectively. The shortest intermolecular contacts form medium strong hydrogen bonds of the type C–H⋯O. Another relatively short intermolecular contact is established for CH3⋯Cl/Br. The planar pyridine rings do not show the C–C bonds alternation typical for resonance forms in aromatic rings. The IR and Raman spectra, measured in the 50–3500 cm−1 region at ambient temperature, are correlated with X-ray structural data. The assignment of IR and Raman bands is given. Comparison of the spectra of dissolved samples with the ones obtained from polycrystalline samples shows the attractive character of the intermolecular C–H⋯O contact for these molecules. No strong spectroscopic support is found for the existence of a significant CH3⋯Cl/Br intermolecular interaction.