Structural and vibrational study of 3- or 5-methyl substituted 2-N-ethylamino-4-nitropyridine N-oxides

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• 作者：J. Lorenc^a ; ^{jadwiga.lorenc@ue.wroc.pl} ; J. Hanuza^a ; ^b ; J. Janczak^b
• 关键词：2-N-ethylamino-3-methyl-4-nitropyridine N-oxide ; 2-N-ethylamino-5-methyl-4-nitropyridine N-oxide ; Crystal structure ; Hydrogen bonds ; Vibrational properties ; DFT calculations
• 刊名：Vibrational Spectroscopy
• 出版年：2012
• 期刊代码：113_09242031
• 类别：ms
• 出版时间：March, 2012
• 卷：59
• 期：Complete
• 页码：59-70
• 文件大小：1335 K

摘要

X-ray crystal structures of two isomers C₈H₁₁N₃O₃, i.e. 2-N-ethylamino-5-methyl-4-nitropyridine N-oxide (EN5MPO) and 2-N-ethylamino-3-methyl-4-nitropyridine N-oxide (EN3MPO) have been determined. The different substitutions of the CH₃ groups lead to change of the unit-cell structure, molecular and intermolecular arrangement. Both structures are monoclinic, space group P2₁/c and P2₁/n with a parallel and antiparallel orientation along the a-axis, respectively. In each of the two subunits, the methyl carbons and N-atoms of the nitro group are almost coplanar with the pyridine ring, but the N-oxide bonds are inclined from this plane. The crystal structures are stabilized by a set of the weak inter- and intramolecular hydrogen bonds of the NH鈰疧 type. The structures of both isomers have been confirmed by the results of IR and Raman spectra measurements, quantum chemical calculations and potential energy distribution (PED). The role of methyl group introduced in 3 or 5 position of 2-N-ethylamino-4-nitropyridine N-oxide has been analysed.