Torsional vibration and central bond length of N-benzylideneanilines
Torsional vibration and central bond length of N-benzylideneanilines
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DOI：
10.1107/s0108768104016532
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发表时间：
2004-10-01
影响因子：
1.9
通讯作者：
Ogawa, K
中科院分区：
文献类型：
--
作者：
Harada, J;Harakawa, M;Ogawa, K
N-亚苄基苯胺（1）、N-亚苄基-4-羧基苯胺（2）、N-（4-甲基亚苄基）-4-硝基苯胺（3），N-（4-硝基亚苄基）-4-甲氧基苯胺（4），N-（4-硝基亚苄基）-4-甲基苯胺（5），用X射线衍射法测定了N-（4-甲氧基苯亚甲基）苯胺（6）和N-（4-甲氧基苯亚甲基）-4-甲基苯胺（7）在不同温度下的结构。在所有化合物的晶体结构中，在室温下观察到中心C=N键的明显缩短。随着温度的降低，观察到的键长增加到约1.28埃，在90 K，在分子中的取代基无关。C=N键长的缩短和温度依赖性被解释为由晶体中C-Ph和N-Ph键的扭转振动引起的伪影。在（1）和（7）的晶体结构中，观察到C=N键周围的静态无序，这也是C=N键明显缩短的原因。
The crystal structures of N-benzylideneaniline (1), N-benzylidene-4-carboxyaniline (2), N-(4-methylbenzylidene)-4-nitroaniline (3), N-(4-nitrobenzylidene)-4-methoxyaniline (4), N-(4-nitrobenzylidene)-4-methylaniline (5), N-(4-methoxybenzylidene) aniline (6) and N-(4-methoxybenzylidene)-4-methylaniline (7) were determined by X-ray diffraction analyses at various temperatures. In the crystal structures of all the compounds, an apparent shortening of the central C=N bond was observed at room temperature. As the temperature was lowered, the observed bond lengths increased to approximately 1.28 Angstrom at 90 K, irrespective of substituents in the molecules. The shortening and the temperature dependence of the C=N bond length are interpreted in terms of an artifact caused by the torsional vibration of the C-Ph and N-Ph bonds in the crystals. In the crystal structures of (1) and (7), a static disorder around the C=N bond was observed, which is also responsible for the apparent shortening of the C=N bond.