Acta Crystallographica Section B

Structural Science

Volume 60, Part 5 (October 2004)

research papers

Acta Cryst. (2004). B60, 578-588 [ doi:10.1107/S0108768104016532 ]

Torsional vibration and central bond length of N-benzylideneanilines

J. Harada, M. Harakawa and K. Ogawa

Abstract: 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 Å 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.

Keywords: torsional vibration; central bond length; variable-temperature analysis.


	Structure factor file (CIF format) (148.5 kbytes) Contains datablock 1_rt

	Structure factor file (CIF format) (142.0 kbytes) Contains datablock 1_90K

	Structure factor file (CIF format) (165.4 kbytes) Contains datablock 2_rt

	Structure factor file (CIF format) (159.8 kbytes) Contains datablock 2_90K

	Structure factor file (CIF format) (175.4 kbytes) Contains datablock 3_rt

	Structure factor file (CIF format) (168.4 kbytes) Contains datablock 3_90K

	Structure factor file (CIF format) (182.6 kbytes) Contains datablock 4_rt

	Structure factor file (CIF format) (176.6 kbytes) Contains datablock 4_90K

	Structure factor file (CIF format) (352.8 kbytes) Contains datablock 5_rt

	Structure factor file (CIF format) (338.6 kbytes) Contains datablock 5_90K

	Structure factor file (CIF format) (342.8 kbytes) Contains datablock 6_rt

	Structure factor file (CIF format) (327.3 kbytes) Contains datablock 6_90K

	Structure factor file (CIF format) (183.3 kbytes) Contains datablock 7_rt

	Structure factor file (CIF format) (176.3 kbytes) Contains datablock 7_90K

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