organic papers o1996 Awaleh et al.  C 24 H 32 N 2 O 2 doi:10.1107/S1600536806014231 Acta Cryst. (2006). E62, o1996–o1997 Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 N,N 0 -Octamethylenebis(4-methylbenzamide) Mohamed Osman Awaleh,* Antonnella Badia and Franc¸ois Brisse De ´partement de Chimie, Universite ´ de Montre ´al, CP 6128, Succ. Centre-ville, Montre ´al, Que ´bec, Canada H3C 3J7 Correspondence e-mail: moawaleh2000@yahoo.fr Key indicators Single-crystal X-ray study T = 100 K Mean (C–C) = 0.003 A ˚ R factor = 0.054 wR factor = 0.166 Data-to-parameter ratio = 14.7 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. Received 17 April 2006 Accepted 19 April 2006 # 2006 International Union of Crystallography All rights reserved In the title structure, C 24 H 32 N 2 O 2 , the molecule lies on a crystallographic inversion centre at the mid-point of the central C—C bond. The planar OCN—(CH 2 ) n —NCO segment is in an all-trans configuration. The NH group of the amide group is involved in a single hydrogen bond to the O atom of a symmetry-related molecule to form one-dimen- sional ribbons parallel to the b direction. Comment In organic crystal engineering, the directional hydrogen-bond interaction is widely used to design constructor molecules incorporating sites that can engage reliable directional inter- action in order to build up predictable supramolecular archi- tecture with potential application as functional materials (Simard et al., 1991; Leininger et al., 2000 and Holliday & Mirkin, 2001). In addition, it has been observed that chemi- cally symmetrical molecules containing a central aliphatic segment with an even number of methylene groups often have a crystallographic centre of symmetry at the mid-point of the central CH 2 —CH 2 bond and the molecules preferentially adopt the fully extended conformation (Awaleh et al., 2005a,b,c; Hou et al., 2005). In our continuing effort to study the structure of the organic polymer as well as the metal- organic supramolecular architecture, the title compound, (I), has been synthesized and its structure is reported here. The molecular structure of (I) is shown in Fig. 1. The mol- ecule has a centre of symmetry at the mid-point of the central C—C bond, namely C1—C1 i [symmetry code: (i) 2  x,1  y, 2  z]. The values of the torsion angles in the planar sequence [OCN—(CH 2 ) 8 —NCO] indicate an all trans arrangement and that the molecules are in a fully extended conformation (Table 1). The dihedral angle between the benzene ring and the [OCN—(CH 2 ) 8 —NCO] sequence is 26.4 (1)  . The bond distances and angles in (I) (Table 1) fall in the normal range (Allen et al., 1987). In the crystal structure, the NH group of the amide group is involved in a weak hydrogen-bond inter- action with the O atom of a symmetry-related molecule (Table 2) to form one-dimensional ribbons parallel to the b direction (Fig. 2). The are no significant – stacking inter- actions.