1,1′-[Imidazolidine-1,3-diylbis(methylene)]bis(1H-benzotriazole)

In the title compound, C17H18N8, the imidazolidine ring adopts an envelope conformation with the substituents at the N atoms in trans positions with respect to the central ring. The dihedral angle between the two benzotriazole rings is 71.65 (10)°. In the crystal, non-classical C—H⋯N interactions link the molecules into helical chains along the b axis. The crystal packing is further stabilized by weak C—H⋯π interactions.

In the title compound, C 17 H 18 N 8 , the imidazolidine ring adopts an envelope conformation with the substituents at the N atoms in trans positions with respect to the central ring. The dihedral angle between the two benzotriazole rings is 71.65 (10) . In the crystal, non-classical C-HÁ Á ÁN interactions link the molecules into helical chains along the b axis. The crystal packing is further stabilized by weak C-HÁ Á Á interactions.

Comment
The anomeric effect is a stereoelectronic effect observed in various heterocyclic compounds and some acyclic structures with a great deal of importance due its implications on the molecular structure, conformational properties and reactivity of organic compounds (Zefirov & Shekhtman, 1971;Selámbaron, et al., 2001;Dabbagh, et al., 2002). Our investigations on the synthesis and structural studies of heterocyclic compounds have evidenced the occurrence of a n(N)→σ* (C-N) electron delocalization (Rivera et al., 2011a(Rivera et al., , 2011b. In this article, we discussed the crystal structure of the title compound, which can be synthetized by a three component condensation between ethylenediamine, formaldehyde and benzotriazole (Katriztky et al., 1990) or using a novel methodology involving a Mannich type reaction between the aminal cage 1, 3,6,8tetrazatricyclo[4.4.1.1 3,8 ]dodecane and benzotriazole (Rivera et al., 2004). By recrystallization from ethanol we obtained suitable crystals for X-rays analysis.
The molecular structure and atom-numbering scheme for (I) are shown in Fig

Experimental
For the originally reported synthesis, see: Rivera et al. (2004). Single crystals of the title compound (I) were grown from ethanol by recrystallization.
supplementary materials sup-2 Refinement All H atoms atoms were positioned geometrically and treated as riding on their parent atoms. The isotropic atomic displacement parameters of hydrogen atoms were evaluated as 1.2×U eq of the parent atom. As the structure contains only light atoms, the Friedel-pair reflections were merged and the Flack parameter has not been determined. Fig. 1. A view of (I) with the numbering scheme.displacement ellipsoids are drawn at the 50% probability level.
Refinement. The refinement was carried out against all reflections. The conventional R-factor is always based on F. The goodness of fit as well as the weighted R-factor are based on F and F 2 for refinement carried out on F and F 2 , respectively. The threshold expression is used only for calculating R-factors etc. and it is not relevant to the choice of reflections for refinement.
The program used for refinement, Jana2006, uses the weighting scheme based on the experimental expectations, see _refine_ls_weighting_details, that does not force S to be one. Therefore the values of S are usually larger than the ones from the SHELX program.