1,1′-[(2-Phenyl-2,3-dihydro-1H-benzimidazole-1,3-diyl)bis(methylene)]bis(1H-benzotriazole)

The imidazole ring in the title compound, C27H22N8, adopts a slight envelope conformation with the C atom carrying the phenyl ring being the flap atom. The phenyl ring is almost perpendicular to the mean plane of the imidazole ring [dihedral angle = 88.90 (7)°]. The (1H-benzotriazol-1-yl)methyl groups bound to the imidazole ring are positioned on the same side of the imidazole ring. The dihedral angle between these benzotriazolyl rings is 17.71 (5)°. The crystal packing is stabilized by a C—H⋯π interaction, which connects the molecules into zigzag chains running along the b axis.

The imidazole ring in the title compound, C 27 H 22 N 8 , adopts a slight envelope conformation with the C atom carrying the phenyl ring being the flap atom. The phenyl ring is almost perpendicular to the mean plane of the imidazole ring [dihedral angle = 88.90 (7) ]. The (1H-benzotriazol-1-yl)methyl groups bound to the imidazole ring are positioned on the same side of the imidazole ring. The dihedral angle between these benzotriazolyl rings is 17.71 (5) . The crystal packing is stabilized by a C-HÁ Á Á interaction, which connects the molecules into zigzag chains running along the b axis.

Related literature
For a related structure see: Rivera et al. (2011). For the synthesis of the precursor and the title compound, see: Rivera et al. (2000Rivera et al. ( , 2004. For ring conformations, see: Cremer & Pople (1975 Table 1 Hydrogen-bond geometry (Å , ).
Cg6 is the centroid of the C15-C20 aromatic ring.

Comment
Considerable work from our laboratory has been concerned with the synthesis of benzotriazol-1-ylmethyl groups attached to imidazolidine-like nitrogen atoms in heterocyclic aminals. The title compound (I) was synthesized via route modified from that reported (Rivera et al., 2000) by reaction of 1,1'-(1H-benzimidazole-1,3(2H)-diyl)bis(methylene)-bis-(1H-benzotriazole) with benzaldehyde. The whole procedure is a two-step method with a good overall yield. The starting compound was prepared according to literature procedure (Rivera et al., 2004). The structure of this precursor, whose structure we reported previously (Rivera et al., 2011), showed that the compound exists in a conformation in which the benzotriazol-1ylmethyl moieties arranged in anti disposition with respect to benzimidazolidine ring. In the title compound, the presence of a phenyl substituent on the central carbon of the benzimidazolidine ring may influence the pendant substituent to occupy a syn conformation.
Although the molecule potentially exhibits mirror symmetry, in the crystalline state the spatial disposition of two 1Hbenzotriazol-1-yl)methyl units are not perfectly identical ( Figure 1). However, the measured bond lengths and angles are extremely close and consequently only mean values will be cited in this discussion. The interatomic distances and angles of title compound (I) are comparable with a related structure (Rivera et al., 2011). The imidazole ring is an envelope conformation with the central C8 atom being the flap atom as seen in the puckering parameters Q(2) = 0.1259 (16) Å and φ2 = 41.2 (7) ° (Cremer & Pople, 1975). With reference to this plane, the phenyl ring lies to one side of the plane and is almost perpendicular to the mean plane of the heterocyclic ring, with a dihedral angle of 88.898 (66)°. The (1H-benzotriazol-1-yl)methyl groups bound to the central heterocyclic ring are almost syn as seen in the C7-N4···N5-C21 torsion angle of 9.91 (37)°. This is contrary to what is observed in the related structure (Rivera et al., 2011), where the two (benzotriazol-1-yl)methyl groups are located in an anti position with respect to the benzimidazoline moiety. In the title compund the dihedral angle between these benzotriazolyl rings is 17.712 (47)°.

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 set to 1.2×U eq of the parent atom. As the structure contains only light atoms, Friedel pairs 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.