Crystal structure of 1,3-bis(1H-benzotriazol-1-ylmethyl)benzene

The crystal structure of 1,3-bis(1H-benzotriazol-1-ylmethyl)benzene shows an interesting three-dimensional assembly influenced by its non-planar molecular conformation.


Chemical context
Bis(1H-benzotriazol-1-ylmethyl)arene compounds are used as precursors for the synthesis of benzotriazolophanes, a class of positively charged cyclophanes that have the potential ability to trap anions and guest molecules with high electron density (Rajakumar & Murali, 2000). On the other hand, the study of the self-assembly of helicates from the reaction of metal ions with bis(1H-benzotriazol-1-ylmethyl)arene ligands has been of great interest. In these complexes, the metal center coordinates through the N3-nitrogen of the benzotriazole ring (O'Keefe & Steel, 2000). We have been interested in the synthesis of metal complexes with ligands derived from benzotriazole, which show high activity as catalysts for oxidative amination of allyl butyl ether (Hurtado et al., 2013).The crystal structures for a number of bis(1H-benzotriazol-1-ylmethyl)arene ligands have been determined: 2,6bis(1H-benzotriazol-1-ylmethyl)pyridine (Selvanayagam et al., 2002), 1,4-bis(1H-benzotriazol-1-ylmethyl)benzene tetrahydrate (Cai et al., 2004) and benzyl 3,5-bis(1H-benzotriazol-1-ylmethyl)phenyl ether (Selvanayagam et al., 2004). As part of structural studies of the self-assembly process of metal ions with ligands derived from benzotriazole, we report here the crystal structure of the ligand 1,3-bis(1H-benzotriazol-1-ylmethyl)benzene. Fig. 1 shows the molecule of the title compound. The molecular structure is built by two benzotriazole groups describing a meta substitution of the central benzene ring. The dihedral angle between the two benzotriazole units is 57.08 (9) and those between each benzotriazole moiety (N1-N3/C2-C7) and the central benzene ring are 88.74 (11) and 85.83 (10) for the A and B groups, respectively. These values differ from the related structures 2,6-bis(N,N 0 -benzotriazol-1-ylmethyl)pyridine, with a pyridine central ring, where the angle between the two benzotriazole units is 72.49 (6) and those between the pyridine ring and the two benzotriazole units are 70.26 (6) and 57.70 (7) (Selvanayagam et al., 2002), and from the 1,4-bis(1H-benzotriazol-1-ylmethyl)benzene tetrahydrate, with para substitution, where the two benzotriazole units are parallel and the dihedral angle between each benzotriazole unit and the central benzene ring is 74.95 (9) (Cai et al., 2004).

Supramolecular features
The packing is directed by weak C-HÁ Á ÁN and C-HÁ Á Á interactions as shown in Table 1 The molecular structure of the title compound, showing anisotropic displacement ellipsoids drawn at the 50% probability level. Table 1 Hydrogen-bond geometry (Å , ).

Database survey
A search of the Cambridge Structural Database (CSD Version 5.36 with one update; Groom et al., 2016) for the 1,3-bis(1Hbenzotriazol-1-ylmethyl)benzene molecular structure with the possibility of any group replacing the 2,4,5,6-H atoms in the central benzene ring gave four hits, from which two have one additional arene substituent (Br, -OCH 2 Ph), one has the bis(1H-benzotriazole-1-ylmethanone) moiety instead of bis(1H-benzotriazol-1-ylmethyl) and the last one corresponds to a more complex molecular structure. When the search also considers heterocyclic compounds, two new hits (in addition to the first four structures) appear, one cyclic bipyridine and the related molecular structure 2,6-bis(1H-benzotriazol-1-ylmethyl)pyridine. A search for the 1,4-bis(1H-benzotriazol-1ylmethyl)-substituted benzene ring gave four hits, one of which corresponds to a ligand with additional methyl groups at the 1,3,5,6-sites of the central benzene ring and the other to its corresponding palladium complex. The remaining two relate to the same compound, viz. 1,4-bis(1H-benzotriazol-1-ylmethyl)benzene tetrahydrate, a related molecular structure.

Synthesis and crystallization
m-Xylylene dibromide (1.16 g, 4.4 mmol) was added to a solution of 1H-benzotriazole (1.04 g, 8.7 mmol) in toluene (60 mL), and the mixture was heated at reflux for 72 h. The resulting mixture was filtered, and the toluene solution was concentrated and cooled to give a white solid. Single crystals suitable for X-ray structure analysis were obtained by dissolving the compound in the minimum volume of dichloromethane, adding diethyl ether and cooling the solution to 277 K. The title compound formed colorless parallelepipeds.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms were placed in calculated positions (C-H: 0.93-0.97 Å ) and included as riding contributions with isotropic displacement parameters set at 1.2-1.5 times the U eq value of the parent atom.

1,3-Bis(1H-benzotriazol-1-ylmethyl)benzene
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.