1,1′-[2,3,5,6-Tetramethyl-p-phenylenebis(methyleneoxy)]di-1H-benzotriazole

The complete molecule of the title compound, C24H24N6O2, is generated by a crystallographic inversion centre. The benzotriazole rings form dihedral angles of 2.10 (7)° with the central aromatic ring. The crystal packing is consolidated by π–π interactions, with centroid–centroid distances of 3.6234 (10) Å, together with weak C—H⋯π interactions.

The complete molecule of the title compound, C 24 H 24 N 6 O 2 , is generated by a crystallographic inversion centre. The benzotriazole rings form dihedral angles of 2.10 (7) with the central aromatic ring. The crystal packing is consolidated byinteractions, with centroid-centroid distances of 3.6234 (10) Å , together with weak C-HÁ Á Á interactions.   Table 1 Hydrogen-bond geometry (Å , ).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT2912).

Comment
Benzotriazole derivatives show biological activities such as anti-inflammatory, diuretic, antiviral and antihypertensive agents (Katarzyna et al., 2005;Sarala et al., 2007). It is used as a corrosion inhibitor, antifreeze agent, ultraviolet light stabilizer for plastics and as an antifoggant in photography (Krawczyk & Gdaniec, 2005;Smith et al., 2001). N-aryloxy derivatives of benzotriazoles have antimycobacterial activity (Kopec et al., 2008). Benzotriazole possessing three vicinal N atoms, is used as an antifouling and antiwear reagent (Sha et al., 1996). 1-Hydroxybenzotriazole is widely being used as a reagent for peptide synthesis (Anderson et al., 1963). The crystal structure of benzotriazole 1-oxide has been reported (Bosch et al., 1983). Due to the above mentioned applications of benzotriazole we have synthesized and report here the crystal structure of the title compound (I).

Experimental
A mixture of 1,4-bis(bromomethyl)-2,3,5,6-tetramethyl-benzene (0.320 g, 1 mmol) and sodium salt of 1-hydroxybenzotriazole (0.314 2 mmol) in ethanol (10 ml) was heated at 333 K with stirring for 30 min. The product formed was filtered off and dried. The product was dissolved in ethanol and on slow evaporation crystals suitable for x-ray diffraction are obtained.

Refinement
All the H atoms were positioned geometrically (C aromatic -H=0.95 Å, C methyl -H=0.98 or C methylene -H=0.99 Å) and refined using a riding model with, U iso (H)=1.2U eq (C) and 1.5U eq (C methyl ). A rotating group model was used for the methyl groups.

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.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.