Crystal structure of 2-[(E)-2-(4-bromophenyl)diazen-1-yl]-4,5-bis(4-methoxyphenyl)-1H-imidazole: the first example of a structurally characterized triarylazoimidazole

The molecule of the title compound adopts a trans configuration with respect to the azo double bond.

The PASS program (Filimonov et al., 2014) predicted the potential activity of the title compound as a thiol protease inhibitor and an aspulvinone dimethylallyltransferase inhibitor at 81% and 76% probability levels, respectively.

Structural commentary
The molecular structure of the title compound is shown in Fig. 1. Overall, bond dimensions within the molecule are similar to those reported for structurally relevant azo compounds (Tskhovrebov et al., 2014(Tskhovrebov et al., , 2015Liu et al., 2019;Eymann et al., 2016;Nenajdenko et al., 2020). The molecule adopts a trans configuration with respect to the azo double bond. The N N bond distance of 1.274 (3) Å is slightly longer than that in azobenzene. The imidazole and aryl rings attached to the azo group are coplanar within 12.73 (14) , which indicates significant electron delocalization within the molecule. The two other aromatic rings, C4-C9 and C11-C16, form dihedral angles with the plane of the imidazole ring of 60.64 (14) and 22.38 (13) , respectively.

Synthesis and crystallization
Triarylazoimidazole was prepared according to the literature method (Fun et al., 1999) via azo coupling of p-bromophenyldiazonium tetrafluoroborate with di(p-anisyl)imidazole and isolated in 84% yield as a red solid. Crystals suitable for X-ray analysis were obtained by slow evaporation of a saturated MeOH solution.

Refinement
Crystal data, details of data collection, and results of structure refinement are summarized in Table 2. The X-ray diffraction study was performed using the equipment of the Center for Molecular Studies of INEOS RAS. The hydrogen atom of the NH group was localized in the difference-Fourier map and refined with a fixed isotropic displacement parameter [U iso (H) = 1.2U eq (N)]. The other hydrogen atoms were placed in calculated positions with C-H = 0.95-0.98 Å and refined using a riding model with fixed isotropic displacement parameters [U iso (H) = 1.5U eq (C) for CH 3 groups and U iso (H) = 1.2U eq (C) for other groups].

Special details
Experimental. SADABS-2014/5 (Bruker, 2014/5) was used for absorption correction. wR2(int) was 0.0815 before and 0.0536 after correction. The Ratio of minimum to maximum transmission is 0.8000. The λ/2 correction factor is 0.00150. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq