Crystal structure of 2-[(E)-2-(4-bromo-phen-yl)diazen-1-yl]-4,5-bis-(4-meth-oxy-phen-yl)-1H-imidazole: the first example of a structurally characterized tri-aryl-azo-imid-azole.

The title compound, C23H19BrN4O2, is a product of an azo coupling reaction between 3,4-bis-(4-meth-oxy-phen-yl)imidazole and 4-bromo-phenyl-diazo-nium tetra-fluoro-borate. Its crystal structure was determined using data collected at 120 K. The mol-ecule adopts a trans configuration with respect to the N=N double bond. The imidazole and aryl rings attached to the azo linkage are coplanar within 12.73 (14)°, which indicates significant electron delocalization within the mol-ecule. In the crystal, the mol-ecules form centrosymmetric dimers via pairs of N-H⋯O hydrogen bonds.