( E)-4-(4-Bromo­phenyl­diazen­yl)-2,6-dimethyl­phenyl acrylate and ( E)-2,6-dimethyl-4-(4-methyl­phenyl­diazen­yl)­phenyl acrylate.

The crystal structures of the title compounds, C17H15BrN2O2, (I), and C18H18N2O2, (II), determined at room temperature, have a trans configuration with respect to the diazene linkage, as found for other azo (diazene) derivatives. The aromatic mean planes are nearly coplanar, with a dihedral angle between these planes of 8.31 (2)° for (I) and 3.74 (2)° for (II). In both complexes, the mean plane of the ester group is nearly perpendicular to the aromatic ring planes. In both compounds, the crystal packing involves only π–π and π–ring inter­actions, which combine to stabilize the extended structure. [ABSTRACT FROM AUTHOR]