4′-(Dimethylamino)-4-nitroazobenzene

The title compound [systematic name: (4-dimethylaminophenyl)(4-nitrophenyl)diazene], C14H14N4O2, has trans geometry about the azo linkage and is planar. Although the crystal structure is non-centrosymmetric, the overall net dipole moment is minimized by antiparallel arrangement of chains of molecules related by translation (1 + x, y, 2 + z) and by marked orientational disorder in the azo moiety, through rotation about the C...C axis that it bridges. The chains are connected by weak C-H...O hydrogen bonding between nitro and dimethylamino groups. They lie perpendicular to the (103) plane and form stacks through pi-pi interaction, propagating along the crystallographic a axis. The stacks interact through a combination of van der Waals interactions and edge-to-face pi-pi interaction to give a herring-bone appearance in the view along their long axis.