Crystal structures and Hirshfeld surface analyses of methyl 4-{2,2-dichloro-1-[(E)-phenyldiazenyl]ethenyl}benzoate, methyl 4-{2,2-dichloro-1-[(E)-(4-methylphenyl)diazenyl]ethenyl}benzoate and methyl 4-{2,2-dichloro-1-[(E)-(3,4-dimethylphenyl)diazenyl]ethenyl}benzo ate

The crystal structures and Hirshfeld surface analyses of three similar azo compounds are reported. Methyl 4-{2,2-dichloro-1-[(E)-phenyldiazenyl]ethenyl} benzoate, C16H12Cl2N2O2, (I), and methyl 4-{2,2-dichloro- 1-[(E)-(4-methylphenyl)diazenyl]ethenyl}benzoate, C17H14Cl2N2O2, (II), crystallize in the space group P2(1)/c with Z = 4, and methyl 4-{2,2-dichloro-1-[(E)-(3,4-dimethylphenyl)diazenyl]ethenyl}benzoate, C18H16Cl2N2O2, (III), in the space group P1 with Z = 2. In the crystal of (I), molecules are linked by C-H center dot center dot center dot N hydrogen bonds, forming chains with C(6) motifs parallel to the b axis. Short intermolecular Cl center dot center dot center dot O contacts of 2.8421 (16) angstrom and weak van der Waals interactions between these chains stabilize the crystal structure. In (II), molecules are linked by C-H center dot center dot center dot O hydrogen bonds and C-Cl center dot center dot center dot pi interactions, forming layers parallel to (010). Weak van der Waals interactions between these layers consolidate the molecular packing. In (III), molecules are linked by C-H center dot center dot center dot pi and C-Cl center dot center dot center dot pi interactions forming chains parallel to [011]. Furthermore, these chains are connected by C-Cl center dot center dot center dot pi interactions parallel to the a axis, forming (011) layers. The stability of the molecular packing is ensured by van der Waals forces between these layers.