Crystal structures and Hirshfeld surface analyses of methyl 4-{2,2-dichloro-1-[(E)-phenyldiazenyl]eth-enyl}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}benzoate

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-methyl-phenyl)diazenyl]ethenyl}benzoate, C17H14Cl2N2O2, (II), crystallize in the space group P21/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. . .N hydrogen bonds, forming chains with C(6) motifs parallel to the b axis. Short intermolecular Cl. . .O contacts of 2.8421 (16) Å and weak van der Waals interactions between these chains stabilize the crystal structure. In (II), molecules are linked by C—H. . .O hydrogen bonds and C—Cl. . .π 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. . .π and C—Cl. . .π interactions forming chains parallel to [011]. Furthermore, these chains are connected by C—Cl. . .π 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. © 2024 International Union of Crystallography. All rights reserved.