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}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-methyl­phen­yl)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 P 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 (0 1) layers. The stability of the mol­ecular packing is ensured by van der Waals forces between these layers. [ABSTRACT FROM AUTHOR]