Syntheses, crystal structures and Hirshfeld surface analyses of ( E )-1-[2,2-dichloro-1-(2,3-dimethoxyphenyl)ethen-1-yl]-2-phenyldiazene and ( E )-1-(4-chlorophenyl)-2-[2,2-dichloro-1-(2,3-dimethoxyphenyl)ethen-1-yl]diazene

The crystal structures and Hirshfeld surface analyses of two similar azo compounds are reported. ( E )-1-[2,2-dichloro-1-(2,3-dimethoxyphenyl)ethen-1-yl]-2-phenyldiazene, C 16 H 14 Cl 2 N 2 O 2 , ( I ), crystallizes in space group P 2 1 / c with Z = 4, and ( E )-1-(4-chlorophenyl)-2-[2,2-dichloro-1-(2,3-dimethoxyphenyl)ethen-1-yl]diazene, C 16 H 13 Cl 3 N 2 O 2 , ( II ), in the space group P 1 with Z = 4. In the crystal structure of ( I ), the molecules form layers parallel to the (010) plane through C—H...π and C—Cl...π interactions and van der Waals interactions between these layers consolidate the packing. There are two symmetry-independent molecules in the asymmetric unit of ( II ). In the crystal, molecules are connected by C—H...O and C—H...Cl hydrogen bonds, forming a three-dimensional network. C—Cl...π interactions also contribute to the packing. The intermolecular contacts in the crystals ( I ) and ( II ) were analysed using Hirshfeld surface analysis and two-dimensional fingerprint plots.