Crystal structures and Hirshfeld surface analyses of (E)-1-[1-(4-tert-butylphenyl)-2,2-dichloroethenyl]-2-phenyldiazen e, (E)-1-[1-(4-tert-butylphenyl)-2,2-dichloroethenyl]-2-(4-methylphe nyl)diazene, (E)-1[1-(4-tert-butylphenyl)-2,2-dichloroethenyl]-2-(4-methoxyphe nyl)diazene and (E)-1-[1-(4-tert-butylphenyl)-2,2-dichloroethenyl]-2-(3-methylphe nyl)diazene

The crystal structures and Hirshfeld surface analyses of four similar azo compounds are reported. (E)-1-[1-(4-tert-Butylphenyl)-2,2-dichloroethenyl]-2phenyldiazene, C18H18Cl2N2, (I), and (E)-1-[1-(4-tert-butylphenyl)-2,2-dichloroethenyl]-2-(4-methylphenyl)diazene, C19H20Cl2N2, (II), crystallize in the monoclinic space group C2/c with Z = 8, and (E)-1-[1-(4-tert-butylphenyl)-2,2-dichloroethenyl]-2-(4-methoxyphenyl)diazene, C19H20Cl2N2O, (III), in the monoclinic space group P2(1)/c with Z = 4. (E)-1-[1-(4-tert-Butylphenyl)-2,2-dichloroethenyl]-2-(3-methylphenyl)diazene, C19H20Cl2N2, (IV), crystallizes in the triclinic space group P (1) over bar with Z = 4 and comprises two molecules (A and B) in the asymmetric unit. In the crystal structures of (I) and (II), 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 layers parallel to ((2) over bar 02), while molecules of (III) are linked by C-H center dot center dot center dot O contacts, C-H center dot center dot center dot pi and C-Cl center dot center dot center dot pi interactions forming layers parallel to ((3) over bar 02). The stability of the molecular packing is ensured by van der Waals forces between these layers. In the crystal structure of (IV), 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 a tri-periodic network.