Crystal structures and Hirshfeld surface analyses of the two isotypic compounds (E)-1-(4-bromo-phen-yl)-2-[2,2-di-chloro-1-(4-nitro-phen-yl)ethen-yl]diazene and (E)-1-(4-chloro-phen-yl)-2-[2,2-di-chloro-1-(4-nitro-phen-yl)ethen-yl]diazene

Abstract

In the two isotypic title compounds, C₁₄H₈BrCl₂N₃O₂, (I), and C₁₄H₈Cl₃N₃O₂, (II), the substitution of one of the phenyl rings is different [Br for (I) and Cl for (II)]. Aromatic rings form dihedral angles of 60.9 (2) and 64.1 (2)°, respectively. Mol-ecules are linked through weak X⋯Cl contacts [X = Br for (I) and Cl for (II)], C-H⋯Cl and C-Cl⋯π inter-actions into sheets parallel to the ab plane. Additional van der Waals inter-actions consolidate the three-dimensional packing. Hirshfeld surface analysis of the crystal structures indicates that the most important contributions for the crystal packing for (I) are from C⋯H/H⋯C (16.1%), O⋯H/H⋯O (13.1%), Cl⋯H/H⋯Cl (12.7%), H⋯H (11.4%), Br⋯H/H⋯Br (8.9%), N⋯H/H⋯N (6.9%) and Cl⋯C/C⋯Cl (6.6%) inter-actions, and for (II), from Cl⋯H / H⋯Cl (21.9%), C⋯H/H⋯C (15.3%), O⋯H/H⋯O (13.4%), H⋯H (11.5%), Cl⋯C/C⋯Cl (8.3%), N⋯H/H⋯N (7.0%) and Cl⋯Cl (5.9%) inter-actions. The crystal of (I) studied was refined as an inversion twin, the ratio of components being 0.9917 (12):0.0083 (12).

Keywords: Hirshfeld surface analysis; crystal structure; diazene derivatives; dyes; inter­molecular halogen bonds.

Figure 1

The mol­ecular structure of (I) with displacement ellipsoids drawn at the 30% probability level.

Figure 2

The mol­ecular structure of (II) with displacement ellipsoids drawn at the 30% probability level.

Figure 3

Packing in the crystal structure of (I) showing chains running parallel to the a-axis.

Figure 4

A view of the packing in (I) along the a axis showing C—H⋯Cl contacts.

Figure 5

Formation of sheets in (II) parallel to ab through C—Cl⋯π contacts.

Figure 6

Hirshfeld surface representations and full two-dimensional fingerprint plots for (I), showing (a) all inter­actions, and delineated into (b) C⋯H/H⋯C (c), O⋯H/H⋯O (d), Cl⋯H/H⋯Cl (e), H⋯H (f), Br⋯H/H⋯Br (g), N⋯H/H⋯N and (h) Cl⋯C/C⋯Cl inter­actions. The d _i and d _e values are the closest inter­nal and external distances (in Å) from a given point on the Hirshfeld surface.

Figure 7

The Hirshfeld surface representations and the full two-dimensional fingerprint plots for (II), showing (a) all inter­actions, and delineated into (b) Cl⋯H/H⋯Cl, (c) C⋯H/H⋯C, (d) O⋯H/H⋯O, (e) H⋯H, (f) Cl⋯C/C⋯Cl, (g) N⋯H/H⋯N and (h) Cl⋯Cl inter­actions. The d _i and d _e values are the closest inter­nal and external distances (in Å) from a given point on the Hirshfeld surface.