Crystal structure and Hirshfeld surface analysis of (E)-2-(4-bromo-phen-yl)-1-[2,2-di-bromo-1-(4-nitro-phen-yl)ethen-yl]diazene

Crystal structures and Hirshfeld surface analyses of methyl 4-{2,2-di-chloro-1-[(E)-phenyl-diazen-yl]eth-enyl}benzoate, methyl 4-{2,2-di-chloro-1-[(E)-(4-methyl-phen-yl)diazen-yl]ethen-yl}benzoate and methyl 4-{2,2-di-chloro-1-[(E)-(3,4-di-methyl-phen-yl)diazen-yl]ethen-yl}benzoate

The crystal structures and Hirshfeld surface analyses of three similar azo compounds are reported. Methyl 4-{2,2-di-chloro-1-[(E)-phenyl-diazen-yl]ethen-yl}benzoate, C16H12Cl2N2O2, (I), and methyl 4-{2,2-di-chloro-1-[(E)-(4-methyl-phen-yl)diazen-yl]ethen-yl}benzoate, C17H14Cl2N2O2, (II), crystallize in the space group P21/c with Z = 4, and methyl 4-{2,2-di-chloro-1-[(E)-(3,4-di-methyl-phen-yl)diazen-yl]ethen-yl}benzoate, C18H16Cl2N2O2, (III), in the space group P with Z = 2. In the crystal of (I), mol-ecules are linked by C-H⋯N hydrogen bonds, forming chains with C(6) motifs parallel to the b axis. Short inter-molecular Cl⋯O contacts of 2.8421 (16) Å and weak van der Waals inter-actions between these chains stabilize the crystal structure. In (II), mol-ecules are linked by C-H⋯O hydrogen bonds and C-Cl⋯π inter-actions, forming layers parallel to (010). Weak van der Waals inter-actions between these layers consolidate the mol-ecular packing. In (III), mol-ecules are linked by C-H⋯π and C-Cl⋯π inter-actions forming chains parallel to [011]. Furthermore, these chains are connected by C-Cl⋯π inter-actions parallel to the a axis, forming (01) layers. The stability of the mol-ecular packing is ensured by van der Waals forces between these layers.

Crystal structures and Hirshfeld surface analyses of (E)-1-[1-(4-tert-butyl-phen-yl)-2,2-di-chloro-ethen-yl]-2-phenyl-diazene, (E)-1-[1-(4-tert-butyl-phen-yl)-2,2-di-chloro-ethen-yl]-2-(4-methyl-phen-yl)diazene, (E)-1-[1-(4-tert-butyl-phen-yl)-2,2-di-chloro-ethen-yl]-2-(4-meth-oxy-phen-yl)diazene and (E)-1-[1-(4-tert-butyl-phen-yl)-2,2-di-chloro-ethen-yl]-2-(3-methyl-phen-yl)diazene

The crystal structures and Hirshfeld surface analyses of four similar azo compounds are reported. (E)-1-[1-(4-tert-Butyl-phen-yl)-2,2-di-chloro-ethen-yl]-2-phenyl-diazene, C18H18Cl2N2, (I), and (E)-1-[1-(4-tert-butyl-phen-yl)-2,2-di-chloro-ethen-yl]-2-(4-methyl-phen-yl)diazene, C19H20Cl2N2, (II), crystallize in the monoclinic space group C2/c with Z = 8, and (E)-1-[1-(4-tert-butyl-phen-yl)-2,2-di-chloro-ethen-yl]-2-(4-meth-oxy-phen-yl)diazene, C19H20Cl2N2O, (III), in the monoclinic space group P21/c with Z = 4. (E)-1-[1-(4-tert-Butyl-phen-yl)-2,2-di-chloro-ethen-yl]-2-(3-methyl-phen-yl)diazene, C19H20Cl2N2, (IV), crystallizes in the triclinic space group P with Z = 4 and comprises two mol-ecules (A and B) in the asymmetric unit. In the crystal structures of (I) and (II), mol-ecules are linked by C-H⋯π and C-Cl⋯π inter-actions, forming layers parallel to (02), while mol-ecules of (III) are linked by C-H⋯O contacts, C-H⋯π and C-Cl⋯π inter-actions forming layers parallel to (02). The stability of the mol-ecular packing is ensured by van der Waals forces between these layers. In the crystal structure of (IV), mol-ecules are linked by C-H⋯π and C-Cl⋯π inter-actions, forming a tri-periodic network.

Structural Organization of Dibromodiazadienes in the Crystal and Identification of Br···O Halogen Bonding Involving the Nitro Group

Nitro functionalized dibromodiazadiene dyes were prepared and fully characterized including X-ray single crystal analysis. Electron deficient dibromodiazadienes were found to be able to act as donors of halogen bonding (XB), while the nitro group acted as an acceptor of the XB. Depending on the substituents, the Br···O XB competed with other weak interactions, and for some of the dyes, they even outcompeted the XB involving the nitro group. However, the nitro functionalized dibromoalkenes 6a and 10a, which had only the nitro moiety as the most plausible acceptor of the XB, reliably formed 1D chains via Br⋯O XB. Experimental work was supported by the DFT calculations and topological analysis of the electron density distribution within the framework of Bader’s theory (QTAIM method).

Crystal structure and Hirshfeld surface analysis of a new polymorph of (E)-2-(4-bromo-phen-yl)-1-[2,2-di-bromo-1-(3-nitro-phen-yl)ethen-yl]diazene

A new polymorph of the title compound, C14H8Br3N3O2, (form-2) was obtained in the same manner as the previously reported form-1 [Akkurt et al. (2022 ▸). Acta Cryst. E78, 732-736]. The structure of the new polymorph is stabilized by a C-H⋯O hydrogen bond that links mol-ecules into chains. These chains are linked by face-to-face π-π stacking inter-actions, resulting in a layered structure. Short inter-mol-ecular Br⋯O contacts and van der Waals inter-actions between the layers aid in the cohesion of the crystal packing. In the previously reported form-1, C-H⋯Br inter-actions connect mol-ecules into zigzag chains, which are linked by C-Br⋯π inter-actions into layers, whereas the van der Waals inter-actions between the layers stabilize the crystal packing of form-2. Hirshfeld mol-ecular surface analysis was used to compare the inter-molecular inter-actions of the polymorphs.