title: Comparison of the structure of (E)-2-(2-benzylidenehydrazinylidene)quinoxaline with those of its chloro- and bromobenzylidene analogues.
abstract: (E)-2-(2-Benzylidenehydrazinylidene)quinoxaline, C₁₅H₁₂N₄, crystallized with two molecules in the asymmetric unit. The structures of six halogen derivatives of this compound were also investigated: (E)-2-[2-(2-chlorobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁ClN₄; (E)-2-[2-(3-chlorobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁ClN₄; (E)-2-[2-(4-chlorobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁ClN₄; (E)-2-[2-(2-bromobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁BrN₄; (E)-2-[2-(3-bromobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁BrN₄; (E)-2-[2-(4-bromobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁BrN₄. The 3-Cl and 3-Br compounds are isomorphous, as are the 4-Cl and 4-Br compounds. In all of these compounds, it was found that the supramolecular structures are governed by similar predominant patterns, viz. strong intermolecular N-H...N(pyrazine) hydrogen bonds supplemented by weak C-H∙∙∙N(pyrazine) hydrogen-bond interactions in the 2- and 3-halo compounds and by C-H∙∙∙Cl/Br interactions in the 4-halo compounds. In all compounds, there are π-π stacking interactions.
authors.affiliation: REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua Campo Alegre, 687, P-4169-007, Porto, P-4200-150, Portugal.
authors.forename: Ligia Rebelo
authors.initials: LR
authors.lastname: Gomes
authors.forename: John Nicolson
authors.initials: JN
authors.lastname: Low
authors.forename: Ana S M C
authors.initials: AS
authors.lastname: Rodrigues
authors.forename: James L
authors.initials: JL
authors.lastname: Wardell
authors.forename: Marcus V N
authors.initials: MV
authors.lastname: de Souza
authors.forename: Thais C M
authors.initials: TC
authors.lastname: Noguiera
authors.forename: Alessandra C
authors.initials: AC
authors.lastname: Pinheiro
mesh_terms: D018360:Crystallography, X-Ray; D006834:Hydrazines / Q000138:chemical synthesis / Q000737:chemistry*; D006842:Hydrocarbons, Brominated / Q000737:chemistry; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D011810:Quinoxalines / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D006834:Hydrazines; D006842:Hydrocarbons, Brominated; D006843:Hydrocarbons, Chlorinated; D011810:Quinoxalines
keywords: crystal structure; hydrogen bonding; quinoxalines