title: Crystal structure and stereochemistry study of 2-substituted benzoxazole derivatives.
abstract: The structure of 2-[(4-chlorophenylazo) cyanomethyl] benzoxazole, C15H9ClN4O (I), has triclinic ([Formula: see text]) symmetry. The structure displays N-H ⋯ N hydrogen bonding. The structure of 2-[(arylidene) cyanomethyl] benzoxazoles, C17H10N2O3 (II), has triclinic ([Formula: see text]) symmetry. The structure displays C-H ⋯ N, C-H ⋯ C hydrogen bonding. In (I), the chlorophenyl and benzoxazole groups adopt a trans configuration with respect to the central cyanomethyle hydrazone moiety. Compound (II) crystallized with two molecules in the asymmetric unit shows cisoid conformation between cyano group and benzoxazole nitrogen, contrary to (I). In (II) the benzodioxole has an envelope conformation (the C17 atom is the flap atom). The molecular geometry obtained using molecular mechanics (MM) calculations has been discussed along with the results of single crystal analysis.
authors.affiliation: Crystallography Laboratory, Physics Division, National Research Center, Dokki, Giza 12622, Egypt.
authors.forename: Ahmed F
authors.initials: AF
authors.lastname: Mabied
authors.affiliation: Crystallography Laboratory, Physics Division, National Research Center, Dokki, Giza 12622, Egypt.
authors.forename: Elsayed M
authors.initials: EM
authors.lastname: Shalaby
authors.affiliation: Physics Department, Women's College, Ain Shams University, Cairo 11757, Egypt.
authors.forename: Hamdia A
authors.initials: HA
authors.lastname: Zayed
authors.affiliation: Crystallography Laboratory, Physics Division, National Research Center, Dokki, Giza 12622, Egypt.
authors.forename: Esmat
authors.initials: E
authors.lastname: El-Kholy
authors.affiliation: Crystallography Laboratory, Physics Division, National Research Center, Dokki, Giza 12622, Egypt.
authors.forename: Ibrahim S A
authors.initials: IS
authors.lastname: Farag
authors.affiliation: Crystallography Laboratory, Physics Division, National Research Center, Dokki, Giza 12622, Egypt.
authors.forename: Naima A
authors.initials: NA
authors.lastname: Ahmed