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  • Küçük Resim
    Öğe
    Conformational study and structure of bis-N,N′-p-bromo-salicylideneamine-1,2-diaminobenzene
    (Elsevier Science Bv, 2000) Kabak, M; Elmali, A; Elerman, Y; Durlu, TN
    Bis-N,N'-p-bromo-salicylideneamine-1,2-diaminobenzene (C20H14Br2N2 O-2) has been investigated by X-ray analysis and AM1 semi-empirical quantum mechanical method. Thc crystal is in the orthorhombic space group Pbca with a = 18.805(3), b = 25,394(4), c = 7.549(2) Angstrom, V = 3604.9(1) Angstrom (3), Z = 8, D-c = 1.747 g cm(-3) and mu (MoKalpha) = 4.515 mm(-1). The title structure was solved by direct methods and refined to R = 0.0477 for 1262 reflections [l > 2 sigma (1)]. The title compound is photochromic and the molecule is not planar. Intramolecular hydrogen bonds occur between O(1) and N(1) (2.605(7) Angstrom) and between O(2) and N(2) (2.601(8) Angstrom) atoms, the hydrogen atom essentially being bonded to the oxygen atom. Minimum energy conformations from AM 1 were calculated as a function of two torsion angles theta (1) (C8-N1-C7-C6) and theta (2) (C15-C14-N2-C13), varied every 5 degrees. The optimized geometry of the crystal structure corresponding to the non-planar conformation is the most stable conformation in all calculations. The results strongly indicate that the minimum energy conformation is primarily determined by nonbonded hydrogen-hydrogen repulsions between the ortho-hydrogens on the aldehyde rings. (C) 2000 Elsevier Science B.V. All rights reserved.
  • [ X ]
    Öğe
    [N,N '-bis(5-bromosalicylidene)-1,3-diaminopropane]copper(II)
    (Munksgaard Int Publ Ltd, 1999) Kabak, M; Elmali, A; Kavlakoglu, E; Elerman, Y; Durlu, TN
    The title compound, [Cu(C17H14Br2N2O2)], has a crystallographic twofold axis. The coordination geometry about the Cu-II centre is a tetrahedrally distorted square plane formed by the four-coordinate N2O2 donor set of the Schiff base imine-phenol ligand. The Cu-N and Cu-O distances are 1.967(5) and 1.914(4) Angstrom, respectively.
  • Küçük Resim
    Öğe
    Tautomeric properties, conformations and structure of N-(2-hydroxy-5-chlorophenyl) salicylaldimine
    (Elsevier Science Bv, 1999) Elmali, A; Kabak, M; Kavlakoglu, E; Elerman, Y; Durlu, TN
    The crystal structure of N-(2-hydroxy-5-chlorophenyl) salicylaldimine (C13H10NO2Cl) was determined by X-ray analysis. It crystallizes orthorhombic space group P2(1)2(1)2(1) with a = 12.967(2) Angstrom, b = 14.438(3) Angstrom, c = 6.231(3) Angstrom, V = 1166.5(6) Angstrom(3), Z = 4, D-c = 1.41 g cm(-3) and mu(MoKalpha) = 0.315 mm(-1). The title compound is thermochromic and the molecule is nearly planar. Both tautomeric forms (keto and enol forms in 68(3) and 32(3)%, respectively) are present in the solid state, The molecules contain strong intramolecular hydrogen bonds, N1-H1 ... O1/O2 (2.515(1) and 2.581(2) Angstrom) for the keto form and O1-H01 ... N1 for the enol one. There is also strong intermolecular O2-H ... O1 hydrogen bonding (2.599(2) Angstrom) between neighbouring molecules. Minimum energy conformations AM1 were calculated as a function of the three torsion angles, theta(1)(N1-C7-C6-C5), theta(2)(C8-N1-C7-C6) and theta(3)(C9-C8-N1-C7), varied every 10 degrees. Although the molecule is nearly planar, the AM1 optimized geometry of the title compound is not planar. The non-planar conformation of the title compound corresponding to the optimized X-ray structure is the most stable conformation in all calculations. (C) 1999 Elsevier Science B.V. All rights reserved.