Showing papers by "T. N. Guru Row published in 2000"

Analysis of weak interactions involving fluorine: a comparative study of crystal packing of some benzodiazepinone drug intermediates and their non-fluorinated analogues

Abstract: Weak interactions involving fluorine have been analyzed in terms of altered packing modes in the crystalline lattice in four benzodiazepinone drug intermediates which are determined by X-ray diffraction. Two of them are non-fluorinated and the other two are corresponding mono-fluorosubstituted derivatives. The compounds are 2-chloroacetamido-5-chlorobenzophenone (C15H11Cl2NO), 2-chloroacetamido-5-chloro-2'-fluorobenzophenone (C15H10Cl2FNO2), 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzadiazapin-2-one (C15H12ClN2O) and 7-chloro-1,3-dihydro-5-(2'-fluorophenyl)-2H-1,4-benzadiazapin-2-one (C15H11ClN2OF). The conformational features in the first two compounds are essentially governed by strong intramolecular interactions. Specific C-H...F intermolecular interactions along with C-H...π interactions generate altered packing modes in fluorinated intermediates. The latter two compounds have strong N-H...O intermolecular hydrogen bonds as well

A Novel Oxide Ion Conductor in a Doped Bi2O3-V2O5 System: Ab Initio Structure of a New Polymorph of NaBi3V2O10 via Powder X-ray Diffraction†

Abstract: The crystal structure of NaBi3V2O10 has been determined using the ab initio approach followed by Rietveld refinement via powder X-ray diffraction. The unit cell is triclinic, space group P1, with a = 7.1964(4) A, b = 7.0367(3) A, c = 5.5139(2) A, α = 84.440(3)°, β = 113.461(2)°, γ =112.319(2)°, and V =236.46(2) A3. The final refinements gave Rp = 9.94%, Rwp = 13.11%, and R(I,hkl) = 8.73% for 30 parameters and 4871 data points. These results indicate that this is a polymorph different from that reported previously and represents a new class of oxide ion conductors in solid solution of the Na2O−Bi2O3−V2O5 ternary system. The (Bi2O2)2+ chains extend along the c axis with VO4 units joining the chains along both a and b directions resulting in a hitherto unknown motif in this class of compounds. The structure hence points to a new mode for the mechanism of oxide ion conduction.

Charge densities from high-resolution synchrotron X-ray diffraction experiments.

Abstract: The combination of intense X-ray sources, especially synchrotron radiation, with area-detector technology has accomplished an enormous advance in the experimental conditions available for charge-density analysis by single-crystal high-resolution X-ray diffraction. Such experiments can now be carried out in a time measured in hours rather than weeks. Some features of these experiments are examined and preliminary results are reported for charge-density studies of 2-hydroxy-5-nitrobenzaldehyde N-cyclohexylimine (1), octakis(m-tolylthio)naphthalene (2), and 7-fluoro-4-styrylcoumarin (3). Weak interactions in crystals of (1) and (3) are found to have similar charge-density characteristics. Cages in the crystal lattice of (2) have a complex charge distribution.

Low-temperature tris(tert-butyl 3-oxo­butan­oato)­iron(III)

Abstract: The low-temperature (173 K) structure of the title complex, [Fe(C8H13O3)3], a metal–organic chemical vapour deposition (MOCVD) precursor, has been analyzed The Fe atom is octahedrally coordinated and the three chelate rings are found to be significantly non-planar, adopting a half-chair conformation with the Fe atom out of the plane