Displaying publications 21 - 40 of 52 in total

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  1. Razak IA, Usman A, Fun HK, Yamin BM, Kasim NA
    Acta Crystallogr C, 2002 Apr;58(Pt 4):M225-7.
    PMID: 11932524
    In the title compound, [Fe(C(34)H(29)O(2)P(2))](2)[Sb(2)Cl(8)], the discrete centrosymmetric [Sb(2)Cl(8)]2- anions are formed from two edge-shared square pyramids of Cl atoms about each Sb atom. Within the cation, the two diphenylphosphinate groups share one H atom and the ferrocene cyclopentadienyl rings are in a staggered conformation, with the average value of the twist angle being 46 degrees. In the crystal, each [Sb(2)Cl(8)]2- anion is involved in eight C-H* * *Cl interactions with four surrounding cations and these interactions interconnect the ions to form molecular columns along the a direction.
  2. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 Apr;58(Pt 4):O239-41.
    PMID: 11932554
    The crystal of the title compound, C(20)H(17)NO(4), which was used for collecting intensity data was twinned. Each of the two crystallographically independent molecules in the asymmetric unit has a planar indole moiety perpendicular to a planar oxopropyl moiety. The distribution of the bonds at the central C atom joining the oxopropyl, phenyl and indole substituents is also planar. The packing is stabilized by intermolecular C-H* * *O interactions, as well as by dipole-dipole and van der Waals interactions.
  3. Usman A, Chantrapromma S, Fun HK
    Acta Crystallogr C, 2001 Dec;57(Pt 12):1443-6.
    PMID: 11740112
    The title compound, 3,5,7-triaza-1-azoniatricyclo[3.3.1.1(3,7)]decane 2,4-dinitrophenolate monohydrate, C6H13N4+*C6H3N2O5-*H2O, the 1:1 hydrate adduct of hexamethylenetetramine (HMT) and 2,4-dinitrophenol, undergoes a temperature phase transition. In the room-temperature phase, the adduct crystallizes in the monoclinic P2(1)/m space group, whereas in the low-temperature phase, the adduct crystallizes in the triclinic P1 space group. This phase transition is reversible, with the transition temperature at 273 K, and the phase transition is governed by hydrogen bonds and weak interactions. In both these temperature-dependent polymorphs, the crystal structure is alternately layered with sheets of hexamethylenetetramine and sheets of dinitrophenol stacked along the c axis. The hexamethylenetetramine and dinitrophenol moieties are linked by intermolecular hydrogen bonds. The water molecule in the adduct plays an important role, forming O-H...O hydrogen bonds which, together with C-H...O hydrogen bonds, bridge the adducts into molecular ribbons. Extra hydrogen bonds and weak interactions exist for the low-temperature polymorph and these interconnect the molecular ribbons into a three-dimensional packing structure. Also in these two temperature-dependent polymorphs, dinitrophenol acts as a hydrogen-bond acceptor and HMT acts as a hydrogen-bond donor.
  4. Usman A, Razak IA, Chantrapromma S, Fun HK, Ray JK, Das Adhikari S, et al.
    Acta Crystallogr C, 2001 Dec;57(Pt 12):1441-2.
    PMID: 11740111
    In the title compound, C20H20FNO5S, the pyrrolidine ring adopts an envelope conformation. The fluorophenyl and thiophene rings are individually planar. The molecular and crystal structures are stabilized by intra- and intermolecular C-H...O interactions.
  5. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2001 Dec;57(Pt 12):1438-40.
    PMID: 11740110
    In the title compound, C25H19NO4, the indole moiety is not completely planar, the heterocyclic ring being distorted very slightly towards a half-chair conformation. The benzoyl and 4-methoxyphenyl substituents are individually almost planar and are in a bisecting and nearly perpendicular configuration, respectively, with respect to the plane of the indole moiety. The molecular and packing structures in the crystal are stabilized by intramolecular and intermolecular C-H...O interactions.
  6. Raj SS, Fun HK, Zhao PS, Jian FF, Lu LD, Yang XJ, et al.
    Acta Crystallogr C, 2000 Jul;56 ( Pt 7):742-3.
    PMID: 10935066
  7. Rahman AA, Usman A, Chantrapromma S, Fun HK
    Acta Crystallogr C, 2003 Sep;59(Pt 9):i92-4.
    PMID: 12944636
    A sample of hydronium perchlorate, H(3)O(+) x ClO(4)(-), crystallized from ethanol at ambient temperature, was found to be orthorhombic (space group Pnma) at both 193 and 293 K, with no phase transition observed in this temperature range. This contrasts with the earlier observation [Nordman (1962). Acta Cryst. 15, 18-23] of a monoclinic phase (space group P2(1)/n) at 193 K for crystals grown at that temperature from perchloric acid. The hydronium and perchlorate ions lie across a mirror plane but it is not possible to define at either temperature a simple description of the H-atom positions due to the three-dimensional tumbling of the hydronium cation.
  8. Usman A, Fun HK, Chantrapromma S, Zhu HL, Wang XJ
    Acta Crystallogr C, 2003 Mar;59(Pt 3):m97-9.
    PMID: 12711770
    In the ternary title compound, catena-poly[[silver(I)-mu-ethylenediamine-kappa(2)N:N'] 3-nitrobenzoate monohydrate], [[Ag(C(2)H(8)N(2))](C(7)H(4)NO(4)) x H(2)O](n), the Ag atom is bicoordinated in a linear configuration by two different N atoms from two symmetry-related ethylenediamine ligands, thus giving linear polymeric chains with an [-Ag-N-C-C-N-](n) backbone running parallel to the a axis. In the crystal packing, these linear chains are interconnected by N-H...O and O-H...O hydrogen bonds to form layers parallel to the ab plane.
  9. Razak IA, Raj SS, Fun HK, Jian F, Bei F, Yang X, et al.
    Acta Crystallogr C, 2000 Jun;56 (Pt 6):666-7.
    PMID: 10902013
  10. Razak IA, Raj SS, Fun HK, Yamin BM, Hashim N
    Acta Crystallogr C, 2000 Jun;56 (Pt 6):664-5.
    PMID: 10902012
  11. Du Boulay D, Shaari K, Skelton BW, Waterman PG, White AH
    Acta Crystallogr C, 2000 Feb;56 ( Pt 2):199-200.
    PMID: 10777886
  12. Bis
    Razak IA, Raj SS, Fun HK, Tong YX, Lu ZL, Kang BS
    Acta Crystallogr C, 2000 Mar;56 (Pt 3):291-2.
    PMID: 10777923
  13. Usman A, Chantrapromma S, Fun HK, Poh BL, Karalai C
    Acta Crystallogr C, 2002 Jan;58(Pt 1):o48-50.
    PMID: 11781494
    In the title complex, C6H12N4*C8H8O3, the hexamethylenetetramine molecule accepts a single intermolecular O-H...N hydrogen bond from the hydroxy group of the 4-hydroxy-3-methoxybenzaldehyde moiety. The non-centrosymmetric crystal structure is built from alternating molecular sheets of 4-hydroxy-3-methoxybenzaldehyde and hexamethylenetetramine molecules, and is stabilized by intermolecular O-H...N, C-H...O and C-H...pi interactions.
  14. Usman A, Chantrapromma S, Fun HK, Poh BL, Karalai C
    Acta Crystallogr C, 2002 Jan;58(Pt 1):o46-7.
    PMID: 11781493
    In the title complex, the 1:1 ionic adduct of hexamethylenetetraminium and 2,4,6-trinitrophenolate, C6H13N4+*C6H2N3O7-, the cation acts as a donor for bifurcated hydrogen bonds to the O atoms of the phenolate and one of the nitro groups of the 2,4,6-trinitrophenolate anion. The crystal structure is built from sheets of cations and anions, and is stabilized by intermolecular C-H...O and C-H...pi interactions.
  15. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhao BG, Xu JH
    Acta Crystallogr C, 2002 Jan;58(Pt 1):o24-5.
    PMID: 11781485
    In the title compound, C20H16N2O5, both of the 1-acetylisatin (1-acetyl-1H-indole-2,3-dione) moieties are planar and form a dihedral angle of 74.1 (1) degrees. Weak intermolecular hydrogen bonds and C-H...pi interactions stabilize the packing in the crystal.
  16. Usman A, Chantrapromma S, Fun HK
    Acta Crystallogr C, 2002 Jan;58(Pt 1):m45-7.
    PMID: 11781470
    The title compound, bis(2,4-dinitrophenolato-kappa2O,O')(1,4,7,10,13,16-hexaoxadecane-kappa6O)barium(II), [Ba(C6H3N2O5)2(C12H24O6)], is a 1:1 complex of barium(II)-2,4-dinitrophenolate and 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6). Its structure is located on a crystallographic inversion centre. The temperature dependence of the crystal structure has been studied. The monoclinic beta angle of the P2(1)/n space group increases with increasing temperature. The packing structure of the complex is stabilized by intermolecular C-H...O interactions.
  17. Razak IA, Usman A, Fun HK, Yamin BM, Keat GW
    Acta Crystallogr C, 2002 Jan;58(Pt 1):m31-3.
    PMID: 11781464
    In the title compound, [Zn(CH3COO)2(C4H8N2S)2]*H2O, the Zn atom is tetrahedrally coordinated in the ZnO2S2 form. N-H...O and O-H...O intramolecular and intermolecular hydrogen bonds are formed by the four N atoms and the water molecule. N-H...O intermolecular hydrogen bonds and C-H...S and C-H...O intermolecular interactions interconnect columns formed by the molecules into layers. Adjacent layers are then linked by other N-H...O and O-H...O intermolecular hydrogen bonds to form a three-dimensional framework throughout the structure. The orientations of the acetate planes are such that the Zn atom lies within them.
  18. Shanmuga Sundara Raj S, Fun HK, Wu J, Tian YP, Xie FX, Shao ZH, et al.
    Acta Crystallogr C, 2000 Nov;56 Pt 11:1321-2.
    PMID: 11077284
    The title compound, [Ni(C(21)H(15)N(2)S(2))(2)], has a novel cis configuration with two fluorene moieties on the same side. The Ni atom is in a square-planar configuration. The molecular packing is stabilized by intramolecular stacking between the fluorene moieties and extensive C-H.pi interactions.
  19. Shanmuga Sundara Raj S, Surya Prakash Rao H, Sakthikumar L, Fun HK
    Acta Crystallogr C, 2000 Sep;56 (Pt 9):1113-4.
    PMID: 10986500
    In the crystal structure of the title compound, C(3)H(3)NO(2)S(2), the four-membered C(2)S(2) ring is planar, as is the whole molecule. The short intramolecular S.O distance of 2.687 (2) A shows the five-atom system to be conjugated. The molecules pack as a two-dimensional network in the (010) plane through short intermolecular S.O [2.900 (2) and 3.077 (2) A] interactions.
  20. Usman A, Fun HK, Wang L, Zhang Y, Xu JH
    Acta Crystallogr C, 2003 Jun;59(Pt 6):o305-7.
    PMID: 12794346
    In the title compounds, C(21)H(18)N(2)O(4) and C(25)H(18)N(2)O(4), respectively, the five-membered ring of the indole system is almost planar. The oxetane and oxazole rings are individually planar. The orientations of the indole, oxetane, oxazole and phenyl moieties are conditioned by the sp(3) nature of the spiro-C atoms. In both compounds, the relative orientation of the indole and oxazole rings is opposite.
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