Displaying publications 1 - 20 of 52 in total

  1. Suleiman Gwaram N, Khaledi H, Ali HM, Olmstead MM
    Acta Crystallogr C, 2011 Jan;67(Pt 1):o6-9.
    PMID: 21206084 DOI: 10.1107/S0108270110046317
    The title compound, C(4)H(6)N(4)O·H(2)O, crystallized simultaneously as a triclinic and a monoclinic polymorph from an aqueous solution of 2,4-diaminopyrimidin-6-ol. Previously, an orthorhombic polymorph was isolated under the same experimental conditions. The molecular geometric parameters in the two present polymorphs and the previously reported orthorhombic polymorph are similar, but the structures differ in the details of their crystal packing. In the triclinic system, the diaminopyrimidinone molecules are connected to one another via N-H···O and N-H···N hydrogen bonding to form infinite chains in the [011] direction. The chains are further hydrogen bonded to the water molecules, resulting in a three-dimensional network. In the monoclinic system, the diaminopyrimidinone molecules are hydrogen bonded together into two-dimensional networks parallel to the bc plane. The water molecules link the planes to form a three-dimensional polymeric structure.
  2. Ganesan K, Alias Y, Ng SW
    Acta Crystallogr C, 2008 Sep;64(Pt 9):o478-80.
    PMID: 18758014 DOI: 10.1107/S0108270108023111
    Crystallization of the ionic liquid 3,3'-dimethyl-1,1'-(1,4-phenylenedimethylene)diimidazolium bis(tetrafluoroborate), C(16)H(20)N(4)(2+).2BF(4)(-), (I), from its solution in water has permitted the first single-crystal study of an imidazolium-based ionic liquid having a tetrafluoroborate ion as counter-ion. Despite the expectation that the anion would not participate in nonclassical hydrogen bonding, the ionic liquid features C-H...F hydrogen bonds. The dication lies about a center of inversion. The ionic liquid 3,3'-di-n-butyl-1,1'-(1,4-phenylenedimethylene)diimidazolium bis(trifluoromethanesulfonate), C(22)H(32)N(4)(2+).2CF(3)SO(3)(-), (II), features both C-H...F and C-H...O hydrogen bonds.
  3. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 Aug;58(Pt 8):o477-9.
    PMID: 12154304
    In the title compounds, C(24)H(17)NO(3), (I), and C(43)H(27)NO(5), (II), the dioxine ring is not planar and tends toward a boat conformation. The oxazoline ring adopts a twisted conformation in molecule (I) but is essentially planar in molecule (II). The configuration of the dioxine-oxazoline system is determined by the sp(3) state of the two shared atoms. The phenanthrene moiety is nearly coplanar with the dioxine ring, while the phenyl ring is perpendicular to the attached oxazole ring. The triclinic unit cell of (II) contains two crystallographically independent molecules related by a pseudo-inversion centre.
  4. Fun HK, Hao Q, Wu J, Yang X, Lu L, Wang X, et al.
    Acta Crystallogr C, 2002 Feb;58(Pt 2):m87-8.
    PMID: 11828089
    In the structure of the title compound, [Cu(II)(en)(2)][(EtO)(2)P(S)S](2) (en is ethylenediamine) or [Cu(C(2)H(8)N(2))(2)](C(4)H(10)O(2)PS(2))(2), the Cu atom lies on a center of inversion and is coordinated in a slightly distorted square coordination geometry by four N atoms from two ethylenediamine molecules. The diethyl dithiophosphate moieties, (EtO)(2)P(S)S(-), act as counter-anions.
  5. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 Feb;58(Pt 2):o59-62.
    PMID: 11828108
    In the syn- and anticlinal isomers of the title compound, C(22)H(18)N(2)O(6), the indole moiety is not completely planar, with the pyrrolidine ring being distorted very slightly towards a conformation intermediate between half-chair and envelope. The molecular and packing structures in the crystals of these isomers are stabilized by C-H...O interactions.
  6. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhao BG, Xu JH
    Acta Crystallogr C, 2002 Feb;58(Pt 2):o57-8.
    PMID: 11828107
    In the title compound, C(26)H(22)O(4), the pyranone ring adopts a twisted boat conformation, while the cyclohexane ring is close to an envelope conformation. The dihedral angle between the mean planes of the coumarin and naphthalene systems is 78.8(1) degree. The attached phenyl ring is in an equatorial position with respect to the cyclohexane ring.
  7. Razak IA, Usman A, Fun HK, Yamin BM, Keat GW
    Acta Crystallogr C, 2002 Feb;58(Pt 2):m122-3.
    PMID: 11828100
    In the title compound, [SbCl(2)(C(4)H(8)N(2)S)(2)]Cl, the coordination around the Sb atom can be described as distorted pseudo-octahedral. Both rings of the trimethylenethiourea ligands [alternatively 3,4,5,6-tetrahydropyrimidine-2(1H)-thione] adopt an envelope conformation. The molecules are connected into dimers in the ab plane by two intermolecular hydrogen bonds. The dimers are arranged into infinite one-dimensional chains along the a axis as a result of the Cl(-) ions forming intermolecular hydrogen bonds with three NH groups.
  8. Ng SW, Chantrapromma S, Razak IA, Fun HK
    Acta Crystallogr C, 2001 Mar;57(Pt 3):291-2.
    PMID: 11250582
    The triclinic cell of the title compound contains 2C(12)H(24)N(+) x 2C(6)H(5)O(2)S(-) ion pairs that are linked by four hydrogen bonds [N...O = 2.728 (3) and 2.758 (3) A] across a centre of inversion.
  9. Usman A, Chantrapromma S, Fun HK, Poh BL, Karalai C
    Acta Crystallogr C, 2002 Mar;58(Pt 3):o136-8.
    PMID: 11870305
    In the title 1/2/2 adduct, C(4)H(12)N(2)(2+) x 2C(6)H(3)N(2)O(5)(-) x 2H(2)O, the dication lies on a crystallographic inversion centre and the asymmetric unit also has one anion and one water molecule in general positions. The 2,4-dinitrophenolate anions and the water molecules are linked by two O-H...O and two C-H...O hydrogen bonds to form molecular ribbons, which extend along the b direction. The piperazine dication acts as a donor for bifurcated N-H...O hydrogen bonds with the phenolate O atom and with the O atom of the o-nitro group. Six symmetry-related molecular ribbons are linked to a piperazine dication by N---H.O and C---H.O hydrogen bonds.
  10. Abdul-Razak I, Usman A, Fun HK, Yamin BM, Kasim NA
    Acta Crystallogr C, 2002 Mar;58(Pt 3):m162-4.
    PMID: 11870289
    In the title compound, [Fe(C(17)H(14)P)(2)](2)[Sb(4)Cl(16)] x C(2)H(6)O, the Fe atoms lie on inversion centres and the pairs of cyclopentadienyl rings are consequently in a fully staggered conformation. The centrosymmetric anionic clusters formed by [Sb(4)Cl(16)](4-) are surrounded by the cations and are held together by weak C-H...Cl interactions. These formations stack along the a axis to form columns, and the columns are interconnected by another weak C-H...Cl interaction along the b axis.
  11. Shanmuga Sundara Raj S, Fun HK, Zhang XJ, Tian YP, Xie FX, Ma JL
    Acta Crystallogr C, 2000 Oct;56 (Pt 10):1238-9.
    PMID: 11025310
    In the crystal structure of the title compound, C(11)H(16)N(4)OS, the phenyl ring and the thiosemicarbazone moiety from a dihedral angle of 7.7 (1) degrees. The crystal structure is governed by N-H.O and O-H.S hydrogen bonds leading to the formation of a two-dimensional network.
  12. Shanmuga Sundara Raj S, Yamin BM, Yussof YA, Tarafder MT, Fun HK, Grouse KA
    Acta Crystallogr C, 2000 Oct;56 (Pt 10):1236-7.
    PMID: 11025309
    In the crystal structure of the title compound, C(8)H(10)N(2)S(2), the molecules are linked by N-H.S hydrogen bonds between the imino group and the thione-S atoms to form a chain along the b axis. The dithiocarbazate moiety is rotated by 85.8 (2) degrees with respect to the phenyl ring.
  13. Usman A, Nayar CR, Unnikrishnan PA, Sreeja PB, Prathapachandra Kurup MR, Fun HK
    Acta Crystallogr C, 2002 Dec;58(Pt 12):o724-6.
    PMID: 12466626
    The title molecule, C(13)H(13)N(3)O(3).H(2)O, is in the form of a monohydrated zwitterion. The tetrahydropyridinium ring adopts an envelope conformation and is nearly coplanar with the plane of the imidazoline ring. The water solvate molecule plays an important role as a bridge between zwitterions, forming molecular chains running along the c direction, which are interconnected by N-H.O hydrogen bonds into molecular ribbons. The crystal packing is further stabilized by another N-H.O and one O-H.N hydrogen bond, which interconnect the molecular ribbons.
  14. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 Sep;58(Pt 9):o543-4.
    PMID: 12205382
    In the title compound, C(24)H(17)NO(2)S, the dioxine and thiazoline rings are distorted from planarity towards a half-chair and an envelope conformation, respectively. The configurations of the dioxine ring, the thiazoline ring and the attached phenyl ring are conditioned by the sp(3) state of the two bridgehead C atoms. The phenanthrene system is nearly coplanar with the dioxine ring, while the attached phenyl ring is orthogonal to the thiazoline ring.
  15. Usman A, Razak IA, Chantrapromma S, Fun HK, Sreekanth A, Sivakumar S, et al.
    Acta Crystallogr C, 2002 Sep;58(Pt 9):m461-3.
    PMID: 12205370
    One half of the molecule of the title complex, [Mn(C(14)H(13)N(4)S)(2)], is related to the other half by a twofold axis passing through the Mn atom. This high-spin Mn atom is six-coordinated, in an octahedral geometry, by the azomethine N, the pyridyl N and the thiolate S atom of two planar 1-(pyridin-2-yl)ethanone N(4)-phenylthiosemicarbazone ligands. In the crystal, the molecules are interconnected by N-H.S and C-H.N interactions, forming a three-dimensional network.
  16. Chantrapromma S, Usman A, Fun HK, Poh BL, Karalai C
    Acta Crystallogr C, 2002 Sep;58(Pt 9):o589-90.
    PMID: 12205398
    In the title ternary complex, C(10)H(9)N(2)(+).C(7)H(3)N(2)O(6)(-).C(7)H(4)N(2)O(6), the pyridinium cation adopts the role of the donor in an intermolecular N-H.O hydrogen-bonding interaction with the carboxylate group of the 3,5-dinitrobenzoate anion. The molecules of the ternary complex form molecular ribbons perpendicular to the b direction, which are stabilized by one N-H.O, one O-H.O and five C-H.O intermolecular hydrogen bonds. The ribbons are further interconnected by three intermolecular C-H.O hydrogen bonds into a three-dimensional network.
  17. Usman A, Razak IA, Chantrapromma S, Ghorai SK, Mal D, Fun HK, et al.
    Acta Crystallogr C, 2001 Sep;57(Pt 9):1118-9.
    PMID: 11588390
    The title compound, C(19)H(16)O, crystallizes with two molecules of opposite chirality in the asymmetric unit. In both molecules, the naphthalene and cyclopentanone moieties are individually planar. The two cyclopentane rings adopt envelope conformations, while the cyclohexane ring adopts a boat conformation.
  18. Usman A, Razak IA, Chantrapromma S, Fun HK, Sarkar TK, Basak S, et al.
    Acta Crystallogr C, 2001 Sep;57(Pt 9):1116-7.
    PMID: 11588389
    In the title compound, C(16)H(19)ClN(2)O(4), the pyridine ring is nearly planar, the piperidine ring is non-planar and the cyclohexane ring adopts a screw-boat conformation. The carboxylate group makes a dihedral angle of 80.9 (2) degrees with the least-squares plane through the cyclohexane ring.
  19. Chantrapromma S, Usman A, Fun HK, Poh BL, Karalai C
    Acta Crystallogr C, 2002 Nov;58(Pt 11):o675-7.
    PMID: 12415179
    In the title adduct, 1,3,5,7-tetraazatricyclo[,7)]decane-4-nitrobenzene-1,2-diol-water (1/2/1), C(6)H(12)N(4).2C(6)H(5)NO(4).H(2)O, the hexamethylenetetramine molecule acts as an acceptor of intermolecular O-H.N hydrogen-bonding interactions from the water molecule and the hydroxy groups of one of the two symmetry-independent 4-nitrocatechol molecules. The structure is built from molecular layers which are stabilized by three intermolecular O-H.O, two intermolecular O-H.N and four intermolecular C-H.O hydrogen bonds. The layers are further interconnected by one additional intermolecular O-H.N and two intermolecular C-H.O hydrogen bonds.
  20. Usman A, Razak IA, Chantrapromma S, Fun HK, Philip V, Sreekanth A, et al.
    Acta Crystallogr C, 2002 Nov;58(Pt 11):o652-4.
    PMID: 12415171
    The title compound, C(16)H(17)N(5)S, is in the thione form and crystallizes with two independent molecules in the asymmetric unit. In both molecules, the pentamethyleneimine five-membered ring adopts an envelope conformation, and in one of the molecules this ring shows positional disorder. The thione S and hydrazine N atoms are in the Z configuration with respect to the C-N bond.
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