Displaying publications 1 - 20 of 136 in total

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  1. Abdullah N, Mohamadin MI, Safwan AP, Tiekink ER
    PMID: 21588481 DOI: 10.1107/S1600536810030436
    The title complex, [Cu(C(7)H(3)N(2)O(6))(2)(C(10)H(8)N(2))(H(2)O)]·C(4)H(8)O, features a penta-coordinate Cu(II) atom bound by two monodentate carboxyl-ate ligands, a bidentate 2,2'-bipyridine mol-ecule [dihedral angle between pyridine rings = 5.0 (2)°] and a water mol-ecule. The resulting N(2)O(3) donor set defines a distorted square-pyramidal geometry with the coordinated water mol-ecule in the apical position. In the crystal, the presence of O-H(w)⋯O(c) (w = water and c = carbon-yl) hydrogen bonding leads to the formation of a supra-molecular chain propagating along the c axis, which associates into a double chain via C-H⋯ O and π-π contacts between pyridyl rings [centroid-centroid distance = 3.527 (3) Å]. The solvent mol-ecules, which are disordered over two orientations in a 0.678 (11):0.322 (11) ratio, occupy voids defined by the complex mol-ecules and are held in place via C-H⋯O inter-actions.
  2. Affan MA, Salam MA, Asaruddin MR, Ng SW, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2012 Jul 1;68(Pt 7):m909-10.
    PMID: 22807748 DOI: 10.1107/S1600536812025937
    Two independent mol-ecules comprise the asymmetric unit in the title compound, [Sn(C₄H₉)(C₁₄H₁₉N₄S)Cl₂]. In each mol-ecule, the Sn(IV) atom exists within a distorted octa-hedral geometry defined by the N,N',S-tridentate mono-deprotonated Schiff base ligand, two mutually trans Cl atoms, and the α-C atom of the n-butyl group; the latter is trans to the azo-N atom. The greatest distortion from the ideal geometry is found in the nominally trans angle formed by the S and pyridyl-N atoms at Sn [151.72 (7) and 152.04 (7)°, respectively]. In the crystal, mol-ecules are consolidated into a three-dimensional architecture by a combination of N-H⋯Cl, C-H⋯π and π-π inter-actions [inter-centroid distances = 3.6718 (19) and 3.675 (2) Å].
  3. Aiyub Z, Badaruddin E, Abdullah Z, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588567 DOI: 10.1107/S1600536810034033
    In the centrosymmetric title mol-ecule, [Cu(2)(CH(3)COO)(4)(C(6)H(9)N(3))(2)], each of the four acetate groups bridges a pair of Cu(II) atoms [Cu-Cu = 2.6540 (4) Å]. The distorted octa-hedral geometry of the metal atom is completed by an N-donor atom of the N-ethyl-pyrimidin-2-amine ligand: an intra-molecular N-H⋯O hydrogen links its N-H group to an acetate carboxyl-ate O atom. In the crystal, C-H⋯O inter-actions link the mol-ecules into a supra-molecular chain along the b axis.
  4. Akhmad Aznan AM, Abdullah Z, Tiekink ER
    PMID: 25161500 DOI: 10.1107/S1600536814011532
    The 1:1 co-crystallization of 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO) with 4-nitro-benzoic acid in ethanol-water (3/1) gave the salt dihydrate C6H13N2 (+)·C7H4NO4 (-)·2H2O, (1), whereas from methanol, the salt C6H14N2 (2+)·2C7H4NO4 (-), (2), was isolated. In (1), the cation and anion are linked by a strong N-H⋯O hydrogen bond, and the carboxyl-ate anion is close to planar [dihedral angle between terminal residues = 6.83 (9)°]. In (2), a three-ion aggregate is assembled by two N-H⋯O hydrogen bonds, and the carboxyl-ate anions are again close to planar [dihedral angles between terminal residues = 1.7 (3) and 5.9 (3)°]. Through the inter-vention of solvent water mol-ecules, which self-assemble into helical supra-molecular chains along the b axis, the three-dimensional architecture in (1) is stabilized by water-DABCO O-H⋯N and water-carboxyl-ate O-H⋯O hydrogen bonds, with additional stability afforded by C-H⋯O inter-actions. The global crystal structure comprises alternating layers of water mol-ecules and ion pairs stacked along the c axis. In the crystal of (2), the three-ion aggregates are assembled into a three-dimensional architecture by a large number of methyl-ene-carboxyl-ate/nitro C-H⋯O inter-actions as well as π-π contacts between inversion-related benzene rings [inter-centroid distances = 3.5644 (16) and 3.6527 (16) Å]. The cations and anions assemble into alternating layers along the c axis.
  5. Al-Mehana WN, Shakir RM, Yahya R, Abd Halim SN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1659.
    PMID: 21837059 DOI: 10.1107/S1600536811022410
    The complete mol-ecule in the title compound, C(22)H(20)N(2)O(4), is generated by the application of an inversion centre. With the exception of the terminal acetyl-ene groups [C-O-C-C = -78.02 (17)°], the remaining atoms constituting the mol-ecule are essentially coplanar. The configuration around the C=N bond [1.282 (2) Å] is E. The formation of supra-molecular chains mediated by C-H⋯O inter-actions, occurring between methyl-ene H and meth-oxy O atoms, is the most notable feature of the crystal packing.
  6. Al-Mohammed NN, Shakir RM, Alias Y, Abdullah Z, Abd Halim SN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1838.
    PMID: 21837205 DOI: 10.1107/S1600536811024664
    The title mol-ecule, C(26)H(30)O(9)S(3), adopts an extended conformation whereby two approximately parallel benzene rings [dihedral angle = 8.32 (10)°] are orientated in opposite directions along the pseudo-threefold axis through the central quaternary C atom, while a third ring occupies a position mid-way and face-on to these rings [dihedral angles = 82.28 (10) and 78.81 (7)°]. The crystal packing is dominated by C-H⋯O contacts and π-π inter-actions [ring centroid distance = 3.6902 (12) Å].
  7. Arman HD, Kaulgud T, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Apr 1;70(Pt 4):o402-3.
    PMID: 24826120 DOI: 10.1107/S1600536814004838
    The sulfa-thia-zole mol-ecule in the title 1:1 co-crystal, C9H9N3O2S2·C18H12N6, adopts an approximate L-shape [dihedral angle between the five- and six-membered rings = 86.20 (9)°] and features an intra-molecular hypervalent S⋯O inter-action [2.8666 (15) Å]. Overall, the triazine mol-ecule has the shape of a disk as the pendant pyridine rings are relatively close to coplanar with the central ring [dihedral angles = 18.35 (9), 6.12 (9) and 4.67 (9)°]. In the crystal packing, a linear supra-molecular chain aligned along [01-1] is formed as a result of amino-pyridyl N-H⋯N hydrogen bonding with syn-disposed pyridyl mol-ecules of one triazine, and amine-pyridyl N-H⋯N hydrogen bonding with the third pydridyl ring of a second triazine mol-ecule. A three-dimensional architecture arises as the chains are connected by C-H⋯O inter-actions.
  8. Arman HD, Tiekink ER
    PMID: 24427074 DOI: 10.1107/S160053681302271X
    The asymmetric unit of title co-crystal, C10H8N2·2C7H7NO2, comprises a centrosymmetric 4,4'-bi-pyridine mol-ecule, and a 2-amino-benzoic acid mol-ecule in a general position. The latter is effectively planar [C-C-C-O torsion angle = 5.0 (3)°] owing to an intra-molecular N-H⋯O(carbon-yl) hydrogen bond. Three-mol-ecule aggregates are formed via O-H⋯N(pyrid-yl) hydrogen bonds and these are connected into supra-molecular layers in the bc plane by N-H⋯O(carbon-yl) hydrogen bonds and π-π inter-actions between pyridyl and benzene rings [inter-centroid distance = 3.634 (2) Å]. Layers are connected along the a axis by weak π-π inter-actions between benzene rings [3.964 (2) Å].
  9. Arman HD, Kaulgud T, Tiekink ER
    PMID: 24427073 DOI: 10.1107/S1600536813022691
    The asymmetric unit of the title co-crystal, 2C14H13N2 (+)·C10H4O8 (2-)·2C14H12N2·C10H6O8, comprises a 2,9-dimethyl-1,10-phenanthrolin-1-ium cation (Me2PhenH(+)) and a 2,9-dimethyl-1,10-phenanthroline mol-ecule (Me2Phen), each in a general position, and half each of a 2,5-di-carb-oxy-benzene-1,4-di-carboxyl-ate dianion (LH2 (2-)) and a benzene-1,2,4,5-tetra-carb-oxy-lic acid mol-ecule (LH4), each being disposed about a centre of inversion. Small twists are evident in the dianion [the C-C-C-O torsion angles are 168.41 (18) and 16.2 (3)°], whereas a major twist is found for one carb-oxy-lic acid group in the neutral mol-ecule [C-C-C-O = 66.3 (2) and 18.2 (3)°]. The most prominent feature of the crystal packing is the formation of linear supra-molecular chains along [001] mediated by charge-assisted O-H⋯O(-) hydrogen bonding between alternating LH4 and LH2 (2-). These are connected to the Me2PhenH(+) and Me2Phen species by N-H⋯O and O-H⋯N hydrogen bonds, respectively. A three-dimensional architecture is formed by C-H⋯O and π-π inter-actions [inter-centroid distance = 3.5337 (17) Å].
  10. Arman HD, Tiekink ER
    PMID: 24427071 DOI: 10.1107/S1600536813022563
    The asymmetric unit of the title co-crystal, C10H6O8·2C8H10N4O2, comprises a centrosymmetric benzene-1,2,4,5-tetra-carb-oxy-lic acid (LH4) mol-ecule and a mol-ecule of caffeine in a general position. LH4 is nonplanar, with the dihedral angles between the ring and pendent carb-oxy-lic acid groups being 44.22 (7) and 49.74 (7)°. By contrast, the caffeine mol-ecule is planar (r.m.s. deviation = 0.040 Å). Supra-molecular layers parallel to (-1-10) are sustained by carb-oxy-lic acid O-H⋯O(carbon-yl) and O-H⋯N(imidazole) hydrogen bonds, as well as by meth-yl-carbonyl C-H⋯O inter-actions. These stack via π-π inter-actions between the benzene and imidazole rings [inter-centroid distance = 3.4503 (10) Å].
  11. Arman HD, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Oct 5;69(Pt 11):o1616.
    PMID: 24454067 DOI: 10.1107/S1600536813027128
    The asymmetric unit of the title co-crystal, C12H12N2·2C7H7NO2, comprises a centrosymmetric 4-[2-(pyridin-4-yl)eth-yl]pyridine mol-ecule and a 2-amino-benzoic acid mol-ecule in a general position. The acid has a small twist between the carb-oxy-lic acid residue and the ring [dihedral angle = 7.13 (6)°] despite the presence of an intra-molecular N-H⋯O(carbon-yl) hydrogen bond. Three-mol-ecule aggregates are formed via O-H⋯N(pyrid-yl) hydrogen bonds, and these are connected into supra-molecular layers in the bc plane by N-H⋯O(carbon-yl) hydrogen bonds and π-π inter-actions between pyridine and benzene rings [inter-centroid distance = 3.6332 (9) Å]. Layers are connected along the a axis by weak π-π inter-actions between benzene rings [3.9577 (10) Å].
  12. Arman HD, Kaulgud T, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Oct 5;69(Pt 11):o1615.
    PMID: 24454066 DOI: 10.1107/S1600536813027037
    The asymmetric unit of the title co-crystal, C12H14N4O2S·0.5C6H12N2, comprises the sulfonamide mol-ecule and half a mol-ecule of 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO), the latter being disposed about a crystallographic twofold rotation axis. In the sulfonamide mol-ecule, the aromatic rings are almost perpendicular to one another [dihedral angle = 75.01 (8)°]. In the crystal, mol-ecules are connected into a three-mol-ecule aggregate via amide-DABCO N-H⋯N hydrogen bonds, and these are connected into a three-dimensional architecture via amino-DABCO N-H⋯O and amino-pyrimidine N-H⋯N hydrogen bonds.
  13. Arman HD, Miller T, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Oct 2;69(Pt 11):o1606.
    PMID: 24454058 DOI: 10.1107/S1600536813026810
    The asymmetric unit of the title salt, C12H14N2 (2+)·2C7H3N2O6 (-), comprises half a 4-[2-(pyridin-1-ium-4-yl)eth-yl]pyridin-1-ium dication, being disposed about a centre of inversion, and a 2,6-di-nitro-benzoate anion, in a general position. In the anion, the carboxyl-ate group is inclined to the benzene ring [dihedral angle = 85.45 (9)°], whereas near-coplanar and twisted arrangements are found for the nitro groups [O-N-C-C torsion angles = 179.80 (14) and 20.2 (2)°]. In the crystal, three-component aggregates sustained by charge-assisted N(+)-H⋯O(-) hydrogen bonds are found and these are consolidated into a three-dimensional architecture by C-H⋯O and π-π [inter-centroid distances = 3.6796 (14) and 3.7064 (14) Å] inter-actions.
  14. Arman HD, Poplaukhin P, Tiekink ER
    PMID: 24426981 DOI: 10.1107/S1600536813021569
    The asymmetric unit of title salt co-crystal, [K(C9H11N2S2)(C12H24O6)], comprises a K(+) cation, an (-)S2CN(Et)py anion and a 18-crown-6 mol-ecule. Substantial delocalization of π-electron density is evident in the di-thio-carbamate anion, as indicated by the equivalent C-S bond lengths. The K(+) cation sits within an O6S2 donor set lying 0.7506 (6) Å out of the least-squares plane through the six O atoms (r.m.s. deviation = 0.1766 Å) of the 18-crown-6 mol-ecule with the two S atoms being on one side of this plane. Supra-molecular layers in the bc plane, sustained by C-H⋯O and C-H⋯π inter-actions, feature in the crystal packing.
  15. Asiri AM, Faidallah HM, Sobahi TR, Ng SW, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Nov 1;71(Pt 11):e4.
    PMID: 26617187 DOI: 10.1107/S2056989015019271
    In the paper by Asiri et al. [Acta Cryst. (2012), E68, o1154], the title and the chemical name of one of the reagents used in the synthesis are corrected.[This corrects the article DOI: 10.1107/S1600536812011579.].
  16. Aziz NA, Yusof EN, Ravoof TB, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Apr 1;71(Pt 4):o233-4.
    PMID: 26029430 DOI: 10.1107/S2056989015004764
    In the title compound, C15H16N2S2, the central CN2S2 residue is almost planar (r.m.s. deviation = 0.0354 Å) and forms dihedral angles of 56.02 (4) and 75.52 (4)° with the phenyl and tolyl rings, respectively; the dihedral angle between the aromatic rings is 81.72 (5)°. The conformation about the N-N bond is gauche [C-N-N-C = -117.48 (15)°]. Overall, the mol-ecule has the shape of the letter L. In the crystal packing, supra-molecular chains along the a axis are formed by N-H⋯S(thione) hydrogen bonds whereby the thione S atom accepts two such bonds. The hydrogen bonding leads to alternating edge-shared eight-membered {⋯HNCS}2 and 10-membered {⋯HNNH⋯S}2 synthons. The chains are connected into layers by phen-yl-tolyl C-H⋯π inter-actions; the layers stack along the c axis with no specific inter-actions between them.
  17. Aznan AM, Abdullah Z, Lee VS, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Aug 1;70(Pt 8):58-61.
    PMID: 25249854 DOI: 10.1107/S1600536814012227
    The title compound, C12H11N3O2, is a second monoclinic polymorph (P21, with Z' = 4) of the previously reported monoclinic (P21/c, with Z' = 2) form [Akhmad Aznan et al. (2010 ▶). Acta Cryst. E66, o2400]. Four independent mol-ecules comprise the asymmetric unit, which have the common features of a syn disposition of the pyridine N atom and the toluene ring, and an intra-molecular amine-nitro N-H⋯O hydrogen bond. The differences between mol-ecules relate to the dihedral angles between the rings which range from 2.92 (19) to 26.24 (19)°. The geometry-optimized structure [B3LYP level of theory and 6-311 g+(d,p) basis set] has the same features except that the entire mol-ecule is planar. In the crystal, the three-dimensional architecture is consolidated by a combination of C-H⋯O, C-H⋯π, nitro-N-O⋯π and π-π inter-actions [inter-centroid distances = 3.649 (2)-3.916 (2) Å].
  18. Aznan Akhmad MA, Abdullah Z, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588732 DOI: 10.1107/S1600536810033040
    Two independent mol-ecules comprise the asymmetric unit of the title compound, C(12)H(11)N(3)O(2). These differ in terms of the relative orientations of the benzene rings as seen in the respective dihedral angles formed between the pyridine and benzene rings [17.42 (16) and 34.64 (16)°]. Both mol-ecules are twisted about the amine-tolyl N-C bonds [respective torsion angles = 22.3 (5) and 35.9 (5)°] but only about the amine-pyridine N-C bond in the first independent mol-ecule [respective torsion angles = -11.7 (5) and 0.8 (5)°]. Intra-molecular N-H⋯O hydrogen bonds preclude the amine H atoms from forming significant inter-molecular inter-actions. The crystal packing features inter-molecular C-H⋯O and C-H⋯π and π-π [centroid-centroid distance: pyridine-benzene = 3.6442 (19) Å and pyridine-pyridine = 3.722 (2) Å] contacts.
  19. Badaruddin E, Aiyub Z, Abdullah Z, Ng SW, Tiekink ER
    PMID: 21588767 DOI: 10.1107/S1600536810033301
    Two independent mol-ecules comprise the asymmetric unit in the title compound, C(11)H(11)N(3). These differ in terms of the relative orientations of the aromatic rings: the first is somewhat twisted, while the second is approximately planar [dihedral angles between the pyrimidine and phenyl rings = 39.00 (8) and 4.59 (11)°]. The mol-ecules also form distinct patterns in their hydrogen bonding. The first independent mol-ecule forms centrosymmetric dimers featuring an eight-membered {HNCN}(2) synthon. The second independent mol-ecule forms an N-H⋯N hydrogen bond with the other pyrimidine N atom of the first mol-ecule. Thereby, tetra-meric aggregates are formed. These associate via C-H⋯N and C-H⋯π inter-actions, consolidating the crystal packing.
  20. Basu Baul TS, Longkumer I, Ng SW, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Nov 6;69(Pt 12):m633-4.
    PMID: 24454154 DOI: 10.1107/S1600536813029693
    The title dimethyl sulfoxide solvate, [Hg2(C12H9ClN2)I2]·C2H6OS, features tetra-hedrally and linearly coordinated Hg(II) atoms. The distorted tetrahedral coordination sphere is defined by chelating N atoms that define an acute angle [69.6 (3)°] and two I atoms that form a wide angle [142.80 (4)°]. The linearly coordinated Hg(II) atom [177.0 (4)°] exists with a donor set defined by C and Cl atoms. Secondary inter-actions are apparent in the crystal packing with the tetra-hedrally and linearly coordinated Hg(II) atoms expanding their coordination environments by forming weak Hg⋯I [3.772 (7) Å] and Hg⋯O [2.921 (12) Å] inter-actions, respectively. Mercury-containing mol-ecules stack along the a axis, are connected by π-π inter-actions [inter-centroid distance between pyridine and benzene rings = 3.772 (7) Å] and define channels in which the dimethyl sulfoxide mol-ecules reside. The latter are connected by the aforementioned Hg⋯O inter-actions as well as C-H⋯I and C-H⋯O inter-actions, resulting in a three-dimensional architecture.
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