Displaying publications 21 - 40 of 136 in total

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  1. 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].
  2. 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].
  3. Ishak DH, Tajuddin HA, Abdullah Z, Abd Halim SN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1658.
    PMID: 21837058 DOI: 10.1107/S1600536811022409
    In the title compound, C(10)H(9)N(3)O(3), there is a small twist between the benzene and triazole rings [dihedral angle = 6.32 (7)°]; the carb-oxy-lic acid residue is almost coplanar with the benzene ring to which it is attached [O-C-C-C torsion angle = 1.49 (19)°]. The main deviation from coplanarity of the non-H atoms is found for the hy-droxy group which is almost perpendicular to the remaining atoms [N-C-C-O torsion angle = -75.46 (16)°]. In the crystal, the presence of O-H⋯O (between carboxyl groups) and O-H⋯N (between the hy-droxy group and the triazole ring) hydrogen bonds leads to supra-molecular chains along [03[Formula: see text]]. The chains are connected into sheets via C-H⋯O(hy-droxy) inter-actions.
  4. 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.
  5. Hussen RS, Heidelberg T, Rodzi NZ, Ng SW, Tiekink ER
    PMID: 21754110 DOI: 10.1107/S1600536811008257
    The galactose ring in the title compound, C(21)H(24)O(11), has a chair conformation with the substituted benzene ring occupying an equatorial position. The crystal packing features C-H⋯O inter-actions that lead to the formation of supra-molecular layers in the ab plane.
  6. Heidelberg T, Hussen RS, Rodzi NZ, Ng SW, Tiekink ER
    PMID: 21754109 DOI: 10.1107/S1600536811008099
    The pyran-oside ring in the title compound, C(21)H(24)O(11), has a chair conformation with the substituted benzene ring occupying an equatorial position. The crystal packing is dominated by C-H⋯O inter-actions that lead to the formation of supra-molecular layers in the ab plane.
  7. 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.
  8. Hassan ND, Abdullah Z, Tajuddin HA, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588753 DOI: 10.1107/S1600536810034100
    In the title mol-ecule, C(14)H(9)N(3)O(3), the dihedral angle between the quinoxaline and benzene rings is 77.13 (9)°. The mol-ecule is twisted about the ether-benzene O-C bond, with a C-O-C-C torsion angle of -102.8 (2)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming layers in the ab plane, with one nitro O atom accepting two such inter-actions. The layers stack along the c-axis direction via weak C-H⋯π inter-actions.
  9. Nasir SB, Abdullah Z, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588752 DOI: 10.1107/S1600536810034057
    In the title mol-ecule, C(12)H(10)N(2)O(4), the pyridine and benzene rings are almost orthogonal [dihedral angle = 86.69 (11)°], with the pyridine N atom directed towards the centre of the benzene ring. The -NO(2) [O-N-C-C = -26.1 (3)°] and -OMe [C-O-C-C = 166.5 (2)°] substituents are not coplanar with their respective aromatic rings. In the crystal, supra-molecular layers in the ab plane are formed via C-H⋯π inter-actions involving methyl H atoms and the pyridine and benzene rings. Short N-O⋯π contacts (where the π-system is derived from the pyridine ring) occur between layers in the c-axis direction.
  10. Idris A, Abdullah Z, Ariffin A, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588631 DOI: 10.1107/S1600536810031260
    The quinoxaline system in the title hydrate, C(15)H(13)N(3)·H(2)O, is roughly planar, the r.m.s. deviation for the 18 non-H atoms being 0.188 Å; this conformation features a short intra-molecular C-H⋯N(pyrazine) inter-action. In the crystal, the amine H atom forms an N-H⋯O hydrogen bond to the water mol-ecule, which in turn forms two O-H⋯N hydrogen bonds to the pyrazine N atoms of different organic mol-ecules. These inter-actions lead to supra-molecular arrays in the bc plane that are two mol-ecules thick; additional π-π inter-actions stabilize the layers [ring centroid-centroid distance = 3.5923 (7) Å]. The layers stack along the a-axis direction via C-H⋯π contacts.
  11. 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.
  12. Nasir SB, Abdullah Z, Mainal A, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588653 DOI: 10.1107/S1600536810031946
    In the title compound, C(11)H(10)N(2)O(2), the aromatic rings are almost orthogonal to each other [dihedral angle = 86.97 (8)°], with the benzene ring orientated to face one of the pyrazine N atoms. In the crystal, centrosymmetrically related pairs are connected via pairs of C-H⋯π inter-actions and the dimeric units thus formed pack into undulating layers that stack along the a axis.
  13. Nasir SB, Abdullah Z, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588583 DOI: 10.1107/S1600536810030448
    The pyrimidine and benzene rings in the title compound, C(10)H(8)N(2)O(2), form a dihedral angle of 71.03 (7)°, with the roughly orthogonal benzene ring being folded towards one of the pyrimidine N atoms. In the crystal, pairs of O-H⋯N hydrogen bonds connect mol-ecules related by twofold symmetry into dimeric aggregates. These associate into a supra-molecular chain propagating along the b axis by way of C-H⋯π contacts. The chains are cross-linked by π-π inter-actions that occur between pyrimidine rings [ring centroid-centroid distances = 3.5393 (9) and 3.5697 (9) Å].
  14. Fairuz ZA, Aiyub Z, Abdullah Z, Ng SW, Tiekink ER
    PMID: 21588477 DOI: 10.1107/S1600536810030187
    In the crystal structure of the title complex, [Cu(2)(CH(3)COO)(4)(C(12)H(11)ClN(2))(2)], the complete binuclear mol-ecule is generated by a crystallographic centre of inversion; the four acetate groups each bridge a pair of Cu(II) atoms. The coordination of the metal atom is distorted octa-hedral within a donor set defined by four O atoms, the heterocyclic N atom and the second Cu atom. The pyridine ring is twisted with respect to the benzene ring, forming a dihedral angle of 33.9 (2)°. An intra-molecular N-H⋯O hydrogen bond is present between the amino group and a carboxyl O atom. Inter-molecular inter-actions of the C-H⋯π type link mol-ecules in the crystal structure.
  15. Fairuz ZA, Aiyub Z, Abdullah Z, Ng SW, Tiekink ER
    PMID: 21588497 DOI: 10.1107/S1600536810031168
    The title complex, [Cu(2)(CH(3)COO)(4)(C(13)H(14)N(2))(2)], features a binuclear mol-ecule, which lies about a crystallographic centre of inversion; the four acetate ions each bridge a pair of Cu(II) atoms. The coordination of the metal atom is distorted octa-hedral within a donor set defined by four O atoms, the heterocyclic N atom and the second Cu atom. The pyridine ring is twisted with respect to the tolyl ring and forms a dihedral angle of 35.34 (9)°. A bifurcated N-H⋯(O,O) hydrogen bond is present, linking the amine group to two carboxyl-ate O atoms derived from different acetate ions. In the crystal, C-H⋯π inter-actions link mol-ecules into a supra-molecular array in the bc plane.
  16. Nasir SB, Abdullah Z, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588464 DOI: 10.1107/S160053681003014X
    In the title compound, C(11)H(10)N(2)O(2), the benzene ring faces towards one of the pyrimidine N atoms, and is almost orthogonal to the plane through the pyrimidine ring [dihedral angle = 84.40 (14)°]. In the crystal, the presence of C-H⋯π and π-π [centroid-centroid separation = 3.7658 (18) Å] inter-actions leads to a supra-molecular array in the ac plane. The layers thus formed inter-digitate along the b axis.
  17. Fairuz ZA, Aiyub Z, Abdullah Z, Ng SW, Tiekink ER
    PMID: 21588463 DOI: 10.1107/S1600536810030138
    In the title compound, C(12)H(11)ClN(2), the dihedral angle between the benzene and pyridyl rings is 48.03 (8)°. Twists are also evident in the mol-ecule, in particular about the N(a)-C(b) (a = amine and b = benzene) bond [C-N-C-C = -144.79 (18)°]. In the crystal, inversion dimers linked by pairs of N-H⋯N hydrogen bonds result in the formation of eight-membered {⋯NCNH}(2) synthons [or R(2) (2)(8) loops].
  18. Tayamon S, Ravoof TB, Tahir MI, Crouse KA, Tiekink ER
    PMID: 23476568 DOI: 10.1107/S1600536813003966
    In the title salt, C14H17N2(+)·Cl(-), the central N atom is pyramidal (sum of bond angles = 330.9°) and there is a near orthogonal relationship between the benzene rings [dihedral angle = 89.95 (10)°]. The crystal packing features N-H⋯Cl hydrogen bonds, which lead to a supra-molecular undulating ribbon along the a axis comprising edge-shared eight-membered {⋯HNH⋯Cl}2 synthons. The chains are connected into layers in the ab plane by C-H⋯π inter-actions.
  19. Low ML, Ravoof TB, Tahir MI, Crouse KA, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Feb 1;69(Pt 2):o167-8.
    PMID: 23424455 DOI: 10.1107/S1600536812051537
    In the title compound, C(16)H(15)N(3)S(2), the central C(2)N(2)S(2) residue is planar (r.m.s. deviation = 0.045 Å) and the pyridyl and benzene rings are inclined and approximately coplanar to this plane, respectively [dihedral angles = 72.85 (9) and 10.73 (9)°], so that, overall, the mol-ecule adopts an L-shape. The conformation about each of the N=C [1.290 (3) Å] and C=C [1.340 (3) Å] bonds is E. Supra-molecular chains along [1-10] are stabilized by N-H⋯N(pyridine) hydrogen bonding and these are connected into a double layer that stacks along the c-axis direction by C-H⋯π(pyridine) inter-actions.
  20. Rodrigues A, Olivato PR, Zukerman-Schpector J, Maganhi SH, Reis AK, Tiekink ER
    J Phys Chem A, 2015 Aug 13;119(32):8714-23.
    PMID: 26213179 DOI: 10.1021/acs.jpca.5b04019
    The X-ray single crystal analysis of isomeric ortho, meta, and para bromo-substituted α-methylsulfonyl-α-diethoxyphosphoryl acetophenones showed that this class of compound adopts synclinal (gauche) conformations for both [-P(O)(OEt)2] and [-S(O)2Me] groups, with respect to the carbonyl functional group. The phosphonate, sulfonyl, and carbonyl functional groups are joined through an intramolecular network of attractive interactions, as detected by molecular orbital calculations at the M06-2X/6-31G(d,p) level. These interactions are responsible for the more stable conformations in the gas phase, which also persist in the solid-state structures. The main structural distinction in the title compounds relates to the torsion angle of the aryl group (with respect to the carbonyl group), which gives rise to different interactions in the crystal packing, due to the different positions of the Br atom.
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