Displaying all 15 publications

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  1. Kia R, Fun HK
    PMID: 21581793 DOI: 10.1107/S1600536809001044
    In the title compound, [ReBr(C(16)H(12)Cl(2)F(2)N(2))(CO)(3)], the Re atom is in a slightly distorted octa-hedral coordination environment with the three carbonyl ligands having a fac configuration. The diimine ligand is equatorial and is bonded to the Re centre in an N,N'-bidentate chelating fashion, with a bite angle of 77.7 (2)°. The dihedral angle between the two benzene rings is 88.7 (6)°. In the crystal structure, there are F⋯O [2.856 (9) Å], Cl⋯C [3.150 (8) Å] and O⋯C [2.984 (10) Å] contacts which are shorter than the sum of the van der Waals radii for these atoms. In addition, symmetry-related mol-ecules are linked via inter-molecular C-H⋯O, C-H⋯Br and the F⋯O inter-actions into one-dimensional chains extending along the a axis. The crystal structure is further stabilized by inter-molecular π-π inter-actions [centroid-centroid distance = 3.571 (5) Å].
  2. Kia R, Fun HK
    PMID: 21581029 DOI: 10.1107/S1600536808033916
    The asymmetric unit of the title Schiff base compound, C(16)H(12)Cl(2)F(2)N(2), contains one half of the centrosymmetric mol-ecule. Mol-ecules related by translation along the a axis form stacks with short inter-molecular C⋯C distances of 3.429 (3) Å. The crystal packing also exhibits short inter-molecular Cl⋯F contacts of 3.087 (1) Å.
  3. Fun HK, Kia R
    PMID: 21201086 DOI: 10.1107/S1600536808027608
    The mol-ecule of the title Schiff base compound, C(16)H(14)I(2)N(2), lies across a crystallographic inversion centre. An intra-molecular C-H⋯I hydrogen bond forms a five-membered ring, producing an S(5) ring motif. The C=N bond is coplanar with the benzene ring and adopts a trans configuration. Within the mol-ecule, the planar units are parallel, but extend in opposite directions from the dimethyl-ene bridge. An inter-esting feature of the crystal structure is the short I⋯N [3.2096 (15) Å] inter-action, which is significantly shorter than the sum of the van der Waals radii of these atoms. In the crystal structure, mol-ecules are linked into one-dimensional extended chains along the c axis and also into one-dimensional extended chains along the b axis through short inter-molecular I⋯N inter-actions, forming two-dimensional networks parallel to the bc plane.
  4. Kia R, Fun HK
    PMID: 21201050 DOI: 10.1107/S1600536808029966
    In the title compound, [Re(CF(3)COO)(CH(3)CN)(2)(CO)(3)], the Re atom has a distorted octa-hedral configuration. The two acetonitrile mol-ecules and two of the three carbonyl groups occupy the equatorial plane of the complex, with the third carbonyl ligand and the trifluoroacetato ligand in the axial positions. The three carbonyl ligands are arranged in a fac configuration around the Re atom. The CF(3) segment of the trifluoroacetato ligand shows rotational disorder and the refined site-occupancy factors of the disordered parts are ca 0.5/0.5. The crystal structure is stabilized by C-H⋯O and C-H⋯F hydrogen bonds.
  5. Fun HK, Kia R
    PMID: 21201579 DOI: 10.1107/S1600536808024306
    In the title compound, [Ni(C(22)H(26)N(2)O(2))]·CH(3)OH·CHCl(3), the Ni(II) ion is in a slightly distorted square-planar geometry involving an N(2)O(2) atom set of the tetra-dentate Schiff base ligand. The asymmetric unit contains one mol-ecule of the complex and one mol-ecule each of chloro-form and methanol. The methanol mol-ecule is hydrogen bonded to the phenolate O atoms. In the crystal structure, short inter-molecular distances between the centroids of six-membered chelate rings [3.7002 (9) Å] indicate the presence of π-π inter-actions, which link the mol-ecules into stacks along the a axis. In addition, there are Ni⋯Ni distances which are shorter than the sum of the van der Waals radii of two Ni atoms. The crystal structure is further stabilized by inter-molecular O-H⋯O and C-H⋯O hydrogen bonds, and weak inter-molecular C-H⋯π inter-actions linking mol-ecules into extended one-dimensional chains along the c axis.
  6. Fun HK, Kia R
    PMID: 21201124 DOI: 10.1107/S1600536808028419
    The mol-ecule of the title centrosymmetric Schiff base compound, C(16)H(12)Cl(2)F(2)N(2), adopts an E configuration with respect to the azomethine C=N bond. The imino groups are coplanar with the aromatic rings. Within the mol-ecule, the planar units are parallel, but extend in opposite directions from the dimethyl-ene bridge. An inter-esting feature of the crystal structure is the short inter-molecular Cl⋯F [3.1747 (5) Å] inter-actions, which are shorter than the sum of the van der Waals radii of these atoms. These inter-actions link neighbouring mol-ecules along the b axis. The crystal structure is further stabilized by π-π inter-actions, with a centroid-centroid distance of 3.5244 (4) Å.
  7. Fun HK, Kia R
    PMID: 21201652 DOI: 10.1107/S1600536808023738
    In the crystal structure, the title Schiff base compound, C(21)H(26)N(2)O(4), has twofold rotation symmetry. The imino group is coplanar with the aromatic ring. An intra-molecular O-H⋯N hydrogen bond forms a six- membered ring, producing an S(6) ring motif. The two benzene rings are almost perpendicular to each other, making a dihedral angle of 85.00 (2)°. The meth-oxy group is approximately coplanar with the benzene ring, with a C-O-C-C torsion angle of 2.34 (12)°. Neighbouring mol-ecules are linked together by weak inter-molecular C-H⋯O hydrogen bonds and a C-H⋯π inter-action, forming a sheet parallel to the ab plane. The mol-ecules also adopt a zigzag arrangement along the c axis.
  8. Fun HK, Kia R
    PMID: 21201706 DOI: 10.1107/S1600536808024926
    The mol-ecule of the title Schiff base compound, C(18)H(12)Cl(2)F(6)N(2), adopts an E configuration with respect to the azomethine C=N bond. Intra-molecular C-H⋯F (× 2) and C-H⋯Cl (× 2) hydrogen bonds generate S(5) ring motifs. The imino group is coplanar with the aromatic ring. Within the mol-ecule, the planar units are parallel, but extend in opposite directions from the methyl-ene bridge, as indicated by the dihedral angle between the two benzene rings of 3.74 (6)°. The inter-esting features of the crystal structure are weak inter-molecular Cl⋯N and F⋯F inter-actions, with distances of 2.9192 (11) and 3.2714 (10) Å, respectively, which are shorter than the sum of the van der Waals radii of the relevent atoms. These inter-actions link neighbouring mol-ecules into dimers which are stacked down the b axis.
  9. Fun HK, Kia R
    PMID: 21201147 DOI: 10.1107/S1600536808029000
    The mol-ecule of the title Schiff base compound, C(16)H(12)Br(2)F(2)N(2), lies across a crystallographic inversion centre and adopts an E configuration with respect to the azomethine C=N bonds. The imino groups are coplanar with the aromatic rings. Within the mol-ecule, the planar units are parallel, but extend in opposite directions from the dimethyl-ene bridge. An inter-esting feature of the crystal structure is the short inter-molecular Br⋯F inter-actions [3.2347 (16) Å, which is shorter than the sum of the van der Waals radii of these atoms]. These inter-actions link neighbouring mol-ecules along the c axis. The crystal structure is further stabilized by inter-molecular C-H⋯N hydrogen bonds.
  10. Fun HK, Kia R
    PMID: 21201812 DOI: 10.1107/S1600536808027232
    The mol-ecule of the title compound, C(11)H(12)ClF(3)N(2)·H(2)O, is a substituted hexa-hydro-pyrimidine. There are two crystallographically independent mol-ecules (A and B) and two water mol-ecules in the asymmetric unit of the title compound. Inter-molecular C-H⋯Cl (× 2), C-H⋯F, and C-H⋯N (× 2) hydrogen bonds generate S(5) ring motifs. The dihedral angle between the two benzene rings is 8.17 (11)°. The F atoms in mol-ecule B are disordered over four positions with refined site-occupancies of ca 0.35/0.19/0.29/0.17 for the four components. In the crystal structure, mol-ecules are arranged into one-dimensional extended chains along the c axis and are further stacked along the a axis by directed four-membered O-H⋯O-H inter-actions, forming two-dimensional networks parallel to the ac plane. The short distances between the centroids of the benzene rings (3.8002-3.8327 Å) indicate the existence of π-π inter-actions. In addition, the crystal structure is further stabilized by N-H⋯O, O-H⋯N (× 4), N-H⋯Cl and C-H⋯O (× 2) hydrogen-bonding inter-actions.
  11. Fun HK, Kia R
    PMID: 21203060 DOI: 10.1107/S1600536808023362
    In the title complex, [Ni(C(20)H(22)N(2)O(4))]·0.5H(2)O, the Ni(II) ion is in a slightly distorted square-planar geometry involving an N(2)O(2) atom set of the tetra-dentate Schiff base ligand. The asymmetric unit contains one mol-ecule of the complex and half a water solvent mol-ecule. The solvent water mol-ecule lies on a crystallographic twofold rotation axis. An inter-molecular O-H⋯O hydrogen bond forms an R(2) (1)(4) ring motif involving a bifurcated hydrogen bond to the phenolate O atoms of the complex. In the crystal structure, mol-ecules are linked by π-π stacking inter-actions, with centroid-centroid distances in the range 3.5310 (11)-3.7905 (12) Å, forming extended chains along the b axis. In addition, there are Ni⋯Ni and Ni⋯N inter-actions [3.4404 (4)-4.1588 (4) and 3.383 (2)-3.756 (2) Å, respectively] which are shorter than the sum of the van der Waals radii of the relevant atoms. Further stabilization of the crystal structure is attained by weak inter-molecular C-H⋯O and C-H⋯π inter-actions.
  12. Fun HK, Kia R
    Acta Crystallogr Sect E Struct Rep Online, 2008 Oct 18;64(Pt 11):o2131.
    PMID: 21580993 DOI: 10.1107/S1600536808033588
    The mol-ecule of the title Schiff base compound, C(16)H(12)Cl(4)N(2), lies across an inversion centre and adopts an E configuration with respect to the azomethine C=N bond. The imine groups are coplanar with the aromatic rings. Within the mol-ecule, the planar units are parallel but extend in opposite directions from the dimethyl-ene bridge. In the crystal structure, mol-ecules are linked together by inter-molecular C-H⋯Cl hydrogen bonds along the a axis.
  13. Fun HK, Kia R
    Acta Crystallogr Sect E Struct Rep Online, 2008 Jul 31;64(Pt 8):o1617-8.
    PMID: 21203308 DOI: 10.1107/S1600536808023350
    The title compound, C(14)H(8)F(2)O(2), is a substituted benzil with an s-trans conformation of the dicarbonyl unit. This conformation is also shown by the O-C-C-O torsion angle of -110.65 (12)°. An unusual feature of the structure is the length, 1.536 (2) Å, of the central C-C bond connecting the carbonyl units, which is significantly longer than a normal Csp(2)-Csp(2) single bond. This is probably the result of decreasing the unfavourable vicinal dipole-dipole inter-actions by increasing the distance between the two electronegative O atoms [O⋯O = 3.1867 (12) Å] and allowing orbital overlap of the dione with the π system of the benzene rings. The dihedral angle between the aromatic rings is 64.74 (5)°. In the crystal structure, neighbouring mol-ecules are linked together by weak inter-molecular C-H⋯O (× 2) hydrogen bonds. In addition, the crystal structure is further stabilized by inter-molecular π-π inter-actions with centroid-centroid distances in the range 3.6416 (6)-3.7150 (7) Å.
  14. Fun HK, Kia R
    Acta Crystallogr Sect E Struct Rep Online, 2008 Jul 31;64(Pt 8):o1615-6.
    PMID: 21203307 DOI: 10.1107/S1600536808023386
    In the mol-ecule of the title compound, C(16)H(14)O(2), a substituted benzil, the dicarbonyl unit has an s-trans conformation. This conformation is substanti-ated by the O-C-C-O torsion angle of 108.16 (15)°. The dihedral angle between the two aromatic rings is 72.00 (6)°. In the crystal structure, neighbouring mol-ecules are linked together by weak inter-molecular C-H⋯O hydrogen bonds and weak inter-molecular C-H⋯π inter-actions. In addition, the crystal structure is further stabilized by inter-molecular π-π inter-actions with centroid-centroid distances in the range 3.6000 (8)-3.8341 (8) Å.
  15. Yeap CS, Kia R, Fun HK
    PMID: 21201825 DOI: 10.1107/S1600536808027220
    The title Schiff base compound, C(23)H(30)N(2)O(2), has crystallographic twofold rotation symmetry. An intra-molecular O-H⋯N hydrogen bond forms a six-membered ring, producing an S(6) ring motif. The imino group is coplanar with the benzene ring. The two benzene rings are almost perpendicular to each other, making a dihedral angle of 87.38 (4)°. In the crystal structure, neighbouring mol-ecules are linked along the c axis by weak inter-molecular C-H⋯O hydrogen bonds and are further packed into columns along the b axis, forming sheets which are parallel to the bc plane.
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