Department of Chemistry

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    5,7-Bis(benz-yloxy)-2-phenyl-4H-chromen-4-one
    (International Union of Crystallography, 2008-11-29) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Jaswant, Buckle; Sulochana, Nagarajan
    In the title compound, C29H22O4, the chromene ring is almost planar with a small puckering [0.143 (2) Å]. The crystal structure is stabilized by C - H⋯O and C - H⋯π inter-actions. Edge-to-face (centroid-centroid distances of 3.894 and 3.673 Å) and face-to-face (centroid-centroid distance of 3.460 Å) π-π-ring electron inter-actions are also observed. © 2008.
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    2-Phenyl-5,7-bis(prop-2-en-1-yloxy)-4H-chromen-4-one
    (International Union of Crystallography, 2008-12-03) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
    In the title compound, C21H18O4, tthe dihedral angle between the chromene ring system and the pendant phenyl ring is 6.1 (1)°. The crystal structure is stabilized by an intermolecular C - H⋯O and C - H⋯π inter-actions.
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    Dimethyl 2,2′-[(4-oxo-2-phenyl-4H-chromene-5,7-diyl)dioxy]diacetate: A more densely packed polymorph
    (International Union of Crystallography, 2009-01-14) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Jaswant, Buckle; Sulochana, Nagarajan
    The title mol-ecule, C21H18O8, crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o314-o315]. The mol-ecules of both polymorphs differ by the conformation of the oxomethyl-acetate groups. The title mol-ecules are rather planar compared to the mol-ecules of the other polymorph. In the title mol-ecule, one of the oxomethyl-acetate groups is disordered (occupancies of 0.6058/0.3942). The structures of both polymorphs are stabilized by C - H⋯O and C - H⋯π inter-actions. Due to the planarity of the title mol-ecules and similar inter-molecular inter-actions, the title mol-ecules are more densely packed than those of the other polymorph.
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    5,7-Dimeth-oxy-2-phenyl-4H-chromen-4-one
    (International Union of Crystallography, 2009-02-11) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
    The asymmetric unit of the title compound, C17H 14O4, contains two independent mol-ecules which differ in the relative orientations of the phenyl rings with repect to the essentially planar [maximum deviations of 0.029 (2) and 0.050 (2) Å in the two mol-ecules] chromene fused-ring system, forming dihedral angles of 10.3 (5) and 30.86 (5)° in the two mol-ecules. The crystal structure is stabilized by weak C - H⋯O and C - -H⋯π inter-actions, and π-π stacking inter-actions.
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    6,8-Dibromo-5-hydr-oxy-4-oxo-2-phenyl-4H-chromen-7-yl acetate
    (International Union of Crystallography, 2009-02-21) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
    In the title compound, C17H10Br2O5, the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) Å]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)°. The crystal structure is stabilized by intermolecular C - H⋯O inter-actions and an intramolecular O - H⋯O hydrogen bond also occurs.
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    1-Benzoyl-3,3-bis(propan-2-yl)thiourea
    (International Union of Crystallography, 2010-07-24) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    Two independent thiourea derivatives comprise the asymmetric unit of the title compound, C14H20N2OS. The major difference between the mol-ecules relates to a twist in the relative orientation of the benzene rings [torsion angles = 4.5 (2) and -19.9 (2)° for the two independent mol-ecules]. The thio-carbonyl and carbonyl groups lie to opposite sides of the mol-ecule as there are twists about the central N - S bond [torsion angles = 83.90 (15) and 81.77 (15)°]. Supra-molecular chains extending parallel to [101] with a stepped topology and mediated by N - H⋯O hydrogen bonding feature in the crystal structure. C - H⋯O and C - H⋯π inter-actions are also present.
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    3-Benzoyl-1,1-dibenzylthiourea
    (International Union of Crystallography, 2010-09-18) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    Two independent thio-urea molecules comprise the asymmetric unit of the title compound, C22H20N2OS. The central N-C(=S)N(H)C(=O) atoms in each molecule are virtually superimposable and each is twisted [C - N - C - S torsion angles = 121.3 (3) and -62.3 (4)°]. The molecules differ only in terms of the relative orientations of the benzyl benzene rings [major difference between the C - N - C - C torsion angles of -146.6 (3) and -132.9 (3)°]. The presence of N - H⋯S hydrogen bonding leads to the formation of supra-molecular chains along the a axis. These are consolidated in the crystal packing by C - H⋯O interactions. The crystal was found to be a combined non-merohedral and racemic twin (twin law 1̄00/01̄0/001), with the fractional contribution of the minor components being approximately 9 and 28%.
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    1-Benzoyl-3,3-dibutylthiourea
    (International Union of Crystallography, 2010-09-25) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    The title molecule, C16H24N2OS, is twisted about the central N(H) - C bond with a C - N(H) - C - N torsion angle of -62.67 (15)°. The carbonyl group is twisted out of the plane of the benzene ring, forming a C - C - C=O torsion angle of -25.06 (17)°. In the crystal, molecules related by centres of symmetry are linked by pairs of inter-molecular N - H⋯S hydrogen bonds, forming eight-membered {⋯HNCS}2 synthons. These are further connected by weak via C - H⋯O contacts, forming a two-dimensional array in the bc plane.
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    1-Benzoyl-3,3-bis-(2-methylpropyl)thiourea
    (International Union of Crystallography, 2011-02-12) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R.T.
    The title compound, C16H24N2OS, is twisted about the central N(H) - C bond with the C - N - C - S torsion angle being 119.6 (3)°. The carbonyl O and thione S atoms are directed to opposite sides of the molecule, a conformation that allows for the formation of a linear supramolecular chain comprising alternating eight-membered {⋯HNCS} 2 and 14-membered {⋯HCNCNCO}2 synthons.
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    {4-Bromo-2-[(2-sulfidophenyl)iminomethyl]phenolato-k3 S,N,O}(triphenylphosphane-kP)nickel(II)
    (International Union of Crystallography, 2011-03-12) Muthu Tamizh, M.; Karvembu, R; Varghese, B; Tiekink, Edward R. T.
    The NiII atom in the title complex, [Ni(C13H 8BrNOS)(C18H15P)], is coordinated by the N, O and S atoms of he dianionic tridentate ligand, and its square-planar geometry is completed by a phosphane P atom. The dihedral angle between the aromatic rings in the 4-bromo-2-[(2-sulfidohenyl)imino-meth-yl]phenolate ligand is 2.01 (14)°. The most prominent feature of the packing is the presence of supramolecular chains aligned along the a axis, mediated by C - H⋯S interactions.
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    1-Benzoyl-3-methyl-3-pentylthiourea
    (International Union of Crystallography, 2011-04-16) Gunasekaran, N; Jerome, P; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    Two independent molecules comprise the asymmetric unit of the title compound, C14H20N2OS. These differ in the relative orientations of the pentyl chains [C-C-C-C torsion angles = 176.7 (3) and 176.4 (3)°]. Significant twists are evident in each molecule, the dihedral angles formed between the thiourea and amide residues being 53.47 (17) and 55.81 (17)°. In the crystal, each molecule self-associates via a centrosymmetric eight-membered {⋯HNC S}2 synthon, and these are connected into a supramolecular chain along [110] via C-H⋯O contacts. Disorder is noted for one of the independent molecules in that two orientations (50:50) were resolved for its benzene ring.
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    Bis(3-benzoyl-1,1-disecbutyl-thioureato- 2 O,S)palladium(II)
    (International Union of Crystallography, 2011-09-17) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    The complex molecule of the title complex, [Pd(C 16H 23N 2OS) 2], is completed by crystallographic twofold symmetry with the metal atom lying on the rotation axis. The Pd II atom exists within a slightly distorted squareplanar geometry defined by a cis-O 2S 2 donor set. The dihedral angle formed between the mean planes of the symmetry-related six-membered chelate rings is 12.88 (7)° and the bond lengths within the rings are indicative of significant electron delocalization. In the crystal, molecules aggregate into dimers linked by four C-H⋯O interactions.
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    Dicyclohexylammonium thiocyanate: Monoclinic polymorph
    (International Union of Crystallography, 2011-10-05) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    The title salt, C12H24N+·NCS -, represents a monoclinic polymorph of the previously reported ortho-rhom-bic form [Khawar Rauf et al. (2008). Acta Cryst. E64, o366]. Two independent formula units comprise the asymmetric unit with the major difference in their mol-ecular structures relating to the relative dispositions of the cyclohexyl rings [dihedral angles = 79.88 (6) and 67.72 (5)°]. Further, the independent anions form distinctive patterns of hydrogen-bonding interactions, i.e. 2 × N - H⋯N versus N - H⋯N and N - H⋯S. The resulting supra-molecular architecture is a supra-molecular chain along the c axis based on a square-wave topology. © Selvakumaran et al. 2011.
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    Dibenzylazanium chloride
    (International Union of Crystallography, 2012-02-04) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    In the title salt, C 14H 16N +·Cl -, the complete cation and complete anion are generated by the application of mirror symmetry. The molecule is nonplanar, as seen in the dihedral angle between the terminal phenyl rings [70.92 (5)°]. In the crystal, N - H⋯Cl hydrogen bonds involving both azanium H atoms link the ions into a zigzag supramolecular chain along [100].
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    3-Benzoyl-1-(2-methoxyphenyl)thiourea
    (International Union of Crystallography, 2012-11-03) Selvakumaran, N; Sheeba, M. Mary; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    In the title compound, C15H14N2O2S, the central C2N2OS moiety is planar (r.m.s. deviation of fitted atoms = 0.0336 Å). This is ascribed to the formation of an S(6) loop stabilized by an intramolecular N-H⋯O hydrogen bond; additional intramolecular N-H⋯O and C-H⋯S contacts are also noted. The dihedral angles between the central unit and the phenyl and benzene rings are 23.79 (7) and 29.52 (5)°, respectively. The thione S and ketone O atoms are mutually anti, as are the N-H H atoms; the O atoms lie to the same side of the molecule. Centrosymmetric eight-membered {⋯HNC=S}2 synthons feature in the crystal packing. The resulting inversion dimers stack along the a axis and are connected into a three-dimensional structure by C-H⋯O and C-H⋯π interactions.
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    1-Benzoyl-3-(4-chlorophenyl)thiourea dichloromethane hemisolvate
    (International Union of Crystallography, 2012-11-10) Selvakumaran, N; Sheeba, M. Mary; Karvembu, R Ng,; Ng, Seik Weng; Tiekink, Edward R. T.
    In the title hemisolvate, C14H11ClN2OS·0.5CH2Cl2, an anti disposition is found for the thione and ketone atoms, as well as the N-H H atoms; the dichloromethane C atom lies on a twofold axis. The central chromophore (including the two adjacent ipso C atoms) is planar (r.m.s. deviation = 0.021 Å) owing to the presence of an intramolecular N-H⋯O hydrogen bond, which closes an S(6) loop. Significant twists are evident in the molecule, the dihedral angles between the central moiety and the phenyl and benzene rings being 29.52 (7) and 40.02 (7)°, respectively. In the crystal, eight-membered {⋯HNC= S}2 synthons with twofold symmetry form via N-H⋯S hydrogen bonds. The dimers are connected into a supramolecular chain along [111] by C-H⋯O interactions. The chains stack along the c axis, forming columns which define channels in which the occluded dichloromethane molecules reside.
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    3-{[(Dibenzylcarbamothioyl)amino]carbonyl}benzamide
    (International Union of Crystallography, 2013-06-29) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    Two independent molecules with quite similar conformations, A and B, comprise the asymmetric unit of the title compound, C23H21N3O2S. The terminal amide substituent is coplanar with the attached benzene ring [the O - C - C - C torsion angles are 174.0 (2) (A) and 6.3 (3)° (B)]. In the same way, the central amide group [C - C - C - O = 7.8 (3) (A) and 11.5 (3)° (B)] is approximately coplanar with the ring to which it is attached. A major twist is noted between the amide and adjacent thioamide residues [C - N - C - S = -109.29 (19) (A) and -112.29 (19)° (B)]. In the crystal, supramolecular chains along [100] are formed by N - H...O and N - H...S hydrogen bonding. These are connected into a three-dimensional architecture by C - H...π and π-π interactions [inter-centroid distance = 3.9157 (12) Å].
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    3-({[Bis(2-methylpropyl)carbamothioyl]amino}carbonyl)benzamide
    (International Union of Crystallography, 2013-06-29) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    In the title compound, C17H25N3O2S, the terminal and central amide groups are, respectively, twisted and coplanar with the attached benzene ring [O - C - C - C torsion angles = 22.7 (3) and 5.4 (3)°]. In the central part of the molecule, the amide and thioamide residues are approximately perpendicular [C - N - C - S torsion angle = -104.98 (18)°]. Supramolecular layers with a zigzag topology are formed in the crystal packing by N - H...O, N - H...S and C - H...O interactions; these stack along c, being separated by hydrophobic interactions.
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    1-[3-({[bis(2-methylpropyl)carbamothioyl]amino}carbonyl)benzoyl]-3, 3-bis(2-methylpropyl)thiourea
    (International Union of Crystallography, 2013-08-03) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
    The title compound, C26H42N4O 2S2, adopts a shallow U-shape as both pendant arms of the 1,3-substituted benzene ring are orientated in the same direction. The thione S atoms lie to the same side of the benzene ring and the carbonyl O atoms to the other. The most prominent feature of the crystal packing is the formation of inversion dimers mediated by N - H⋯S hydrogen bonds. One of the 2-methylpropyl groups is statistically disordered over two positions. © 2013 Selvakumaran et al.
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    Crystal structure of (2E)-N-methyl-2-[(4-oxo-4H-chromen-3-yl)methylidene]hydrazinecarbothioamide
    (International Union of Crystallography, 2014-10-08) Vimala, G; Govindaraj, J; Haribabu. J; Karvembu, R; Subbiahpandi, A
    In the title compound, C12H11N3O2S, the dihedral angle between the 4H-chromen-4-one ring system and the -CH=N - NH - CS - NH- unit is 6.22 (1)°. In the crystal, inversion dimers linked by pairs of N - H⋯O hydrogen bonds generate R 2/2(14) loops. The dimers are reinforced by a pair of C - H⋯O interactions, which generate R 2/2(10) loops.