Search tips
Search criteria

Results 1-25 (1232)

Clipboard (0)

Select a Filter Below

Year of Publication
Document Types
author:("Ng, seek Weng")
1.  4-Chloro-2,6-dinitro­phenol 
The aromatic ring of the title compound, C6H3ClN2O5, is almost planar (r.m.s. deviation = 0.007 Å); one nitro substituent is nearly coplanar with the ring [dihedral angle = 3(1)°], whereas the other is twisted [dihedral angle = 36 (1)°]. The phenol OH group is intra­molecularly hydrogen bonded to the nitro group that is coplanar with the ring, generating an S(6) graph-set motif.
PMCID: PMC3011538  PMID: 21589498
2.  Redetermination of 4-(dimethyl­amino)­pyridinium tribromide 
In the title salt, C7H11N2 +·Br3 −, the essentially planar cation (r.m.s. deviation = 0.006 Å) forms an N—H⋯Br hydrogen bond to one of the Br atoms of the almost linear anion [Br—Br—Br = 179.31 (2)°]. The crystal studied was found to be a racemic twin. The whole-mol­ecule disorder of the cation and anion about a twofold rotation axis described earlier [Ng (2009). Acta Cryst. E65, o1276] is an artifact of halving one of the axes of the ortho­rhom­bic unit cell.
PMCID: PMC3008028  PMID: 21588594
3.  2-Chloro-3-nitro­pyridine 
In the title compound, C5H3ClN2O2, the nitro group is twisted by 38.5 (2)° with respect to the pyridine ring. In the crystal, adjacent mol­ecules are linked by non-classical C—H⋯N and C—H⋯O hydrogen bonds, forming a layer motif.
PMCID: PMC2979275  PMID: 21579084
4.  2-Chloro-5-nitro­pyridine 
The non-H atoms of the title compound, C5H3ClN2O2, almost lie in a common plane (r.m.s. deviation = 0.090 Å). In the crystal, adjacent mol­ecules feature a short Cl⋯O contact [3.068 (4) Å], forming a chain; these chains are consolidated into a layer structure by non-classical C—H⋯O inter­actions.
PMCID: PMC2983943  PMID: 21580672
5.  4-(Methyl­amino)pyridine 
The non-H atoms of the title compound, C6H8N2, lie in a common plane (r.m.s. deviation = 0.034 Å). In the crystal, adjacent mol­ecules are linked by inter­molecular N—H⋯N hydrogen bonds into a zigzag chain running along the c axis.
PMCID: PMC2983869  PMID: 21580654
6.  5-Chloro-8-hydroxy­quinolinium nitrate 
The 5-chloro-8-hydroxy­quinolinium cation in the the title ion pair, C9H7ClNO+·NO3 −, is approximately coplanar with the nitrate anion [dihedral angle = 16.1 (1)°]. Two ion pairs are hydrogen bonded (2 × O—H⋯O and 2 × N—H⋯O) about a center of inversion, generating an R 4 4(14) ring.
PMCID: PMC2969641  PMID: 21583288
7.  A second monoclinic modification of triphenyl­phosphine oxide hemihydrate 
In the crystal of the title compound, C18H15OP·0.5H2O, a water molecule links to two adjacent triphenylphosphine molecules by way of O—H⋯O hydrogen bonds. The crystal is twinned, the minor twin component being 36%.
PMCID: PMC2969812  PMID: 21583272
8.  Low-temperature redetermination of benzofurazan 1-oxide 
In the six-membered ring of the low-temperature crystal structure of benzofurazan 1-oxide, C6H4N2O2, the two C atoms adjacent to the N atoms are linked by a delocalized aromatic bond [1.402 (2) Å]; each is connected to its neighbour by a longer, more localized, bond [1.420 (2), 1.430 (2) Å]. However, the next two bonds in the ring approximate double bonds [1.357 (2), 1.366 (2) Å]. As such, the six-membered ring is better described as a cyclo­hexa­diene system, in contrast to the description in the room-temperature structure reported by Britton & Olson (1979 ▶) [Acta Cryst. B35, 3076–3078].
PMCID: PMC2969705  PMID: 21583137
9.  5,7-Dichloro­quinolin-8-ol 
The mol­ecule of the title compound, C9H5Cl2NO, is essentially planar [give maximum or r.m.s. deviation] and the hydr­oxy group acts as a hydrogen-bond donor to the N atom of a symmetry-related mol­ecule, generating a hydrogen-bonded dimer,which lies on a twofold rotation axis.
PMCID: PMC2977804  PMID: 21583941
10.  2-Chloro­quinoxaline 
In the title compound, C8H5ClN2, the planar mol­ecules are arranged with their Cl atoms in close contact [Cl⋯Cl = 3.808 (1) and 3.881 (1) Å], indicating weak Cl⋯Cl inter­actions, which give rise to a supra­molecular chain.
PMCID: PMC2968544  PMID: 21582127
11.  Low-temperature redetermination of tribenzyl­chloridotin(IV) 
Compared to the previous studies [Ng (1997 ▶). Acta Cryst. C53, 56–58; Yin et al. (2005 ▶). Huaxue Shiji, 27, 295–296], the redetermined structure of the title compound, [Sn(C7H7)3Cl], exhibits a doubled c unit-cell parameter. There are two mol­ecules in the asymmetric unit, with both Sn and both Cl atoms having 3 site symmetry. The Sn atoms have distorted SnClC3 tetra­hedral geometries and the mol­ecules inter­act by way of short Sn⋯Cl bridges [Sn⋯Cl = 3.418 (2) and 3.475 (2) Å], thereby forming chains propagating in c.
PMCID: PMC2968220  PMID: 21581828
12.  2,3,4-Trihydroxy­benzaldehyde 
The title compound, C7H6O4, crystallizes with two independent mol­ecules in the asymmetric unit. In both mol­ecules, the 2-hydr­oxy group is bound via intra­molecular hydrogen bonds to the aldehyde group. The mol­ecules inter­act through O—H⋯O hydrogen bonds to form a three-dimensional network structure; each hydr­oxy group serves as a donor to only one acceptor atom.
PMCID: PMC2962187  PMID: 21203268
13.  N-Hydroxy-N-methyl­ammonium chloride 
In the crystal structure of the title compound, CH6NO+·Cl−, the cations and anions are linked by N–H⋯Cl and O–H⋯Cl hydrogen bonds into an undulating layer motif [Schläfli symbol: 4(8).6(8).8(2)]. All non-H atoms lie on a mirror plane.
PMCID: PMC2961632  PMID: 21202578
14.  (2-{[4-(Chlorido­mercur­yl)phen­yl]imino­meth­yl}pyridine-κ2 N,N′)di­iodido­mercury(II) dimethyl sulfoxide monosolvate 
The title dimethyl sulfoxide solvate, [Hg2(C12H9ClN2)I2]·C2H6OS, features tetra­hedrally and linearly coordinated HgII 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 HgII atom [177.0 (4)°] exists with a donor set defined by C and Cl atoms. Secondary inter­actions are apparent in the crystal packing with the tetra­hedrally and linearly coordinated HgII atoms expanding their coordination environments by forming weak Hg⋯I [3.772 (7) Å] and Hg⋯O [2.921 (12) Å] inter­actions, respectively. Mercury-containing mol­ecules stack along the a axis, are connected by π–π inter­actions [inter-centroid distance between pyridine and benzene rings = 3.772 (7) Å] and define channels in which the dimethyl sulfoxide mol­ecules reside. The latter are connected by the aforementioned Hg⋯O inter­actions as well as C—H⋯I and C—H⋯O inter­actions, resulting in a three-dimensional architecture.
PMCID: PMC3884979  PMID: 24454154
15.  Di-μ-iodido-bis­(iodido­{methyl 4-[(pyridin-2-yl­methyl­idene)amino]­benzoate-κ2 N,N′}cadmium) 
The complete binuclear molecule of the title compound, [Cd2I4(C14H12N2O2)2], is generated by the application of a centre of inversion. The Cd—I bond lengths of the central core are close and uniformly longer than the exocyclic Cd—I bond. The coordination sphere of the CdII atom is completed by two N atoms of a chelating methyl 4-[(pyridin-2-yl­methyl­idene)amino]­benzoate ligand, and is based on a square pyramid with the terminal I atom in the apical position. The three-dimensional crystal packing is stabilized by C—H⋯O and C—H⋯π inter­actions, each involving the pyridine ring.
PMCID: PMC3884272  PMID: 24454048
16.  Di­chlorido­{2-[(E)-phen­yl(pyridin-2-yl-κN)methyl­idene]-N-phenyl­hydra­zine­carboxamide-κ2 N 2,O}copper(II) 
The title compound, [CuCl2(C19H16N4O)], contains a CuII atom N,N′,O-chelated by a neutral N-phenyl­hy­dra­zine­car­box­amide ligand and additionally coordinated by two Cl atoms, resulting in a distorted square-pyramidal geometry. The ligating atoms in the basal square plane of the complex comprise the azomethine N, the pyridine N, the amide O and one of the Cl atoms, whereas the other Cl atom occupies an apical position. The apical Cl atoms in adjacent layers function as hydrogen-bond acceptors to both NH groups. Intermolecular C—H⋯Cl and C—H⋯O interactions are also observed.
PMCID: PMC3884250  PMID: 24454026
17.  Ethyl (2Z)-3-oxo-2-(3,4,5-tri­meth­oxy­benzyl­idene)butano­ate 
In the title compound, C16H20O6, the conformation about the C=C double bond [1.344 (2) Å] is Z. With respect to this bond, the ketone is almost coplanar [C—C—C—O torsion angle = −179.60 (10)°] and the ester is almost perpendicular [C—C—C—O = 78.42 (13)°]. The meth­oxy substituents of the central benzene ring are either almost coplanar [C—C—O—C = 3.54 (15) and 177.70 (9)°] or perpendicular [C—C—O—C = 80.08 12)° for the central substituent]. In the crystal, the three-dimensional architecture features C—H⋯O and π–π [inter-centroid distance = 3.6283 (6) Å] inter­actions.
PMCID: PMC3884456  PMID: 24427096
18.  (2E)-3-(2-Chloro-7-methyl­quinolin-3-yl)-1-(6-chloro-2-methyl-4-phenyl­quinolin-3-yl)prop-2-en-1-one ethanol monosolvate 
In the title ethanol solvate, C29H20Cl2N2O·C2H5OH, the quinolinyl residues form a dihedral angle of 46.41 (4)° with each other, and each is inclined [Cp—C—C=O and C=C—C—Cp (p = pyridyl) torsion angles = 54.8 (2) and 144.44 (19)°, respectively] with respect to the almost planar bridging prop-2-en-1-one residue [O=C—C=C torsion angle = −4.1 (3)°]. The ethanol solvent mol­ecule is disordered over two positions of equal occupancy and is located close to a centre of inversion. These mol­ecules reside in cavities defined by the organic mol­ecules, which are connected into a three-dimensional architecture by C—H⋯Cl, C—H⋯O and C—H⋯N inter­actions, as well as π–π contacts [inter-centroid distances = 3.5853 (10) and 3.8268 (11) Å], each involving pyridyl rings.
PMCID: PMC3884470  PMID: 24427050
19.  A second monoclinic polymorph of 3,5-di-tert-butyl-2-hy­droxy­benzaldehyde 
In the title mol­ecule, C15H22O2, there is an intra­molecular hydrogen bond involving the hy­droxy and aldehyde groups and forming an S(6) ring. The mean plane of the non-H atoms of this ring [(H)O—C C—C=O, with a maximum deviation of 0.013 (1) Å] are essentially coplanar with the benzene ring, forming a dihedral angle of 2.29 (8)°.
PMCID: PMC3884484  PMID: 24427059
20.  (2E)-3-(2-Chloro­benzo[h]quinolin-3-yl)-1-(2-methyl-4-phenyl­quinolin-3-yl)prop-2-en-1-one 
In the title compound, C32H21ClN2O, an almost planar (r.m.s. deviation = 0.033 Å) prop-2-en-1-one bridge links quinolinyl and benzoquinolinyl residues; the latter are twisted out of the plane of the bridge [dihedral angles = 75.94 (5) and 20.20 (5)°, respectively]. In the crystal, a three-dimensional architecture arises as a result of C—H⋯O, C—H⋯π and π–π [centroid–centroid distances involving pyridine rings = 3.5806 (7)–3.7537 (7) Å] interactions.
PMCID: PMC3884436  PMID: 24427034
21.  1-[3-({[Bis(2-methyl­prop­yl)carbamo­thio­yl]amino}­carbon­yl)benzoyl]-3,3-bis­(2-methyl­prop­yl)thio­urea 
The title compound, C26H42N4O2S2, 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.
PMCID: PMC3884506  PMID: 24427014
22.  (2E)-3-(6-Chloro-2-meth­oxy­quinolin-3-yl)-1-(2-methyl-4-phenyl­quinolin-3-yl)prop-2-en-1-one acetone monosolvate 
In the title solvate, C29H21ClN2O2·C3H6O, a prop-2-en-1-one bridge links two quinolinyl residues; the latter are almost perpendicular [dihedral angle = 78.27 (6)°]. The dihedral angle between the quinonyl ring system and its pendant phenyl group is 59.78 (8)°. A small twist in the bridging prop-2-en-1-one group is noted [O=C—C=C torsion angle = −10.6 (3)°]. In the crystal, a three-dimensional architecture arises as a result of C—H⋯O and π–π stacking [centroid–centroid distances = 3.5504 (12)–3.6623 (12) Å].
PMCID: PMC3793806  PMID: 24109393
23.  (2E)-3-(2-Chloro-8-methyl­quinolin-3-yl)-1-(2-methyl-4-phenyl­quinolin-3-yl)prop-2-en-1-one 
In the title compound, C29H21ClN2O, there is a twist in the bridging prop-2-en-1-one group [C=C—C=O torsion angle = 22.7 (2)°]. The quinolinyl residues form a dihedral angle of 86.92 (4)°, indicating an almost perpendicular relationship. In the crystal, supra­molecular layers in the bc plane are stabilized by C—H⋯π and π–π inter­actions [centroid–centroid distance = 3.4947 (7) Å].
PMCID: PMC3793805  PMID: 24109392
24.  (2E)-3-(6-Chloro-2-meth­oxy­quinolin-3-yl)-1-(2,4-di­methyl­quinolin-3-yl)prop-2-en-1-one 
The mol­ecule of the title compound, C24H19ClN2O2, is bent, with the dihedral angle between the terminal quinoline ring systems being 63.30 (5)°. The quinolinyl residues are connected by an almost planar prop-2-en-1-one bridge (r.m.s. deviation = 0.022 Å), with the dihedral angles between this plane and the appended quinolinyl residues being 75.86 (7) and 38.54 (7)°. The C atom of the meth­oxy group is close to coplanar with its attached ring [deviation = 0.116 (2) Å]. In the crystal, a three-dimensional architecture is constructed by meth­yl–carbonyl C—H⋯O inter­actions and π–π inter­actions between centrosymmetrically related quinolinyl residues [centroid-to-centroid separations 3.5341 (10) and 3.8719 (9) Å].
PMCID: PMC3793769  PMID: 24109356
25.  (2E)-3-(2-Chloro-8-methyl­quinolin-3-yl)-1-(2,4-di­methyl­quinolin-3-yl)prop-2-en-1-one 
In the mol­ecule of the title compound, C24H19ClN2O, the terminal quinolinyl residues are close to perpendicular to each other [dihedral angle 83.72 (4)°]. The quinolinyl residues are connected by and inclined to the prop-2-en-1-one bridge, with the Car—Car—C—C (ar = aromatic) torsion angles being 71.01 (17) and 20.6 (2)°. The crystal structure features phen­yl–carbonyl C—H⋯O inter­actions and π–π inter­actions between centrosymmetrically related quinolinyl residues [3.5341 (10) and 3.8719 (9) Å], which together lead to a three-dimensional architecture.
PMCID: PMC3793770  PMID: 24109357

Results 1-25 (1232)