5,184 research outputs found
(Chloromethyl)pentacarbonylmanganese(I): a crystal structure with a non-crystallographic centre of symmetry
There are two molecules in the asymmetric unit of the P2₁/c unit cell of ClCH₂Mn(CO)₅, the first halomethyl complex of manganese to be structurally determined. The molecules are crystallographically independent, despite an apparent local centre of symmetry. The average bond parameters include Mn–Calkyl 2.128(8) Å, C–Cl 1.811(8) Å and Mn–C–Cl 116.4(4)
N′-(2-Hydroxy-5-nitrobenzylidene)-2-(1H-indol-3-yl)acetohydrazide
The molecule of the title compound, C17H14N4O4, uses its amide –NH– group to form a hydrogen bond to the amido –C(=O)– group of an adjacent molecule to furnish a linear chain structure. The hydroxy group forms an intramolecular hydrogen bond; the indolyl –NH– unit does not engage in any strong hydrogen-bonding interactions
Bis[4-(dimethylamino)pyridinium] tetrabromidobis(4-methylphenyl)stannate(IV)
In the title compound, (C7H11N2)2[SnBr4(C7H7)2], the tetrabromidobis(4-methylphenyl)stannate(IV) anion possesses a centre of inversion located at the SnIV atom. In the crystal structure, two inversion-related cations are linked to the anion via weak N—H⋯Br hydrogen bonds
Bis[4-(dimethylamino)pyridinium] tetrabromidobis(4-chlorophenyl)stannate(IV)–4-bromochlorobenzene (1/1)
In the title compound, (C7H11N2)2[SnBr4(C6H4Cl)2]·C6H4BrCl, the SnIV atom in the tetrabromidobis(4-chlorophenyl)stannate(IV) anion lies on a centre of inversion. The distances between the 4-(dimethylamino)pyridinium N atom and the Br atoms of the anion are 3.450 (2) and 3.452 (2) Å, suggesting weak hydrogen bonding. The 4-bromochlorobenzene solvent molecule, which is a bromination by-product from the reaction, is disordered about a twofold rotation axis with approximately equal occupancy
Extranuclear X-ray Emission in the Edge-on Seyfert Galaxy NGC 2992
We found several extranuclear (r >~ 3") X-ray nebulae within 40" (6.3 kpc at
32.5 Mpc) of the nucleus of the Seyfert galaxy NGC 2992. The net X-ray
luminosity from the extranuclear sources is ~2-3 E39 erg/s (0.3-8.0 keV). The
X-ray core itself (r <~ 1") is positioned at 9:45:41.95 -14:19:34.8 (J2000) and
has a remarkably simple power-law spectrum with photon index Gamma=1.86 and
Nh=7E21 /cm2. The near-nuclear (3" <~ r <~ 18") Chandra spectrum is best
modelled by three components: (1) a direct AGN component with Gamma fixed at
1.86, (2) cold Compton reflection of the AGN component, and (3) a 0.5 keV
low-abundance (Z < 0.03 Zsolar) "thermal plasma," with ~10% of the flux of
either of the first two components. The X-ray luminosity of the 3rd component
(the "soft excess") is ~1.4E40 erg/s, or ~5X that of all of the detected
extranuclear X-ray sources. We suggest that most (~75-80%) of the soft excess
emission originates from 1" < r < 3", which is not imaged in our observation
due to severe CCD pile-up. We also require the cold reflector to be positioned
at least 1" (158 pc) from the nucleus, since there is no reflection component
in the X-ray core spectrum. Much of the extranuclear X-ray emission is
coincident with radio structures (nuclear radio bubbles and large-scale radio
features), and its soft X-ray luminosity is generally consistent with
luminosities expected from a starburst-driven wind (with the starburst scaled
from L_FIR). However, the AGN in NGC 2992 seems equally likely to power the
galactic wind in that object. Furthermore, AGN photoionization and
photoexcitation processes could dominate the soft excess, especially the
\~75-80% which is not imaged by our observations.Comment: 34 pages AASTEX, 9 (low-res) PS figures, ApJ, in press. For
full-resolution postscript file, visit
http://www.pha.jhu.edu/~colbert/n2992_chandra.ps.g
N′-[1-(2-Hydroxy-5-methylphenyl)ethylidene]benzenesulfonohydrazide
The two independent molecules in the asymmetric unit of the title compound, C15H16N2O3S, are each linked by an N—H⋯Osulfonyl hydrogen bond into a linear chain that runs along the shortest axis of the triclinic unit cell. The hydroxy groups are engaged in intramolecular hydrogen bonding and the amino N atom shows pyramidal coordination
2-(1,3-Benzoxazol-2-ylsulfanyl)-1-phenylethanone
In the title compound, C15H11NO2S, a new thio-benzoxazole derivative, the dihedral angle between the benzoxazole ring and the phenyl ring is 9.91 (9)°. An interesting feature of the crystal structure is the short C⋯S [3.4858 (17) Å] contact, which is shorter than the sum of the van der Waals radii of these atoms. In the crystal structure, molecules are linked together by zigzag intermolecular C—H⋯N interactions into a column along the a axis. The crystal structure is further stabilized by intermolecular π–π interactions [centroid–centroid = 3.8048 (10) Å]
N′-[1-(5-Bromo-2-hydroxyphenyl)ethylidene]-3,4,5-trihydroxybenzohydrazide dimethyl sulfoxide solvate trihydrate
The benzohydrazide molecule in the title compound, C15H13BrN2O5·C2H6OS·3H2O, is almost planar with an r.m.s. deviation for the non-H atoms of 0.078 Å. The organic molecules, water and dimethyl sulfoxide solvent molecules are linked by N—H⋯O, O—H⋯O and O—H⋯S intermolecular hydrogen bonds, forming zigzag chains along the a axis. Intramolecular O—H⋯O and O—H⋯N hydrogen bonds also occur
3,4,5-Trihydroxy-N′-(1H-indol-2-ylmethylidene)benzohydrazide–1H-indole-2-carbaldehyde azine–methanol (2/1/2)
The title compound, 2C16H13N3O4·C18H14N4·2CH4O, was crystallized from the reaction between 3,4,5-trihydroxybenzoylhydrazine and indole-2-carbaldehyde in a mixture of ethanol and methanol. The compound is a stoichiometric 2:1 cocrystal of the methanol-solvated reaction product, 3,4,5-trihydroxy-N′-(1H-indol-2-ylmethylidene)benzohydrazide and 1H-indole-2-carbaldehyde azine that arose unexpectedly during the synthesis. The former molecules are linked by O—H⋯O hydrogen bonds and also by π–π stacking interactions between benzoylhydrazide rings into a two-dimensional network. The methanol solvent molecules are hydrogen bonded to this network. The centrosymmetric azine molecules are not engaged in hydrogen bonding
A second monoclinic polymorph of 2-(diformylmethylidene)-3,3-dimethyl-2,3-dihydro-1H-indole
The crystal structure of the title compound, C13H13NO2, is a polymorph of the structure first reported by Helliwell et al. [Acta Cryst. (2006), E62, o737-o738]. It is also monoclinic (space group P21/c), but with completely different cell constants. The molecular conformations of these polymorphs differ by a 180° rotation of one formyl group. The present molecule is planar [maximum deviation 0.089 (2) Å] with the exception of the two methyl groups which lie on either side of the plane. There are strong intra- and intermolecular N—H⋯O hydrogen bonds. The latter link pairs of molecules across crystallographic centers of symmetry. Two aldehyde O atoms are brought close together [2.896 (4) Å in this arrangement but are not hydrogen bonded. In the earlier polymorph, one formyl group is rotated by 180° to yield intermolecular hydrogen bonding and an infinite polymeric chain. The other formyl group is involved in the same intramolecular hydrogen bonding as has been found here
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