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Short C (short + c)

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Chemistry	100%

Selected Abstracts

Polymorphs and pseudopolymorphs of N,N,-dithiobisphthalimide

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2002
Dorcas M. M. Farrell
N,N,-Dithiobisphthalimide, C16H8N2O4S2 (I), forms a wide range of polymorphs and solvates (pseudopolymorphs). When (I) is crystallized from methanol it yields a solvent-free polymorph (4), in Pna21 with Z, = 1, in which the molecules are linked into chains by a single C,H,O hydrogen bond: crystallization from either acetonitrile or dimethylformamide produces a monoclinic polymorph (5), in P21/c with Z, = 2, also solvent-free, in which the molecules are linked into molecular ladders. Nitromethane forms a monosolvate, C16H8N2O4S2·CH3NO2 (6), in P21/c with Z, = 1, in which the solvent molecules are linked to the molecules of (I) not only via a conventional C,H,O hydrogen bond but also via a polarized multicentre interaction involving all three C,H bonds of the solvent molecule. Chlorobenzene forms a precise hemisolvate, C16H8N2O4S2·0.5C6H5Cl (7), in P with Z, = 1, while ethylbenzene forms an approximate hemisolvate 2C16H8N2O4S2·0.913C6H5C2H5·0.087H2O (8), in P21/c with eight molecules of (I) per unit cell. In both solvates the molecules of (I) are linked, in (7) by ,,, stacking interactions augmented by weak C,H,O hydrogen bonds and in (8) by stronger C,H,O hydrogen bonds: the solvent molecules lie in isolated cavities, disordered across inversion centres in (7) and fully ordered in general positions in (8). Crystallization of (I) either from tetrahydrofuran or from wet tert -butanol yields isomorphous solvates (9) and (10), respectively, in C2/c with Z, = 0.5, in which molecules of (I) lie across twofold rotation axes and are linked by ,,, stacking interactions and very weak C,H,O hydrogen bonds, forming a framework enclosing continuous channels: highly disordered solvent molecules lie within these channels. p -Xylene and toluene form isomorphous hemisolvates (11) and (12) with unit cells metrically very similar to those of (9) and (10), but in P21/n with Z, = 1: in these two solvates the molecules of (I) are linked into a framework by very short C,H,O hydrogen bonds; the solvent molecules lie within continuous channels, but they are localized across inversion centres so that the toluene is disordered across an inversion centre. [source]

Two concomitant polymorphs of N,N,-bis[4-(diethylamino)phenyl]terephthaldiamide

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2010
Piotr Ku
The title compound, C28H34N4O2, crystallizes simultaneously as a monoclinic, (Im), and a (twinned) triclinic polymorph, (It), from d6 -dimethyl sulfoxide. Polymorph (It) (P, Z = 1) displays the standard `ladder' packing for this group of compounds, with neighbouring inversion-symmetric molecules related by translation and connected by hydrogen bonds of the form N,H...O=C. Polymorph (Im) (Cc, Z = 4) has no imposed symmetry; there are three independent hydrogen bonds, one classical N,H...O=C and a bifurcated system with N,H...O=C augmented by a short C,H...O=C interaction. Each molecule is thereby linked to four neighbouring molecules, two lower and two higher, so that a crosslinked three-dimensional pattern is formed rather than the standard ladder. [source]

N,H...O and O,H...O hydrogen-bonded supramolecular networks in 4-chloroanilinium, 2-hydroxyanilinium and 3-hydroxyanilinium hydrogen phthalates

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009
R. Jagan
The title salts, 4-chloroanilinium hydrogen phthalate (PCAHP), C6H7ClN+·C8H5O4,, 2-hydroxyanilinium hydrogen phthalate (2HAHP), C6H8NO+·C8H5O4,, and 3-hydroxyanilinium hydrogen phthalate (3HAHP), C6H8NO+·C8H5O4,, all crystallize in the space group P21/c. The asymmetric unit of 2HAHP contains two independent ion pairs. The hydrogen phthalate ions of 2HAHP and 3HAHP show a short intramolecular O,H...O hydrogen bond, with O...O distances ranging from 2.3832,(15) to 2.3860,(14),Å. N,H...O and O,H...O hydrogen bonds, together with short C,H...O contacts in PCAHP and 3HAHP, generate extended hydrogen-bond networks. PCAHP forms a two-dimensional supramolecular sheet extending in the (100) plane, whereas 2HAHP has a supramolecular chain running parallel to the [100] direction and 3HAHP has a two-dimensional network extending parallel to the (001) plane. [source]

Salts of maleic and fumaric acids with oxine: the role of isomeric acids in hydrogen-bonding patterns

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009
S. Franklin
Both maleic and fumaric acid readily form adducts or complexes with other organic molecules. The 1:1 adduct formed by quinolin-8-ol (oxine) with maleic and fumaric acid are salts, namely 8-hydroxyquinolinium hydrogen maleate, C9H8NO+·C4H3O4,, (I), and 8-hydroxyquinolinium hydrogen fumarate, C9H8NO+·C4H3O4,, (II). The cations and anions of both salts are linked by ionic N+,H...O, hydrogen bonds. The maleate salt crystallizes in the space group P212121, while the fumarate salt crystallizes in P. The maleic and fumaric acids in their complex forms exist as semimaleate and semifumarate ions (mono-ionized state), respectively. Classical N,H...O and O,H...O hydrogen bonds, together with short C,H...O contacts, generate an extensive hydrogen-bonding network. The crystal structures of the maleate and fumarate salts of oxine have been elucidated to study the importance of noncovalent interactions in the aggregation and interaction patterns of biological molecules. The structures of the salts of the Z and E isomers of butenedioic acid (maleic and fumaric acid, respectively) with quinolin-8-ol are compared. [source]

Sodium tris(glycinium) bis(hexafluorosilicate) glycine trisolvate

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2007
Moolya B. Narayana
The title compound, Na+·3C2H6NO2+·2SiF62,·3C2H5NO2, arose from an unexpected reaction of glycine and HF with the glass container. It is an unusual hybrid organic,inorganic network built up from chains of vertex-sharing NaF4O2 and SiF6 octahedra. A pair of glycinium/glycine molecules bridges the chains into a sheet via a centrosymmetric O...H...O link. The other organic species interact with the network by an extensive N,H...F hydrogen-bond network, including bifurcated and trifurcated bonds. Finally, an extremely short C,H...O interaction (H...O = 2.25,Å) is seen in the crystal structure. The Na atom has site symmetry . [source]

2,3,4,5,6-Pentanitroaniline 1,2-dichloroethane disolvate: `push,pull' deformation of aromatic rings by intramolecular charge transfer

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2006
Sergiy V. Rosokha
The title compound, C6H2N6O10·2C2H4Cl2, forms layered stacks of pentanitroaniline molecules, which possess twofold symmetry. The voids between these stacks are occupied by dichloroethane molecules, which reside near a 2/m symmetry element and display pseudo-inversion symmetry. The C atoms in one of the two solvent molecules are threefold disordered. In the pentanitroaniline molecule, considerable distortion of the benzenoid ring, coupled with the short C,N(H2) bond and out-of-plane NO2 twistings, point to significant intramolecular `push,pull' charge transfer at the amino- and nitro-substituted (ortho and para) positions, as theoretically quantified by natural bond orbital analysis of the ,-electron density. [source]

Four crystal forms of a Bence-Jones protein

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2005
Debora L. Makino
Four crystal forms have been grown and characterized by X-ray diffraction of a Bence-Jones protein collected from the urine of a multiple myeloma patient more than 40,years ago. Closely related tetragonal and orthorhombic forms belonging to space groups P43212 and P212121, with unit-cell parameters a = b = 68.7, c = 182.1 and a = 67.7, b = 69.4, c = 87.3,Å, diffract to 1.5 and 1.9,Å, respectively. Two closely related trigonal forms, both belonging to space group P3121 with unit-cell parameters a = b = 154.3,Å but differing by a doubling of the c axis, one 46.9,Å and the other 94.0,Å, diffract to 2.9 and 2.6,Å resolution, respectively. The trigonal crystal of short c -axis length shows a positive indication of twinning. The trigonal crystal of longer c axis, which appeared only after eight months of incubation at room temperature, is likely to be composed of proteolytically degraded molecules and unlike the other crystal forms contains two entire Bence-Jones dimers in the asymmetric unit. This latter crystal form may shed some light on the formation of fibrils common to certain storage diseases. [source]