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1.  Crystal structure of 2-{[2-(3-phenyl­allyl­idene)hydrazin-1-yl]thio­carbonyl­sulfanylmeth­yl}pyridinium chloride 
In the title salt of an S-substituted di­thio­carbazate, C16H16N3S2 +·Cl−, the dihedral angles between the almost planar (r.m.s deviation = 0.005 Å) central CN2S2 residue and the terminal pyridinium and phenyl rings are 80.09 (11) and 3.82 (11)°, respectively, indicating the cation has an L-shape; the amine H and thione S atoms are syn. The conformation about each of the imine [1.376 (3) Å] and ethene [1.333 (4) Å] bonds is E. The shortened C—C bond [1.444 (4) Å] linking the double bonds is consistent with conjugation in this part of the mol­ecule. In the crystal, supra­molecular layers with a jagged topology are formed by charged-assisted amine-H⋯Cl− and pyridinium-N+—H⋯Cl− hydrogen bonds. The layers stack along the a axis with no specific directional inter­actions between them.
PMCID: PMC4257274  PMID: 25484832
crystal structure; hydrogen bonding; S-substituted di­thio­carbaza­tes; salt
2.  Crystal structure of ethyl 2-[(4-bromo­phen­yl)amino]-3,4-di­methyl­pent-3-enoate 
In the title compound, C15H20BrNO2, there are two independent mol­ecules (A and B) comprising the asymmetric unit and these adopt very similar conformations. In A, the dihedral angle between the CO2 and MeC=CMe2 groups is 80.7 (3)°, and these make dihedral angles of 3.5 (3) and 84.09 (16)°, respectively, with the bromo­benzene ring. The equivalent dihedral angles for mol­ecule B are 78.4 (3), 2.1 (3) and 78.37 (12)°, respectively. The most prominent inter­actions in the crystal packing are amine-N—H⋯O(carbon­yl) hydrogen bonds between the two independent mol­ecules, resulting in non-centrosymmetric ten-membered {⋯OC2NH}2 synthons. Statistical disorder is noted for each of the terminal methyl groups of the ethyl residues.
PMCID: PMC4257164  PMID: 25484707
crystal structure; hydrogen bonding; amine
3.  Crystal structure of (3E)-3-(2,4-di­nitro­phen­oxy­meth­yl)-4-phenyl­but-3-en-2-one 
In the title compound, C17H14N2O6, the conformation about the C=C double bond [1.345 (2) Å] is E, with the ketone moiety almost coplanar [C—C—C—C torsion angle = 9.5 (2)°] along with the phenyl ring [C—C—C—C = 5.9 (2)°]. The aromatic rings are almost perpendicular to each other [dihedral angle = 86.66 (7)°]. The 4-nitro moiety is approximately coplanar with the benzene ring to which it is attached [O—N—C—C = 4.2 (2)°], whereas the one in the ortho position is twisted [O—N—C—C = 138.28 (13)°]. The mol­ecules associate via C—H⋯O inter­actions, involving both O atoms from the 2-nitro group, to form a helical supra­molecular chain along [010]. Nitro–nitro N⋯O inter­actions [2.8461 (19) Å] connect the chains into layers that stack along [001].
PMCID: PMC4186202  PMID: 25309220
crystal structure; hydrogen bonding; N⋯O inter­actions
4.  Crystal structure of (3E)-3-[(4-nitro­phen­oxy)­meth­yl]-4-phenyl­but-3-en-2-one 
In the title compound, C17H15NO4, the conformation about the C=C double bond [1.348 (2) Å] is E with the ketone group almost co-planar [C—C—C—C torsion angle = 7.2 (2)°] but the phenyl group twisted away [C—C—C—C = 160.93 (17)°]. The terminal aromatic rings are almost perpendicular to each other [dihedral angle = 81.61 (9)°] giving the mol­ecule an overall U-shape. The crystal packing feature benzene-C—H⋯O(ketone) contacts that lead to supra­molecular helical chains along the b axis. These are connected by π–π inter­actions between benzene and phenyl rings [inter-centroid distance = 3.6648 (14) Å], resulting in the formation of a supra­molecular layer in the bc plane.
PMCID: PMC4186193  PMID: 25309202
crystal structure; hydrogen bonding; π–π inter­actions
5.  Crystal structure of a new monoclinic polymorph of N-(4-methyl­phen­yl)-3-nitro­pyridin-2-amine 
Molecules in both polymorphs of the title compound display deviations from planarity owing to crystal packing effects.
The title compound, C12H11N3O2, is a second monoclinic polymorph (P21, with Z′ = 4) of the previously reported monoclinic (P21/c, with Z′ = 2) form [Akhmad Aznan et al. (2010 ▶). Acta Cryst. E66, o2400]. Four independent mol­ecules comprise the asymmetric unit, which have the common features of a syn disposition of the pyridine N atom and the toluene ring, and an intra­molecular amine–nitro N—H⋯O hydrogen bond. The differences between mol­ecules relate to the dihedral angles between the rings which range from 2.92 (19) to 26.24 (19)°. The geometry-optimized structure [B3LYP level of theory and 6–311 g+(d,p) basis set] has the same features except that the entire mol­ecule is planar. In the crystal, the three-dimensional architecture is consolidated by a combination of C—H⋯O, C—H⋯π, nitro-N—O⋯π and π–π inter­actions [inter-centroid distances = 3.649 (2)–3.916 (2) Å].
PMCID: PMC4158497  PMID: 25249854
crystal structure; amine; pyridine; polymorph; conformation
6.  Crystal structures of 1,4-di­aza­bicyclo­[2.2.2]octan-1-ium 4-nitro­benzoate dihydrate and 1,4-di­aza­bicyclo­[2.2.2]octane-1,4-diium bis­(4-nitro­benzoate): the influence of solvent upon the stoichiometry of the formed salt 
Solvent-dependent outcomes are noted in co-crystallization experiments between DABCO and 4-nitrobenzoic acid with mono- and diprotonated forms of DABCO are isolated.
The 1:1 co-crystallization of 1,4-di­aza­bicyclo­[2.2.2]octane (DABCO) with 4-nitro­benzoic acid in ethanol–water (3/1) gave the salt dihydrate C6H13N2 +·C7H4NO4 −·2H2O, (1), whereas from methanol, the salt C6H14N2 2+·2C7H4NO4 −, (2), was isolated. In (1), the cation and anion are linked by a strong N—H⋯O hydrogen bond, and the carboxyl­ate anion is close to planar [dihedral angle between terminal residues = 6.83 (9)°]. In (2), a three-ion aggregate is assembled by two N—H⋯O hydrogen bonds, and the carboxyl­ate anions are again close to planar [dihedral angles between terminal residues = 1.7 (3) and 5.9 (3)°]. Through the inter­vention of solvent water mol­ecules, which self-assemble into helical supra­molecular chains along the b axis, the three-dimensional architecture in (1) is stabilized by water–DABCO O—H⋯N and water–carboxyl­ate O—H⋯O hydrogen bonds, with additional stability afforded by C—H⋯O inter­actions. The global crystal structure comprises alternating layers of water mol­ecules and ion pairs stacked along the c axis. In the crystal of (2), the three-ion aggregates are assembled into a three-dimensional architecture by a large number of methyl­ene–carboxyl­ate/nitro C—H⋯O inter­actions as well as π–π contacts between inversion-related benzene rings [inter-centroid distances = 3.5644 (16) and 3.6527 (16) Å]. The cations and anions assemble into alternating layers along the c axis.
PMCID: PMC4120614  PMID: 25161500
crystal structure; amine; carb­oxy­lic acid; co-crystallization; salt formation
7.  2-[(3S,3aS,5R,8S,8aS)-3,8-Di­methyl­hexa­hydro-1H,4H-3a,8a-ep­oxy­azulen-5-yl]propan-2-ol 
Four independent mol­ecules (A–D) comprise the asymmetric unit of the title compound, C15H26O2, which differ only in the relative orientations of the terminal –C(Me)2OH groups [e.g. the range of Cmethyl­ene—Cmethine—Cquaternary—Ohy­droxy torsion angles is 52.7 (7)–57.1 (6)°, where the Cmethyl­ene atom is bound to an epoxide C atom]. The five-membered rings adopt envelope conformations, with the methyl­ene C atom adjacent to the methine C atom being the flap atom in each case. In each mol­ecule, the conformation of the seven-membered ring is a half-chair, with the Cmethyl­ene—Cmethine bond, flanked by methyl­ene C atoms, being the back of the chair. Supra­molecular helical chains along the b axis are found in the crystal packing, sustained by hy­droxy–epoxide O—H⋯O hydrogen bonding. Mol­ecules of A self-associate into a chain as do those of D. A third independent chain comprising B and C mol­ecules is also formed. The studied crystal is a pseudo-merohedral twin (minor component ca 21%).
PMCID: PMC4120619  PMID: 25161564
8.  Corymbolone 
The title compound, C15H24O2 [systematic name: (4S,4aR,6R,8aR)-4a-hy­droxy-4,8a-dimethyl-6-(prop-1-en-2-yl)octahydro­naphthalen-1(2H)-one], features two edge-shared six-membered rings with the hydroxyl and methyl substituents at this bridge being trans. One adopts a flattened chair conformation with the C atoms bearing the carbonyl and methyl substituents lying 0.5227 (16) and 0.6621 (15) Å, respectively, above and below the mean plane through the remaining four C atoms (r.m.s. deviation = 0.0145 Å). The second ring, bearing the prop-1-en-2-yl group, has a chair conformation. Supra­molecular helical chains along the b axis are found in the crystal packing, which are sustained by hy­droxy–carbonyl O—H⋯O hydrogen bonding.
PMCID: PMC4120577  PMID: 25161551
9.  4-Amino-N-(2,3-di­hydro-1,3-thia­zol-2-yl­idene)benzene­sulfonamide–2,4,6-tris­(pyr­idin-2-yl)-1,3,5-triazine (1/1) 
The sulfa­thia­zole mol­ecule in the title 1:1 co-crystal, C9H9N3O2S2·C18H12N6, adopts an approximate L-shape [dihedral angle between the five- and six-membered rings = 86.20 (9)°] and features an intra­molecular hypervalent S⋯O inter­action [2.8666 (15) Å]. Overall, the triazine mol­ecule has the shape of a disk as the pendant pyridine rings are relatively close to coplanar with the central ring [dihedral angles = 18.35 (9), 6.12 (9) and 4.67 (9)°]. In the crystal packing, a linear supra­molecular chain aligned along [01-1] is formed as a result of amino–pyridyl N—H⋯N hydrogen bonding with syn-disposed pyridyl mol­ecules of one triazine, and amine–pyridyl N—H⋯N hydrogen bonding with the third pydridyl ring of a second triazine mol­ecule. A three-dimensional architecture arises as the chains are connected by C—H⋯O inter­actions.
PMCID: PMC3998630  PMID: 24826120
10.  7-Chloro-4-(2-hy­droxy­ethyl­amino)­quinolin-1-ium chloride 
In the title salt, C11H12ClN2O+·Cl−, the ten non-H atoms comprising the quinolinium residue are coplanar (r.m.s. deviation = 0.041 Å) and the hy­droxy­ethyl group is approximately perpendicular to this plane [Cring—N—Cmethyl­ene—C torsion angle = −74.61 (18)°]. A supra­molecular chain aligned along [101] mediated by charge-assisted O/N—H⋯Cl− hydrogen bonds features in the crystal packing. Chains are connected into a three-dimensional architecture by C—H⋯O(hy­droxy) inter­actions.
PMCID: PMC3998632  PMID: 24826110
11.  Poly[(μ3-3,5-di­nitro­benzoato-κ3 O 1:O 1′:O 3)(μ2-hydroxido-κ2 O:O)copper(II)] 
The title complex, [Cu{μ3-O2CC6H3(NO2)2-3,5}(μ-OH)]n, features zigzag chains in which successive pairs of CuII atoms are connected by OH bridges and bidentate carboxyl­ate ligands, leading to six-membered Cu(O)(OCO)Cu rings. The zigzag chains are connected into a three-dimensional architecture by Cu—O(nitro) bonds. The coordination geometry of the CuII atom is square-pyramidal, with the axial position occupied by the nitro O atom, which forms the longer Cu—O bond. Bifurcated hy­droxy–nitro O—H⋯O hydrogen bonds contribute to the stability of the crystal structure.
PMCID: PMC3998500  PMID: 24764942
12.  1-Methyl-3-phenyl­imidazolidine-2-thione 
The asymmetric unit of the title cyclic thio­urea derivative, C10H12N2S, comprises two mol­ecules, each of which has a twist about the CH2—CH2 bond within the five-membered ring. The major difference between the independent mol­ecules is manifested in the relative orientations of the five- and six-membered rings [dihedral angles between the least-squares planes = 28.03 (11) and 41.54 (11)°]. A network of C—H⋯π inter­actions consolidates the three-dimensional crystal packing.
PMCID: PMC3998490  PMID: 24765029
13.  4-Nitro­phthalo­nitrile 
In the title compound, C8H3N3O2 (systematic name: 4-nitro­benzene-1,2-dicarbo­nitrile), the nitro group is twisted out of the plane of the benzene ring to which it is attached [O—N—Cring—Cring torsion angle = 9.80 (13)°]. In the crystal packing, supra­molecular layers with a zigzag topology in the ac plane are sustained by C—H⋯N inter­actions.
PMCID: PMC3998506  PMID: 24765021
14.  4-Nitro­phthalamide 
In the title compound, C8H7N3O4 (systematic name: 4-nitro­benzene-1,2-dicarboxamide), each of the substituents is twisted out of the plane of the benzene ring to which it is attached [dihedral angles of 11.36 (2)° for the nitro group, and 60.89 (6) and 34.39 (6)° for the amide groups]. The amide groups are orientated to either side of the least-squares plane through the benzene ring with the amine groups being directed furthest apart. In the crystal, a three-dimensional architecture is established by a network of N—H⋯O hydrogen bonds.
PMCID: PMC3998509  PMID: 24765000
15.  2-(2-Amino-4-nitro­phen­yl)-7-nitro-4H-3,1-benzoxazin-4-one 
In the title compound, C14H8N4O6, the benzoxazin-4-one fused-ring system (r.m.s. deviation = 0.018 Å) is coplanar with the attached benzene ring [dihedral angle = 0.81 (4)°], there being an intra­molecular N—H⋯N hydrogen bond between them. Each nitro group is twisted out of the plane of the attached benzene ring [O—N—C—C torsion angles = 167.94 (11) and 170.38 (11)°]. In the crystal, amine–nitro N—H⋯O hydrogen bonds lead to centrosymmetric dimeric aggregates that are connected into a three-dimensional architecture by oxazin­yl–nitro C—H⋯O and π–π inter­actions [inter-centroid distance between the oxazinyl and terminal benzene rings = 3.5069 (7) Å].
PMCID: PMC3998318  PMID: 24764879
16.  2-[(E)-2-(3,4-Di­chloro­benzyl­idene)hydrazin-1-yl]quinoxaline 
The 21 non-H atoms of the title compound, C15H10Cl2N4, are almost planar (r.m.s. deviation = 0.032 Å); the conformation about the N=C bond [1.277 (6) Å] is E. In the crystal, zigzag supra­molecular chains along the c axis (glide symmetry) are formed via N—H⋯N hydrogen bonds. These associate along the b axis by π–π inter­actions between the fused and terminal benzene rings [inter­centroid distance = 3.602 (3) Å] so that layers form in the bc plane.
PMCID: PMC3998292  PMID: 24764853
17.  5-Chloro-5′′-[4-(di­methyl­amino)­benzyl­idene]-4′-[4-(di­methyl­amino)­phen­yl]-1′,1′′-di­methyl­dispiro­[indoline-3,2′-pyrrolidine-3′,3′′-piperidine]-2,4′′-dione 
The title compound, C34H38ClN5O2, has spiro links connecting the pyrrolidine ring and indole residue, as well as the piperidine and pyrrolidine rings. A half-chair conformation is found for the piperidine ring with the C atom connected to the spiro-C atom lying 0.738 (4) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.0407 Å). The methyl­ene C atom is the flap in the envelope conformation for the pyrrolidine ring. In the crystal, supra­molecular chains are sustained by alternating eight-membered {⋯HNCO}2 and 14-membered {⋯HC5O}2 synthons. Chains are connected into a three-dimensional network by (pyrrolidine-bound phenyl-meth­yl)C—H⋯π(pyrrolidine-bound phen­yl) edge-to-face inter­actions.
PMCID: PMC4029217  PMID: 24855471
18.  5-Chloro-5′′-(4-chloro­benzyl­idene)-4′-(4-chloro­phen­yl)-1′′-ethyl-1′-methyl­dispiro­[indoline-3,2′-pyrrolidine-3′,3′′-piperidine]-2,4′′-dione 
Two spiro links are found in the title compound, C31H28Cl3N3O2, one connecting the piperidine and pyrrolidine rings, and the other connecting the pyrrolidine ring and indole residue. The piperidine ring adopts a half-chair conformation, in which the C atom connected to the spiro-C atom lies 0.741 (3) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.053 Å). The pyrrolidine ring has an envelope conformation with the flap atom being the methyl­ene C atom. Centrosymmetric eight-membered {⋯HNCO}2 amide dimers are the most significant feature of the crystal packing. These are connected into layers parallel to (-120) by C—H⋯O and π–π inter­actions between pyrrolidine-bound benzene rings [inter-centroid distance = 3.8348 (15) Å]. Slipped face-to-face inter­actions between the edges of pyrrolidine-bound benzene [shortest C⋯C separation = 3.484 (4) Å] connect the layers into a three-dimensional architecture.
PMCID: PMC4029214  PMID: 24855468
19.  5′′-Benzyl­idene-5-chloro-1′,1′′-dimethyl-4′-phenyl­dispiro­[indoline-3,2′-pyrrolidine-3′,3′′-piperidine]-2,4′′-dione 
The title compound, C30H28ClN3O2, features two spiro links, one connecting the piperidine and pyrrolidine rings, and the other connecting the pyrrolidine ring and indole residue. The configuration about the ethene bond is E. The piperidine ring adopts a half-chair conformation where the C atom connected to the spiro-C atom lies 0.713 (3) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.086 Å). The pyrrolidine ring has an envelope conformation with the flap atom being the methyl­ene C atom. Centrosymmetric eight-membered {⋯HNCO}2 amide synthons feature in the crystal packing. These are consolidated into a three-dimensional architecture by phen­yl–pyrrolidine C—H⋯N and chloro­benzene–pyrrolidine-bound phenyl C—H⋯π inter­actions.
PMCID: PMC4029213  PMID: 24855467
20.  (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
21.  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
22.  4-Amino-N-(4,6-di­methyl­pyrimidin-2-yl)benzene­sulfonamide–1,4-di­aza­bicyclo­[2.2.2]octane (2/1) 
The asymmetric unit of the title co-crystal, C12H14N4O2S·0.5C6H12N2, comprises the sulfonamide mol­ecule and half a mol­ecule of 1,4-di­aza­bicyclo­[2.2.2]octane (DABCO), the latter being disposed about a crystallographic twofold rotation axis. In the sulfonamide mol­ecule, the aromatic rings are almost perpendicular to one another [dihedral angle = 75.01 (8)°]. In the crystal, mol­ecules are connected into a three-mol­ecule aggregate via amide–DABCO N—H⋯N hydrogen bonds, and these are connected into a three-dimensional architecture via amino–DABCO N—H⋯O and amino-pyrimidine N—H⋯N hydrogen bonds.
PMCID: PMC3884290  PMID: 24454066
23.  2-Amino­benzoic acid–4-[2-(pyridin-4-yl)eth­yl]pyridine (2/1) 
The asymmetric unit of the title co-crystal, C12H12N2·2C7H7NO2, comprises a centrosymmetric 4-[2-(pyridin-4-yl)eth­yl]pyridine mol­ecule and a 2-amino­benzoic acid mol­ecule in a general position. The acid has a small twist between the carb­oxy­lic acid residue and the ring [dihedral angle = 7.13 (6)°] despite the presence of an intra­molecular N—H⋯O(carbon­yl) hydrogen bond. Three-mol­ecule aggregates are formed via O—H⋯N(pyrid­yl) hydrogen bonds, and these are connected into supra­molecular layers in the bc plane by N—H⋯O(carbon­yl) hydrogen bonds and π–π inter­actions between pyridine and benzene rings [inter-centroid distance = 3.6332 (9) Å]. Layers are connected along the a axis by weak π–π inter­actions between benzene rings [3.9577 (10) Å].
PMCID: PMC3884291  PMID: 24454067
24.  4-[2-(Pyridin-1-ium-4-yl)eth­yl]pyridin-1-ium bis­(2,6-di­nitro­benzoate) 
The asymmetric unit of the title salt, C12H14N2 2+·2C7H3N2O6 −, comprises half a 4-[2-(pyridin-1-ium-4-yl)eth­yl]pyridin-1-ium dication, being disposed about a centre of inversion, and a 2,6-di­nitro­benzoate anion, in a general position. In the anion, the carboxyl­ate group is inclined to the benzene ring [dihedral angle = 85.45 (9)°], whereas near-coplanar and twisted arrangements are found for the nitro groups [O—N—C—C torsion angles = 179.80 (14) and 20.2 (2)°]. In the crystal, three-component aggregates sustained by charge-assisted N+—H⋯O− hydrogen bonds are found and these are consolidated into a three-dimensional architecture by C—H⋯O and π–π [inter-centroid distances = 3.6796 (14) and 3.7064 (14) Å] inter­actions.
PMCID: PMC3884282  PMID: 24454058
25.  tert-Butyl 4-{[2-amino-4-(2-hy­droxy­phen­yl)pyrimidin-5-yl]meth­yl}piperazine-1-carboxyl­ate 
In the title compound, C20H27N5O3, the central piperazine ring adopts a chair conformation, with the N-bound carboxyl­ate and methyl­ene substituents occupying bis­ectional and equatorial orientations, respectively. A twist is evident between the aromatic rings [dihedral angle = 25.61 (9)°] but an intra­molecular O—H⋯N hydrogen bond persists between these. Supra­molecular tapes along [1-10] are formed in the crystal packing through N(amino)—H⋯O(hydrox­yl) and N(amino)—H⋯N(pyrimidin­yl) hydrogen bonds, and these are linked into layers in the ab plane by π–π inter­actions [inter-centroid distance between pyrimidinyl rings = 3.5919 (9) Å].
PMCID: PMC3790435  PMID: 24098254

Results 1-25 (591)