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1.  A series of N-(2-phenyl­ethyl)nitro­aniline derivatives as precursors for slow and sustained nitric oxide release agents 
A series of N-(2-phenyl­ethyl)nitro­aniline derivatives is presented, demonstrating that modest changes in the functional groups cause significant differences in mol­ecular conformation, inter­molecular inter­actions and packing.
2,4-Di­nitro-N-(2-phenyl­ethyl)aniline, C14H13N3O4, (I), crystallizes with one independent mol­ecule in the asymmetric unit. The adjacent amine and nitro groups form an intra­molecular N—H⋯O hydrogen bond. The anti conformation about the ethyl C—C bond leads to the phenyl and aniline rings being essentially parallel. Mol­ecules are linked into dimers by inter­molecular N—H⋯O hydrogen bonds, such that each amine H atom participates in a three-centre inter­action with two nitro O atoms. Though the dimers pack so that the arene rings of adjacent mol­ecules are parallel, the rings are staggered and π–π inter­actions do not appear to be favoured. 4,6-Di­nitro-N,N′-bis­(2-phenyl­ethyl)benzene-1,3-di­amine, C22H22N4O4, (II), differs from (I) in the presence of a second 2-phenyl­ethyl­amine group on the substituted ring. Compound (II) also crystallizes with one unique mol­ecule in the asymmetric unit. Both amine groups are involved in intra­molecular N—H⋯O hydrogen bonds with adjacent nitro groups. Although one ethyl group adopts an anti conformation as in (I), the other is gauche, with the result that the pendant phenyl rings are not parallel. The amine group that is part of the gauche conformation participates in a three-centre N—H⋯O hydrogen bond with the nitro group of a neighbouring mol­ecule, leading to dimers as in (I). The other amine H atom does not form any inter­molecular hydrogen bonds. The packing leads to separations of ca 3.4 Å of the parallel anti phenyl and amino­benzene rings. 2-Cyano-4-nitro-N-(2-phenyl­ethyl)aniline, C15H13N3O2, (III), differs from (I) only in having a cyano group in place of the 2-nitro group. The absence of the adjacent nitro group eliminates the intra­molecular N—H⋯O hydrogen bond. Mol­ecules of (III) adopt the same anti conformation about the ethyl group as in (I), but crystallize in the higher-symmetry monoclinic space group P21/n. The mol­ecules are linked into dimers via N—H⋯N amine–cyano hydrogen bonds, while the nitro groups are not involved in any N—H⋯O inter­actions. Owing to the different symmetry, the mol­ecules pack in a herringbone pattern with fewer face-to-face inter­actions between the rings. The closest such inter­actions are about 3.5 Å between rings that are largely slipped past one another. 4-Methyl­sulfonyl-2-nitro-N-(2-phenyl­ethyl)aniline, C15H16N2O4S, (IV), differs from (I) in having a methyl­sulfonyl group in place of the 4-nitro group. The intra­molecular N—H⋯O hydrogen bond is present as in (I). However, unlike (I), the conformation about the ethyl group is gauche, so the two arene rings are nearly per­pen­dicular rather than parallel. The packing is significantly different from the other three structures in that there are no inter­molecular hydrogen bonds involving the N—H groups. The mol­ecules are arranged in tetra­gonal columns running along the c axis, with the aniline rings mostly parallel and separated by ca 3.7 Å. Taken together, these structures demonstrate that modest changes in functional groups cause significant differences in mol­ecular conformation, inter­molecular inter­actions and packing.
doi:10.1107/S0108270113025869
PMCID: PMC3818095  PMID: 24192194
crystal structure; N-(2-phenyl­ethyl)nitro­aniline derivatives; secondary amines; nitric oxide release agents
2.  Crystal structure of 1-(3-chloro­phen­yl)piperazin-1-ium picrate–picric acid (2/1) 
The title salt {systematic name: bis­[1-(3-chloro­phen­yl)piperazinium 2,4,6-tri­nitro­phenolate]–picric acid (2/1)}, 2C10H14ClN2 +·2C6H5N3O7 −·C6H6N3O7, crystallized with two independent 1-(3-chloro­phen­yl)piperazinium cations, two picrate anions and a picric acid mol­ecule in the asymmetric unit. The six-membered piperazine ring in each cation adopts a slightly distorted chair conformation and contains a protonated N atom. In the picric acid mol­ecule, the mean planes of the nitro groups in the ortho-, meta-, and para-positions are twisted from the benzene ring by 31.5 (3), 7.7 (1), and 3.8 (2)°, respectively. In the anions, the dihedral angles between the benzene ring and the ortho-, meta-, and para-nitro groups are 36.7 (1), 5.0 (6), 4.8 (2)°, and 34.4 (9), 15.3 (8), 4.5 (1)°, respectively. The nitro group in one anion is disordered and was modeled with two sites for one O atom with an occupancy ratio of 0.627 (7):0.373 (7). In the crystal, the picric acid mol­ecule inter­acts with the picrate anion through a trifurcated O—H⋯O four-centre hydrogen bond involving an intra­molecular O—H⋯O hydrogen bond and a weak C—H⋯O inter­action. Weak inter­molecular C—H⋯O inter­actions are responsible for the formation of cation–anion–cation trimers resulting in a chain along [010]. In addition, weak C—H⋯Cl and weak π–π inter­actions [centroid–centroid distances of 3.532 (3), 3.756 (4) and 3.705 (3) Å] are observed and contribute to the stability of the crystal packing.
doi:10.1107/S1600536814023654
PMCID: PMC4257327  PMID: 25484834
crystal structure; piperazin-1-ium; picrate; picric acid; salt
3.  Ethyl 4-(2-hydroxy­ethyl­amino)-3-nitro­benzoate 
In the title compound, C11H14N2O5, the mol­ecular structure is stabilized by an intra­molecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. The nitro group is twisted slightly from the attached benzene ring, forming a dihedral angle of 5.2 (2)°. In the crystal packing, inter­molecular O—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network. The crystal studied was a non-merohedral twin, the refined ratio of the twin components being 0.264 (2):0.736 (2).
doi:10.1107/S1600536810008147
PMCID: PMC2983846  PMID: 21580671
4.  2,25-Dioxo-27,28-diphenyl-30-oxa-29-thia-3,10,17,24-tetra­aza­penta­cyclo­[24.2.1.112,15.04,9.018,23]triaconta-5,7,9(4),10,12,14,16,18,20,22,26,28-dodeca­ene chloro­form disolvate 
The macrocycle of the title compound, C36H24N4O3S·2CHCl3, contains a rigid framework with the nitro­gen and oxygen heteroatoms pointing in towards the center of the macrocyclic cavity. The macrocycle is essentially planar (r.m.s. deviation = 0.027 Å) except for the thio­phene ring. The dihedral angle between the thio­phene ring plane and the mean plane of the central macrocyclic core including all atoms except sulfur is 21.6 (1)°. Four intra­molecular hydrogen bonds occur: two are between the amide hydrogen atoms and the Schiff base nitro­gen atoms, while the others are between the amide hydrogen atoms and the sulfur atom of the thio­phene. The two solvate chloro­form mol­ecules are bound to the carbonyl oxygen atoms of the ligand by weak C—H⋯O hydrogen bonding. In addition, the structure reveals inter­molecular Cl⋯Cl close contacts [3.308 (2), 3.404 (2) and 3.280 (2) Å] between the chloro­form solvate mol­ecules. In the crystal, the macrocycles form layers parallel to (101), with an inter­layer distance of 3.362 (3) Å. This short distance is determined by the stacking inter­actions between the amide carbonyl and imine fragments of neighboring ligands.
doi:10.1107/S1600536810006173
PMCID: PMC2983673  PMID: 21580409
5.  Isolation of 3-amino-4-nitro­benzyl acetate: evidence of an undisclosed impurity in 5-amino-2-nitro­benzoic acid 
The crystal stucture of 3-amino-4-nitro­benzyl displays intra­molecular resonance-assisted hydrogen bonding between the ortho amino and nitro groups in addition to an inter­molecular network of hydrogen bonding and π-stacking.
Yellow crystals of the title compound 3-amino-4-nitro­benzyl acetate, C9H10N2O4, were isolated from the reaction of acetic anhydride with (5-amino-2-nitro­phen­yl)methanol, prepared from reduction of commerically available 5-amino-2-nitro­benzoic acid with borane–THF. The mol­ecule is essentially planar (r.m.s. deviation = 0.028 Å). The mol­ecules are linked by inter­molecular N—H⋯O hydrogen-bonding inter­actions between the carbonyl and amine groups, forming a zigzag chain along the b-axis direction lying in a plane parallel to (-102). The chains are stacked along the c axis by π–π inter­actions [centroid–centroid distances = 3.6240 (3) and 3.5855 (4) Å]. A strong intra­molecular N—H⋯O hydrogen-bonding inter­action is observed between the nitro group and the amine group [2.660 (2) Å].
doi:10.1107/S2056989015008750
PMCID: PMC4459301  PMID: 26090132
crystal structure; 3-amino-4-nitro­benzyl acetate; intra­molecular; inter­molecular; resonance-assisted hydrogen bonding; 5-amino-2-nitro­benzoic acid
6.  Crystal structures of five (2-chloro­quinolin-3-yl)methyl ethers: supra­molecular assembly in one and two dimensions mediated by hydrogen bonding and π–π stacking 
Five closely related (2-chloro­quinlin-3-yl)methyl ethers all exhibit different patterns of direction-specific inter­molecular inter­actions, leading to the formation of different types of chain in four of them and sheets in the fifth.
In the mol­ecules of the title compounds, methyl 5-bromo-2-[(2-chloro­quinolin-3-yl)meth­oxy]benzoate, C18H13BrClNO3, (I), methyl 5-bromo-2-[(2-chloro-6-methyl­quinolin-3-yl)meth­oxy]benzoate, C19H15BrClNO3, (II), methyl 2-[(2-chloro-6-methyl­quinolin-3-yl)meth­oxy]benzoate, C19H16ClNO3, (III), which crystallizes with Z′ = 4 in space group P212121, and 2-chloro-3-[(naphthalen-1-yl­oxy)meth­yl]quinoline, C20H14ClNO, (IV), the non-H atoms are nearly coplanar, but in {5-[(2-chloro­quinolin-3-yl)meth­oxy]-4-(hy­droxy­meth­yl)-6-methyl­pyridin-3-yl}methanol, C18H17ClN2O3, (V), the planes of the quinoline unit and of the unfused pyridine ring are almost parallel, although not coplanar. The mol­ecules of (I) are linked by two independent π–π stacking inter­actions to form chains, but there are no hydrogen bonds present in the structure. In (II), the mol­ecules are weakly linked into chains by a single type of π–π stacking inter­action. In (III), three of the four independent mol­ecules are linked by π–π stacking inter­actions but the other mol­ecule does not participate in such inter­actions. Weak C—H⋯O hydrogen bonds link the mol­ecules into three types of chains, two of which contain just one type of independent mol­ecule while the third type of chain contains two types of mol­ecule. The mol­ecules of (IV) are linked into chains by a C—H⋯π(arene) hydrogen bond, but π–π stacking inter­actions are absent. In (V), there is an intra­molecular O—H⋯O hydrogen bond, and mol­ecules are linked into sheets by a combination of O—H⋯N hydrogen bonds and π–π stacking inter­actions.
doi:10.1107/S2056989015008233
PMCID: PMC4459322  PMID: 26090133
crystal structure; 2-chloro­quinolines; mol­ecular conformation; hydrogen bonding; π–π stacking inter­actions
7.  4-Butyl­amino-3-nitro­benzoic acid 
The asymmetric unit of the title compound, C11H14N2O4, comprises four crystallographically independent mol­ecules (A, B, C and D) with similar geometries. In each mol­ecule, the butyl­amino side chain is in an extended conformation, and the carboxyl and butyl­amino groups are almost coplanar with the attached benzene ring; the nitro group is slightly twisted away from the benzene ring. In the asymmetric unit, the benzene rings of mol­ecules A, B and C are stacked parallel to one another, with a centroid–centroid distance of 3.6197 (11) or 3.6569 (11) Å, indicating π–π inter­actions. An intra­molecular N—H⋯O hydrogen bond is observed in each independent mol­ecule. In addition to the π–π inter­actions, the crystal packing is consolidated by inter­molecular O—H⋯O and C—H⋯O hydrogen bonds and C—H⋯π inter­actions. The crystal studied was a non-merohedral twin. The minor twin component refined to a value of 0.290 (1).
doi:10.1107/S1600536809014780
PMCID: PMC2977797  PMID: 21583933
8.  N-(4-Methyl-2-nitro­phen­yl)succinamic acid 
In the title compound, C11H12N2O5, the conformation of the N—H bond in the amide segment is syn to the ortho-nitro group in the benzene ring. The amide C=O and the carboxyl C=O of the acid segment are syn to each other and both are anti to the H atoms on the adjacent –CH2 groups. Furthermore, the C=O and O—H bonds of the acid group are in syn positions with respect to each other. The dihedral angle between the benzene ring and the amide group is 36.1 (1)°. The amide H atom shows bifurcated intra­molecular hydrogen bonding with an O atom of the ortho-nitro group and an inter­molecular hydrogen bond with the carbonyl O atom of another mol­ecule. In the crystal, the N—H⋯O(C) hydrogen bonds generate a chain running along the [100] direction. Inversion dimers are formed via a pair of O—H⋯O(C) interactions, that form an eight-membered hydrogen-bonded ring involving the carboxyl group.
doi:10.1107/S1600536812007258
PMCID: PMC3297880  PMID: 22412683
9.  Ethyl 5-amino-1-(4-chloro-2-nitro­phen­yl)-1H-pyrazole-4-carboxyl­ate 
In the mol­ecule of the title compound, C12H11ClN4O4, the pyrazole ring is coplanar with the amino and ethoxy­carbonyl groups within 0.026 (2) and 0.105 (2) Å, respectively. The C 6 ring of the 4-chloro-2-nitro­phenyl group is twisted by 53.58 (4)° relative to the plane of the pyrazole ring. The planar structure of the pyrazole ring is stabilized by an intra­molecular N—H⋯O hydrogen bond between its substituents. Neighbouring mol­ecules are linked through inter­molecular N—H⋯N and N—H⋯O hydrogen bonds, giving rise to one-dimensional tapes along the b axis. Mol­ecules in the chain are linked to those of an adjacent chain through weak C—H⋯O inter­actions, forming a three-dimensional network.
doi:10.1107/S1600536809000488
PMCID: PMC2968147  PMID: 21581889
10.  2-(4-Chloro-2-nitro­phen­yl)-9-phenyl­sulfonyl-9H-carbazole-3-carbaldehyde 
In the title compound, C25H15ClN2O6S, the carbazole ring system is essentially planar, with a maximum deviation of 0.152 (3) Å for the C atom to which the 4-chloro-2-nitro­phenyl ring is attached. Its mean plane is almost orthogonal to the phenyl­sulfonyl and nitro­phenyl rings, making dihedral angles of 82.64 (14) and 79.89 (13)°, respectively. The N atom of the nitro group deviates by 0.032 (3) Å from the benzene ring to which it is attached. The mol­ecular structure features intra­molecular O—H⋯O and C—H⋯O hydrogen bonds, which generate three S(6) ring motifs. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, which generate C(6) and C(9) chains running in the [100] and [010] directions, respectively, forming a two-dimensional network lying parallel to (001). There are also R 4 3(28) supra­molecular graph-set ring motifs enclosed within these networks.
doi:10.1107/S1600536813022253
PMCID: PMC3884462  PMID: 24427055
11.  1-(2-Chloro-5-nitro­phen­yl)-3-(2,2-di­methyl­propion­yl)thio­urea 
With the exception of the C atoms of two of the methyl groups of the tert-butyl substituent, all of the non-H atoms of the title compound, C12H14ClN3O3S, lie on a mirror plane. The 2-chloro-5-nitro­phenyl and 2,2-dimethyl­propionyl substituents are, respectively, cis and trans relative to the thio­carbonyl S atom across the two C—N bonds. Intra­molecular N—H⋯O and C—H⋯S hydrogen bonds form S(6) ring motifs, also in the mirror plane. Despite the presence of two N—H subsituents, no inter­molecular hydrogen bonds are observed in the crystal structure. Weak π–π contacts [centroid–centroid distances of 4.2903 (17) Å] involving adjacent aromatic rings link the mol­ecules in a head-to-tail fashion above and below the mol­ecular plane.
doi:10.1107/S1600536809024672
PMCID: PMC2977335  PMID: 21583450
12.  Dichloridobis(N,N′-diethyl­thio­urea-κS)mercury(II) 
There are two mol­ecules in the asymmetric unit of the title compound, [HgCl2(C5H12N2S)2]. In both mol­ecules, the N,N′-diethyl­thio­urea ligands exhibit a cis,trans geometry around their C—N amide bonds. The shapes of the mol­ecules are, to a large extent, determined by intra­molecular N—H⋯Cl hydrogen bonds formed by the N—H groups from the cis amide groups. In one mol­ecule, these groups are involved in three-center hydrogen bonds involving both chloride ligands, whereas in the other mol­ecule only one Cl ligand takes part in intra­molecular hydrogen bonding. The coordination around the Hg atom is distorted tetra­hedral with an S2Cl2 donor set. Inter­molecular hydrogen bonds between N—H groups from the trans amide units of the thio­amide ligands and the chloride ligands connect the mol­ecules into a polymeric chain extending along the c axis. One of the ethyl groups of the N,N′-diethyl­thio­urea ligands is disordered over two positions in one of the mol­ecules, with an occupancy of 0.654 (17) for the major component.
doi:10.1107/S1600536810028825
PMCID: PMC3007422  PMID: 21588084
13.  Ethyl 2-[3-(4-nitro­benzo­yl)thio­ureido]benzoate 
In the title compound, C17H15N3O5S, the nitro and thio­ureido groups are twisted by 7.2 (7) and 21.4 (2)°, respectively, from the nitro­benzene ring plane whereas the thio­ureido and the ethyl ester group make dihedral angles of 43.0 (1) and 18.0 (2)°, respectively, with the benzene rings to which they are attached. Intra­molecular N—H⋯O hydrogen-bonding inter­actions are observed. In the crystal, inter­molecular N—H⋯O hydrogen bonds connect the mol­ecules into chains running along the a axis.
doi:10.1107/S1600536810011116
PMCID: PMC2984025  PMID: 21580777
14.  Relative substituent orientation in the structure of cis-3-chloro-1,3-dimethyl-N-(4-nitro­phen­yl)-2-oxo­cyclo­pentane-1-carboxamide 
The crystal structure of the title compound allowed the cis substituent orientation on the cyclo­penta­none ring to be established. The mol­ecular conformation and crystal packing are governed by a network of hydrogen bonds and by π–π stacking.
The structure of the title compound, C14H15ClN2O4, prepared by reaction of a methacryloyl dimer with nitro­aniline, was determined to establish the relative substituent orientation on the cyclo­penta­none ring. In agreement with an earlier proposed reaction mechanism, the amide group and the methyl group adjacent to the chloro substituent adopt equatorial positions and relative cis orientation, whereas the Cl substituent itself and the methyl group adjacent to the amide have axial orientations relative to the mean plane of the five-membered ring. The conformation of the mol­ecule is stabilized by one classical N—H⋯O (2.18 Å) and one non-classical C—H⋯O (2.23 Å) hydrogen bond, each possessing an S(6) graph-set motif. The crystal packing is defined by several non-classical intra­molecular hydrogen bonds, as well as by partial stacking of the aromatic rings.
doi:10.1107/S1600536814017711
PMCID: PMC4186136  PMID: 25309157
crystal structure; hydrogen bonds; π–π stacking; methacryloyl chloride dimer; Diels–Alder reaction
15.  Ferrocene-1-carbaldehyde 4-ethyl­thio­semi­carbazone 
The asymmetric unit of title compound, [Fe(C5H5)(C9H12N3S)], contains two crystallographically independent mol­ecules, A and B. The two cyclo­penta­dienyl (Cp) rings are parallel to each other in both mol­ecules, forming dihedral angles of 2.3 (3) and 1.0 (3)°, respectively, and adopt an eclipsed conformation. The mean plane of the semicarbazone group is twisted slightly away from the attached Cp ring in both mol­ecules, the dihedral angles between the mean plane and the Cp ring being 15.3 (2) and 10.8 (2)°. The ethyl group in mol­ecule A is coplanar with the mean plane of the semicarbazone group [C—N—C—C torsion angle = −175.2 (4)°], whereas it is nearly perpendicular in mol­ecule B [C—N—C—C torsion angle = 84.8 (6)°]. In the crystal structure, inter­molecular N—H⋯S hydrogen bonds link the mol­ecules into dimers. These dimers are further linked into chains via inter­molecular C—H⋯S hydrogen bonds. The crystal studied was a non-merohedral twin with a refined ratio of the twin components of 0.265 (2):0.735 (2).
doi:10.1107/S1600536810018209
PMCID: PMC2979492  PMID: 21579333
16.  (E)-2-[(2-Hydr­oxy-5-nitro­phen­yl)iminiometh­yl]-4-nitro­phenolate 
The title mol­ecule, C13H9N3O6, consists of a 2-hydr­oxy-5-nitro­phenyl­iminio group and a 4-nitro­phenolate group bonded to a methyl­ene C atom with both of the planar six-membered rings nearly in the plane of the mol­ecule [dihedral angle = 1.3 (4)°]. Each of the nitro O atoms is twisted slightly out of the plane of the mol­ecule. The amine group forms an intra­molecular hydrogen bond with both nearby O atoms, each of which has partial occupancy of attached H atoms [0.36 (3) and 0.64 (3)]. An extended π-delocalization throughout the entire mol­ecule exists producing a zwitterionic effect in this region of the mol­ecule. The shortened phenolate C—O bond [1.2749 (19)°], in concert with the slightly longer phenol C—O bond [1.3316 (19) Å], provides evidence for this effect. The crystal packing is influenced by extensive strong inter­molecular O—H⋯O hydrogen bonding between the depicted phenolate and hydr­oxy O atoms and their respective H atoms within the π-delocalized region of the mol­ecule. As a result, mol­ecules are linked into an infinite polymeric chain diagonally along the [110] plane of the unit cell in an alternate inverted pattern. A MOPAC AM1 calculation provides support for these observations.
doi:10.1107/S1600536809000543
PMCID: PMC2968345  PMID: 21581902
17.  Methyl (2Z)-3-[(4-nitro­phen­yl)carbamo­yl]prop-2-enoate 
In the title compound, C11H10N2O5, the amide group is nearly coplanar and the ester group approximately perpendicular to the vinyl C—HC=CH—C group [dihedral angles of 5.0 (2) and 88.89 (5)°, respectively]. This results in a short intra­molecular O =C⋯O=C contact of 2.7201 (17) Å between the amide O atom and the ester carbonyl C atom. The prop-2-enamide fragment and the nitro group make dihedral angles of 20.42 (6) and 13.54 (17)°, respectively, with the benzene ring. An intra­molecular C—H⋯O inter­action between the benzene ring and the amide group generates an S(6) ring motif. Inter­molecular C—H⋯O and N—H⋯O hydrogen bonds complete R 2 2(11) ring motifs and join mol­ecules into [100] chains.
doi:10.1107/S1600536810050956
PMCID: PMC3050372  PMID: 21522788
18.  1-(3-Chloro­phen­yl)-3-(4-nitro­phen­yl)urea 
In the title compound, C13H10ClN3O3, prepared by the reaction of 1-chloro-3-isocyanato­benzene with 4-nitro­benzenamine, the two substituent benzene rings are roughly coplanar [inter-ring dihedral angle = 8.70 (7)°]. In the crystal, mol­ecules make cyclic inter­molecular associations through two urea–nitro N—H⋯O hydrogen bonds, forming a chain structure [give chain direction] in which there are also weak inter­molecular C—H⋯Cl inter­actions. The urea O atom has only intra­molecular aromatic ring C—H⋯O associations.
doi:10.1107/S1600536810040201
PMCID: PMC3009072  PMID: 21589003
19.  N-(3-Nitro­phen­yl)maleamic acid 
In the title compound, C10H8N2O5, the mol­ecule is slightly distorted from planarity. The mol­ecular structure is stabilized by two intra­molecular hydrogen bonds. The first is a short O—H⋯O hydrogen bond (H⋯O distance = 1.57 Å) within the maleamic acid unit and the second is a C—H⋯O hydrogen bond (H⋯O distance = 2.24 Å) which connects the amide group with the benzene ring. The nitro group is twisted by 6.2 (2)° out of the plane of the benzene ring. The crystal structure manifests a variety of hydrogen bonding. The packing is dominated by a strong inter­molecular N—H⋯O inter­action which links the mol­ecules into chains running along the b axis. The chains within a plane are further assembled by three additional types of inter­molecular C—H⋯O hydrogen bonds to form a sheet parallel to the (01) plane.
doi:10.1107/S1600536810022245
PMCID: PMC3007040  PMID: 21587897
20.  Crystal structure of 2-hy­droxy­imino-2-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethyl­idene]acetohydrazide 
The mol­ecule of the title compound is approximately planar with the planes of the two pyridine rings inclined to one another by 5.51 (7)°. In the crystal, mol­ecules are linked by bifurcated O—H⋯(O,N) hydrogen bonds, forming inversion dimers, which are in turn linked via C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (502).
The mol­ecule of the title compound, C14H13N5O2, is approximately planar (r.m.s deviation for all non-H atoms = 0.093 Å), with the planes of the two pyridine rings inclined to one another by 5.51 (7)°. The oxime group is syn to the amide group, probably due to the formation of an intra­molecular N—H⋯N hydrogen bond that forms an S(6) ring motif. In the crystal, mol­ecules are linked by pairs of bifurcated O—H⋯(O,N) hydrogen bonds, forming inversion dimers. The latter are linked via C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (502). The sheets are linked via π–π stacking inter­actions [inter-centroid distance = 3.7588 (9) Å], involving the pyridine rings of inversion-related mol­ecules, forming a three-dimensional structure.
doi:10.1107/S1600536814025793
PMCID: PMC4257442  PMID: 25552998
crystal structure; hy­droxy­imino; acetohydrazide; pyridyl­ethyl­idene; hydrogen bonding; π–π stacking inter­actions
21.  Ethyl 2-{3-[(2-chloro-1,3-thia­zol-5-yl)meth­yl]-4-nitro­imino-1,3,5-triazinan-1-yl}acetate 
In the title compound, C11H15ClN6O4S, which belongs to the neonicotinoid class of insecticidally active heterocyclic compounds, the six-membered triazine ring adopts an opened envolope conformation. The planar nitro imine group [dihedral angle between nitro and imine groups = 1.07 (7)°] and the thia­zole ring are oriented at a dihedral angle of 69.62 (8)°. A classical intra­molecular N—H⋯O hydrogen bond is found in the mol­ecular structure. Moreover, one classical inter­molecular N—H⋯N and four non-classical C—H⋯O and C—H⋯N hydrogen bonds are also present in the crystal structure. Besides inter­molecular hydrogen bonds, the Cl atom forms an inter­molecular short contact [3.020 (2) Å] with one of the nitro O atoms.
doi:10.1107/S1600536810018878
PMCID: PMC2979404  PMID: 21579526
22.  N-(3,5-Dimethyl­phen­yl)-2-nitro­benzene­sulfonamide 
The asymmetric unit of the title compound, C14H14N2O4S, consists of two crystallographically independent mol­ecules. The mol­ecules are twisted at the S—N bonds with C—S—N—C torsion angles of 44.2 (3) and −49.3 (3)°. The dihedral angles between the benzene rings in the two mol­ecules are 71.53 (7) and 72.11 (7)°. The amide H atoms exhibit bifurcated intra- and inter­molecular hydrogen bonds; the intra­molecular N—H⋯O(N) hydrogen bonds generate S(7) motifs. In the crystal, the independent mol­ecules are separately connected through the inter­molecular N—H⋯O(S) hydrogen bonds, generating a C(4) motif and a helical chain along the b axis for one mol­ecule and an R 2 2(8) motif and an inversion dimer for the other. The crystal studied was a pseudo-merohedral twin with twin law (-100/0-10/001), the refined ratio of the twin domains being 0.7876 (12):0.2124 (12).
doi:10.1107/S1600536812036926
PMCID: PMC3470185  PMID: 23125629
23.  (E)-1-[1-(2-Chloro­phen­yl)ethyl­idene]-2-(2,4-dinitro­phen­yl)hydrazine 
The title mol­ecule, C14H11ClN4O4, is in an E configuration and is twisted with the dihedral angle between the two benzene rings being 38.48 (8)°. The ethyl­idenehydrazine plane makes dihedral angles of 6.03 (10) and 44.04 (11)°, respectively, with the dinitro- and chloro-substituted benzene rings. The two nitro groups are essentially coplanar with the bound benzene ring, making dihedral angles of 0.9 (2) and 1.65 (18)°. An intra­molecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, mol­ecules are linked by a weak C—H⋯O inter­action into a chain along the c axis. The chains are further stacked along the b axis by a π–π inter­action with a centroid–centroid distance of 3.6088 (10) Å.
doi:10.1107/S160053681105001X
PMCID: PMC3239123  PMID: 22199971
24.  Ethyl 2-(4-nitro­benzamido)­benzoate, a non-merohedral twin 
In the title compound, C16H14N2O5, a non-merohedral twin, the dihedral angle between the mean planes of the two benzene rings is 4.0 (9)°. The ethyl group is disordered [0.643 (14) and 0.357 (14) occupancy]. The nitro group is twisted by 16.4 (4)° from the mean plane of the benzene ring and the mean plane of the carbonyl group is twisted from the mean planes of the two benzene rings by 4.5 (0) and 4.7 (9)°. An intra­molecular N—H⋯O hydrogen bond occurs. The crystal packing is stabilized by weak inter­molecular C—H⋯O hydrogen-bond inter­actions.
doi:10.1107/S1600536811002236
PMCID: PMC3051796  PMID: 21523125
25.  (4-Chloro­phen­yl)[1-(4-methoxy­phen­yl)-3-(5-nitro-2-fur­yl)-1H-pyrazol-4-yl]methanone 
In the title compound, C21H14ClN3O5, an intra­molecular C—H⋯O hydrogen bond generates an S(7) ring motif and the furan and pyrazole rings are almost coplanar, making a dihedral angle of 1.98 (5)°. The pyrazole ring is inclined at dihedral angles of 47.59 (4) and 7.27 (4)° to the chloro­phenyl and methoxy­phenyl groups, respectively. The nitro group is almost coplanar to its attached furan ring [dihedral angle = 2.03 (12)°]. In the crystal, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network. The crystal structure also features short inter­molecular O⋯N [2.8546 (12) Å] and Cl⋯O [3.0844 (9) Å] contacts as well as aromatic π–π stacking inter­actions [centroid–centroid distance = 3.4367 (6) Å].
doi:10.1107/S1600536810011931
PMCID: PMC2979246  PMID: 21579120

Results 1-25 (680336)