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1.  Crystal structure of 2-(4-chloro­phen­yl)-2-oxoethyl 3-bromo­benzoate 
Packing in the title keto ester compound is dominated by the formation of inversion dimers by both non-classical hydrogen bonds and offset π–π stacking inter­actions.
2-(4-Chloro­phen­yl)-2-oxoethyl 3-bromo­benzoate, C15H10BrClO3, was synthesized in a single-step reaction by condensation of 3-bromo­benzoic acid with 2-bromo-1-(4-chloro­phen­yl)ethanone in di­methyl­formamide in the presence of tri­ethyl­amine as a catalyst. The structure consists of an aryl ketone moiety linked to an aryl ester unit by a methyl­ene group. Both units are reasonably planar (r.m.s. deviations of 0.119 and 0.010 Å for the aryl ketone and aryl ester units, respectively) and are almost orthogonal, with an angle of 88.60 (3)° between them. In the crystal, mol­ecules form five separate sets of inversion dimers. Three of these are generated by two C—H⋯O inter­actions and a C—H⋯Br contact, and form chains along c and along the ab cell diagonal. In addition, two inversion-related π–π stacking inter­actions between like aryl rings again form chains of mol­ecules but in this instance along the bc diagonal. These contacts generate infinite layers of mol­ecules parallel to (011) and stack the mol­ecules along the a-axis direction.
doi:10.1107/S1600536814021643
PMCID: PMC4257351  PMID: 25484728
crystal structure; 2-(4-chloro­phen­yl)-2-oxoethyl 3-bromo­benzoate; synthesis; π–π inter­actions; inversion dimers
2.  Eight 7-benzyl-3-tert-butyl-1-phenyl­pyrazolo[3,4-d]oxazines, encompassing structures containing no inter­molecular hydrogen bonds, and hydrogen-bonded structures in one, two or three dimensions 
7-Benzyl-3-tert-butyl-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C22H25N3O, (I), and 3-tert-butyl-7-(4-methyl­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C23H27N3O, (II), are isomorphous in the space group P21, and mol­ecules are linked into chains by C—H⋯O hydrogen bonds. In each of 3-tert-butyl-7-(4-methoxy­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C23H27N3O2, (III), which has cell dimensions rather similar to those of (I) and (II), also in P21, and 3-tert-butyl-1-phenyl-7-[4-(trifluoro­meth­yl)benz­yl]-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C23H24F3N3O, (IV), there are no direction-specific inter­actions between the mol­ecules. In 3-tert-butyl-7-(4-nitro­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C22H24N4O3, (V), a combination of C—H⋯O and C—H⋯N hydrogen bonds links the mol­ecules into complex sheets. There are no direction-specific inter­actions between the mol­ecules of 3-tert-butyl-7-(2,3-dimethoxy­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C24H29N3O3, (VI), but a three-dimensional framework is formed in 3-tert-butyl-7-(3,4-methyl­enedioxy­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C23H25N3O3, (VII), by a combination of C—H⋯O, C—H⋯N and C—H⋯π(arene) hydrogen bonds, while a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds links the mol­ecules of 3-tert-butyl-1-phenyl-7-(3,4,5-trimethoxy­benz­yl)-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C25H31N3O4, (VIII), into complex sheets. In each compound, the oxazine ring adopts a half-chair conformation, while the orientations of the pendent phenyl and tert-butyl substituents relative to the pyrazolo[3,4-d]oxazine unit are all very similar.
doi:10.1107/S0108270109028017
PMCID: PMC2720151  PMID: 19652329
3.  Crystal structures of trans-di­chlorido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-κN 3]iron(II), trans-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-κN 3]iron(II) and trans-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-κN 3]iron(II) diethyl ether disolvate1  
The title compounds are iron(II) dihalide complexes of the bulky arylimidazole ligand 1-(2,6-diisopropylphenyl)-1H-imidazole. The FeCl2 and FeBr2 complexes are isotypic, while the third compound, also an FeBr2 complex, crystallizes as a diethyl ether disolvate.
The title compounds, [FeCl2(C15H20N2)4], (I), [FeBr2(C15H20N2)4], (II), and [FeBr2(C15H20N2)4]·2C4H10O, (IIb), respectively, all have triclinic symmetry, with (I) and (II) being isotypic. The FeII atoms in each of the structures are located on an inversion center. They have octa­hedral FeX 2N4 (X = Cl and Br, respectively) coordination spheres with the FeII atom coordinated by two halide ions in a trans arrangement and by the tertiary N atom of four aryl­imidazole ligands [1-(2,6-diiso­propyl­phen­yl)-1H-imidazole] in the equatorial plane. In the two independent ligands, the benzene and imidazole rings are almost normal to one another, with dihedral angles of 88.19 (15) and 79.26 (14)° in (I), 87.0 (3) and 79.2 (3)° in (II), and 84.71 (11) and 80.58 (13)° in (IIb). The imidazole rings of the two independent ligand mol­ecules are inclined to one another by 70.04 (15), 69.3 (3) and 61.55 (12)° in (I), (II) and (IIb), respectively, while the benzene rings are inclined to one another by 82.83 (13), 83.0 (2) and 88.16 (12)°, respectively. The various dihedral angles involving (IIb) differ slightly from those in (I) and (II), probably due to the close proximity of the diethyl ether solvent mol­ecule. There are a number of C—H⋯halide hydrogen bonds in each mol­ecule involving the CH groups of the imidazole units. In the structures of compounds (I) and (II), mol­ecules are linked via pairs of C—H⋯halogen hydrogen bonds, forming chains along the a axis that enclose R 2 2(12) ring motifs. The chains are linked by C—H⋯π inter­actions, forming sheets parallel to (001). In the structure of compound (IIb), mol­ecules are linked via pairs of C—H⋯halogen hydrogen bonds, forming chains along the b axis, and the diethyl ether solvent mol­ecules are attached to the chains via C—H⋯O hydrogen bonds. The chains are linked by C—H⋯π inter­actions, forming sheets parallel to (001). In (I) and (II), the methyl groups of an isopropyl group are disordered over two positions [occupancy ratio = 0.727 (13):0.273 (13) and 0.5:0.5, respectively]. In (IIb), one of the ethyl groups of the diethyl ether solvent mol­ecule is disordered over two positions (occupancy ratio = 0.5:0.5).
doi:10.1107/S1600536814014056
PMCID: PMC4158527  PMID: 25249858
aryl­imidazole; iron(II); crystal structure
4.  2-Amino-4-(4-chloro­phen­yl)-4H-chromeno[8,7-b]pyridine-3-carbonitrile 
The asymmetric unit of the title compound, C19H12ClN3O, contains two mol­ecules with similar conformations. The 14 non-H atoms comprising the 4H-chromeno[8,7-b]pyridine residue are essentially coplanar (r.m.s. deviations = 0.037 and 0.042 Å for the two mol­ecules) and the main difference between them is seen in the twist about the bond linking the main residue to the attached chloro­benzene rings [dihedral angles = 79.01 (12) and 76.22 (11)° for the two mol­ecules]. Zigzag supra­molecular chains along the a-axis direction mediated by amino–pyridine N—H⋯N hydrogen bonds feature in the crystal packing; these are connected into a three-dimensional architecture by C—H⋯π inter­actions and Cl⋯Cl contacts [Cl⋯Cl = 3.3896 (14) Å].
doi:10.1107/S1600536813005217
PMCID: PMC3629505  PMID: 23634023
5.  4-{2-[5-(4-Chloro­phen­yl)-1-(4-fluoro­phen­yl)-1H-pyrazol-3-yl]thia­zol-4-yl}benzonitrile 
The asymmetric unit of the title compound, C25H14ClFN4S, contains two independent mol­ecules (A and B). Each mol­ecule consists of five rings, namely chloro­phenyl, fluoro­phenyl, 1H-pyrazole, thia­zole and benzonitrile. In mol­ecule A, the 1H-pyrazole ring makes dihedral angles of 52.54 (8), 35.96 (8) and 15.43 (8)° with respect to the attached chloro­phenyl, fluoro­phenyl and thia­zole rings. The corresponding values in mol­ecule B are 51.65 (8), 37.26 (8) and 8.32 (8)°. In the crystal, mol­ecules are linked into dimers by C—H⋯N hydrogen bonds, generating R 2 2(10) ring motifs. These dimers are further linked into two-dimensional arrays parallel to the ab plane via inter­molecular weak C—H⋯N and C—H⋯F hydrogen bonds. The crystal structure is further stabilized by weak π-π inter­actions [with centroid–centroid distances of 3.4303 (9) and 3.6826 (9) Å] and weak C—H⋯π inter­actions.
doi:10.1107/S1600536810031405
PMCID: PMC3007991  PMID: 21588640
6.  rac-4-(4-Chloro­phen­yl)-2-methyl­amino-3-nitro-5,6,7,8-tetra­hydro-4H-chromen-5-one 
The title compound, C16H15ClN2O4, contains a chiral centre and crystallizes as a racemate. The methyl­ene group β-positioned to the carbonyl group is partially (21%) disordered. It flips to the opposite sides of the corresponding six-membered carbocycle by −0.304 (3) and 0.197 (11) Å, producing alternative envelope conformations. The planes of the pyran and chloro­phenyl rings form a dihedral angle of 86.25 (9)°. The mol­ecular structure is characterized by an intra­molecular N—H⋯O inter­action, which generates an S(6) ring motif. The corresponding amino N atom deviates from the plane of the pyran ring by 0.1634 (19) Å. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, forming C(8) chains running parallel to the b-axis direction. The crystal structure also features C—H⋯π inter­actions.
doi:10.1107/S1600536813014530
PMCID: PMC3772485  PMID: 24046628
7.  (E)-1-(4-Amino­phen­yl)-3-(2-chloro­phen­yl)prop-2-en-1-one 
The title compound, C15H12ClNO, a substituted chalcone, adopts an E configuration with respect to the C=C bond of the enone unit. The mol­ecule is not planar, as can be seen from the dihedral angle of 28.9 (2)° between the two rings which are twisted from each other. The enone segment of the mol­ecule is not coplanar with the chloro­phenyl ring, making a dihedral angle of 23.4 (3)° with it. The amino group is also not coplanar with the ring to which it is bound, making a dihedral angle of 35 (4)°. In the crystal structure, adjacent mol­ecules are linked by N—H⋯O inter­actions into one-dimensional infinite chains along the c axis, and are further stacked as one-dimensional zigzag chains down the b axis, forming two-dimensional extended networks parallel to the bc plane.
doi:10.1107/S1600536808030456
PMCID: PMC2959457  PMID: 21201210
8.  Crystal structure of (E)-1,3-dimethyl-2-[3-(3-nitro­phen­yl)triaz-2-en-1-yl­idene]-2,3-di­hydro-1H-imidazole 
The title mol­ecule, a rare example of a π-conjugated triazene, crystallized with two independent mol­ecules in the asymmetric unit. In the crystal, the two independent mol­ecules stack head-to-tail probably due to the presence of the dipole moment of the meta nitro group.
The title compound, C11H12N6O2, a π-conjugated triazene, crystallized with two independent mol­ecules (A and B) in the asymmetric unit. Both mol­ecules have an E conformation about the –N=N– bond and have slightly twisted overall conformations. In mol­ecule A, the imidazole ring is inclined to the benzene ring by 8.12 (4)°, while in mol­ecule B the two rings are inclined to one another by 7.73 (4)°. In the crystal, the independent mol­ecules are linked to each other by C—H⋯O hydrogen bonds, forming –A–A–A– and –B–B–B– chains along [100]. The chains are linked by C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (001). The sheets are linked by further C—H⋯N hydrogen bonds and π–π inter­actions [centroid–centroid distance = 3.5243 (5) Å; involving the imidazole ring of mol­ecule A and the benzene ring of mol­ecule B], forming a three-dimensional framework structure.
doi:10.1107/S1600536814020698
PMCID: PMC4257158  PMID: 25484658
crystal structure; azides; π-conjugated triazene; N-heterocyclic carbene; hydrogen bonds; π–π inter­actions
9.  4-(4-Bromo­phen­yl)-2-methyl­amino-3-nitro-5,6,7,8-tetra­hydro-4H-chromen-5-one 
In the title compound, C16H15BrN2O4, the six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation with the disordered methyl­ene C atom as the flap. The pyran ring is almost orthogonal to the chloro­phenyl ring, making a dihedral angle of 87.11 (12)°. The amine-group N atom deviates significantly from the pyran ring [0.238 (3) Å]. The mol­ecular structure is stabilized by an intra­molecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, which generate C(8) chains running parallel to the b axis. The chains are linked by C—H⋯π inter­actions. The methyl­ene-group C atom of the chromene system that is disordered, along with its attached H atoms and the H atoms on the two adjacent C atoms, has an occupancy ratio of 0.791 (7):0.209 (7).
doi:10.1107/S1600536813012774
PMCID: PMC3685080  PMID: 23795099
10.  1,1′-Methyl­enebis[3-(2,6-diiso­propyl­phen­yl)-3,4,5,6-tetra­hydro­pyrimidin-1-ium] dibromide ethanol monosolvate monohydrate 
In the title methyl­ene-bridged di(tetra­hydro­pyrimidinium) salt, C33H50N4 2+·2Br−·C2H5OH·H2O, the two tetra­hydro­pyrimidinium rings have envelope conformations with the central CH2 C atom as the flap. Their mean planes are inclined to one another by 73.31 (13)° and the attached benzene rings are inclined to one another by 67.39 (15)°. The methylene-C—N bond lengths in the tetra­hydro­pyrimidinium rings are 1.314 (3) and 1.304 (3) Å, values typical for C=N double bonds. The distances between the methyl­ene-bridge C atom and the linked tetra­hydro­pyrimidinium N atom are 1.457 (3) and 1.465 (3) Å, values typical for C—N single bonds. The mol­ecules co-crystallized with H2O and EtOH mol­ecules from the solvent. In the crystal, there is a zigzag chain along [010] of water mol­ecules linked by one of the Br− anions via O—H⋯Br hydrogen bonds. The second Br− anion is hydrogen bonded (O—H⋯Br) to the ethanol solvent mol­ecule. There are also a number of C—H⋯Br and C—H⋯O hydrogen bonds present, leading to the formation of a two-dimensional network lying parallel to the bc plane.
doi:10.1107/S1600536813021004
PMCID: PMC3884396  PMID: 24427021
11.  5-Acetyl-4-(3-hy­droxy­phen­yl)-6-methyl-1,2,3,4-tetra­hydro­pyrimidin-2-one–tris­(hy­droxy­meth­yl)ammonium chloride (2/1) 
The asymmetric unit of the title compound, 2C13H14N2O3·C3H10NO3 +·Cl−, contains two independent mol­ecules (A and B) of the title pyrimidine derivative and one ion-pair of tris­(hy­droxy­meth­yl)ammonium chloride. The pyrimidine ring in each pyrimidine derivative has a half-chair conformation. Its mean plane is inclined to the benzene ring by 87.2 (3)° in mol­ecule A and 85.7 (2)° in mol­ecule B. In the crystal, the pyrimidine derivatives are connected to each other by N—H⋯O hydrogen bonds, forming chains propagating along the b-axis direction. The chains are linked via O—H—Cl hydrogen bonds, forming corrugated sheets lying parallel to the bc plane. The sheets are linked via C—H⋯O hydrogen bonds, forming a three-dimensional framework. The tris­(hy­droxy­meth­yl)ammonium chloride mol­ecules are located in the cages of the framework. There are also further C—H⋯O hydrogen bonds and C—H⋯π inter­actions present in the three-dimensional framework structure. Both the cation and chloride anion of the tris­(hy­droxy­meth­yl)ammonium chloride ion pair are disordered over two positions, with a refined occupancy ratio of 0.418 (8):0.582 (8) for the cation and 0.71 (4):0.29 (4) for the anion.
doi:10.1107/S1600536813030559
PMCID: PMC3885040  PMID: 24454216
12.  2-(2,4-Di­fluoro­phen­yl)-4,5-dimethyl-1-(4-methyl­phen­yl)-1H-imidazole monohydrate 
The asymmetric unit of the title compound, C18H16F2N2·H2O, contains two independent mol­ecules (A and B), and two independent water mol­ecules of crystallization. In mol­ecule A, the imidazole ring makes dihedral angles of 47.46 (7) and 60.98 (6)° with the 2,4-di­fluoro­phenyl and methyl­phenyl rings, respectively. The corresponding angles in mol­ecule B are 45.85 (7) and 62.78 (7)°, respectively. The dihedral angle between the two benzene rings is 64.98 (7)° in mol­ecule A and 65.53 (7)° in mol­ecule B. In the crystal, the two independent mol­ecules are linked by O—H⋯N and O—H⋯O hydrogen bonds, forming chains propagating along [100]. These chains are linked via C—H⋯F hydrogen bonds, forming slab-like two-dimensional networks lying parallel to (001).
doi:10.1107/S1600536813026354
PMCID: PMC3884277  PMID: 24454053
13.  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
14.  Four differently substituted 2-aryl-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepines: hydrogen-bonded structures in one, two and three dimensions 
In (2RS,4SR)-7-chloro-2-exo-(2-chloro-6-fluoro­phen­yl)-2,3,4,5-tetra­hydro-1H-1,4-epoxy-1-benzazepine, C16H12Cl2FNO, (I), mol­ecules are linked into chains by a single C—H⋯π(arene) hydrogen bond. (2RS,4SR)-2-exo-(2-Chloro-6-fluoro­phen­yl)-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C16H13ClFNO, (II), is isomorphous with compound (I) but not strictly isostructural with it, as the hydrogen-bonded chains in (II) are linked into sheets by an aromatic π–π stacking inter­action. The mol­ecules of (2RS,4SR)-7-methyl-2-exo-(4-methyl­phenyl)-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C18H19NO, (III), are linked into sheets by a combination of C—H⋯N and C—H⋯π(arene) hydrogen bonds. (2S,4R)-2-exo-(2-Chloro­phen­yl)-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C16H14ClNO, (IV), crystallizes as a single enantiomer and the mol­ecules are linked into a three-dimensional framework structure by a combination of one C—H⋯O hydrogen bond and three C—H⋯π(arene) hydrogen bonds.
doi:10.1107/S0108270109030339
PMCID: PMC2737425  PMID: 19726863
15.  Ethyl 4-anilino-2,6-bis­(4-chloro­phen­yl)-1-phenyl-1,2,5,6-tetra­hydro­pyridine-3-carboxyl­ate 
The title compound, C32H28Cl2N2O2, was synthesized by a multicomponent reaction of 4-chloro­benzaldehyde, aniline and ethyl aceto­acetate. The central 1,2,5,6-tetra­hydro­pyridine ring exhibits a distorted boat conformation and the two chloro­phenyl rings attached to the central ring at positions 2 and 6 are oriented in opposite directions. The two O atoms of the eth­oxy­carbonyl group are involved in intra­molecular N—H⋯O and C—H⋯O hydrogen bonds. In the crystal, weak C—H⋯O hydrogen bonds link mol­ecules related by translation along the b axis into chains.
doi:10.1107/S1600536813013573
PMCID: PMC3685090  PMID: 23795109
16.  2-Amino-5-chloro­pyridine–fumaric acid (1/2) 
The asymmetric unit of the title compound, C5H5ClN2·0.5C4H4O4, comprises a neutral 2-amino-5-chloro­pyridine mol­ecule and one half of a fumaric acid mol­ecule which lies on an inversion center. The dihedral angle between the pyridine ring and the plane formed by the fumaric acid mol­ecule is 3.22 (8)°. The 2-amino-5-chloro­pyridine mol­ecule is planar, with a maximum deviation of 0.004 (1) Å for the pyridine N atom. In the crystal, the 2-amino-5-chloro­pyridine mol­ecules inter­act with the carboxyl groups of fumaric acid mol­ecules through N—H⋯O and O—H⋯N hydrogen bonds, forming centrosymmetric R 2 2(8) ring motifs and another N—H⋯O hydrogen bond links these motifs into a two-dimensional network parallel to (100).
doi:10.1107/S1600536810018192
PMCID: PMC2979350  PMID: 21579495
17.  N-[4-(Ethyl­sulfamo­yl)phen­yl]acetamide 
The title compound, C10H14N2O3S, crystallized with two mol­ecules (A and B) in the asymmetric unit. The terminal methyl group of the ethyl­sulfonamide moiety in mol­ecule B is disordered over two sets of sites with an occupancy ratio of 0.61 (1):0.39 (1). Both mol­ecules have L-shaped conformations. In mol­ecule A, the dihedral angles between the benzene ring and its ethyl­sulfonamide and methyl­amide substituents are 83.5 (3) and 13.34 (18)°, respectively. Equivalent values for mol­ecule B are 87.9 (3) and 6.32 (16)°, respectively. The C—S—N—C torsion angles are 66.5 (3)° for A and −64.4 (3)° for B, indicating similar twists about the S—N bonds, but in opposite senses. In the crystal, the A mol­ecules are linked by pairs of Ns—H⋯O (s = sulfonamide) hydrogen bonds, generating inversion dimers containing R 2 2(8) rings, while the B mol­ecules are linked by Ns—H⋯O hydrogen bonds into C(10) [100] chains. Finally, Na—H⋯O (a = amide) hydrogen bonds link the A-mol­ecule dimers and B-mol­ecule chains into a three-dimensional network.
doi:10.1107/S1600536811033472
PMCID: PMC3200875  PMID: 22059023
18.  N-(2-Chloro­phen­yl)-N′-(2-methyl­phen­yl)succinamide 
In the title compound, C17H17ClN2O2, the asymmetric unit contains half a mol­ecule with a centre of symmetry at the mid-point of the central C—C bond. The conformations of the amide O atoms are anti to the methyl­ene atoms. Further, the N—H bonds in the amide fragments are anti to the ortho-chloro/methyl groups in the adjacent benzene rings. The dihedral angle between the benzene ring and the NH—C(O)—CH2 segment in the two halves of the mol­ecule is 62.0 (2)°. In the crystal, a series of N—H⋯O inter­molecular hydrogen bonds link the mol­ecules into column-like infinite chains along the a axis. The methyl and Cl groups are disordered with respect to the ortho positions of the benzene ring, with site-occupation factors of 0.5 each.
doi:10.1107/S1600536811035616
PMCID: PMC3201445  PMID: 22065708
19.  3-[5-(4-Chloro­phen­yl)-1-(4-methoxy­phen­yl)-1H-pyrazol-3-yl]propionic acid and the corresponding methyl ester 
The synthesis of 3-[5-(4-chloro­phen­yl)-1-(4-methoxy­phen­yl)-1H-pyrazol-3-yl]propionic acid, C19H17ClN2O3, (I), and its corresponding methyl ester, methyl 3-[5-(4-chloro­phen­yl)-1-(4-methoxy­phen­yl)-1H-pyrazol-3-yl]propionate, C20H19ClN2O3, (II), is regiospecific. However, correct identification of the regioisomer formed by spectroscopic techniques is not trivial and single-crystal X-ray analysis provided the only means of unambiguous structure determination. Compound (I) crystallizes with Z′ = 2. The propionic acid groups of the two crystallographically unique mol­ecules form a hydrogen-bonded dimer, as is typical of carboxylic acid groups in the solid state. Conformational differences between the meth­oxy­benzene and pyrazole rings give rise to two unique mol­ecules. The structure of (II) features just one mol­ecule in the asymmetric unit and the crystal packing makes greater use than (I) of weak C—H⋯A inter­actions, despite the lack of any functional groups for classical hydrogen bonding.
doi:10.1107/S010827010900941X
PMCID: PMC2724994  PMID: 19346614
20.  Phenazine–naphthalene-1,5-diamine–water (1/1/2) 
The asymmetric unit of the title compound, C12H8N2·C10H10N2·2H2O, contains one half-mol­ecule of phenazine, one half-mol­ecule of naphthalene-1,5-diamine and one water mol­ecule. The phenazine and naphthalene-1,5-diamine mol­ecules are located on inversion centers. The water mol­ecules serve as bridges between the naphthalene-1,5-diamine mol­ecules and also between the naphthalene-1,5-diamine and phenazine mol­ecules. The naphthalene-1,5-diamine and water mol­ecules are connected via N—H⋯O and O—H⋯N hydrogen bonds, forming a T4(2) motif. They are arranged into a two-dimensional polymeric structure parallel to (10) in which the water mol­ecule is a single donor and a double acceptor, whereas the amino group is a double donor and a single acceptor in the hydrogen bonding. These two-dimensional assemblies alternate with the layers of phenazine mol­ecules arranged into a herringbone motif. Each phenazine mol­ecule is hydrogen bonded to two water mol­ecules and thus a three-dimensional framework of hydrogen-bonded mol­ecules is generated.
doi:10.1107/S1600536809049009
PMCID: PMC2972038  PMID: 21578891
21.  Chlorido[(E)-2-hydr­oxy-6-(isonicotinoyl­hydrazonometh­yl)phen­yl]mercury(II) monohydrate 
The asymmetric unit of the title compound, [Hg(C13H10N3O2)Cl]·H2O, contains two independent mercury(II) complexes with slightly different conformations, related via a pseudo-inversion centre, and two water mol­ecules. The HgII atoms show a typical linear geometry to a C atom of the benzene ring and to a Cl atom. A benzene C and the azomethine N atom chelate the HgII atoms with weak intra­molecular Hg⋯N bonding distances of 2.735 (3) and 2.739 (3) Å, respectively. The resulting five-membered metallacycles are nearly coplanar with the benzene rings [dihedral angles = 0.9 (1) and 0.7 (1)°], while the pyridine rings make dihedral angles with the benzene units of 58.17 (1) and 56.58 (1)°. In the crystal structure, the HgII complexes are linked by hydr­oxy donor and pyridine acceptor groups into chains along [010]. The water mol­ecules connect the complexes through inter­molecular O—H⋯Ocarbon­yl bonds in the a-axis direction, and the azomethine H atoms donate towards the water O atoms, forming a three-dimensional network of inter­molecular O—H⋯N, O—H⋯O and N—H⋯O hydrogen bonds.
doi:10.1107/S1600536809023824
PMCID: PMC2969284  PMID: 21582756
22.  5,6-Dimethyl-4-(thio­phen-2-yl)-1H-pyrazolo­[3,4-b]pyridin-3-amine 
In the title mol­ecule, C12H12N4S, the thio­phene ring is disordered over two orientations with a refined site-occupancy ratio of 0.777 (4):0.223 (4). The pyrazolo­pyridine ring system is essentially planar with an r.m.s. deviation of 0.0069 (3) Å and makes dihedral angles of 82.8 (2) and 72.6 (5)°, respectively, with the major and minor components of the thio­phene ring. In the crystal, mol­ecules are linked into a chain along the a axis by a pair of N—H⋯N(pyrazole) hydrogen bonds and a pair of N—H⋯N(pyridine) hydrogen bonds, both having a centrosymmetric R 2 2(8) graph-set motif. A C—H⋯π inter­action is also present.
doi:10.1107/S1600536812004126
PMCID: PMC3295413  PMID: 22412524
23.  2-Chloro-8,8-dimethyl-8,9-dihydro-7H-chromeno[2,3-b]quinoline-10,12-dione 
The asymmetric unit of the title compound, C18H14ClNO3, contains two independent mol­ecules (A and B). In both mol­ecules, the cyclo­hexa­none ring has a chair conformation. The dihedral angles between the pyran ring and the pyridine and chloro­phenyl rings are 2.13 (9) and 2.19 (9)°, respectively, in A, and 0.82 (9) and 1.93 (9)°, respectively, in B. The carbonyl O atoms deviate from the pyran and benzene rings to which they are attached by −0.092 (2) and 0.064 (2) Å, respectively, in A, and by −0.080 (2) and −0.063 (2) Å, respectively, in B. In the crystal, the A mol­ecules are linked via C—H⋯O hydrogen bonds, forming double-stranded chains along [100]. They lie parallel to the double-stranded chains formed by the B mol­ecules, which are also linked via C—H⋯O hydrogen bonds. The chains stack up the c axis in an –A–A–B–B–A–A– manner, with a number of π–π inter­actions involving A and B mol­ecules; the centroid–centroid distances vary from 3.4862 (11) to 3.6848 (11) Å
doi:10.1107/S1600536813001062
PMCID: PMC3569785  PMID: 23424531
24.  Crystal structures of 2-benzyl­amino-4-(4-bromo­phen­yl)-6,7,8,9-tetra­hydro-5H-cyclo­hepta­[b]pyridine-3-carbo­nitrile and 2-benzyl­amino-4-(4-chloro­phen­yl)-6,7,8,9-tetra­hydro-5H-cyclo­hepta[b]pyridine-3-carbo­nitrile 
In two cyclo­hepta­[b]pyridine-3-carbo­nitrile derivatives, the cyclo­heptane ring adopts a half-chair conformation. In the crystals of both compounds, pairs of N—H⋯Nnitrile hydrogen bonds link the mol­ecules, forming inversion dimers with (12) ring motifs.
In the title compounds, C24H22BrN3, (I), and C24H22ClN3, (II), the 2-amino­pyridine ring is fused with a cyclo­heptane ring, which adopts a half-chair conformation. The planes of the phenyl and benzene rings are inclined to that of the central pyridine ring [r.m.s. deviations = 0.0083 (1) and 0.0093 (1) Å for (I) and (II), respectively] by 62.47 (17) and 72.51 (14)°, respectively, in (I), and by 71.44 (9) and 54.90 (8)°, respectively, in (II). The planes of the aromatic rings are inclined to one another by 53.82 (17)° in (I) and by 58.04 (9)° in (II). In the crystals of both (I) and (II), pairs of N—H⋯Nnitrile hydrogen bonds link the mol­ecules, forming inversion dimers with R 2 2(12) ring motifs. In (I), the resulting dimers are connected through C—H⋯Br hydrogen bonds, forming sheets parallel to (10-1), and π–π inter­actions [inter-centroid distance = 3.7821 (16) Å] involving inversion-related pyridine rings, forming a three-dimensional network. In (II), the resulting dimers are connected through π–π inter­actions [inter-centroid distance = 3.771 (2) Å] involving inversion-related pyridine rings, forming a two-dimensional network lying parallel to (001).
doi:10.1107/S2056989014025936
PMCID: PMC4331894
crystal structure; cyclo­hepta­[b]pyridine; carbo­nitrile; hydrogen bonding; π–π inter­actions
25.  4-{[(E)-(4-Chloro­phen­yl)methyl­idene]amino}-3-{2-[4-(2-methyl­prop­yl)phen­yl]eth­yl}-1H-1,2,4-triazole-5(4H)-thione 
The asymmetric unit of the title compound, C21H23ClN4S, contains nine crystallographically independent mol­ecules, labelled A to I. The orientation of the 2-[4-(2-methyl­prop­yl)phen­yl]ethyl unit with respect to the rest of the mol­ecule is significantly different in mol­ecules E, F, H and I compared to the other independent mol­ecules. The isobutyl group of mol­ecule B is disordered over two orientations, with occupancies of 0.764 (7) and 0.236 (7). The benzene rings of the chloro­phenyl and methyl­propyl­phenyl units form dihedral angles of 21.90 (11) and 71.47 (11)°, respectively, with the triazole ring in mol­ecule A [9.15 (11) and 80.37 (11)° in B, 7.14 (11) and 84.06 (11)° in C, 25.76 (11) and 76.59 (11)° in D, 13.68 (11) and 76.82 (10)° in E, 8.38 (11) and 69.77 (10)° in F, 30.34 (11) and 78.12 (11)° in G, 21.20 (11) and 71.58 (10)° in H, and 27.65 (11) and 65.23 (11)° in I]. In each independent mol­ecule, a C—H⋯S hydrogen bond is observed. The crystal packing is stabilized by N—H⋯S and C—H⋯S hydrogen bonds, and by C—H⋯π inter­actions involving the methyl­propyl­phenyl ring.
doi:10.1107/S160053680901650X
PMCID: PMC2969595  PMID: 21583109

Results 1-25 (806137)