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1.  Crystal structure of (E)-4-hy­droxy-N′-(3-hy­droxy­benzyl­idene)benzohydrazide monohydrate 
In the title benzohydrazide hydrate, C14H12N2O3·H2O, the dihedral angle between the aromatic rings is 58.11 (6)° and the C=O and N—H groups adopt an anti orientation. The main twist in the mol­ecule occurs about the C(=O)—Car (ar = aromatic) bond, with an N—C(=O)—Car—Car torsion angle of −43.5 (2)°. In the crystal, the components are linked by N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds. These inter­actions generate [10-1] chains, with adjacent organic mol­ecules linked by inversion symmetry generating either pairs of N—H⋯O links [R 2 2(16) loops] or pairs of O—H⋯O links [R 2 2(20) loops]. Pairs of water mol­ecules are located in the R 2 2(20) loops and form their own O—H⋯O and O—H⋯N hydrogen bonds to adjacent organic mol­ecules in the chain. Finally, an inter­chain O—H⋯O hydrogen-bond link from the 4-hy­droxy group generates (010) sheets.
PMCID: PMC4186143  PMID: 25309238
crystal structure; benzohydrazide; hydrate; hydrogen bonding
2.  Crystal structures of potassium tri­fluorido­(4-meth­oxy­phen­yl)borate and potassium tri­fluorido(4-fluoro­phen­yl)borate 
Despite their different compositions and space groups, the irregular KF8 coordination polyhedra of the potassium cations in these structures are almost identical. The layer stacking sequences are AAA… in the p-methoxy compound and ABAB… in the p-fluoro compound.
The title compounds, K+·C7H7BF3O−, (I), and K+·C6H4BF4 −, (II), are mol­ecular salts containing para-substituted phenyl­tri­fluorido­borate anions. In each compound, the B atom adopts a distorted tetra­hedral BCF3 geometry. Despite their different compositions and space groups, the irregular KF8 coordination polyhedra of the potassium cations in the structures are almost identical. These polyhedra share faces and edges, generating infinite (010) layers in (I) and infinite (001) layers in (II). In (I), adjacent layers are stacked in an AAA… fashion, whereas in (II), they are stacked in an ABAB… sequence.
PMCID: PMC4158529  PMID: 25249857
crystal structure; boron; Lewis acid; layered structure
3.  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
4.  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
5.  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
6.  3,3-Dimethyl-cis-9a,13a-diphenyl-2,3,9a,11,12,13a-hexa­hydro-1H-benzo[h][1,4]dioxino[2′,3′:5,6][1,4]dioxino[2,3-f]chromene 
In the title di­hydro­dioxin, C31H28O5, the dioxane ring has a chair conformation, whereas each of the pyran and dioxine rings has an envelope conformation with methyl­ene and quaternary C atoms, respectively, being the flap atoms. The phenyl rings are cis and form a dihedral angle of 82.11 (10)°. The molecular structure is stabilized by C—H⋯O contacts. In the crystal packing, supra­molecular layers parallel to (101) are sustained by C—H⋯π inter­actions.
PMCID: PMC3884479  PMID: 24427106
7.  (2E)-N′-[(E)-2-Hy­droxy­benzyl­idene]-3-phenyl­prop-2-enohydrazide 
In the non-planar title compound, C16H14N2O2, the dihedral angle between the phenyl rings is 16.67 (8)°. An E conformation is found for each of the imine [1.286 (2) Å] and ethyl­ene [1.335 (2) Å] bonds. The amide O and H atoms are anti, and an intra­molecular hy­droxy O—H⋯N hydrogen bond is noted. The formation of N—H⋯O(hy­droxy) hydrogen bonds in the crystal packing leads to helical chains along the b axis. Supra­molecular layers in the ab plane are formed as the chains are linked by C—H⋯O inter­actions.
PMCID: PMC3394040  PMID: 22798905
8.  (2E)-N′-[(E)-Benzyl­idene]-3-phenyl­prop-2-enohydrazide from synchrotron radiation 
In the title compound, C16H14N2O, the dihedral angle between the phenyl rings is 25.48 (12)°. An E conformation is found for each of the imine [1.269 (3) Å] and ethyl­ene [1.313 (3) Å] bonds. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, leading to zigzag chains along [010]. Supra­molecular layers in the ab plane are formed, whereby the chains are linked by C—H⋯N and C—H⋯π inter­actions.
PMCID: PMC3394041  PMID: 22798906
9.  4-(3-Fluoro­anilino)thieno[2,3-b]pyridine-6-carb­oxy­lic acid 
In the title compound, C14H9FN2O2S, the thieno[2,3-b]pyridine residue is almost planar (r.m.s. deviation = 0.0194 Å), with the carb­oxy­lic acid group [dihedral angle = 11.9 (3)°] and the benzene ring [71.1 (4)°] being twisted out of this plane to different extents. An intra­molecular N—H⋯O(carbon­yl) hydrogen bond closes an S(6) ring. Supra­molecular chains along [01-1] mediated by O—H⋯N(pyridine) hydrogen bonds feature in the crystal. A three-dimensional architecture is completed by π–π inter­actions occurring between the benzene ring and the two rings of the thieno[2,3-b]pyridine residue [centroid–centroid distances = 3.6963 (13) and 3.3812 (13) Å]. The F atom is disordered over the two meta sites in a near statistical ratio [0.545 (5):0.455 (5)].
PMCID: PMC3394012  PMID: 22798877
10.  N-(4-Chloro­phen­yl)-5-(4,5-dihydro-1H-imidazol-2-yl)thieno[2,3-b]pyridin-4-amine 
In the title compound, C16H13ClN4S, the thienopyridine fused-ring system is nearly planar (r.m.s. deviation = 0.0333 Å) and forms a dihedral angle of 4.4 (3)° with the attached dihydro­imidazole ring (r.m.s. deviation = 0.0429 Å) allowing for the formation of an intra­molecular (exocyclic amine)N—H⋯N(imine) hydrogen bond. The benzene rings of the disordered (50:50) –N(H)—C6H4Cl residue form dihedral angles of 59.1 (3) and 50.59 (15)° with the fused ring system. In the crystal, (imidazole amine)N—H⋯N(pyridine) hydrogen bonds lead to a supra­molecular helical chain along the b axis. The chains assemble into layers (ab plane) with inter-digitation of the chloro­benzene rings which results in weak C—H⋯Cl inter­actions in the c-axis direction.
PMCID: PMC3393946  PMID: 22798811
11.  4-[(E)-2-(2-Chloro­benzyl­idene)hydrazin-1-yl]quinolin-1-ium chloride dihydrate 
In the title hydrated salt, C16H13ClN3 +·Cl−·2H2O, a small twist is evident in the cation so that the chloro­benzene ring is not coplanar with the central hydrazinyl group [the N—C—C—C torsion angle = −4.8 (12)°]. The conformation about the imine N=C bond [1.284 (10) Å] is E. The components of the structure are connected into a three-dimensional architecture via O—H⋯O, O—H⋯Cl and N—H⋯Cl hydrogen bonds. One water H atom is disposed over two sites of equal occupancy.
PMCID: PMC3379418  PMID: 22719616
12.  4-[(E)-2-(2,4-Dichloro­benzyl­idene)hydrazin-1-yl]quinolin-1-ium chloride monohydrate 
In the title hydrated salt, C16H12Cl2N3 +·Cl−·H2O, there is a small twist in the cation as seen in the torsion angle linking the benzene ring to the rest of the mol­ecule [171.96 (17)°]. In the crystal, the quinolinium H atom forms a hydrogen bond to the lattice water mol­ecule, which also forms hydrogen bonds to two Cl− anions. Each Cl− ion also accepts a hydrogen bond from the hydrazine H atom. The three-dimensional architecture is also stabilized by π–π inter­actions between centrosymmetrically related quinoline residues [centroid–centroid distance = 3.5574 (11) Å].
PMCID: PMC3344163  PMID: 22606166
13.  7-Chloro-4-[(E)-2-(2,5-dimeth­oxy­benzyl­idene)hydrazin-1-yl]quinoline 
In the nearly planar title compound (r.m.s. deviation for the 24 non-H atoms = 0.064 Å), C18H16ClN3O2, the conformation about the N=C bond is E. Supra­molecular chains propagated by glide symmetry along [001] are found in the crystal packing. These are sustained by N—H⋯N hydrogen bonds with the quinoline N atom being the acceptor. The chains are connected into a three-dimensional architecture by π–π inter­actions involving all three aromatic rings [centroid–centroid distances = 3.5650 (9)–3.6264 (9) Å].
PMCID: PMC3344174  PMID: 22606177
14.  7-Chloro-4-[(E)-2-(3,4,5-trimeth­oxy­benzyl­idene)hydrazin-1-yl]quinoline 
In the title compound, C19H18ClN3O3, the r.m.s. deviation through the 23 non-H and non-meth­oxy atoms is 0.088 Å, indicating a planar mol­ecule with the exception of the meth­oxy groups. One meth­oxy group, surrounded on either side by the other meth­oxy groups, is almost normal to the benzene ring to which it is connected [C—O—Car—Car torsion angle = 81.64 (15)°]. In the crystal, N—H⋯O, C—H⋯O and π–π inter­actions [between quinoline residues; centroid–centroid distance = 3.4375 (8) Å] link mol­ecules into a three-dimensional architecture.
PMCID: PMC3344149  PMID: 22606152
15.  7-Chloro-4-[(7-chloro­quinolin-4-yl)sulfan­yl]quinoline dihydrate 
In the title thio­ether dihydrate, C18H10Cl2N2S·2H2O, the S-bound quinolinyl residues are almost orthogonal, forming a dihedral angle of 72.36 (4)°. In the crystal, the four water mol­ecules are connected via an eight-membered {⋯OH}4 synthon with each of the four pendent water H atoms hydrogen bonded to a pyridine N atom to stabilize a three-dimensional architecture.
PMCID: PMC3344064  PMID: 22589973
16.  (2S,3R)-tert-Butyl N-[4-(N-benzyl-4-fluoro­benzene­sulfonamido)-3-hy­droxy-1-phenyl­butan-2-yl]carbamate 
In the title mol­ecule, C28H33FN2O5S, the mean plane about the tertiary amine group (sum of the angles subtended at the sp 2-hybridized N atom = 359.7°) forms a dihedral angle of 16.66 (6)° with the phenyl ring adjacent to the carbamate group. The sulfonamide benzene ring and the hy­droxy group lie to either side of the C2NS plane, whereas the benzyl­phenyl (connected to the N atom) and carbamate substituents lie to the other side. Supra­molecular layers propagating in the ac plane are found in the crystal, linked by hy­droxy–sulfonamide O—H⋯O and carbamate–carbamate N—H⋯O hydrogen bonds along with C—H⋯O and C—H⋯π inter­actions.
PMCID: PMC3344084  PMID: 22606087
17.  1-(4-Methyl­phen­yl)-3-phenyl-1H-pyrazol-5-yl 4-nitro­benzene­sulfonate 
In the title mol­ecule, C22H17N3O5S, the pyrazole ring is planar (r.m.s. deviation = 0.018 Å) and forms dihedral angles of 21.45 (10) and 6.96 (10)° with the N- and C-bound benzene rings, respectively. Supra­molecular layers in the bc plane are formed in the crystal via C—H⋯O and π–π inter­actions involving the sulfonamide benzene ring inter­acting with the N- and C-bound benzene rings [centroid–centroid distances = 3.790 (2) and 3.730 (2) Å, respectively]. The crystal studied was found to be a merohedral twin (twin law 1 0 0.678, 0 -1 0, 0 0 -1), the fractional contribution of the minor component being approximately 36%.
PMCID: PMC3344041  PMID: 22589950
18.  2-Amino-3-chloro-5-nitro­benzamide 
The amide group in the title compound, C7H6ClN3O3, is significantly twisted out of the plane of the benzene ring [C—C—C—O = 34.2 (5)°] whereas the nitro group is almost co-planar [O—N—C—C = 4.0 (5)°] with the ring. Intra­molecular N—H⋯O and N—H⋯Cl hydrogen bonds occur. In the crystal, the mol­ecules are linked by N—H⋯O hydrogen bonds, generating layers propagating in the ab plane.
PMCID: PMC3343961  PMID: 22590042
19.  4-[3,4-Dimethyl-1-(4-methyl­phen­yl)-5-oxo-4,5-dihydro-1H-pyrazol-4-yl]-3,4-dimethyl-1-(4-methyl­phen­yl)-4,5-dihydro-1H-pyrazol-5-one 
In the title compound, C24H26N4O2, the complete mol­ecule is generated by the application of twofold symmetry. The pyrazole ring is approximately planar [r.m.s. deviation = 0.026 Å] and the benzene ring is twisted out of this plane [dihedral angle = 21.94 (7)°]. A twist in the mol­ecule about the central C—C bond [1.566 (3) Å] is also evident [C—C—C—C torsion angle = 44.30 (14)°]. Supra­molecular layers in the bc plane are formed in the crystal packing via C—H⋯O and C—H⋯π inter­actions.
PMCID: PMC3343962  PMID: 22590043
20.  1,3-Diphenyl-4,5-dihydro-1H-pyrazol-5-one 
In the title pyrazolone derivative, C15H12N2O, the five-membered ring is approximately planar (r.m.s. deviation = 0.018 Å), and the N- and C-bound benzene rings are inclined to this plane [dihedral angles = 21.45 (10) and 6.96 (10)°, respectively] and form a dihedral angle of 20.42 (10)° with each other. Supra­molecular layers are formed in the crystal structure via C—H⋯O and C—H⋯N inter­actions, and these are assembled into double layers by C—H⋯π and π–π inter­actions between the pyrazole and C-bound benzene rings [ring centroid–centroid distance = 3.6476 (12) Å]. The double layers stack along the a axis being connected by π–π inter­actions between the N- and C-bound benzene rings [ring centroid–centroid distance = 3.7718 (12) Å].
PMCID: PMC3343981  PMID: 22589890
21.  3,5-Dimethyl-1-(4-nitro­phen­yl)-1H-pyrazole 
In the title pyrazole derivative, C11H11N3O2, the benzene ring is twisted [dihedral angle = 31.38 (12)°] with respect to the pyrazole ring (r.m.s. deviation = 0.009 Å). The nitro group is effectively coplanar with the benzene ring to which it is attached [O—N—C—C torsion angle = −6.5 (3)°]. Supra­molecular chains along the b axis are formed owing to π–π inter­actions [3.8653 (2) Å] between translationally related mol­ecules involving both the five- and six-membered rings.
PMCID: PMC3343982  PMID: 22589891
22.  3-[(E)-(7-Chloro-4-quinol­yl)hydrazono­meth­yl]benzonitrile monohydrate 
The title monohydrate, C17H11ClN4·H2O, features an essentially planar organic mol­ecule, as seen in the dihedral angle of 2.42 (8)° formed between the quinoline and benzene planes. The conformation about the imine bond is E, and the N—H group is oriented towards the quinoline residue. The major feature of the crystal packing is the formation of supra­molecular chains along [100], whereby the water mol­ecule accepts one N—H⋯O hydrogen bond and makes two O—H⋯N hydrogen bonds. A C—H⋯O link is also present.
PMCID: PMC2971809  PMID: 21578942
23.  2-[(E)-(1H-Pyrrol-2-ylmethyl­idene)hydrazinyl]pyridine monohydrate 
The title hydrate, C10H10N4·H2O, shows a small twist in the hydro­zone derivative, the dihedral angle between the pyridine and pyrrole rings being 11.08 (12)°. The pyridine and pyrrole N atoms lie to the same side of the mol­ecule being sustained in place by hydrogen-bonding inter­actions with the water mol­ecule. Further inter­molecular O—H⋯N and N—H⋯O hydrogen bonding leads to the formation of supra­molecular arrays in the ab plane.
PMCID: PMC2971851  PMID: 21578943
24.  4-(Pyrimidin-2-yl)-1-thia-4-aza­spiro­[4.5]decan-3-one 
The title compound, C12H15N3OS, features an envelope conformation for the 1,3-thia­zolidin-4-one ring with the S atom as the flap atom. The pyrimidine ring is almost orthogonal to the 1,3-thia­zolidin-4-one ring as indicated by the N—C—C—N torsion angle of −111.96 (18)°. Supra­molecular dimers are formed in the crystal structure through the agency of C—H⋯O contacts occurring between centrosymmetrically related mol­ecules. These are linked into supra­molecular tapes along [100] via C—H⋯S contacts.
PMCID: PMC2971766  PMID: 21578902
25.  5-(3-Nitro­benz­yl)-1,3,4-thia­diazol-2-amine 
In the title mol­ecule, C9H8N4O2S, the dihedral angle between the thia­diazole and benzene rings is 73.92 (8)° and the thia­diazole group S atom is orientated towards the benzene ring, the central S—C—C—C torsion angle being 45.44 (18)°. In the crystal, supra­molecular tapes mediated by N—H⋯N hydrogen bonds and comprising alternating eight-membered {⋯HNCN}2 and 10-membered {⋯HNH⋯NN}2 synthons are formed along [010]. The tapes are consolidated into a three-dimensional network by a combination of C—H⋯O, C—H⋯S and C—H⋯π inter­actions
PMCID: PMC2971864  PMID: 21578910

Results 1-25 (98)