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1.  (E)-N-(3,3-Di­phenyl­allyl­idene)naph­thal­en-1-amine 
The title compound, C25H19N, adopts an E conformation about the C=N bond. The naphthalene ring system and the phenyl rings form dihedral angles 38.1 (1), 46.9 (8) and 48.5 (1)°, respectively, with the mean plane of the central enimino fragment. The crystal packing exhibits no directional close contacts.
doi:10.1107/S1600536813014888
PMCID: PMC3772462  PMID: 24046605
2.  (E)-N′-(3,3-Diphenyl­allyl­idene)-p-toluene­sulfonohydrazide 
In the title compound, C22H20N2O2S, the mol­ecule adopts a twisted E configuration around the C=N bond. The two phenyl rings are twisted from each other, making a dihedral angle of 78.00 (12)°. The methyl-substituted benzene ring makes dihedral angles of 32.37 (14) and 69.70 (12)° with the two phenyl rings. In the crystal structure, mol­ecules are linked into extended chains along the b axis through inter­molecular N—H⋯O hydrogen bonds.
doi:10.1107/S1600536809013269
PMCID: PMC2977737  PMID: 21583873
3.  (E)-N-(3,3-Diphenyl­allyl­idene)-4-nitro­aniline 
In the title compound, C21H16N2O2, the dihedral angles between the mean planes of the 4-nitro­phenyl ring and the two phenyl rings are 57.3 (5) and 16.8 (6)°. The imine group displays a C—C—N—C torsion angle of −24.9 (3)°.
doi:10.1107/S1600536812040391
PMCID: PMC3470385  PMID: 23125798
4.  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
5.  (E)-N-(3,3-Di­phenyl­allyl­idene)-2-(tri­fluoro­meth­yl)aniline 
In the title compound, C22H16F3N, the C=N bond of the central imine group adopts an E conformation. The dihedral angles between the 2-(tri­fluoro­meth­yl)phenyl ring and the benzene rings are 9.34 (1) and 68.8 (1)°. The imine group displays a C—C—N=C torsion angle of 41.6 (3)°. In the crystal, weak C—H⋯F hydrogen bonds link the mol­ecules into chains parallel to the b-axis direction.
doi:10.1107/S1600536813010283
PMCID: PMC3648283  PMID: 23723903
6.  Crystal structure of bis­(4-nitro­aniline-κN 1)(5,10,15,20-tetra­phenyl­por­phy­rin­ato-κ4 N)cobalt(III) chloride di­chloro­methane monosolvate 
The reaction of [CoIII(TPP)Cl] (TPP is the dianion of 5,10,15,20-tetra­phenyl­porphyrin) with an excess of 4-nitro­aniline in di­chloro­methane leads to the title compound, [CoIII(C44H28N4)(C6H6N2O2)2]Cl·CH2Cl2. The CoIII ion lies on an inversion centre and is octa­hedrally coordinated by two N atoms of the NH2 groups of the two 4-nitro­aniline trans-axial ligands and four pyrrole N atoms of the porphyrin. The asymmetric unit contains one half of the [CoIII(TPP)(4-nitro­aniline)2]+ ion complex, one chloride counter-ion (lying on a twofold rotation axis) and one half di­chloro­methane solvent mol­ecule, where the C atom lies on a twofold rotation axis. The average equatorial Co—N(pyrrole) distance (Co—Np) is 1.982 (2) Å and the axial Co—N(4-nitro­aniline) bond length is 2.006 (2) Å. The crystal packing is stabilized by an N—H⋯Cl hydrogen bond between the N atom of the amino group of the 4-nitro­aniline axial ligand and the chloride counter-ion. The supra­molecular architecture is further stabilized by weak C—H⋯π inter­actions.
doi:10.1107/S1600536814016274
PMCID: PMC4186082  PMID: 25309176
crystal structure; cobalt(III) complex; 5,10,15,20-tetra­phenyl­porphyrin ligand
7.  4-[(1,3-Dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-2-yl)meth­yl]-N′-[(E)-4-nitro­benzyl­idene]benzene­sulfono­hydrazide dimethyl sulfoxide monosolvate 
The mol­ecular structure of the title compound, C26H18N4O6S·C2H6OS, shows an E conformation of the hydrazone double bond. The presence of a methyl­ene group between the benzo[de]isoquinoline and benzene­sulfonyl moieties allows the 4-nitro­phenyl ring and the benzo[de]isoquinoline system to be parallel with respect to each other, so that the mol­ecule adopts a U-shaped spatial conformation. The dihedral angle between mean planes of these aromatic groups is 4.4 (1)°. This special arrangement enables neighboring mol­ecules to be inter­calated, forming slipped π–π inter­actions [centroid–centroid distance = 3.535 (2) Å] between the 4-nitro­phenyl and benzo[de]isoquinoline groups and point-to-face C—H⋯π inter­actions between the benzo[de]isoquinoline and benzene­sulfonyl aromatic systems. In addition, the crystal packing also features an inter­molecular N—H⋯O inter­action involving the amine group and the dimethyl sulfoxide solvent mol­ecule.
doi:10.1107/S1600536811004697
PMCID: PMC3051948  PMID: 21522382
8.  (E)-2-(1,3-Diphenyl­allyl­idene)malononitrile 
The title compound, C18H12N2, adopts an E conformation with the benzyl­idenemalononitrile and phenyl groups located on opposite sides of the C=C bond. The two phenyl rings are oriented at a dihedral angle of 62.49 (7)°.
doi:10.1107/S1600536809048338
PMCID: PMC2972044  PMID: 21578880
9.  3-Methyl-4-{[(3-{[(3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl­idene)(phen­yl)meth­yl]amino­meth­yl}benz­yl)amino](phen­yl)methyl­idene}-1-phenyl-1H-pyrazol-5(4H)-one 
The complete mol­ecule of the title compound, C42H36N6O2, is generated by a crystallographic twofold axis with two C atoms of the central phenyl group lying on the axis. In the independent part of the mol­ecule, one amino group is involved in an intra­molecular N—H⋯O hydrogen bond, and the two adjacent phenyl rings are twisted from the plane of the pyrazolone ring with dihedral angles of 6.82 (3) and 88.32 (6)°. The crystal packing exhibits no classical inter­molecular contacts.
doi:10.1107/S1600536811027000
PMCID: PMC3213468  PMID: 22091047
10.  Dimethyl (2Z)-2-[4-((1Z)-1-{2-[(2Z,5Z)-5-(2-meth­oxy-2-oxo­ethyl­idene)-4-oxo-3-phenyl-1,3-thia­zolidin-2-yl­idene]hydra­zin-1-yl­idene}eth­yl)anilino]but-2-ene­dio­ate 
The mol­ecule of the title compound, C26H24N4O7S, adopts a trans conformation about the central N—N bond, presumably to minimize steric between the substituents on these two atoms. An intra­molecular N—H⋯O hydrogen bond occurs. The phenyl ring is disordered over two sets of sites, with an occupancy ratio of 0.624 (8):0.376 (8). The azolidine ring is essentially planar [maximum deviation = 0.008 (5) Å] and makes a dihedral angle of 4.3 (2)° with the benzene ring and dihedral angles of 74.1 (3) and 69.1 (5)°, respectively, with the mean planes of the major and minor components of the disordered phenyl ring. The packing in the crystal is aided by the formation of several weak C—H⋯O and C—H⋯N inter­actions.
doi:10.1107/S1600536813032042
PMCID: PMC3885086  PMID: 24454262
11.  (E)-1-[1-(3-Chloro­phen­yl)ethyl­idene]-2-(2,4-dinitro­phen­yl)hydrazine 
There are two crystallographically independent mol­ecules in the asymmetric unit of the title compound, C14H11ClN4O4, with the same E conformation about the C=N double bond. The mol­ecules are approximately planar, with a dihedral angle between the benzene rings of 10.24 (12)° in one mol­ecule and 4.73 (12)° in the other. In both mol­ecules, the ortho-nitro groups of the 2,4-dinitro­phenyl units are coplanar to their bound benzene rings, whereas the para-nitro groups are slightly twisted. In each mol­ecule, intra­molecular N—H⋯O hydrogen bonds generate S(6) ring motifs. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions into sheets parallel to the (-102) plane. These sheets are stacked by π–π inter­actions, with centroid–centroid distances of 3.7008 (14) and 3.7459 (14) Å. A Cl⋯O short contact [3.111 (2) Å] is observed.
doi:10.1107/S160053681200548X
PMCID: PMC3295481  PMID: 22412592
12.  (2E)-3-(4-Methyl­phen­yl)-1-(3-nitro­phen­yl)prop-2-en-1-one 
The title compound, C16H13NO3, crystallizes with two independent mol­ecules (A and B) in the asymmetric unit. The dihedral angle between the mean planes of the 4-methyl­phenyl and 3-nitro­phenyl groups is 4.0 (3)° in mol­ecule A and 16.2 (7)° in mol­ecule B. Inter­molecular C—H⋯O hydrogen bonding involving the O atoms of the 3-nitro­phenyl group of both independent mol­ecules link the mol­ecules into layers approximately parallel to the (110) plane. The layers are held together by π–π stacking inter­actions between the 4-methyl­phenyl ring of mol­ecule A and the 3-nitro­phenyl ring of mol­ecule B of the adjacent layer, with the distance between the centroids of inter­acting rings being 3.6987 (7) Å.
doi:10.1107/S160053680706182X
PMCID: PMC2914892  PMID: 21200665
13.  N-(1,5-Dimethyl-3-oxo-2-phenyl-2,3-di­hydro-1H-pyrazol-4-yl)-2-(4-nitro­phen­yl)acetamide 
In the title compound, C19H18N4O4, the nitro­phenyl and phenyl rings are twisted by 67.0 (6) and 37.4 (4)°, respectively, with respect to the pyrazole ring plane [maximum deviation = 0.0042 (16) Å]. The dihedral angle between the mean planes of the phenyl rings is 59.3 (3)°. The amide group, with a C—N—C—C torsion angle of 177.54 (13)°, is twisted away from the plane of the pyrazole ring in an anti­periplanar conformation. In the crystal, N—H⋯O hydrogen bonds involving the carbonyl group on the pyrazole ring and the amide group, together with weak C—H⋯O inter­actions forming R 2 2(10) graph-set motifs, link the mol­ecules into chains along [100]. Additional weak C—H⋯O inter­actions involving the nitro­phenyl rings further link the mol­ecules along [001], also forming R 2 2(10) graph-set motifs, thereby generating (010) layers.
doi:10.1107/S1600536814009738
PMCID: PMC4051092  PMID: 24940224
14.  3-[3-Methyl-4-(3-nitro­benzyl­idene­amino)-5-sulfanyl­idene-4,5-dihydro-1H-1,2,4-triazol-1-yl]-1,3-diphenyl­propan-1-one 
In the title mol­ecule, C25H21N5O3S, the triazole ring forms dihedral angles of 21.4 (2), 61.4 (2) and 102.4 (2)° with the nitro­phenyl and two phenyl rings, respectively. In the crystal, weak C—H⋯O hydrogen bonds and π–π inter­actions between the benzene rings from neighbouring mol­ecules [with a centroid–centroid distance of 3.571 (3) Å] consolidate the crystal packing.
doi:10.1107/S1600536811033587
PMCID: PMC3200841  PMID: 22059037
15.  2-Hy­droxy-5-[(E)-(1H-indol-3-yl­methyl­idene)aza­nium­yl]benzoate 
The zwitterionic title compound, C16H12N2O3, was obtained as a result of the condensation of 5-amino­salicylic acid and 1H-indole-3-carbaldehyde. The whole mol­ecule is roughly planar: the 4-hy­droxy­anilinic group and the 1H-indole-3-carbaldehyde moieties are only slightly twisted, making a dihedral angle of 7.77 (11)°, whereas, the carboxyl­ate group makes a dihedral angle of 3.34 (45)° with the parent 4-hy­droxy­anilinic group. S(6) ring motifs are formed due to intra­molecular O—H⋯O hydrogen bonding. In the crystal, inter­molecular N—H⋯O and C—H⋯O hydrogen bonds build up pseudo-rings with R 1 2(4), R 2 1(7) and R 2 2(14) ring motifs. These pseudo-dimers are further linked by N—H⋯O hydrogen bonds into a chain extending along [101]. C—H⋯π inter­actions also occur, along with offset π–π inter­actions between the anilinic phenyl and the heterocyclic five-membered rings with a centroid–centroid distance of 3.5716 (19) Å.
doi:10.1107/S1600536810048579
PMCID: PMC3011759  PMID: 21589591
16.  3-[3-Methyl-4-(4-nitro­benzyl­idene­amino)-5-sulfanyl­idene-4,5-dihydro-1H-1,2,4-triazol-1-yl]-1,3-diphenyl­propan-1-one dichloro­methane monosolvate 
In the title compound, C25H21N5O3S·CH2Cl2, the dichloro­methane solvent mol­ecule is disordered over four positions, with an occupancy ratio of 0.271 (3):0.3884 (18):0.298 (2):0.0424 (15). The 1,2,4-triazole ring makes dihedral angles of 47.3 (2)/87.3 (2) and 3.6 (2)° with the phenyl and nitro­phenyl rings, respectively. An intra­molecular C—H⋯S hydrogen bond results in the formation of an almost planar six-membered ring [r.m.s. derivation = 0.0051 (2) Å]. Inter­molecular C—H⋯O hydrogen bonding consolidates the structure.
doi:10.1107/S1600536811043777
PMCID: PMC3247519  PMID: 22220137
17.  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
18.  [μ-Bis(diphenyl­arsino)methane-1:2κ2 As:As′]nona­carbonyl-1κ3 C,2κ3 C,3κ3 C-tricyclo­hexyl­phosphine-3κP-triangulo-triruthenium(0) 
In the title triangulo-triruthenium compound, [Ru3(C25H22As2)(C18H33P)(CO)9], the bis­(diphenyl­arsino)methane ligand bridges an Ru—Ru bond and the monodentate phosphine ligand bonds to the third Ru atom. Both the phosphine and arsine ligands are equatorial with respect to the Ru3 triangle. In addition, each Ru atom carries one equatorial and two axial terminal carbonyl ligands. All three cyclo­hexane rings are disordered over two positions with site occupancies of 0.628 (6) and 0.372 (6). The mean planes of these three phosphine-substituted cyclo­hexane rings make dihedral angles of 53.0 (8), 68.3 (6) and 89.9 (7)° (major components), and 46.7 (14), 41.3 (11) and 75.8 (10)° (minor components) with each other. The dihedral angles between the two phenyl rings are 85.0 (2) and 88.1 (2)° for the two diphenyl­arsino groups. Two cyclo­hexane rings adopt a chair conformation whereas the other adopts a slightly twisted chair conformation for the major components; these conformations are similiar for the minor components. Intra­molecular C—H⋯O hydrogen bonds stabilize the mol­ecular structure. In the crystal packing, the mol­ecules are linked together into chains via inter­molecular C—H⋯O hydrogen bonds down the a axis. Weak inter­molecular C—H⋯π inter­actions further stabilize the crystal structure.
doi:10.1107/S1600536809047977
PMCID: PMC2972057  PMID: 21578646
19.  Bis{4-[(Z)-N′-(4-hydroxy­benzyl­idene)hydrazino]-8-(trifluoro­meth­yl)quinolinium} sulfate dihydrate 
The title compound, 2C17H13F3N3O+·SO4 2−·2H2O, crystallizes with four independent cations (A, B, C and D) in the asymmetric unit, which is composed of two groups of two cations, one anion and two water mol­ecules (Z′ = 2). The dihedral angle between the mean planes of the 4-hydroxy­phenyl and quinolinium groups is 8.9 (7)° in A, 30.1 (6)° in B, 28.8 (8)° in C and 12.8 (1)° in D. The crystal packing is stabilized by inter­molecular O—H⋯O and N—H⋯O hydrogen bonding between H atoms from 4-hydroxy­phenyl O atoms and the O atoms of nearby water molecules and sulfate anions, as well as H atoms from the N atom of the hydrazino group to O atoms of neighboring sulfate anions, linking the components into chains with the 4-hydroxy­phenyl and quinolinium rings parallel to the (011) plane. There is also an extensive array of inter­molecular hydrogen bonds between water mol­ecules themselves and with sulfate O atoms, as well as hydrogen-bond inter­actions between H atoms from the hydrazino group and sulfate O atoms. In addition, inter­molecular π–π stacking inter­actions occur between nearby 4-hydroxy­phenyl and quinolinium groups, with distances between the centroids of inter­acting rings in the range 3.4140 (9)–3.9659 (9) Å.
doi:10.1107/S1600536808000561
PMCID: PMC2960448  PMID: 21201506
20.  Benzyl 3-[(E)-2-nitro­benzyl­idene]dithio­carbazate 
The title compound, C15H13N3O2S2, was obtained from a condensation reaction of benzyl dithio­carbazate and 2-nitro­benzaldehyde. In the mol­ecule, the nearly planar dithio­carbazate fragment [r.m.s deviation = 0.0264 Å] is oriented at dihedral angles of 7.25 (17) and 74.09 (9)°with respect to the two benzene rings. The nitro group is twisted by a dihedral angle of 22.4 (7)° to the attached benzene ring. The nitro­benzene ring and dithio­carbazate fragment are located on the opposite sides of the C=N bond, showing an E configuration. In the crystal, mol­ecules are linked via inter­molecular N—H⋯S hydrogen bonds, forming centrosymmetric supra­molecular dimers. Weak C—H⋯π inter­action is also observed in the crystal structure.
doi:10.1107/S1600536811028686
PMCID: PMC3213549  PMID: 22091126
21.  Diethyl 2-{[2-(trifluoro­meth­yl)anil­ino]methyl­idene}propane­dioate 
The title compound, C15H16F3NO4, is an N-substituted derivative of ortho-trifluoro­methyl­aniline featuring a twofold Michael system. The least-squares planes defined by the atoms of the phenyl ring and the atoms of the Michael system enclose an angle of 15.52 (5)°. Apart from classical intra­molecular N—H⋯O and N—H⋯F hydrogen bonds, inter­molecular C—H⋯O contacts are observed, the latter connecting the mol­ecules into chains along [110]. The shortest inter­centroid distance between two aromatic systems is 3.6875 (9) Å.
doi:10.1107/S1600536812002590
PMCID: PMC3275258  PMID: 22347114
22.  Crystal structures of (E)-(3-ethyl-1-methyl-2,6-di­phenyl­piperidin-4-yl­idene)amino phenyl carbonate and (E)-(3-isopropyl-1-methyl-2,6-di­phenyl­piperidin-4-yl­idene)amino phenyl carbonate 
The title compounds are the 3-ethyl, (I), and 3-isopropyl, (II), derivatives of (1-methyl-2,6-diphenylpiperidin-4-ylidene)amino phenyl carbonate. The main difference in the conformation of the two compounds is the angle of inclination of the phenoxycarbonyl ring with respect to the piperidine ring mean plane, with a dihedral angle of 2.05 (8)° in (I) and 45.24 (13)° in (II).
In the title compounds, C27H28N2O3, (I), and C28H30N2O3, (II), the conformation about the C=N bond is E. The piperidine rings adopt chair conformations with the attached phenyl rings almost normal to their mean planes, the dihedral angles being 85.82 (8) and 85.84 (7)° in (I), and 87.98 (12) and 86.42 (13)° in (II). The phenyl rings are inclined to one another by 52.87 (8)° in (I) and by 60.51 (14)° in (II). The main difference in the conformation of the two compounds is the angle of inclination of the phen­oxy­carbonyl ring to the piperidine ring mean plane. In (I), these two planes are almost coplanar, with a dihedral angle of 2.05 (8)°, while in (II), this angle is 45.24 (13)°. In the crystal of (I), mol­ecules are linked by C—H⋯O hydrogen bonds, forming inversion dimers with R 2 2(14) loops. The dimers are linked via C—H⋯π inter­actions forming a three-dimensional network. In the crystal of (II), there are no significant inter­molecular inter­actions present.
doi:10.1107/S1600536814018893
PMCID: PMC4257207  PMID: 25484651
crystal structure; piperidine; oxime; 2,6-di­phenyl­piperidine
23.  3-{4-[(2-Hy­droxy­benzyl­idene)amino]-3-methyl-5-sulfanyl­idene-4,5-dihydro-1H-1,2,4-triazol-1-yl}-1,3-diphenyl­propan-1-one 
There are two crystallographically independent mol­ecules (A and B) in the asymmetric unit of the title compound, C25H22N4O2S, with almost identical mol­ecular conformations. The hy­droxy­phenyl ring plane and the 1,2,4-triazole ring form dihedral angles of 17.1 (2) and 7.4 (2)° in A and B, respectively. The dihedral angles between 1,2,4-triazole ring and the other two phenyl rings are 89.6 (3) and 83.3 (2)° in mol­ecule A, and 89.2 (3) and 82.2 (2)° in mol­ecule B. One intra­molecular O—H⋯N hydrogen bond is present in each mol­ecule. Weak inter­molecular C—H⋯O hydrogen bonds consolidate the crystal packing.
doi:10.1107/S1600536811034878
PMCID: PMC3200874  PMID: 22059065
24.  5-Diethyl­amino-2-{[2-(2,4-dinitro­phen­yl)hydrazin-1-yl­idene]meth­yl}phenol 
In the title compound, C17H19N5O5, obtained from the condensation reaction of 4-diethyl­amino-2-hy­droxy­benzalde­hyde and 2,4-dinitro­phenyl­hydrazine, the two benzene rings are twisted by a dihedral angle of 1.75 (12)°. The nitro groups are slightly twisted with the respect to the benzene ring to which they are attached, making dihedral angles of 8.20 (15) and 5.78 (15)°. An intra­molecular O—H⋯N hydrogen bond occurs. In the crystal, mol­ecules are linked by pairs of inter­molecular N—H⋯O hydrogen bonds, forming dimers through R 2 2(12) rings. These dimers are further linked by C—H⋯O and C—H⋯π and weak slipped π–π inter­actions [centroid–centroid distance = 3.743 (2)Å]. One of the ethyl groups is disordered over two positions, with occupancy factors in the ratio 0.72:0.28.
doi:10.1107/S1600536810044983
PMCID: PMC3011673  PMID: 21589414
25.  N′-[(1E,2E)-1-(2-Phenyl­hydrazin-1-yl­idene)-1-(phenyl­sulfon­yl)propan-2-yl­idene]benzohydrazide 
The configuration about each C=N bond in the title compound, C22H20N4O3S, is E. While to a first approximation the phenyl­hydrazin-1-yl­idene and benzohydrazide residues are coplanar, in part due to the presence of an intra­molecular N—H⋯N hydrogen bond, significant twists are evident in the orientations of the hydrazine [N—N—C—C torsion angle = −170.74 (11)°] and benzoyl benzene [N—C—C—C = −21.72 (18)°] rings. The sulfonyl benzene ring occupies a position almost normal to the rest of the mol­ecule [C—S—C—N = −92.28 (10)°]. Centrosymmetric aggregates mediated by pairs of hydrazide–sulfonyl N—H⋯O hydrogen bonds are the predominant packing motif in the crystal. These are connected into linear supra­molecular chains via C—H⋯O inter­actions which are, in turn, linked into layers in the ac plane via C—H⋯π inter­actions. Connections between layers along the b-axis direction are of the π–π type and occur between centrosymmetrically related hydrazine-bound benzene rings [centroid–centroid separation = 3.7425 (9) Å].
doi:10.1107/S1600536811031953
PMCID: PMC3200681  PMID: 22058945

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