The effect of molecular planarity on crystal non‐centrosymmetry in benzyl­idene–aniline derivatives

In the title compound, N‐(2‐methoxy­phenyl)‐4‐nitro­benzyli­deneamine, C₁₄H₁₂N₂O₃, the two phenyl rings make a dihedral angle of 48.0 (2)° and the nitro group is at an angle of 6.5 (1)° with respect to its attached phenyl ring. In the crystal structure, mol­ecules are related as centrosymmetric pairs through π–π interactions and are further connected through strong C—H?O hydrogen bonds [C?O 3.4259 (17) Å and C—H?O 167°], forming molecular stacks along [100]. These stacks associate further through longer C—H?O interactions, forming two‐dimensional networks. In the c direction, there are only weak van der Waals interactions. The relationship between the molecular planarity and its centrosymmetry is also briefly described.     

Two trans‐4‐aminoazoxybenzenes

Two isomeric trans‐4‐amino­azoxy­benzenes, trans‐1‐(4‐amino­phenyl)‐2‐phenyl­diazene 2‐oxide (α, C₁₂H₁₁N₃O) and trans‐2‐(4‐amino­phenyl)‐1‐phenyl­diazene 2‐oxide (β, C₁₂H₁₁N₃O), have been characterized by X‐ray diffraction. The α isomer is almost planar, having torsion angles along the C_aryl—N bonds of only 4.9 (2) and 8.0 (2)°. The relatively short C_aryl—N bond to the non‐oxidized site of the azoxy group [1.401 (2) Å], together with the significant quinoid deformation of the respective phenyl ring, is evidence of conjugation between the aromatic sextet and the π‐electron system of the azoxy group. The geometry of the β isomer is different. The non‐substituted phenyl ring is twisted with respect to the NNO plane by ca 50°, whereas the substituted ring is almost coplanar with the NNO plane. The non‐oxidized N atom in the β isomer has increased sp³ character, which leads to a decrease in the N—N—C bond angle to 116.8 (2)°, in contrast with 120.9 (1)° for the α isomer. The deformation of the C—C—C angles (1–2°) in the phenyl rings at the substitution positions is evidence of the different character of the oxidized and non‐oxidized N atoms of the azoxy group. In the crystal structures, mol­ecules of both isomers are arranged in chains connected by weak N—H?O (α and β) and N—H?N (β) hydrogen bonds.     

A cis‐stilbene derivative

The title compound, 4′‐methoxy‐α,2,3′,4‐tetra­nitro­stilbene, C₁₅H₁₀N₄O₉, crystallizes in the centrosymmetric space group P2₁/c with one mol­ecule in the asymmetric unit. The phenyl rings are inclined to one another and form a dihedral angle of 57.4 (1)°. The size of this angle is a result of intermolecular C—H⃛O interactions involving the phenyl H atoms. The torsion angle between the phenyl rings, −7.5 (3)°, indicates a cis geometry between them. The methoxy group is almost coplanar with the phenyl ring, and the nitro groups are twisted with respect to the phenyl rings because of the short H⃛O contacts. The crystal packing is stabilized by C—H⃛O hydrogen bonds, and the intermolecular hydrogen bonds form a C(12) graph‐set chain running along the [010] direction.     

2‐Nitrophenyl 4‐nitrophenyl disulfide

The structure of the title compound, C₁₂H₈N₂O₄S₂, contains no direction‐specific intermolecular interactions, i.e. no C—H?O hydrogen bonds, no aromatic π–π‐stacking interactions and no C—H?π(arene) interactions. This behaviour is compared with the three known symmetrical isomers of bis­(nitro­phenyl) di­sulfide, having the nitro groups on the two 2‐, 3‐ or 4‐positions, all of which exhibit direction‐specific supramolecular aggregation.     

Methyl {1‐[2,3‐O‐iso­propyl­idene‐5‐O‐(4‐nitro­benzoyl)‐α‐d‐ribo­furan­osyl]‐4‐methoxy­carbonyl‐1H‐1,2,3‐triazol‐5‐yl}acetate

In the title compound, C₂₂H₂₄N₄O₁₁, the N‐glycosidic torsion angles O′—C′—N—C and O′—C′—N—N are ?34.1 (6) and 148.8 (3)°, respectively. The mol­ecule displays an α‐d configuration with the ribo­furan­ose moiety in an O′‐exo–C′‐endo pucker. There are only weak C—H?O and C—H?N intra‐ and intermolecular interactions.     

1,3‐Dimethyl‐2‐oxo‐4,6‐diphenyl‐1,2,3,4‐tetrahydropyridine‐3‐carbonitrile

The crystal structure of the title compound, C₂₀H₁₈N₂O, reveals a distorted half‐chair conformation of the central tetra­hydro­pyridine (THP) ring, with the cyano‐ and adjacent phenyl‐substituted C atoms displaced by 0.329 (1) and ?0.315 (1) Å, respectively, from the THP best plane. Steric interactions force the phenyl rings out of the THP plane by 49.21 (9) and 65.76 (5)°. The cyano moiety is coplanar with the THP plane.     

5‐Acetyl‐2‐amino‐6‐methyl‐4‐(3‐nitrophenyl)‐4H‐pyran‐3‐carbonitrile and 2‐amino‐5‐ethoxycarbonyl‐6‐methyl‐4‐(3‐nitrophenyl)‐4H‐pyrano‐3‐carbonitrile

The structures of the title compounds, C₁₅H₁₃N₃O₄, (I), and C₁₆H₁₅N₃O₅ [IUPAC name: ethyl 6‐amino‐5‐cyano‐2‐methyl‐4‐(3‐nitro­phenyl)‐4H‐pyrano‐3‐carboxyl­ate], (II), are very similar, with the heterocyclic rings adopting boat conformations. The pseudo‐axial m‐nitro­phenyl substituents are rotated by 84.0 (1) and 98.7 (1)° in (I) and (II), respectively, with respect to the four coplanar atoms of the boat. The dihedral angles between the phenyl rings and nitro groups are 12.1 (2) and 8.4 (2)° in (I) and (II), respectively. The two compounds have similar patterns of intermolecular N—H?O and N—H?N hydrogen bonding, which link mol­ecules into infinite tapes along b .     

4‐Chloro­aceto­phenone [1‐(4‐methoxyphenyl)­ethyl­idene]­hydra­zone

The crystal structure of the title mixed azine, C₁₇H₁₇ClN₂O, contains four independent mol­ecules, A–D, and mol­ecule B is disordered. All four mol­ecules have an N—N gauche conformation, with C—N—N—C torsion angles of 136.5 (4), 137.0 (4), ?134.7 (4) and ?134.7 (4)°, respectively. The phenyl rings are also somewhat twisted with respect to the plane defined by C_ipso and the imine bond. On average, the combined effect of these twists results in an angle of 64.7° between the best planes of the two phenyl rings. Arene–arene double T‐contacts are the dominant intermolecular inter­action. The methoxy‐substituted phenyl ring of one azine mol­ecule interacts to form a T‐contact with the methoxy‐substituted phenyl ring of an adjacent mol­ecule and, similarly, two chloro‐substituted phenyl rings of neighboring mol­ecules interact to form another T‐contact. The only exception is for mol­ecule B, for which the disorder leads to the formation of T‐­contacts between methoxy‐ and chloro‐substituted phenyl rings. The prevailing structural motif of T‐contact formation between like‐substituted arene rings results in a highly dipole‐parallel‐aligned crystal structure.     

3‐(4‐Acetyl­phenyl)‐1‐(4‐nitro­phenyl)­triazene

The crystal structure of the title compound, C₁₄H₁₂N₄O₃, shows that the stereochemistry about the N=N double bond of the N=N—N(H) moiety is trans. The whole mol­ecule is almost planar (r.m.s. deviation = 0.0654 Å), the interplanar angle between the phenyl rings being 0.7 (1)° and the largest interplanar angle being that between the phenyl ring and the nitro group of the 4‐nitro­phenyl substituent [11.5 (2)°]. Intermolecular N—H⋯O interactions between mol­ecules related by translation give rise to chains along the [110] and [10] directions, and these chains are held together by N⋯O π–π interactions. An unequal distribution of the double‐bond character among the N atoms suggests a delocalization of π electrons over the diazo­amine group and the adjacent aryl substituents.     

Two N‐ortho‐nitro­benzene­sulfonyl α,α‐disubstituted amino acid adducts

The carboxy group of 2‐methyl‐N‐[(2‐nitrophenyl)sulfonyl]­alanine, C₁₀H₁₂N₂O₆S, forms centrosymmetric hydrogen‐bonded dimers with an O?O distance of 2.629 (2) Å and an intramolecular N—H?O(nitro) hydrogen bond N?O distance of 2.823 (2) Å. 1‐[(2‐Nitro­phenyl)­sulfonyl­amino]­cyclo­hexane­carboxyl­ic acid, C₁₃H₁₆N₂O₆S, has Z′ = 2 and forms similar interactions.     

Hydro­gen bonds and C—H⋯O interactions in 2,2′‐dimethoxybiphenyl‐5,5′‐dimethanol at 150 K

The title compound, C₁₆H₁₈O₄, crystallized in the centrosymmetric space group P2₁/c with one mol­ecule in the asymmetric unit. The two hydroxyl‐H atoms are ordered, and are involved in intermolecular hydrogen bonds with O_donor?O_acceptor distances of 2.761 (1) and 2.699 (1) Å, and O—H?O angles of 157 (2) and 168 (2)°. Seven leading intermolecular C—H?O interactions have H?O distances ranging from 2.41 to 2.76 Å and C—H?O angles ranging from 125 to 170°. The hydrogen bonds and C—H?O interactions form chain and ring patterns, resulting in a richly three‐dimensional network. The bi­phenyl twist angle is 67.2 (1)°.     

1,3‐Bis(4‐nitro­phenyl)­triazene

The structure of the title compound, C₁₂H₉N₅O₄, reveals an almost planar mol­ecule (r.m.s. deviation = 0.061 Å), in which the interplanar angle between the phenyl rings is 5.7 (1)° and the largest interplanar angle is that between the phenyl ring and the nitro group of one of the 4‐nitro­phenyl substituents [8.8 (3)°]. The observed mol­ecular conformation suggests a delocalization of π‐electrons extended over the diazo­amine group and the terminal aryl substituents. Intermolecular N—H⃛O interactions between the twofold screw‐related mol­ecules give rise to helical chains along the [010] direction. Intermolecular C—H⃛O interactions then generate sheets of mol­ecules in the (10) plane, and these sheets are held together by N⃛C and O⃛O π–π interactions.     

p‐Nitro­phenyl isocyanide

Achiral p‐nitro­phenyl isocyanide, C₇H₄N₂O₂, crystallizes in the orthorhombic chiral space group P2₁2₁2₁. Attractive intermolecular interactions between the nitro O atoms and both aromatic H and nitro N atoms of neighbouring mol­ecules are observed. The O⋯N interaction is surprisingly strong [N⋯O = 2.869 (2) Å] compared with other aromatic nitro compounds.     

4‐Fluoro‐2‐(phospho­no­methyl)­benzene­sulfonic acid monohydrate

The title compound, C₇H₈FO₆PS·H₂O, contains both phospho­nic and sulfonic acid functionalities. An extensive network of O—H?O hydrogen bonds is present in the crystal structure. The three acidic protons are associated with the phospho­nate group. Two protons experience typical hydrogen‐bond contacts with the sulfonate‐O atoms, while the third has a longer covalent bond of 1.05 (3) Å to the phospho­nate‐O atom and a short hydrogen‐bond contact of 1.38 (3) Å to the water O atom (all O—H?O angles are in the range 162–175°). The sulfonate group is positioned so that one S—O bond is nearly coplanar with the phenyl ring [torsion angle O—S—C—C ?8.6 (2)°]. The phospho­nate group is oriented approximately perpendicular to the ring [torsion angle P—C—C—C 99.2 (2)°] with one P—O bond anti to the benzyl C—C bond. The mol­ecules pack in layers in the b–c plane with the water mol­ecules in between adjacent pairs of inverted layers.     

2‐Iodo‐N‐(3‐nitrobenzyl)aniline and 3‐iodo‐N‐(3‐nitrobenzyl)aniline exhibit entirely different patterns of supramolecular aggregation

In 2‐iodo‐N‐(3‐nitro­benzyl)­aniline, C₁₃H₁₁IN₂O₂, the mol­ecules are linked into a three‐dimensional structure by a combination of C—H?O hydrogen bonds, iodo–nitro interactions and aromatic π–π‐stacking interactions, but N—H?O and C—H?π(arene) hydrogen bonds are absent. In the isomeric 3‐iodo‐N‐(3‐nitro­benzyl)­aniline, a two‐dimensional array is generated by a combination of N—H?O, C—H?O and C—H?π(arene) hydrogen bonds, but iodo–nitro interactions and aromatic π–π‐stacking interactions are both absent.     

Solvated and solvent‐free forms of N,N′‐di­thio­diphthal­imide

N,N′‐Di­thio­diphthal­imide, C₁₆H₈N₂O₄S₂, crystallizes from ethyl acetate with two independent mol­ecules in the asymmetric unit, in which the N—S—S—N torsion angles are ?83.59 (19) and 92.9 (2)°. The mol­ecules are linked by C—H?O hydrogen bonds and aromatic π–π‐stacking interactions into a three‐dimensional framework. When crystallized from either di­chloro­methane or ethanol, solvates are formed in which the mol­ecules of the title compound lie across twofold rotation axes in space group C2/c, with N—S—S—N torsion angles of 93.54 (7) and 96.14 (11)°. There are no hydrogen bonds in these solvates, but the mol­ecules are linked by aromatic π–π‐stacking interactions into chains, between which there are continuous channels. Disordered solvent mol­ecules occupy these channels, which account for ca 20% of the unit‐cell volume.     

3‐(1‐Hydroxy­ethyl­idene)‐1‐phenyl­pyrrolidine‐2,4‐dione

Analysis of C₁₂H₁₁NO₃ revealed a coplanar N‐substituted phenyl group on a pyrrolidine ring with two keto moieties and a hydroxy­ethyl­idene functionality. The hydroxy group forms part of a hydrogen‐bonding network characterized by a short intramolecular H?O distance of 1.81 (3) Å, and a longer intermolecular interaction with an H?O distance of 2.38 (3) Å. Both keto groups form additional intra‐ and intermolecular C—H?O contacts with H?O distances ranging from 2.26 to 2.41 Å.     

5‐Nitro‐N‐phenyl‐2‐thio­fur­amide

The title compound, C₁₁H₈N₂O₃S, crystallizes with two crystallographically independent mol­ecules, which are conformationally almost identical, per asymmetric unit. The dihedral angles between the phenyl and 2‐thio­fur­amide planes are 46.3 (1) and 47.0 (1)° for the first and second mol­ecule, respectively. Strong intramolecular N—H?O hydrogen bonds [N?O 2.664 (2) and 2.661 (2) Å] dictate an anti conformation of the C=S groups in relation to the furan‐O atoms.     

A benzopyran derivative substituted at position 3

In (E)‐3‐{[(di­phenoxy­phospho­ryl)­methyl­hydrazono]­methyl}‐4H‐1‐benzo­pyran‐4‐one, C₂₃H₁₉N₂O₅P, the benzo­pyran–methyl­hydrazone moiety is planar and the two phenoxy phenyl rings are inclined at angles of 21.29 (6) and 89.33 (5)°. Weak C—H?O and C—H?N intramolecular interactions exert some influence on the planarity and orientation of that moiety.     

{2,6‐Bis­[(di­methyl­amino)­methyl]­phenyl‐N2,C1,N6}di­phenyl­tin(II) bromide monohydrate

In the title compound, [Sn(C₆H₅)₂(C₁₂H₁₉N₂)]Br·H₂O, the Sn^IV atom lies on a twofold axis and is coordinated by a C and two N atoms from the 2,6‐bis­[(di­methyl­amino)­methyl]­phenyl ligand in a tridentate fashion and by two phenyl groups. The resulting geometry is intermediate between square pyramidal and trigonal bipyramidal, with three C atoms in equatorial and the two N atoms in axial positions. The main deformation from ideal trigonal‐bipyramidal geometry is seen for the N—Sn—N angle [152.18 (7)°]. The Br^? anion and the water solvate mol­ecule are on an inversion centre and twofold axis, respectively. They form an infinite chain of Br?H—O—H?Br hydrogen bonds [Br?O 3.529 (2) Å] without contributing to the primary coordination sphere of the Sn atom.