Hydrogen bonding and π–π inter­actions in a laminar structure: benzene‐1,3‐dicarboxylic acid–4‐methyl­pyridine (1/2)

The title complex, C₈H₆O₄·2C₆H₇N, consists of two crystallographically independent 1:2 clusters of benzene‐1,3‐­dicarboxylic acid and 4‐methyl­pyridine. Each cluster, the components of which are linked by O—H⋯N hydrogen bonds, is almost planar by alignment of C—H⋯O hydrogen bonds. Herring‐bone ribbons of clusters are formed by other C—H⋯O hydrogen bonds, and these ribbons are further packed to form a laminar structure by π–π inter­actions.     

Ethyl N‐[2‐(hydroxy­acetyl)­phenyl]­carbamate,ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]­carbamate and ethyl N‐[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]­carbamate

In ethyl N‐[2‐(hydroxy­acetyl)phenyl]carbamate, C₁₁H₁₃NO₄, all of the non‐H atoms lie on a mirror plane in the space group Pnma; the mol­ecules are linked into simple chains by a single C—H⋯O hydrogen bond. The mol­ecules of ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]carbamate, C₁₁H₁₂INO₄, are linked into sheets by a combination of O—H⋯I and C—H⋯O hydrogen bonds and a dipolar I⋯O contact. Ethyl N‐­[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]carbamate, C₁₂H₁₅NO₄, crystallizes with Z′ = 2 in the space group P; pairs of mol­ecules are weakly linked by an O—H⋯O hydrogen bond and these aggregates are linked into chains by two independent aromatic π–π stacking inter­actions.     

N,N′‐Bis(2‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide and N,N′‐bis­(3‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide

The mol­ecules of N,N′‐bis­(2‐pyridylmeth­yl)ferrocene‐1,1′‐diyl­dicarboxamide, [Fe(C₁₂H₁₁N₂O)₂], contain intra­molecular N—H⋯N hydrogen bonds and are linked into sheets by three independent C—H⋯O hydrogen bonds. The mol­ecules of the isomeric compound N,N′‐bis­(3‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide lie across inversion centres, and the mol­ecules are linked into sheets by a combination of N—H⋯N hydrogen bonds and π–π stacking inter­actions between pyridyl groups.     

C—H⋯O,C—H⋯π and π–π inter­actions in three benzofuran‐2‐yl ketone derivatives

The mol­ecules of 2‐benzoyl‐1‐benzofuran, C₁₅H₁₀O₂, (I), inter­act through double C—H⋯O hydrogen bonds, forming dimers that are further linked by C—H⋯O, C—H⋯π and π–π inter­actions, resulting in a three‐dimensional supramolecular network. The dihedral angle between the benzo­yl and benzofuran fragments in (I) is 46.15 (3)°. The mol­ecules of bis­(5‐bromo‐1‐benzofuran‐2‐yl) ketone, C₁₇H₈Br₂O₃, (II), exhibit C₂ symmetry, with the carbon­yl group (C=O) lying along the twofold rotation axis, and are linked by a combination of C—H⋯O and C—H⋯π inter­actions and Br⋯Br contacts to form sheets. The stability of the mol­ecular packing in 3‐mesit­yl‐3‐methyl­cyclo­but­yl 3‐methyl­naphtho[1,2‐b]furan‐2‐yl ketone, C₂₈H₂₈O₂, (III), arises from C—H⋯π and π–π stacking inter­actions. The fused naphthofuran moiety in (III) is essentially planar and makes a dihedral angle of 81.61 (3)° with the mean plane of the trimethyl­benzene ring.     

4‐(4‐Fluoro‐3‐phenoxy­phen­yl)‐6‐(4‐fluoro­phen­yl)‐2‐oxo‐1,2‐dihydro­pyridine‐3‐carbonitrile and the 6‐(4‐methyl­phen­yl)‐ analogue

The crystal structures of the title compounds, viz. C₂₄H₁₄F₂N₂O₂, (I), and C₂₅H₁₇FN₂O₂, (II), respectively, have been determined in order to unravel the role of an ordered F atom in generating stable supra­molecular assemblies. On changing the substitution from fluorine to a methyl group, C—H⋯F inter­actions are replaced by C—H⋯π inter­actions, revealing the importance of such weak inter­actions when present alongside N—H⋯O and C—H⋯O hydrogen bonds. The dihedral angle between the planes of the 4‐fluoro­phenyl ring and the pyridine ring is 26.8 (1)° in (I), while that between the planes of the 4‐methyl­phenyl and pyridine rings is 29.5 (1)° in (II).     

Two N‐substituted 3,5‐diphenyl‐2‐pyrazoline‐1‐thiocarboxamides

The structures of N‐ethyl‐3‐(4‐fluoro­phen­yl)‐5‐(4‐methoxy­phen­yl)‐2‐pyrazoline‐1‐thio­carboxamide, C₁₉H₂₀FN₃OS, (I), and 3‐(4‐fluoro­phen­yl)‐N‐methyl‐5‐(4‐methyl­phen­yl)‐2‐pyrazoline‐1‐thio­carboxamide, C₁₈H₁₈FN₃S, (II), have similar geometric parameters. The meth­oxy/methyl‐substituted phenyl groups are almost perpendicular to the pyrazoline (pyraz) ring [inter­planar angles of 89.29 (8) and 80.39 (10)° for (I) and (II), respectively], which is coplanar with the fluoro­phenyl ring [inter­planar angles of 5.72 (9) and 10.48 (10)°]. The pyrazoline ring approximates an envelope conformation in both structures, with the two‐coordinate N atom involved in an intra­molecular N—H⋯N_pyraz inter­action. In (I), N—H⋯O and C—H⋯S inter­molecular hydrogen bonds are the primary inter­actions, whereas in (II), there are no intermolecular hydrogen bonds.     

2‐(2‐Oxazolin‐2‐yl)benzene‐1,4‐diol: X‐ray and density functional theory studies

In the crystal structure of the title compound, C₉H₉NO₃, there are strong intra­molecular O—H⋯N and inter­molecular O—H⋯O hydrogen bonds which, together with weak inter­molecular C—H⋯O hydrogen bonds, lead to the formation of infinite chains of mol­ecules. The calculated inter­molecular hydrogen‐bond energies are −11.3 and −2.7 kJ mol⁻¹, respectively, showing the dominant role of the O—H⋯O hydrogen bonding. A natural bond orbital analysis revealed the electron contribution of the lone pairs of the oxazoline N and O atoms, and of the two hydr­oxy O atoms, to the order of the relevant bonds.     

3,4‐Di‐2‐pyridyl‐1,2,5‐oxadiazole and its perchlorate salt

In 3,4‐di‐2‐pyridyl‐1,2,5‐oxadiazole (dpo), C₁₂H₈N₄O, each mol­ecule resides on a twofold axis and inter­acts with eight neighbours via four C—H⋯N and four C—H⋯O inter­actions to generate a three‐dimensional hydrogen‐bonded architecture. In the perchlorate analogue, 2‐[3‐(2‐pyrid­yl)‐1,2,5‐oxadiazol‐4‐yl]pyridinium perchlorate, C₁₂H₉N₄O⁺·ClO₄⁻ or [Hdpo]ClO₄, the [Hdpo]⁺ cation is bisected by a crystallographic mirror plane, and the additional H atom in the cation is shared by the two pyridyl N atoms to form a symmetrical intra­molecular N⋯H⋯N hydrogen bond. The cations and perchlorate anions are linked through C—H⋯O hydrogen bonds and π–π stacking inter­actions to form one‐dimensional tubes along the b‐axis direction.     

1‐(1‐Amino‐4‐bromo‐9,10‐dioxo‐9,10‐dihydro­anthracen‐2‐ylcarbon­yl)‐1,3‐dicyclo­hexyl­urea

In the title compound, C₂₈H₃₀BrN₃O₄, the mol­ecules are linked by C—H⋯Br and N—H⋯O hydrogen bonds into one‐dimensional chains, which are arranged into a three‐dimensional network through a combination of C—H⋯O hydrogen bonds and two kinds of π–π inter­actions between the benzene rings of the anthraquinone units.     

Bis(3‐amino­pyridine‐κN)(4,4′‐di­methyl‐2,2′‐bipyridine‐κ2N,N′)(per­chlorato‐κO)copper(II) per­chlorate

The title compound, [Cu(ClO₄)(C₅H₆N₂)₂(C₁₂H₁₂N₂)]ClO₄, was prepared by in situ partial ligand substitution between 3‐amino­pyridine and 4,4′‐dimethyl‐2,2′‐bipyridine at room temperature. The central copper(II) ion is five‐coordinated by one bidentate 4,4′‐dimethyl‐2,2′‐bipyridine mol­ecule, two monodentate pyridine‐coordinated 3‐amino­pyridine mol­ecules and one apical O atom from the perchlorate counter‐ion. Inter­molecular N—H⋯O and C—H⋯O hydrogen‐bonding inter­actions form a hydrogen‐bond‐sustained network.     

Dichloro­(O‐ethyl 3‐methyl­pyridine‐2‐carboximidic acid‐κ2N,N′)copper(II)

In the title compound, [CuCl₂(C₉H₁₂N₂O)], the Cu^II atom is coordinated by two Cl⁻ anions and two N atoms of one O‐ethyl 3‐methyl­pyridine‐2‐carboximidic acid mol­ecule in a slightly distorted square‐planar geometry, with Cu—N distances of 2.0483 (17) and 1.9404 (18) Å, and Cu—Cl distances of 2.2805 (10) and 2.2275 (14) Å. In addition, each Cu^II atom is connected by one Cl⁻ anion and the Cu^II atom from a neighbouring mol­ecule, with Cu⋯Cl and Cu⋯Cu distances of 2.9098 (13) and 3.4022 (12) Å, respectively, and, therefore, a centrosymmetric dimer is formed. Adjacent mol­ecular dimers are connected by π–π stacking inter­actions between pyridine rings to form a zigzag mol­ecular chain. The mol­ecular chains are also enforced by N—H⋯Cl and C—H⋯Cl inter­actions.     

Hydro­gen‐bonded supramolecular motifs in 4,4′‐bipyridinium 8‐hydroxy‐7‐iodo­quinoline‐5‐sulfonate dihydrate

In the title compound, C₁₀H₉N₂⁺·C₉H₅INO₄S⁻·2H₂O, the 4,4′‐bi­pyridine mol­ecule is protonated at one of the pyridine N atoms. These moieties self‐assemble into a supramolecular chain along the a axis through N—H⋯N hydrogen bonds. The quinolinol OH group acts as a donor with respect to a sulfonate O atom [O—H⋯O(sulfonate)] and acts as an acceptor with respect to a C—H group of ferron [C—H⋯O(hydroxy)], forming a supramolecular chain along the b axis. These two types of supramolecular chains (one type made up of bi­pyridine motifs and the other made up of sulfoxine motifs) interact viaπ–π stacking, generating a three‐dimensional framework. These chains are further crosslinked by C—­H⋯O hydrogen bonds and O—H⋯O hydrogen bonds involving water mol­ecules.     

2‐(4‐Hydroxy­phenyl)‐4,4‐dimethyl‐2‐oxazoline: X‐ray and density functional theory study

In the crystal structure of the title compound, C₁₁H₁₃NO₂, there are strong inter­molecular O—H⋯N hydrogen bonds which, together with weak intra­molecular C—H⋯O hydrogen bonds, lead to the formation of infinite chains of mol­ecules, held together by weak inter­molecular C—H⋯O hydrogen bonds. A theoretical investigation of the hydrogen bonding, based on density functional theory (DFT) employing periodic boundary conditions, is in agreement with the experimental data. The cluster approach shows that the influence of the crystal field and of hydrogen‐bond formation are responsible for the deformation of the 2‐oxazoline ring, which is not planar and adopts a ⁴T₃ (^C3T_C2) conformation.     

1‐((E)‐{(1R,2R)‐2‐[(E)‐(2‐Hydr­oxy‐1‐naphth­yl)methyl­eneamino]cyclo­hexyl}iminiometh­yl)naphthalen‐2‐olate: a Schiff base compound having both OH and NH character

The title Schiff base compound, C₂₈H₂₆N₂O₂, possesses both OH and NH tautomeric character in its mol­ecular structure. While the OH side of the compound is described as an inter­mediate state, its NH side adopts a predominantly zwitterionic form. The mol­ecular structure of the compound is stabilized by both N⁺—H⋯O⁻ and O—H⋯N intra­molecular hydrogen bonds. There are two weak C—H⋯O hydrogen bonds leading to polymeric chains of topology C(5) and C(13) running along the b axis of the unit cell. In addition, inter­molecular C—H⋯π inter­actions serve to stabilize the extended structure.     

2,3‐Difluoro‐4‐formyl­phenyl­boronic acid

The mol­ecule of the title compound, 2,3‐F₂‐4‐(CHO)C₆H₂B(OH)₂ or C₇H₅BF₂O₃, contains a formyl group coplanar with the benzene ring. The boronic acid group is twisted with respect to the benzene ring plane. The mol­ecules are organized into infinite chains via inter­molecular O—H⋯O hydrogen bonds. These chains are additionally connected via strong O—H⋯O hydrogen bonds, producing a folded layer structure perpendicular to the a axis. These layers are paired due to B⋯F inter­actions.     

(Z)‐1‐Ferrocenyl‐3‐(3‐hydroxy­anilino)­but‐2‐en‐1‐one and (Z)‐1‐ferrocenyl‐3‐(4‐hydroxy­anilino)­but‐2‐en‐1‐one

The title compounds, both [Fe(C₅H₅)(C₁₅H₁₄NO₂)], crystallize with Z′ = 2 in the centrosymmetric space group P. In each compound, there is an intra­molecular N—H⋯O=C hydrogen bond, and pairs of inter­molecular O—H⋯O=C hydrogen bonds link the mol­ecules into chains, parallel to [10] in the 3‐hydr­oxy compound and parallel to [10] in the 4‐hydr­oxy compound.     

Naphthalene‐1,7‐diol

The asymmetric unit of the title compound, C₁₀H₈O₂, contains two planar symmetry‐independent mol­ecules linked by an O—H⋯O hydrogen bond. In the crystal structure, mol­ecules are linked into infinite chains of rings, formed by a combination of O—H⋯O and C—H⋯O hydrogen bonds, and additionally reinforced by π–π stacking inter­actions. Adjacent chains are connected by weak C—H⋯π inter­actions.     

(R)‐N‐[(R)‐1‐(2‐Hydroxy‐5‐methyl­phenyl)‐2‐phenyl­ethyl]‐2‐methyl‐1‐phenyl­propyl­ammonium chloride

In the title compound, C₂₅H₃₀NO⁺·Cl⁻, the mol­ecules are linked by a combination of inter­molecular N—H⋯Cl and O—H⋯Cl hydrogen bonds and intra­molecular N—H⋯O hydrogen bonds. The absolute configuration of the new stereogenic centre (the C atom adjacent to the N atom on the phenol side) is determined to have an R configuration.     

3,3′‐Dihydr­oxy‐5,5,5′,5′‐tetra­methyl‐2,2′‐thio­dicyclo­hex‐2‐en‐1‐one

Mol­ecules of the title compound, C₁₆H₂₂O₄S, have twofold crystallographic symmetry and are stabilized by strong intra­molecular O—H⋯O hydrogen bonds and very weak inter­molecular C—H⋯O hydrogen bonds, forming layers normal to the c axis. The mol­ecular structure is compared with those of the Se‐ and CH₂‐bridged analogues.     

N,N′‐Bis(2‐methoxy­phenyl)­naphthalene‐1,4‐dicarboxamide

The title compound, C₂₆H₂₂N₂O₄, crystallizes in an anti‐C=O orientation, with the two N‐substituted benzene rings in different conformations relative to the naphthalene ring. These conformations allow two strong N—H⋯O hydrogen bonds and one C—H⋯π inter­action to generate mol­ecular chains in the cell.