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The structure of the title compound, C24H26S2, an example of a pincer ligand with an SCS-chelation motif, illustrates the steric effects of the methyl groups in the thio­phenyl rings at the 2- and 6-positions, forcing a dissimilar spatial orientation of the thio­phenyl rings relative to the central aryl group [dihedral angles = 33.58 (7) and 40.49 (7)°]. In the crystal, weak S⋯S contacts [3.4009 (7) Å] link the mol­ecules into inversion dimers.

In the complex cation of title compound, [Fe(C56H52N4)(C5H8N2)2]ClO4·1.5C6H5Cl, the ironIII atom is coordinated in a distorted octa­hedral manner by four pyrrole N atoms of the porphyrin ring system in the equatorial plane, and by two N atoms of the 1-ethyl­imidazole ligands in the axial sites. A disordered perchlorate anion and one and a half chloro­benzene solvent mol­ecules are also present. The cationic complex exhibits a highly ruffled porphyrin core. The average Fe—Np (Np is a porphyrin N atom) bond length is 1.988 (5), and the axial Fe—NIm (NIm is an imidazole N atom) bond lengths are 1.962 (3) and 1.976 (3) Å. The two 1-ethyl­imidazole ligands are inclined to each other by a dihedral angle of 68.62 (16)°. The dihedral angles between the 1-ethyl­imidazole planes and the planes of the closest Fe—Np vector are 28.52 (18) and 43.57 (13)°. Inter­molecular C—H⋯Cl inter­actions are observed.

In the crystal structure of the title compound, [Sn(C42H26N6)(C7H5O2)2], the SnIV ion is located on a crystallographic inversion centre and is octa­hedrally coordinated with an N4O2 set. Four N atoms of the porphyrin ring form the equatorial plane while the axial positions are occupied by two O atoms from benzoate anions. The molecular packing of the title complex involves non-classical hydrogen bonds of the types C—H⋯O and C—H⋯N, leading to a three-dimensional network structure.

The title compound, [Co(NCS)2(C15H22N2O2)2] or C32H44CoN6O4S2, was prepared from cobalt(II) nitrate, benzyl carbazate and ammonium thio­cyanate in the presence of 4-hepta­none. The compound crystallizes with two centrosymmetric complexes in which the cobalt(II) atoms have a trans-CoO2N4 octa­hedral coordination geometry. In the crystal, N—H⋯S, C—H⋯S and C—H⋯.π contacts stack the complex mol­ecules along the b-axis direction.

In the title compound, [Cd2(C9H6O5)2(H2O)2]n, the crystallographically distinct CdII cations are coordinated in penta­gonal–bipyramidal and octa­hedral fashions. The 2-(carb­oxy­meth­oxy)benzoate (cmb) ligands connect the Cd atoms into [Cd2(cmb)2(H2O)2)]n coordination polymer ribbons that are oriented along the a-axis direction. Supra­molecular layers are formed parallel to (01overline{1}) by O—H⋯O hydrogen bonding between the ribbons. The supra­molecular three-dimensional crystal structure of the title compound is then constructed by π–π stacking inter­actions with a centroid–centroid distance of 3.622 (2) Å between cmb ligands in adjacent layer motifs.

The asymmetric unit of the title sulfodi­imide, C22H22N2OS, consists of two crystallographically independent mol­ecules with similar conformations The environment around each sulfur atom is a slightly distorted tetra­hedron with two S=N bonds and two S—C bonds. The S= N(m-methyl­benzo­yl) and S=N(NEt) bond lengths are 1.584 (3) and 1.528 (2) Å, respectively, for one mol­ecule, and 1.575 (2) and 1.529 (3) Å, respectively, for the other. The dihedral angles between the two phenyl rings in the mol­ecules are 86.76 (8) and 82.49 (8)°. The N—S—N—C(m-methyl­benzo­yl) and N—S—N—C(eth­yl) torsion angles are −60.5 (2) and −50.28 (19)°, respectively, for one mol­ecule, and 62.9 (2) and 44.2 (3)°, respectively, for the other. In the crystal, each independent mol­ecule is linked to its inversion-related mol­ecule via a pair of C—H⋯O hydrogen bonds, forming a dimer.

The title compound, C6Cl4I2·C6H6, crystallizes from benzene solution as cube-shaped crystals in the triclinic space group Poverline{1} with Z = 1. The asymmetric unit of the crystal structure contains one half of each mol­ecule. In the crystal, the benzene ring is almost orthogonal to the perhalo­benzene ring and the mol­ecules are linked by C—I⋯π inter­actions, with a close contact between the iodine atom and the benzene ring of 3.412 (1) Å.

The title compound, [Ag2(C2H3O2)2(C19H20N2)2] (2), was readily synthesized by treatment of 3-benzyl-1-(2,4,6-tri­methyl­phen­yl)imidazolium chloride with silver acetate. The solution structure of the complex was analyzed by NMR spectroscopy, while the solid-state structure was confirmed by single-crystal X-ray diffraction studies. Compound 2 crystallizes in the triclinic space group Poverline{1}, with a silver-to-carbene bond length (Ag—CNHC) of 2.084 (3) Å. The mol­ecule resides on an inversion center, so that only half of the mol­ecule is crystallographically unique. The planes defined by the two imidazole rings are parallel to each other, but not coplanar [inter­planar distance is 0.662 (19) Å]. The dihedral angles between the imidazole ring and the benzyl and mesityl rings are 77.87 (12) and 72.86 (11)°, respectively. The crystal structure features π–π stacking inter­actions between the benzylic groups of inversion-related (−x + 1, −y + 1, −z + 1) mol­ecules and C—H⋯π inter­actions.

Single crystals of the title complex, [Zn(C7H5N2O4)2(C2H6OS)2] or [Zn(NBZH)2(DMSO)2], were isolated from a dimethyl sulfoxide (DMSO) solution containing [Zn(NBZH)2]·2H2O (NBZH = 3-nitro­benzo­hydroxamate anion). The asymmetric unit comprises of one O,O'-chelating NBZH anion, one O-bound DMSO ligand and one zinc(II) cation localized on an inversion centre. The three-dimensional crystal packing includes N—H⋯O and C—H⋯O hydrogen bonding, as well as O⋯H and H⋯H contacts identified by Hirshfeld isosurface analysis.

The title complex, [RuCl(C10H14)(C10H8N2)](C24H20B), has monoclinic (P21) symmetry at 100 K. It was prepared by the reaction of the di­chlor­ido[1-methyl-4-(propan-2-yl)benzene]­ruthenium(II) dimer with 2,2'-bi­pyridine, followed by the addition of ammonium tetra­phenyl­borate. The 1-methyl-4-(propan-2-yl)benzene group, the 2,2'-bi­pyridine unit and a chloride ion coordinate the ruthenium(II) atom, with the 1-methyl-4-(propan-2-yl)benzene ring and bi­pyridine moieties trans to each other. In the crystal, the complex cations are linked by C—H⋯Cl hydrogen bonds, forming chains parallel to [010]. These chains are linked by a number of C—H⋯π inter­actions, involving the phenyl rings of the tetra­phenyl­borate anion and a pyridine ring of the bpy ligand, resulting in the formation of layers parallel to (10overline{1}).

In the title compound, [Zn(C9H6O4)]n, the ZnII cations are coordinated in a tetra­hedral fashion by carboxyl­ate O-atom donors belonging to four 4-(carb­oxy­meth­yl) benzoate (4-cmb) ligands. Each 4-cmb ligand binds to four ZnII cations in an exo­tetra­dentate fashion to create a non-inter­penetrated [Zn(4-cmb)]n three-dimensional coordination polymer network with a new non-diamondoid 66 topology. The crystal studied was refined as an inversion twin.

In the title compound, C16H19NSe, the dihedral angle between the benzene rings is 66.49 (12) and a weak intra­molecular N—H⋯Se hydrogen bond generates an S(6) ring. In the crystal, weak N—H⋯N hydrogen bonds link the mol­ecules into [100] chains.

The title salt, C24H27N2OS+·BF4−, was prepared by an alkyl­ation at the amino N atom attached to the sulfur atom of the corresponding sulfodi­imide. The configuration around the sulfur atom is a slightly distorted tetra­hedral geometry with two S—N bonds and two S—C bonds. The lengths of the S—N(di­ethyl­amine) and S=N(m-methyl­benzoyl­imine) bonds are 1.619 (2) and 1.551 (2) Å, respectively. The two N—S—N—C(eth­yl) and the N—S—N—C(m-methyl­benzoyl­imine) torsion angles are −85.43 (3), 58.94 (17) and 62.03 (16)°, respectively. The dihedral angle between the two phenyl rings is 84.03 (14)°. In the crystal, C—H⋯F hydrogen bonds link the cation and anion, forming a three-dimensional network.

The asymmetric unit of the title compound, [Fe(C5H5)(C12H7ClNO)], consists of one ferrocenyl group bonded to chloro­benzo[d]oxazole. The conformation of the ferrocenyl moiety is slightly away from eclipsed. The bond angles between the 5-chloro-benzoxazole and ferrocenyl fragments are N—C—C = 127.4 (7)° and O—C—C = 116.8 (7)°. The benzo[d]oxazole ring is planar (r.m.s. deviation = 0.0042 Å) and makes an angle of 11.3 (4)° with the cyclo­penta­dienyl ring attached to it. The crystal packing is characterized by inter­molecular π–π contacts, resulting in chain formation along the b-axis direction. The centroid-to-centroid distance between the six- and five-membered rings is 3.650 (5) Å. Together with a C—H⋯π inter­action, these inter­molecular contacts form laminar arrays along the ac plane.

In the title compound, C7H4N2O3S, the dihedral angle between the fused ring system (r.m.s. deviation = 0.008 Å) and the nitro group at the 6-position is 7.3 (2)°. In the crystal, bifurcated N—H⋯(O,O) hydrogen bonds link the mol­ecules into [010] chains. The chains are cross-linked by π–π stacking inter­actions to form (001) sheets.

In the title sulfanilamide derivative, C15H13NO2S, which shows significant activity against Staphylococcus aureus and Escherichia coli, the dihedral angle between the planes of the aromatic rings is 62.15 (19)° and the four-coordinate S atom adopts an almost ideal tetra­hedral geometry. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network.

Trinuclear copper–pyrazolate entities are present in various Cu-based enzymes and nanojar supra­molecular arrangements. The reaction of copper(II) chloride with pyrazole (pzH) and sodium benzoate (benzNa) assisted by microwave radiation afforded a neutral centrosymmetric hexa­nuclear copper(II) complex, [Cu6(C7H5O2)4(OH)2(C3H3N2)6(C2H5OH)2]·2C2H5OH. Half a mol­ecule is present in the asymmetric unit that comprises a [Cu3(μ3-OH)(pz)3]2+ core with the copper(II) atoms arranged in an irregular triangle. The three copper(II) atoms are bridged by an O atom of the central hydroxyl group and by three bridging pyrazolate ligands on each of the sides. The carboxyl­ate groups show a chelating mode to one and a bridging syn,syn mode to the other two CuII atoms. The coordination environment of one CuII atom is square-planar while it is distorted square-pyramidal for the other two. Two ethanol mol­ecules are present in the asymmetric unit, one binding to one of the CuII atoms, one as a solvent mol­ecule. In the crystal, stabilization arises from inter­molecular O—H⋯O hydrogen-bonding inter­actions.

The title structure, C12H8Cl2O2, is a putative metabolite of 3,5-di­chloro­biphenyl (PCB 14). The dihedral angle between the two benzene rings of the title compounds is 58.86 (4)°. In the crystal, it displays intra- and inter­molecular O—H⋯O hydrogen bonding and inter­molecular O—H⋯Cl hydrogen⋯chlorine inter­actions. The inter­molecular inter­actions form a two-dimensional network parallel to (010).

In the title compound, C34H35NO4, the dihedral angle between the pyridine ring and attached benzene ring is 79.17 (8)°. The meth­oxy­eth­oxy–eth­oxy side chain is disordered over two orientations in a 0.732 (7):0.268 (7) ratio. In the crystal, very weak C—H⋯N and C—H⋯O inter­actions link the mol­ecules.

The title magnesium complex, [Mg(C21H20NO2)2(C4H8O)]n, exhibits two N,O-bidentate 2-(di­methyl­amino)-α,α-di­phenyl­benzene­methano­late ligands, form­ing two six-membered chelate rings. The distorted square-pyramidal coordination sphere of the MgII atom is completed by the O atom of a tetra­hydro­furan ligand, with its O atom in the apical position. The O and N atoms are in a mutual trans arrangement. Except for two C—H⋯π inter­actions, no significant inter­molecular inter­actions are observed in the crystal.

The title compound, C18H20N4O4, was synthesized via the base-assisted reaction of piperazine and 2-nitro­benyl bromide in toluene: the complete mol­ecule is generated by a crystallographic inversion centre in the solid state.

The title compound, C26H22O2P+·PF6−·C4H7O, crystallizes as a cation-anion pair with a single solvent mol­ecule in the asymmetric unit. Hydrogen bonding occurs between the carb­oxy­lic acid group on the cation and the oxygen atom of the solvent mol­ecule. Longer hydrogen-bonding inter­actions are observed between fluorine atoms of the anion and H atoms on the phenyl rings of the cation.

In the title compound, C21H17N3O2, the triazole ring system is inclined at dihedral angles of 4.14 (18) and 69.24 (11)° with the naphthalene ring system and phenyl ring, respectively. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds into double columns propagating along the b-axis direction.

The title compound, C9H7NO2, was prepared by alkynylation of 4-iodo­nitro­benzene with 1,3-dili­thio­propyne in the presence of 1 equivalent of CuI and catalytic amounts of Pd(PPh3)2Cl2. The complete mol­ecule is generated by crystallographic twofold symmetry with the C—N and C—C≡C—C units lying on the rotation axis. No directional inter­actions beyond normal van der Waals contacts could be identified in the packing.

In the title compound, [Cu2(C7HF4O2)4(C12H8N2)2(CH3OH)], the mol­ecule lies on a twofold rotation axis in space group C2/c. The Cu2+ ion exhibits a distorted octa­hedral sphere with two N atoms from the phenanthroline ligand, three O atoms from the 2,3,4,5-tetra­fluoro­benzoate ligands and one O atom from a methanol mol­ecule. The distortion from an octa­hedral shape is a consequence of the Jahn–Teller effect of CuII and the small bite angle for the bidentate fluoro­benzoate ligand [54.50 (11)°]. The methanol mol­ecule bridges two symmetry-related CuII atoms to form the complete mol­ecule. In the bidentate fluoro­benzoate ligand, one F atom is disordered over two positions of equal occupancy. In the crystal structure, only weak inter­molecular inter­actions are observed.

The structure of the title compound, [Os(C6HF4S)4{P(C6H5)3}], has been previously reported [Arroyo et al. (1994). J. Chem. Soc. Dalton Trans. pp. 1819–1824], in the space group Poverline{1}. We have now obtained a monoclinic polymorph for this compound, crystallized from ethanol, while the previous form was obtained from a hexa­ne/chloro­form mixture. The mol­ecular structure is based on a trigonal–bipyramidal OsIV coordination geometry, close to that observed previously in the triclinic form.

The crystal structure of the benzene monosolvate of the well known organic diphosphite ligand BIPHEPHOS, C46H44O8P2·C6H6, is reported for the first time. Single crystals of BIPHEPHOS were obtained from a benzene solution after layering with n-heptane at room temperature. One specific property of this type of diphosphite structure is the twisting of the biphenyl units. In the crystal, C—H⋯π contacts and π–π stacking inter­actions [centroid-to-centroid distance = 3.8941 (15) Å] are observed.

In the title hydrated salt, [Ni(C21H17F2N3)2](NO3)2·2H2O, the central NiII ion is coordinated by six N atoms from two tridentate chelating 2,6-bis­[(E)-(4-fluoro­benzyl­imino)­meth­yl]pyridine ligands. While the central NiII ion is six-coordinate, its environment is distorted from an octa­hedral structure because of the unequal Ni—N distances. The Ni—N bond lengths vary from 1.8642 (14) to 2.2131 (15) Å, while the N—Ni—N angles range from 79.98 (6) to 104.44 (6)°. Three coordinating sites of each chelating agent are almost coplanar with respect to the pyridine ring, and two pyridine moieties are perpendicular to each other. Two non-coordinating nitrate anions within the asymmetric unit balance the charges of the central metal ion, and are linked with two crystal water mol­ecules, forming a water–nitrate cyclic tetra­meric unit [O⋯O = 2.813 (2) to 3.062 (2) Å]. In an isolated mol­ecule, the fluoro­phenyl rings of one ligand are stacked with the central ring of the other ligand via π–π inter­actions, with the closest centroid-to-plane distances being 3.359 (6), 3.408 (5), 3.757 (6) and 3.659 (5) Å.

In the title hydrated Schiff base, C13H12N4O3·H2O, the dihedral angle between the aromatic rings is 5.06 (11)° and an intra­molecular O—H⋯N hydrogen bond closes an S(6) ring. In the crystal, Ow—H⋯O and Ow—H⋯N (w = water) hydrogen bonds link the components into centrosymmetric tetra­mers (two Schiff bases and two water mol­ecules). Longer N—H⋯O hydrogen bonds link the tetra­mers into [010] chains. A weak C—H⋯O hydrogen bond and aromatic π–π stacking between the pyrazine and phenyl rings [centroid–centroid separations = 3.604 (2) and 3.715 (2) Å] are also observed.

In the title complex, [NiCl2(C12H9N3)2]·H2O, a divalent nickel atom is coordinated by two 2-(pyridin-2-yl)-1H-benzimidazole ligands in a slightly distorted octa­hedral environment defined by four N donors of two N,N'-chelating ligands, along with two cis-oriented anionic chloride donors. The title complex crystallized with a water mol­ecule disordered over two positions. In the crystal, a combination of O—H⋯Cl, O—H.·O and N—H⋯Cl hydrogen bonds, together with C—H⋯O, C—H⋯Cl and C—H⋯π inter­actions, links the complex mol­ecules and the water mol­ecules to form a supra­molecular three-dimensional framework. The title complex is isostructural with the cobalt(II) dichloride complex reported previously [Das et al. (2011). Org. Biomol. Chem. 9, 7097–7107].

The structure of the title salt, C6H10N22+·2C7H7O3S−, consists of a unique benzene-1,2-diaminium dication charge balanced by a pair of crystallographically independent 4-methyl­benzene-1-sulfonate anions. The cations and anions are inter­linked by several N—H⋯O hydrogen bonds.

In the title compound, C19H13IO2, the dihedral angle between the naphthyl ring system and the pendant iodo­phenyl ring is 72.48 (11)°. In the crystal, C—H⋯π inter­actions and I⋯O [3.293 (2) Å] halogen bonds are observed, which combine to generate a herringbone packing motif.

In the extended structure of the title mol­ecular salt, C6H9N2+·C7H7O3S−, the cations and anions are linked by N—H⋯O hydrogen bonds to generate [010] chains.

The relative stereo- and regiochemistry of the racemic title compound, C25H19NO7, were established from the crystal structure. The fused benzene ring forms dihedral angles of 77.3 (1) and 60.3 (1)° with the hy­droxy-substituted benzene ring and the nitro-substituted benzene ring, respectively. The dihedral angle between the hy­droxy-substituted benzene ring and the nitro-substituted benzene ring is 76.4 (1)°. An intra­molecular O—H⋯O hydrogen bond closes an S(6) ring. In the crystal, weak C—H⋯O hydrogen bonds connect the mol­ecules, forming layers parallel to (100). Within these layers, there are weak π–π stacking inter­actions with a ring centroid–ring centroid distance of 3.555 (1) Å.

The structure of the tertiary amine tris­(1H-benzimidazol-2-ylmeth­yl)amine (C24H21N7, abbreviated ntb) has been previously reported twice as solvates, namely the monohydrate and the aceto­nitrile–methanol–water (1/0.5/1.5) solvate, both with the tripodal conformation formed via multiple hydrogen bonds. Now, we report the tri­methanol adduct, ntb·3CH3OH, where the amine has the stair conformation featuring one benzimidazole group oriented in the opposite direction from the other two. The asymmetric unit contains one-half amine, completed through the mirror plane m in space group Pmn21 to form the ntb mol­ecule, with the H atom for each imidazole moiety equally disordered between both N sites available in the imidazole ring. The asymmetric unit also contains one and a half methanol mol­ecules, one being placed in general position with the hy­droxy H atom disordered over two sites with occupancy ratio 1:1, while the other lies on the m mirror plane, and has thus its hy­droxy H atom disordered by symmetry. As in the previously reported solvates, all imine and amine groups of the ntb mol­ecules and the methanol mol­ecules are involved in N—H⋯O and O—H⋯N hydrogen bonds. In the title compound, however, the involved H atom is systematically a disordered H atom provided by an imidazole group or a methanol mol­ecule.

In the title compound, C14H11ClN2O2S, the dihedral angle between the pyrrolo­[1,2-c]pyrimidine ring system (r.m.s. deviation = 0.008 Å) and the benzene ring is 80.2 (9)°. In the crystal, inversion dimers linked by pairs of C—H⋯O inter­actions generate R22(16) loops. Several aromatic π–π stacking inter­actions between the pyrrolo­[1,2-c]pyrimidine rings, as well as separately between the pyrrolo and pyrimidine groups [shortest centroid–centroid separation = 3.5758 (14) Å], help to consolidate the packing.

The title compound, C26H22O6, is formed as the major product from the reaction between syn-1,2-bis­(pinacolatoboron)-1,2-bis­(4-methyl­carb­oxy­phen­yl)ethene and excess methyl 4-iodo­benzoate in basic DMSO using a palladium catalyst at 80°C via Suzuki coupling followed by protodeboronation. Crystals were grown by slow evaporation of a hexa­nes solution at room temperature.

The asymmetric unit of the binuclear title compound, [Cu2(C8H7O3)4(H2O)2], comprises two halves of diaquatetra­kis­(μ-3-meth­oxy­benzoato-κ2O1:O1')dicopper(II) units. The paddle-wheel structure of each complex is completed by application of inversion symmetry, with the inversion centre situated at the midpoint between two CuII atoms in each dimer. The two CuII atoms of each centrosymmetric dimer are bridged by four 3-meth­oxy­benzoate anions resulting in Cu⋯Cu separations of 2.5961 (11) and 2.6060 (12) Å, respectively. The square-pyramidal coordination sphere of each CuII atom is completed by an apical water mol­ecule. Inter­molecular O—H⋯O hydrogen bonds of weak nature link the complexes into layers parallel to (100). The three-dimensional network structure is accomplished by C—H⋯O hydrogen bonds inter­linking adjacent layers.

The title compound, C16H16N2, was synthesized by dispersing 3,4-hexa­nedione in a methanol–water solution containing the acid catalyst NH4HF2, then adding 1,2-di­aminona­phthalene. The fused-ring system of the title compound is close to planar (r.m.s. deviation = 0.028 Å); one of the pendant methyl C atoms lies close to the ring plane [deviation = 0.071 (2) Å; N—C—C—C = −0.27 (18)°] whereas the other is significantly displaced [–1.7136 (18) Å; 91.64 (16)°]. The mol­ecules pack in space group Ioverline{4} in a distinctive criss-cross motif supported by numerous aromatic π–π stacking inter­actions [shortest centroid–centroid separation = 3.5805 (6) Å].

This work presents the synthesis and structural characterization of [4-(1H-benzo[d]imidazol-2-yl)phen­oxy]phthalo­nitrile, a phthalo­nitrile derivative carrying a benzimidazole moiety. The compound crystallizes as its dimethyl sulfoxide monosolvate, C21H12N4O·(CH3)2SO. The dihedral angle between the two fused rings in the heterocyclic ring system is 2.11 (1)°, while the phenyl ring attached to the imidazole moiety is inclined by 20.7 (1)° to the latter. In the crystal structure, adjacent mol­ecules are connected by pairs of weak inter­molecular C—H⋯N hydrogen bonds into inversion dimers. N—H⋯O and C—H⋯O hydrogen bonds with R21(7) graph-set motifs are also formed between the organic mol­ecule and the disordered dimethyl sulfoxide solvent [occupancy ratio of 0.623 (5):0.377 (5) for the two sites of the sulfur atom]. Hirshfeld surface analysis and fingerprint plots were used to investigate the inter­molecular inter­actions in the crystalline state.

The mol­ecule of the title Schiff base compound, C14H13N3O3·H2O, displays a trans configuration with respect to the C=N bond. The dihedral angle between the benzene and pyridine rings is 29.63 (7)°. The crystal structure features inter­molecular N—H⋯O, C—H⋯O, O—H⋯O and O—H⋯N hydrogen-bonding inter­actions, leading to the formation of a supramolecular framework. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (37.0%), O⋯H/H⋯O (23.7%)), C⋯H/H⋯C (17.6%) and N⋯H/H⋯N (11.9%) inter­actions. The title compound has also been characterized by frontier mol­ecular orbital analysis.

The title compounds, C24H22O6 (I) and C24H22O6 (II), each crystallize with half a mol­ecule in the asymmetric unit. The whole mol­ecule of compound (I) is generated by twofold rotation symmetry, the twofold axis bis­ecting the central benzene ring. The whole mol­ecule of compound (II) is generated by inversion symmetry, the central benzene ring being located on an inversion center. In (I), the outer benzene rings are inclined to each other by 59.96 (10)° and by 36.74 (9)° to the central benzene ring. The corresponding dihedral angles in (II) are 0.0 and 89.87 (12)°. In the crystal of (I), mol­ecules are linked by C—H⋯O hydrogen bonds and C—H⋯π inter­actions, forming ribbons propagating along the [10overline{1}] direction. In the crystal of (II), mol­ecules are linked by C—H⋯O hydrogen bonds, forming a supra­molecular framework. The Hirshfeld surface analyses indicate that for both compounds the H⋯H contacts are the most significant, followed by O⋯H/H⋯O and C⋯H/H⋯C contacts.