Hydrogen‐bonded sheet structures in methyl 4‐(4‐chloroanilino)‐3‐nitrobenzoate and methyl 1‐benzyl‐2‐(4‐chlorophenyl)‐1H‐benzimidazole‐5‐carboxylate

In methyl 4‐(4‐chloroanilino)‐3‐nitrobenzoate, C₁₄H₁₁ClN₂O₄, (I), there is an intramolecular N—H...O hydrogen bond and the intramolecular distances provide evidence for electronic polarization of the o‐quinonoid type. The molecules are linked into sheets built from N—H...O, C—H...O and C—H...π(arene) hydrogen bonds, together with an aromatic π–π stacking interaction. The molecules of methyl 1‐benzyl‐2‐(4‐chlorophenyl)‐1H‐benzimidazole‐5‐carboxylate, C₂₂H₁₇ClN₂O₂, (II), are also linked into sheets, this time by a combination of C—H...π(arene) hydrogen bonds and aromatic π–π stacking interactions.     

N‐Benzyloxy‐1H‐benzotriazole‐1‐carboxamide: a hydrogen‐bonded tetramer based upon a rare R44(20) structural motif

The title compound, C₁₄H₁₂N₄O₂, is the first example of a heterocyclic substituted hydroxamic derivative. The asymmetric unit consists of two molecules. The molecules are linked into centrosymmetric R₄⁴(20) tetramers by four strong hydrogen bonds of the N—H...O and N—H...N types. These tetramers are connected through C—H...O interactions into a three‐dimensional network.     

Hydrogen‐bonded chains of rings in 1‐(4‐chloroanilinomethyl)‐5‐(4‐chlorophenyl)‐1,3,5‐triazinane‐2‐thione and hydrogen‐bonded sheets in 1‐anilinomethyl‐5‐phenyl‐1,3,5‐triazinane‐2‐thione

In 1‐(4‐chloroanilinomethyl)‐5‐(4‐chlorophenyl)‐1,3,5‐triazinane‐2‐thione, C₁₆H₁₆Cl₂N₄S, there are two independent molecules in the asymmetric unit which form inversion dimers via two weak N—H...S hydrogen bonds. The dimers are then linked into C(9)C(14) chains by a C—H...S hydrogen bond and a C—H...Cl contact. In 1‐(anilinomethyl)‐5‐phenyl‐1,3,5‐triazinane‐2‐thione, C₁₆H₁₈N₄S, molecules are linked into complex sheets via a combination of N—H...S and C—H...π hydrogen bonds.     

Two polymorphs of N‐(2‐methoxyphenyl)‐4‐oxo‐4H‐chromone‐3‐carboxamide

The title compound, C₁₇H₁₃NO₄, crystallizes in two polymorphic forms, each with two molecules in the asymmetric unit and in the monoclinic space group P2₁/c. All of the molecules have intramolecular hydrogen bonds involving the amide group. The amide N atoms act as donors to the carbonyl group of the pyrone and also to the methoxy group of the benzene ring. The carbonyl O atom of the amide group acts as an acceptor of the β and β′ C atoms belonging to the aromatic rings. These intramolecular hydrogen bonds have a profound effect on the molecular conformation. In one polymorph, the molecules in the asymmetric unit are linked to form dimers by weak C—H...O interactions. In the other, the molecules in the asymmetric unit are linked by a single weak C—H...O hydrogen bond. Two of these units are linked to form centrosymmetric tetramers by a second weak C—H...O interaction. Further interactions of this type link the molecules into chains, so forming a three‐dimensional network. These interactions in both polymorphs are supplemented by π–π interactions between the chromone rings and between the chromone and methoxyphenyl rings.     

(2R*,4S*)‐2‐(Pyridin‐3‐yl)‐2,3,4,5‐tetrahydro‐1H‐1‐benzazepin‐4‐ol: a three‐dimensional framework built from O—H...N,C—H...O and C—H...π(arene) hydrogen bonds

The title compound, C₁₅H₁₆N₂O, crystallizes in the space group P2₁2₁2₁ with Z′ = 1. The seven‐membered ring adopts a chair‐type conformation with the hydroxy and pyridyl substituents in equatorial sites. Molecules are linked into a three‐dimensional framework structure by a combination of O—H...N, C—H...O and C—H...π(arene) hydrogen bonds, but N—H...O and N—H...π(arene) interactions are absent from the structure. Comparisons are made with some related compounds.     

Assembling an isomer grid: the isomorphous 4‐, 3‐ and 2‐fluoro‐N′‐(4‐pyridyl)benzamides

The three title isomers, 4‐, (I), 3‐, (II), and 2‐fluoro‐N′‐(4‐pyridyl)benzamide, (III), all C₁₂H₉FN₂O, crystallize in the P2₁/c space group (No. 14) with similar unit‐cell parameters and are isomorphous and isostructural at the primary hydrogen‐bonding level. An intramolecular C—H...O=C interaction is present in all three isomers [C...O = 2.8681 (17)–2.884 (2) Å and C—H...O117–118°], with an additional N—H...F [N...F = 2.7544 (15) Å] interaction in (III). Intermolecular amide–pyridine N—H...N hydrogen bonds link molecules into one‐dimensional zigzag chains [graph set C(6)] along the [010] direction as the primary hydrogen bond [N...N = 3.022 (2), 3.049 (2) and 3.0213 (17) Å]. These are augmented in (I) by C—H...π(arene) and cyclic C—F...π(arene) contacts about inversion centres, in (II) by C—F...F—C interactions [C...F = 3.037 (2) Å] and weaker C—H...π(arene)/C—H...F contacts, and in (III) by C—H...π(arene) and C=O...O=C interactions, linking the alternating chains into two‐dimensional sheets. Typical amide N—H...O=C hydrogen bonds [as C(4) chains] are not present [N...O = 3.438 (2) Å in (I), 3.562 (2) Å in (II) and 3.7854 (16) Å in (III)]; the C=O group is effectively shielded and only participates in weaker interactions/contacts. This series is unusual as the three isomers are isomorphous (having similar unit‐cell parameters, packing and alignment), but they differ in their interactions and contacts at the secondary level.     

N‐(4‐Nitrobenzoyl)‐N′‐phenylhydrazine: a three‐dimensional hydrogen‐bonded framework

In the title compound (systematic name: N‐anilino‐4‐nitrobenzamide), C₁₃H₁₁N₃O₃, the molecules are linked into a complex three‐dimensional framework structure by a combination of two‐centre N—H...O and C—H...O hydrogen bonds and a three‐centre N—H...(O,N) hydrogen bond.     

A three‐dimensional hydrogen‐bonded framework in 2‐amino‐6‐(N‐methylanilino)pyrimidin‐4(3H)‐one and a ribbon of fused hydrogen‐bonded rings in 2‐amino‐6‐(N‐methylanilino)‐5‐nitropyrimidin‐4(3H)‐one

The molecular dimensions of both 2‐amino‐6‐(N‐methylanilino)pyrimidin‐4(3H)‐one, C₁₁H₁₂N₄O, (I), and 2‐amino‐6‐(N‐methylanilino)‐5‐nitropyrimidin‐4(3H)‐one, C₁₁H₁₁N₅O₃, (II), are consistent with considerable polarization of the molecular–electronic structures. The molecules of (I) are linked into a three‐dimensional framework by a combination of one N—H...N hydrogen bond, two independent N—H...O hydrogen bonds and one C—H...π(arene) hydrogen bond. The molecules of (II) are linked into ribbons containing three types of edge‐fused ring by the combination of two independent three‐centre N—H...(O)₂ hydrogen bonds.     

The first structurally analysed nucleic acid building block containing the Reese protecting group: 2′‐O‐[1‐(2‐fluorophenyl)‐4‐methoxypiperidin‐4‐yl]‐β‐D‐(1′R,2′R,3′R,4′R)‐uridine

The title compound, C₂₁H₂₆FN₃O₇, is assembled by N—H...O and O—H...O hydrogen bonds into well‐separated two‐dimensional layers of about 15 Å thickness. The crescent conformation of the molecules is stabilized by weak intramolecular C—H...O and C—H...F hydrogen bonds. The uridine moiety adopts an anti conformation. The ribofuranose ring exists in an envelope conformation. All the endocyclic uracil bonds are shorter than normal single C—N and C—C bonds, and five of them have comparable lengths, which implies a considerable degree of delocalization of the electron density within this ring.     

Supramolecular aggregation in three 4‐aryl‐6‐(1H‐indol‐3‐yl)‐3‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine‐5‐carbonitriles

Both 6‐(1H‐indol‐3‐yl)‐3‐methyl‐4‐(4‐methylphenyl)‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine‐5‐carbonitrile and 6‐(1H‐indol‐3‐yl)‐3‐methyl‐4‐(4‐methoxyphenyl)‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine‐5‐carbonitrile crystallize from dimethylformamide solutions as stoichiometric 1:1 solvates, viz. C₂₉H₂₁N₅·C₃H₇NO, (I), and C₂₉H₂₁N₅O·C₃H₇NO, (II), respectively; however, 6‐(1H‐indol‐3‐yl)‐3‐methyl‐1‐phenyl‐4‐(3,4,5‐trimethoxyphenyl)‐1H‐pyrazolo[3,4‐b]pyridine‐5‐carbonitrile, C₃₁H₂₅N₅O₃, (III), crystallizes in the unsolvated form. The heterocyclic components of (I) are linked by C—H...π(arene) hydrogen bonds to form cyclic centrosymmetric dimers, from which the solvent molecules are pendent, linked by N—H...O hydrogen bonds. In (II), the heterocyclic components are linked by a combination of C—H...N and C—H...π(arene) hydrogen bonds into chains containing two types of centrosymmetric ring, and the pendent solvent molecules are linked to these chains by N—H...O hydrogen bonds. Molecules of (III) are linked into simple C(12) chains by an N—H...O hydrogen bond, and these chains are weakly linked into pairs by an aromatic π–π stacking interaction.     

3‐(1H‐Pyrrol‐2‐yl)‐1H‐pyrazole forms an unusual hydrogen‐bonded two‐dimensional (3,4)‐connected net

The title compound, C₇H₇N₃, is the first crystallographically characterized 1H‐pyrrolyl‐1H‐pyrazole derivative and contains two unique molecules in its asymmetric unit (Z′ = 2). These molecules associate into centrosymmetric tetramers through N—H...N hydrogen bonding, including a cyclic dimerization of one of the two unique pyrazole rings. These tetramers are linked further by two weaker N—H...π contacts to give a novel two‐dimensional (3,4)‐connected net with a (3².8)₂(3.8²)₂ topology.     

Two Fe3(μ3‐S)2(CO)8 clusters with terminal N‐heterocyclic carbenes

The title compounds with terminal N‐heterocyclic carbenes, namely octacarbonyl(imidazolidinylidene‐κC²)di‐μ₃‐sulfido‐triiron(II)(2 Fe—Fe), [Fe₃(C₃H₆N₂)(μ₃‐S)₂(CO)₈], (I), and octacarbonyl(1‐methylimidazo[1,5‐a]pyridin‐3‐ylidene‐κC³)di‐μ₃‐sulfido‐triiron(II)(2 Fe—Fe), [Fe₃(C₈H₈N₂)(μ₃‐S)₂(CO)₈], (II), have been synthesized. Each compound contains two Fe—Fe bonds and two S atoms above and below a triiron triangle. One of the eight carbonyl ligands deviates significantly from linearity. In (I), dimers generated by an N—H...S hydrogen bond are linked into [001] double chains by a second N—H...S hydrogen bond. These chains are packed by a C—H...O hydrogen bond to yield [101] sheets. In (II), dimers generated by an N—H...S hydrogen bond are linked by C—H...O hydrogen bonds to form [111] double chains.     

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.     

Three‐dimensional networks in bis(imidazolium) 2,2′‐dithiodibenzoate and 4‐methylimidazolium 2‐[(2‐carboxyphenyl)disulfanyl]benzoate

Cocrystallization of imidazole or 4‐methylimidazole with 2,2′‐dithiodibenzoic acid from methanol solution yields the title 2:1 and 1:1 organic salts, 2C₃H₅N₂⁺·C₁₄H₁₀O₄S₂²⁻, (I), and C₄H₇N₂⁺·C₁₄H₁₀O₄S₂⁻, (II), respectively. Compound (I) crystallizes in the monoclinic C2/c space group with the mid‐point of the S—S bond lying on a twofold axis. The component ions in (I) are linked by intermolecular N—H...O hydrogen bonds to form a two‐dimensional network, which is further linked by C—H...O hydrogen bonds into a three‐dimensional network. In contrast, by means of N—H...O, N—H...S and O—H...O hydrogen bonds, the component ions in (II) are linked into a tape and adjacent tapes are further linked by π–π, C—H...O and C—H...π interactions, resulting in a three‐dimensional network.     

A hydrogen‐bonded heterodimer of 1‐(4‐hexyloxyphenyl)pyridin‐4(1H)‐one with 4‐cyano­benzoic acid

The two components of the title heterodimer, C₁₇H₂₁NO₂·C₈H₅NO₂, are linked end‐to‐end via O—H⋯O(=C) and C—H⋯O(=C) hydrogen‐bond inter­actions. Additional lateral C—H⋯O inter­actions link the dimers in a side‐by‐side fashion to produce wide infinite mol­ecular ribbons. Adjacent ribbons are inter­connected viaπ–π stacking and C—H⋯π(arene) inter­actions. This structure represents the first evidence of robust hydrogen‐bond formation between the moieties of pyridin‐4(1H)‐one and benzoic acid.     

Three‐dimensional hydrogen‐bonded framework structures in flunarizinium nicotinate and flunarizinediium bis(4‐toluenesulfonate) dihydrate

The structures of two salts of flunarizine, namely 1‐bis[(4‐fluorophenyl)methyl]‐4‐[(2E)‐3‐phenylprop‐2‐en‐1‐yl]piperazine, C₂₆H₂₆F₂N₂, are reported. In flunarizinium nicotinate {systematic name: 4‐bis[(4‐fluorophenyl)methyl]‐1‐[(2E)‐3‐phenylprop‐2‐en‐1‐yl]piperazin‐1‐ium pyridine‐3‐carboxylate}, C₂₆H₂₇F₂N₂⁺·C₆H₄NO₂⁻, (I), the two ionic components are linked by a short charge‐assisted N—H...O hydrogen bond. The ion pairs are linked into a three‐dimensional framework structure by three independent C—H...O hydrogen bonds, augmented by C—H...π(arene) hydrogen bonds and an aromatic π–π stacking interaction. In flunarizinediium bis(4‐toluenesulfonate) dihydrate {systematic name: 1‐[bis(4‐fluorophenyl)methyl]‐4‐[(2E)‐3‐phenylprop‐2‐en‐1‐yl]piperazine‐1,4‐diium bis(4‐methylbenzenesulfonate) dihydrate}, C₂₆H₂₈F₂N₂²⁺·2C₇H₇O₃S⁻·2H₂O, (II), one of the anions is disordered over two sites with occupancies of 0.832 (6) and 0.168 (6). The five independent components are linked into ribbons by two independent N—H...O hydrogen bonds and four independent O—H...O hydrogen bonds, and these ribbons are linked to form a three‐dimensional framework by two independent C—H...O hydrogen bonds, but C—H...π(arene) hydrogen bonds and aromatic π–π stacking interactions are absent from the structure of (II). Comparisons are made with some related structures.     

A structural systematic study of three isomers of difluoro‐N‐(4‐pyridyl)benzamide

The isomers 2,3‐, (I), 2,4‐, (II), and 2,5‐difluoro‐N‐(4‐pyridyl)benzamide, (III), all with formula C₁₂H₈F₂N₂O, all exhibit intramolecular C—H...O=C and N—H...F contacts [both with S(6) motifs]. In (I), intermolecular N—H...O=C interactions form one‐dimensional chains along [010] [N...O = 3.0181 (16) Å], with weaker C—H...N interactions linking the chains into sheets parallel to the [001] plane, further linked into pairs via C—H...F contacts about inversion centres; a three‐dimensional herring‐bone network forms via C—H...π(py) (py is pyridyl) interactions. In (II), weak aromatic C—H...N(py) interactions form one‐dimensional zigzag chains along [001]; no other interactions with H...N/O/F < 2.50 Å are present, apart from long N/C—H...O=C and C—H...F contacts. In (III), N—H...N(py) interactions form one‐dimensional zigzag chains [as C(6) chains] along [010] augmented by a myriad of weak C—H...π(arene) and O=C...O=C interactions and C—H...O/N/F contacts. Compound (III) is isomorphous with the parent N‐(4‐pyridyl)benzamide [Noveron, Lah, Del Sesto, Arif, Miller & Stang (2002). J. Am. Chem. Soc. 124 , 6613–6625] and the three 2/3/4‐fluoro‐N‐(4‐pyridyl)benzamides [Donnelly, Gallagher & Lough (2008). Acta Cryst. C 64 , o335–o340]. The study expands our series of fluoro(pyridyl)benzamides and augments our understanding of the competition between strong hydrogen‐bond formation and weaker influences on crystal packing.     

Poly[(μ‐pentafluorobenzoato‐κ2O:O′)(pentafluorobenzoato‐κO)(μ‐pyrazine‐κ2N:N′)copper(II)]: a coordination polymer linked into a three‐dimensional network by intermolecular C—H...F—C interactions

In the title compound, [Cu(C₆F₅COO)₂(C₄H₄N₂)]_n, (I), the asymmetric unit contains one Cu^II cation, two anionic pentafluorobenzoate ligands and one pyrazine ligand. Each Cu^II centre is five‐coordinated by three O atoms from three independent pentafluorobenzoate anions, as well as by two N atoms from two pyrazine ligands, giving rise to an approximately square‐pyramidal coordination geometry. Adjacent Cu^II cations are bridged by a pyrazine ligand and two pentafluorobenzoate anions to give a two‐dimensional layer. The layers are stacked to generate a three‐dimensional supramolecular architecture via strong intermolecular C—H...F—C interactions, as indicated by the F...H distance of 2.38 Å.     

Crystal structures of the pyrazinamide–p‐aminobenzoic acid (1/1) cocrystal and the transamidation reaction product 4‐(pyrazine‐2‐carboxamido)benzoic acid in the molten state

The synthesis of pharmaceutical cocrystals is a strategy to enhance the performance of active pharmaceutical ingredients (APIs) without affecting their therapeutic efficiency. The 1:1 pharmaceutical cocrystal of the antituberculosis drug pyrazinamide (PZA) and the cocrystal former p‐aminobenzoic acid (p‐ABA), C₇H₇NO₂·C₅H₅N₃O, (1), was synthesized successfully and characterized by relevant solid‐state characterization methods. The cocrystal crystallizes in the monoclinic space group P2₁/n containing one molecule of each component. Both molecules associate via intermolecular O—H...O and N—H...O hydrogen bonds [O...O = 2.6102 (15) Å and O—H...O = 168.3 (19)°; N...O = 2.9259 (18) Å and N—H...O = 167.7 (16)°] to generate a dimeric acid–amide synthon. Neighbouring dimers are linked centrosymmetrically through N—H...O interactions [N...O = 3.1201 (18) Å and N—H...O = 136.9 (14)°] to form a tetrameric assembly supplemented by C—H...N interactions [C...N = 3.5277 (19) Å and C—H...N = 147°]. Linking of these tetrameric assemblies through N—H...O [N...O = 3.3026 (19) Å and N—H...O = 143.1 (17)°], N—H...N [N...N = 3.221 (2) Å and N—H...N = 177.9 (17)°] and C—H...O [C...O = 3.5354 (18) Å and C—H...O = 152°] interactions creates the two‐dimensional packing. Recrystallization of the cocrystals from the molten state revealed the formation of 4‐(pyrazine‐2‐carboxamido)benzoic acid, C₁₂H₉N₃O₃, (2), through a transamidation reaction between PZA and p‐ABA. Carboxamide (2) crystallizes in the triclinic space group P with one molecule in the asymmetric unit. Molecules of (2) form a centrosymmetric dimeric homosynthon through an acid–acid O—H...O hydrogen bond [O...O = 2.666 (3) Å and O—H...O = 178 (4)°]. Neighbouring assemblies are connected centrosymmetrically via a C—H...N interaction [C...N = 3.365 (3) Å and C—H...N = 142°] engaging the pyrazine groups to generate a linear chain. Adjacent chains are connected loosely via C—H...O interactions [C...O = 3.212 (3) Å and C—H...O = 149°] to generate a two‐dimensional sheet structure. Closely associated two‐dimensional sheets in both compounds are stacked via aromatic π‐stacking interactions engaging the pyrazine and benzene rings to create a three‐dimensional multi‐stack structure.     

Hydrogen‐bonded dimers in 3‐amino‐4‐anilino‐1H‐isochromen‐1‐one and a hydrogen‐bonded sheet in 3‐amino‐4‐[methyl(phenyl)amino]‐1H‐isochromen‐1‐one

The molecules of 3‐amino‐4‐anilino‐1H‐isochromen‐1‐one, C₁₅H₁₂N₂O₂, (I), and 3‐amino‐4‐[methyl(phenyl)amino]‐1H‐isochromen‐1‐one, C₁₆H₁₄N₂O₂, (II), adopt very similar conformations, with the substituted amino group PhNR, where R = H in (I) and R = Me in (II), almost orthogonal to the adjacent heterocyclic ring. The molecules of (I) are linked into cyclic centrosymmetric dimers by pairs of N—H...O hydrogen bonds, while those of (II) are linked into complex sheets by a combination of one three‐centre N—H...(O)₂ hydrogen bond, one two‐centre C—H...O hydrogen bond and two C—H...π(arene) hydrogen bonds.