Hydrogen bonding in 4‐nitrobenzene‐1,2‐diamine and two hydrohalide salts

The structures of 4‐nitrobenzene‐1,2‐diamine [C₆H₇N₃O₂, (I)], 2‐amino‐5‐nitroanilinium chloride [C₆H₈N₃O₂⁺·Cl⁻, (II)] and 2‐amino‐5‐nitroanilinium bromide monohydrate [C₆H₈N₃O₂⁺·Br⁻·H₂O, (III)] are reported and their hydrogen‐bonded structures described. The amine group para to the nitro group in (I) adopts an approximately planar geometry, whereas the meta amine group is decidedly pyramidal. In the hydrogen halide salts (II) and (III), the amine group meta to the nitro group is protonated. Compound (I) displays a pleated‐sheet hydrogen‐bonded two‐dimensional structure with R₂²(14) and R₄⁴(20) rings. The sheets are joined by additional hydrogen bonds, resulting in a three‐dimensional extended structure. Hydrohalide salt (II) has two formula units in the asymmetric unit that are related by a pseudo‐inversion center. The dominant hydrogen‐bonding interactions involve the chloride ion and result in R₄²(8) rings linked to form a ladder‐chain structure. The chains are joined by N—H...Cl and N—H...O hydrogen bonds to form sheets parallel to (010). In hydrated hydrohalide salt (III), bromide ions are hydrogen bonded to amine and ammonium groups to form R₄²(8) rings. The water behaves as a double donor/single acceptor and, along with the bromide anions, forms hydrogen bonds involving the nitro, amine, and ammonium groups. The result is sheets parallel to (001) composed of alternating R₅⁵(15) and R₆⁴(24) rings. Ammonium N—H...Br interactions join the sheets to form a three‐dimensional extended structure. Energy‐minimized structures obtained using DFT and MP2 calculations are consistent with the solid‐state structures. Consistent with (II) and (III), calculations show that protonation of the amine group meta to the nitro group results in a structure that is about 1.5 kJ mol⁻¹ more stable than that obtained by protonation of the para‐amine group. DFT calculations on single molecules and hydrogen‐bonded pairs of molecules based on structural results obtained for (I) and for 3‐nitrobenzene‐1,2‐diamine, (IV) [Betz & Gerber (2011). Acta Cryst. E 67 , o1359] were used to estimate the strength of the N—H...O(nitro) interactions for three observed motifs. The hydrogen‐bonding interaction between the pairs of molecules examined was found to correspond to 20–30 kJ mol⁻¹.     

Polymorphism in 2‐(4‐hydroxy‐2,6‐dimethylanilino)‐5,6‐dihydro‐4H‐1,3‐thiazin‐3‐ium chloride

Details of the structures of two conformational polymorphs of the title compound, C₁₂H₁₇N₂OS⁺·Cl⁻, are reported. In form (I) (space group P), the two N—H groups of the cation are in a trans conformation, while in form (II) (space group P2₁/c), they are in a cis arrangement. This results in different packing and hydrogen‐bond arrangements in the two forms, both of which have extended chains lying along the a direction. In form (I), these chains are composed of centrosymmetric R₄²(18) (N—H...Cl and O—H...Cl) hydrogen‐bonded rings and R₂²(18) (N—H...O) hydrogen‐bonded rings. In form (II), the chains are formed by centrosymmetric R₄²(18) (N—H...Cl and O—H...Cl) hydrogen‐bonded rings and by R₄²(12) (N—H...Cl) hydrogen‐bonded rings.     

Hydrogen‐bonded ribbons in ethyl (E)‐3‐[2‐amino‐4,6‐bis(dimethylamino)pyrimidin‐5‐yl]‐2‐cyanoacrylate and 2‐[(2‐amino‐4,6‐di‐1‐piperidylpyrimidin‐5‐yl)methylene]malononitrile

The pyrimidine rings in ethyl (E)‐3‐[2‐amino‐4,6‐bis(dimethylamino)pyrimidin‐5‐yl]‐2‐cyanoacrylate, C₁₄H₂₀N₆O₂, (I), and 2‐[(2‐amino‐4,6‐di‐1‐piperidylpyrimidin‐5‐yl)methylene]malononitrile, C₁₈H₂₃N₇, (II), which crystallizes with Z′ = 2 in the space group, are both nonplanar with boat conformations. The molecules of (I) are linked by a combination of N—H...N and N—H...O hydrogen bonds into chains of edge‐fused R₂²(8) and R₄⁴(20) rings, while the two independent molecules in (II) are linked by four N—H...N hydrogen bonds into chains of edge‐fused R₂²(8) and R₂²(20) rings. This study illustrates both the readiness with which highly‐substituted pyrimidine rings can be distorted from planarity and the significant differences between the supramolecular aggregation in two rather similar compounds.     

Amide hydrogen bonding: control of the molecular and extended structures of two symmetrical pyridine‐2‐carboxamide derivatives

The crystal structures of two symmetrical pyridine‐2‐carboxamides, namely N,N′‐(propane‐1,3‐diyl)bis(pyridine‐2‐carboxamide), C₁₅H₁₆N₄O₂, (I), and N,N′‐(butane‐1,4‐diyl)bis(pyridine‐2‐carboxamide), C₁₆H₁₈N₄O₂, (II), exhibit extended hydrogen‐bonded sequences involving their amide groups. In (I), conventional bifurcated amide–carbonyl (N—H)...O hydrogen bonding favours the formation of one‐dimensional chains, the axes of which run parallel to [001]. Unconventional bifurcated pyridine–carbonyl C—H...O hydrogen bonding links adjacent one‐dimensional chains to form a `porous' three‐dimensional lattice with interconnected, yet unfilled, voids of 60.6 (2) ų which combine into channels that run parallel to, and include, [001]. 4% of the unit‐cell volume of (I) is vacant. Compound (II) adopts a Z‐shaped conformation with inversion symmetry, and exhibits an extended structure comprising one‐dimensional hydrogen‐bonded chains along [100] in which individual molecules are linked by complementary pairs of amide N—H...O hydrogen bonds. These hydrogen‐bonded chains interlock viaπ–π interactions between pyridine rings of neighbouring molecules to form sheets parallel with (010); each sheet is one Z‐shaped molecule thick and separated from the next sheet by the b‐axis dimension [7.2734 (4) Å].     

Hydrogen‐bonded assemblies of 20‐(4‐pyridyl)porphyrin‐54,104,154‐tribenzoic acid with dimethyl sulfoxide and 4‐acetylpyridine in their dimethyl sulfoxide and tetrahydrofuran solvates

Crystals of the title compounds, 20‐(4‐pyridyl)porphyrin‐5⁴,10⁴,15⁴‐tribenzoic acid–dimethyl sulfoxide (2/5), C₄₆H₂₉N₅O₆·2.5C₂H₆OS, (I), and 20‐(4‐pyridyl)porphyrin‐5⁴,10⁴,15⁴‐tribenzoic acid–4‐acetylpyridine–tetrahydrofuran (1/2/10), C₄₆H₂₉N₅O₆·2C₇H₇NO·10C₄H₈O, (II), consist of hydrogen‐bonded supramolecular chains of porphyrin units solvated by molecules of dimethyl sulfoxide [in (I)] and 4‐acetylpyridine [in (II)]. In (I), these chains consist of heterogeneous arrays with alternating porphyrin and dimethyl sulfoxide species, being sustained by COOH...O=S hydrogen bonds. They adopt a zigzag geometry and link on both sides to additional molecules of dimethyl sulfoxide. In (II), the chains consist of homogeneous linear supramolecular arrays of porphyrin units, which are directly connected to one another via COOH...N(pyridyl) hydrogen bonds. As in the previous case, these arrays are solvated on both sides by molecules of the 4‐acetylpyridine ligand via similar COOH(porphyrin)...N(ligand) hydrogen bonds. The two crystal structures contain wide interporphyrin voids, which accommodate disordered/diffused solvent molecules, viz. dimethyl sulfoxide in (I) and tetrahydrofuran in (II).     

Crystal packing of two 5‐substituted 2‐methyl‐4‐nitro‐1H‐imidazoles

Infinite chains connected by N—H...N hydrogen bonding form the primary packing motif in two closely related 4‐nitroimidazole derivatives, viz. 5‐bromo‐2‐methyl‐4‐nitro‐1H‐imidazole, C₄H₄BrN₃O₂, (I), and 2‐methyl‐4‐nitro‐1H‐imidazole‐5‐carbonitrile, C₅H₄N₄O₂, (II). These chains are almost identical, even though in (II) there are two symmetry‐independent molecules in the asymmetric unit. The differences appear in the interactions between the chains; in (I), there are strong C—Br...O halogen bonds, which connect the chains into a two‐dimensional grid, while in (II), the cyano group does not participate in specific interactions and the chains are only loosely connected into a three‐dimensional structure.     

Different molecular conformations co‐exist in each of three 2‐aryl‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamides: hydrogen bonding in zero,one and two dimensions

4‐Antipyrine [4‐amino‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one] and its derivatives exhibit a range of biological activities, including analgesic, antibacterial and anti‐inflammatory, and new examples are always of potential interest and value. 2‐(4‐Chlorophenyl)‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamide, C₁₉H₁₈ClN₃O₂, (I), crystallizes with Z′ = 2 in the space group P, whereas its positional isomer 2‐(2‐chlorophenyl)‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamide, (II), crystallizes with Z′ = 1 in the space group C2/c; the molecules of (II) are disordered over two sets of atomic sites having occupancies of 0.6020 (18) and 0.3980 (18). The two independent molecules of (I) adopt different molecular conformations, as do the two disorder components in (II), where the 2‐chlorophenyl substituents adopt different orientations. The molecules of (I) are linked by a combination of N—H…O and C—H…O hydrogen bonds to form centrosymmetric four‐molecule aggregates, while those of (II) are linked by the same types of hydrogen bonds forming sheets. The related compound N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)‐2‐(3‐methoxyphenyl)acetamide, C₂₀H₂₁N₃O₃, (III), is isomorphous with (I) but not strictly isostructural; again the two independent molecules adopt different molecular conformations, and the molecules are linked by N—H…O and C—H…O hydrogen bonds to form ribbons. Comparisons are made with some related structures, indicating that a hydrogen‐bonded R₂²(10) ring is the common structural motif.     

Seven 5‐benzylamino‐3‐tert‐butyl‐1‐phenyl‐1H‐pyrazoles: unexpected isomorphisms,and hydrogen‐bonded supramolecular structures in zero,one and two dimensions

5‐Benzylamino‐3‐tert‐butyl‐1‐phenyl‐1H‐pyrazole, C₂₀H₂₃N₃, (I), and its 5‐[4‐(trifluoromethyl)benzyl]‐, C₂₁H₂₂F₃N₃, (III), and 5‐(4‐bromobenzyl)‐, C₂₀H₂₂BrN₃, (V), analogues, are isomorphous in the space group C2/c, but not strictly isostructural; molecules of (I) form hydrogen‐bonded chains, while those of (III) and (V) form hydrogen‐bonded sheets, albeit with slightly different architectures. Molecules of 3‐tert‐butyl‐5‐(4‐methylbenzylamino)‐1‐phenyl‐1H‐pyrazole, C₂₁H₂₅N₃, (II), are linked into hydrogen‐bonded dimers by a combination of N—H...π(arene) and C—H...π(arene) hydrogen bonds, while those of 3‐tert‐butyl‐5‐(4‐chlorobenzylamino)‐1‐phenyl‐1H‐pyrazole, C₂₀H₂₂ClN₃, (IV), form hydrogen‐bonded chains of rings which are themselves linked into sheets by an aromatic π–π stacking interaction. Simple hydrogen‐bonded chains built from a single N—H...O hydrogen bond are formed in 3‐tert‐butyl‐5‐(4‐nitrobenzylamino)‐1‐phenyl‐1H‐pyrazole, C₂₀H₂₂N₄O₂, (VI), while in 3‐tert‐butyl‐5‐(3,4,5‐trimethoxybenzylamino)‐1‐phenyl‐1H‐pyrazole, C₂₃H₂₉N₃O₃, (VII), which crystallizes with Z′ = 2 in the space group P, pairs of molecules are linked into two independent centrosymmetric dimers, one generated by a three‐centre N—H...(O)₂ hydrogen bond and the other by a two‐centre N—H...O hydrogen bond.     

Bilayers in 4‐iodo‐N‐(2‐iodo‐4‐nitrophenyl)benzamide generated by a combination of an N—H⋯O=C hydrogen bond and two independent iodo–nitro interactions

Molecules of the title compound, C₁₃H₈I₂N₂O₃, are linked into C(4) chains by a single N—H⋯O=C hydrogen bond [H⋯O = 2.10 Å, N⋯O = 2.832 (5) Å and N—H⋯O = 140°]. Two independent two‐centre iodo–nitro interactions, both involving the same O atom but different I atoms [I⋯O = 3.205 (3) and 3.400 (3) Å, and C—I⋯O = 160.4 (2) and 155.7 (2)°], link the hydrogen‐bonded chains into bilayers.     

Two polymorphs of 5‐cyclohexyl‐5‐ethylbarbituric acid and their packing relationships with other barbiturates

Polymorph (Ia) (m.p. 474 K) of the title compound, C₁₂H₁₈N₂O₃, displays an N—H...O=C hydrogen‐bonded layer structure which contains R₆⁶(28) rings connecting six molecules, as well as R₂²(8) rings linking two molecules. The 3‐connected hydrogen‐bonded net resulting from these interactions has the hcb topology. Form (Ib) (m.p. 471 K) displays N—H...O=C hydrogen‐bonded looped chains in which neighbouring molecules are linked to one another by two different R₂²(8) rings. Polymorph (Ia) is isostructural with the previously reported form II of 5‐(2‐bromoallyl)‐5‐isopropylbarbituric acid (noctal) and polymorph (Ib) is isostructural with the known crystal structures of four other barbiturates.     

L‐Leucylglycine 0.67‐hydrate and [(4S)‐2,2‐dimethyl‐4‐(2‐methylpropyl)‐5‐oxoimidazolidin‐3‐ium‐1‐yl]acetate

Crystals of L‐leucylglycine (L‐Leu–Gly) 0.67‐hydrate, C₈H₁₆N₂O₃·0.67H₂O, (I), were obtained from an aqueous solution. There are three symmetrically independent dipeptide zwitterionic molecules in (I) and they are parallel to one another. The hydrogen‐bond network composed of carboxylate and amino groups and water molecules extends parallel to the ab plane. Hydrophilic regions composed of main chains and hydrophobic regions composed of the isobutyl groups of the leucyl residues are aligned alternately along the c axis. An imidazolidinone derivative was obtained from L‐Leu–Gly and acetone, viz. [(4S)‐2,2‐dimethyl‐4‐(2‐methylpropyl)‐5‐oxoimidazolidin‐3‐ium‐1‐yl]acetate, C₁₁H₂₀N₂O₃, (II), and was crystallized from a methanol–acetone solution of L‐Leu–Gly. The unit‐cell parameters coincide with those reported previously for L‐Leu–Gly dihydrate revealing that the previously reported values should be assigned to the structure of (II). One of the imidazolidine N atoms is protonated and the ring is nearly planar, except for the protonated N atom. Protonated N atoms and deprotonated carboxy groups of neighbouring molecules form hydrogen‐bonded chains. The ring carbonyl group is not involved in hydrogen bonding.     

2‐Ethyl‐6‐methylpyridin‐3‐ol and its salt bis(2‐ethyl‐3‐hydroxy‐6‐methylpyridinium) succinate

The title compounds, C₈H₁₁NO, (I), and 2C₈H₁₂NO⁺·C₄H₄O₄²⁻, (II), both crystallize in the monoclinic space group P2₁/c. In the crystal structure of (I), intermolecular O—H...N hydrogen bonds combine the molecules into polymeric chains extending along the c axis. The chains are linked by C—H...π interactions between the methylene H atoms and the pyridine rings into polymeric layers parallel to the ac plane. In the crystal structure of (II), the succinate anion lies on an inversion centre. Its carboxylate groups interact with the 2‐ethyl‐3‐hydroxy‐6‐methylpyridinium cations via intermolecular N—H...O hydrogen bonds with the pyridine ring H atoms and O—H...O hydrogen bonds with the hydroxy H atoms to form polymeric chains, which extend along the [01] direction and comprise R₄⁴(18) hydrogen‐bonded ring motifs. These chains are linked to form a three‐dimensional network through nonclassical C—H...O hydrogen bonds between the pyridine ring H atoms and the hydroxy‐group O atoms of neighbouring cations. π–π interactions between the pyridine rings and C—H...π interactions between the methylene H atoms of the succinate anion and the pyridine rings are also present in this network.     

Quinolin‐6‐ol at 100 K

The title compound, C₉H₇NO, has two symmetry‐independent molecules in the asymmetric unit, which have different conformations of the hydroxy group with respect to the quinoline ring. One of the molecules adopts a cis conformation, while the other shows a trans conformation. Each type of independent molecule links into a separate infinite O—H...N hydrogen‐bonded chain with the graph‐set notation C(7). These chains are perpendicular in the unit cell, one extended in the a‐axis direction and the other in the b‐axis direction. There is also a weak C—H...O hydrogen bond with graph‐set notation D(2), which runs in the c‐axis direction and joins the two separate O—H...N chains. The significance of this study lies in the comparison drawn between the experimental and calculated data of the crystal structure of the title compound and the data of several other derivatives possessing the hydroxy group or the quinoline ring. The correlation between the IR spectrum of this compound and the hydrogen‐bond energy is also discussed.     

Hydrogen‐bonded networks in trans‐3‐(3‐pyridyl)acrylic acid and rctt‐3,3′‐(3,4‐dicarboxycyclobutane‐1,2‐diyl)dipyridinium dichloride

The structure of trans‐3‐(3‐pyridyl)acrylic acid, C₈H₇NO₂, (I), possesses a two‐dimensional hydrogen‐bonded array of supramolecular ribbons assembled via heterodimeric synthons between the pyridine and carboxyl groups. This compound is photoreactive in the solid state as a result of close contacts between the double bonds of neighbouring molecules [3.821 (1) Å] along the a axis. The crystal structure of the photoproduct, rctt‐3,3′‐(3,4‐dicarboxycyclobutane‐1,2‐diyl)dipyridinium dichloride, C₁₆H₁₆N₂O₄²⁺·2Cl⁻, (II), consists of a three‐dimensional hydrogen‐bonded network built from crosslinking of helical chains integrated by self‐assembly of dipyridinium cations and Cl⁻ anions via different O—H...Cl, C—H...Cl and N⁺—H...Cl hydrogen‐bond interactions.     

1,3‐Bis(ethylamino)‐2‐nitrobenzene, 1,3‐bis(n‐octylamino)‐2‐nitrobenzene and 4‐ethylamino‐2‐methyl‐1H‐benzimidazole

1,3‐Bis(ethylamino)‐2‐nitrobenzene, C₁₀H₁₅N₃O₂, (I), and 1,3‐bis(n‐octylamino)‐2‐nitrobenzene, C₂₂H₃₉N₃O₂, (II), are the first structurally characterized 1,3‐bis(n‐alkylamino)‐2‐nitrobenzenes. Both molecules are bisected though the nitro N atom and the 2‐C and 5‐C atoms of the ring by twofold rotation axes. Both display intramolecular N—H...O hydrogen bonds between the amine and nitro groups, but no intermolecular hydrogen bonding. The nearly planar molecules pack into flat layers ca 3.4 Å apart that interact by hydrophobic interactions involving the n‐alkyl groups rather than by π–π interactions between the rings. The intra‐ and intermolecular interactions in these molecules are of interest in understanding the physical properties of polymers made from them. Upon heating in the presence of anhydrous potassium carbonate in dimethylacetamide, (I) and (II) cyclize with formal loss of hydrogen peroxide to form substituted benzimidazoles. Thus, 4‐ethylamino‐2‐methyl‐1H‐benzimidazole, C₁₀H₁₃N₃, (III), was obtained from (I) under these reaction conditions. Compound (III) contains two independent molecules with no imposed internal symmetry. The molecules are linked into chains via N—H...N hydrogen bonds involving the imidazole rings, while the ethylamino groups do not participate in any hydrogen bonding. This is the first reported structure of a benzimidazole derivative with 4‐amino and 2‐alkyl substituents.     

(S,S)‐Lactoyllactic acid and (S,S,S)‐lactoyllactoyllactic acid

The dimeric condensation product of lactic acid, namely (S,S)‐2‐[(2‐hydroxypropanoyl)oxy]propanoic acid, C₆H₁₀O₅, (I), crystallizes with two independent molecules in the asymmetric unit, which both have an essentially planar backbone. The trimeric condensation product, namely (S,S,S)‐3‐hydroxybut‐3‐en‐2‐yl 2‐[(2‐hydroxypropanoyl)oxy]propanoate, C₉H₁₄O₇, (II), has one molecule in the asymmetric unit and consists of two essentially planar parts, with the central C—O bond in a gauche conformation. Both molecules of the dimer are involved in intermolecular hydrogen bonds, forming chains with a C(8) graph set. These chains are connected by D(2) hydrogen bonds to form a two‐dimensional layer. The trimer forms hydrogen‐bonded C(10) and C₂²(6) chains, which together result in a two‐dimensional motif. The Hooft method [Hooft, Straver & Spek (2008). J. Appl. Cryst. 41 , 96–103] was successfully applied to the determination of the absolute structure of (I).     

Two two‐dimensional hydrogen‐bonded coordination networks: bis(3‐carboxybenzoato‐κO)bis(4‐methyl‐1H‐imidazole‐κN3)copper(II) and bis(3‐methylbenzoato‐κN)bis(4‐methyl‐1H‐imidazole‐κN3)copper(II) monohydrate

The title two‐dimensional hydrogen‐bonded coordination compounds, [Cu(C₈H₅O₄)₂(C₄H₆N₂)₂], (I), and [Cu(C₈H₇O₂)₂(C₄H₆N₂)₂]·H₂O, (II), have been synthesized and structurally characterized. The molecule of complex (I) lies across an inversion centre, and the Cu²⁺ ion is coordinated by two N atoms from two 4‐methyl‐1H‐imidazole (4‐MeIM) molecules and two O atoms from two 3‐carboxybenzoate (HBDC⁻) anions in a square‐planar geometry. Adjacent molecules are linked through intermolecular N—H...O and O—H...O hydrogen bonds into a two‐dimensional sheet with (4,4) topology. In the asymmetric part of the unit cell of (II) there are two symmetry‐independent molecules, in which each Cu²⁺ ion is also coordinated by two N atoms from two 4‐MeIM molecules and two O atoms from two 3‐methylbenzoate (3‐MeBC⁻) anions in a square‐planar coordination. Two neutral complex molecules are held together via N—H...O(carboxylate) hydrogen bonds to generate a dimeric pair, which is further linked via discrete water molecules into a two‐dimensional network with the Schläfli symbol (4³)₂(4⁶,6⁶,8³). In both compounds, as well as the strong intermolecular hydrogen bonds, π–π interactions also stabilize the crystal stacking.     

The effect of hydrogen bonding on the conformations of 2‐(1H‐indol‐3‐yl)‐2‐oxoacetamide and 2‐(1H‐indol‐3‐yl)‐N,N‐dimethyl‐2‐oxoacetamide

In the title compounds, C₁₀H₈N₂O₂, (I), and C₁₂H₁₂N₂O₂, (II), the two carbonyl groups are oriented with torsion angles of −149.3 (3) and −88.55 (15)°, respectively. The single‐bond distances linking the two carbonyl groups are 1.528 (4) and 1.5298 (17) Å, respectively. In (I), the molecules are linked by an elaborate system of N—H...O hydrogen bonds, which form adjacent R²₂(8) and R⁴₂(8) ring motifs to generate a ladder‐like construct. Adjacent ladders are further linked by N—H...O hydrogen bonds to build a three‐dimensional network. The hydrogen bonding in (II) is far simpler, consisting of helical chains of N—H...O‐linked molecules that follow the 2₁ screw of the b axis. It is the presence of an elaborate hydrogen‐bonding system in the crystal structure of (I) that leads to the different torsion angle for the orientation of the two adjacent carbonyl groups from that in (II).     

Two methyl 3‐(1H‐pyrazol‐4‐yl)octahydropyrrolo[3,4‐c]pyrrole‐1‐carboxylates form different hydrogen‐bonded sheets

In the molecules of both methyl (1RS,3SR,3aRS,6aSR)‐1‐methyl‐3‐(3‐methyl‐1‐phenyl‐1H‐pyrazol‐4‐yl)‐4,6‐dioxo‐5‐phenyloctahydropyrrolo[3,4‐c]pyrrole‐1‐carboxylate, C₂₅H₂₄N₄O₄, (I), and methyl (1RS,3SR,3aRS,6aSR)‐5‐(4‐chlorophenyl)‐1‐methyl‐3‐(3‐methyl‐1‐phenyl‐1H‐pyrazol‐4‐yl)‐4,6‐dioxooctahydropyrrolo[3,4‐c]pyrrole‐1‐carboxylate, C₂₅H₂₃ClN₄O₄, (II), the two rings of the pyrrolopyrrole fragment are both nonplanar, with conformations close to half‐chair forms. The overall conformations of the molecules of (I) and (II) are very similar, apart from the orientation of the ester function. The molecules of (I) are linked into sheets by a combination of an N—H...π(pyrrole) hydrogen bond and three independent C—H...O hydrogen bonds. The molecules of (II) are also linked into sheets, which are generated by a combination of an N—H...N hydrogen bond and two independent C—H...O hydrogen bonds, weakly augmented by a C—H...π(arene) hydrogen bond.     

4‐Anilino‐3‐nitro­pyridine

The structure of the title compound, C₂₂H₁₈N₆O₄, (I), comprises two unique mol­ecules that separately form hydrogen‐bonded polymer chains via N—H?N interactions. Molecular independence arises due to a difference in the dihedral angles between the linked rings, i.e. 52.19 (4) and 46.17 (5)°.