5‐Methyl‐N‐[2‐nitro‐4‐(trifluoromethyl)phenyl]‐1H‐pyrazole‐3‐amine: a chain of hydrogen‐bonded R22(6) and R22(16) rings

The molecular skeleton of the title compound, C₁₁H₉F₃N₄O₂, is almost planar and exhibits a polarized (charge‐separated) electronic structure in the nitroaniline portion. Molecules are linked by N—H...N and C—H...O hydrogen bonds to form a chain in which centrosymmetric R₂²(6) and R₂²(16) rings alternate.     

Two closely related,and unexpected,quinolinone derivatives: a three‐dimensional hydrogen‐bonded framework structure and a hydrogen‐bonded molecular ribbon of R22(18) and R44(24) rings

1,5‐Bis(4‐chlorophenyl)‐3‐(2‐oxo‐1,2‐dihydroquinolin‐3‐yl)pentane‐1,5‐dione, (Ia), and 1,5‐bis(2‐chlorophenyl)‐3‐(2‐oxo‐1,2‐dihydroquinolin‐3‐yl)pentane‐1,5‐dione, (Ib), crystallize as an 84:16 mixture, 0.84C₂₆H₁₉Cl₂NO₃·0.16C₂₆H₁₉Cl₂NO₃, in the space group I4₁/a, where the molecules of the two isomers occupy very similar sites in the unit cell. A combination of one N—H...O hydrogen bond and one C—H...O hydrogen bond links the molecules, regardless of isomeric form, into a single three‐dimensional framework structure. The molecules of (9RS,10RS)‐8,9‐bis(4‐chlorobenzyl)‐10‐(2‐oxo‐1,2‐dihydroquinolin‐3‐yl)‐5,6,9,10‐tetrahydrophenanthridine, C₃₆H₂₂Cl₂N₂O₄, (II), are linked by two hydrogen bonds, one each of the N—H...O and C—H...O types, into a molecular ribbon in which centrosymmetric rings of R₂²(18) and R₄⁴(24) types alternate. The hydrogen‐bonded ribbons enclose channels, which contain highly disordered solvent molecules.     

(E)‐2‐(1,3‐Benzothiazol‐2‐yl)‐3‐(4‐fluorophenyl)acrylonitrile: a chain of π‐stacked hydrogen‐bonded rings

The title compound, C₁₆H₉FN₂S, crystallizes as a nonmerohedral twin with twin rotation about the reciprocal‐lattice vector [10]*. The molecules are nearly planar and the dihedral angle between the planes of the two aryl rings is only 4.4 (2)°. The molecules are linked by pairs of C—H...N hydrogen bonds to form cyclic centrosymmetric R₂²(18) dimers, which are linked into chains by an aromatic π–π stacking interaction. Comparisons are made with some related 3‐aryl‐2‐thienylacrylonitriles.     

2‐Amino‐5‐nitro­thia­zole monoethanol solvate: triply‐interwoven hydrogen‐bonded sheets containing centrosymmetric R(8) and R(38) rings

2‐Amino‐5‐nitro­thia­zole crystallizes from solution in ethanol as a monosolvate, C₃H₃N₃O₂S·C₂H₆O, in which the thia­zole component has a strongly polarized molecular–electronic structure. The thia­zole mol­ecules are linked into centrosymmetric dimers by paired N—H⋯N hydrogen bonds [H⋯N = 2.09 Å, N⋯N = 2.960 (6) Å and N—H⋯N = 169°], and these dimers are linked by the ethanol mol­ecules, via a two‐centred N—H⋯O hydrogen bond [H⋯O = 1.98 Å, N⋯O = 2.838 (5) Å and N—H⋯O = 164°] and a planar asymmetric three‐centred O—H⋯(O)₂ hydrogen bond [H⋯O = 2.07 and 2.53 Å, O⋯O = 2.900 (5) and 3.188 (5) Å, O—H⋯O = 169 and 136°, and O⋯H⋯O = 55°], into sheets built from alternating (8) and (38) rings. These sheets are triply interwoven.     

2‐tert‐Butylamino‐4‐chloro‐6‐ethylamino‐1,3,5‐triazine: a structure with Z′ = 4 containing two different molecular conformations and two independent chains of hydrogen‐bonded R22(8) rings

The title compound (trivial name terbutylazine), C₉H₁₆ClN₅, (I), crystallizes with Z′ = 4 in the space group Pca2₁, and equal numbers of molecules adopt two different conformations for the ethylamine groups. The four independent molecules form two approximately enantiomorphic pairs. Eight independent N—H...N hydrogen bonds link the molecules into two independent chains of R₂²(8) rings, in which the arrangement of the alkylamine substituents in the independent molecules precludes any further crystallographic symmetry. The significance of this study lies in its finding of two distinct molecular conformations within the structure and two distinct ways in which the molecules are organized into hydrogen‐bonded chains, and in its comparison of the hydrogen‐bonded structure of (I) with those of analogous 1,3,5‐triazines and pyrimidines.     

4‐Amino‐2,6‐di­methoxy­pyrimidine: hydrogen‐bonded sheets of R22(8) and R66(28) rings,reinforced by an aromatic π–π‐stacking interaction

Molecules of the title compound, C₆H₉N₃O₂, are linked by an N—H⃛O hydrogen bond [H⃛O = 2.29 Å, N⃛O = 3.169 (2) Å and N—H⃛O = 173°] and an N—H⃛N hydrogen bond [H⃛N = 2.12 Å, N⃛N = 2.999 (2) Å and N—H⃛N = 175°] into sheets containing centrosymmetric R(8) and R(28) rings; the sheets are reinforced by a single aromatic π–π‐stacking interaction.     

A hydrogen‐bonded chain of rings in 5‐amino‐1‐(4‐methoxybenzoyl)‐3‐methylpyrazole and a three‐dimensional hydrogen‐bonded framework in 5‐amino‐3‐methyl‐1‐(2‐nitrobenzoyl)pyrazole

The molecules of 5‐amino‐1‐(4‐methoxybenzoyl)‐3‐methylpyrazole, C₁₂H₁₃N₃O₂, (I), and 5‐amino‐3‐methyl‐1‐(2‐nitrobenzoyl)pyrazole, C₁₁H₁₀N₄O₃, (II), both contain intramolecular N—H...O hydrogen bonds. The molecules of (I) are linked into a chain of rings by a combination of N—H...N and N—H...π(arene) hydrogen bonds, while those of (II) are linked into a three‐dimensional framework structure by N—H...N and C—H...O hydrogen bonds.     

(E)‐N′‐[5‐Chloro‐3‐methoxy‐2‐(4‐methylphenylsulfonyloxy)benzylidene]isonicotinohydrazide acetic acid solvate: hydrogen‐bonded network of alternating R44(42), R55(33) and R66(40) rings

In the title compound, C₂₁H₁₈ClN₃O₅S·C₂H₄O₂, a combination of O—H...O, N—H...O, C—H...O and C—H...N hydrogen bonds links the components into a complex network containing alternating R₄⁴(42), R₅⁵(33) and R₆⁶(40) rings.     

2‐Amino‐4‐chloro‐5‐formyl‐6‐[methyl(2‐methylphenyl)amino]pyrimidine and 2‐amino‐4‐chloro‐5‐formyl‐6‐[(2‐methoxyphenyl)methylamino]pyrimidine are isostructural and form hydrogen‐bonded sheets of R22(8) and R66(32) rings

2‐Amino‐4‐chloro‐5‐formyl‐6‐[methyl(2‐methylphenyl)amino]pyrimidine, C₁₃H₁₃ClN₄O, (I), and 2‐amino‐4‐chloro‐5‐formyl‐6‐[(2‐methoxyphenyl)methylamino]pyrimidine, C₁₃H₁₃ClN₄O₂, (II), are isostructural and essentially isomorphous. Although the pyrimidine rings in each compound are planar, the ring‐substituent atoms show significant displacements from this plane, and the bond distances provide evidence for polarization of the electronic structures. In each compound, a combination of N—H...N and N—H...O hydrogen bonds links the molecules into sheets built from centrosymmetric R₂²(8) and R₆⁶(32) rings. The significance of this study lies in its observation of the isostructural nature of (I) and (II), and in the comparison of their crystal and molecular structures with those of analogous compounds.     

(E)‐3‐{2‐Amino‐4‐ethoxy‐6‐[N‐(4‐methoxyphenyl)‐N‐methylamino]pyrimidin‐5‐yl}‐1‐phenylprop‐2‐en‐1‐one: a boat‐shaped pyrimidine ring and a chain of hydrogen‐bonded R42(8) and R22(20) rings

In the title compound, C₂₃H₂₄N₄O₃, the pyrimidine ring adopts an almost perfect boat conformation, and the bond distances provide evidence for some polarization of the molecular–electronic structure. Two independent N—H...O hydrogen bonds link the molecules into chains of edge‐fused R²₄(8) and R²₂(20) rings.     

Chains of edge‐fused hydrogen‐bonded R33(22) rings in 5,3′‐dihydr­oxy‐3,6,7,4′,5′‐penta­methoxy­flavone

The title compound [systematic name: 5‐hydroxy‐2‐(3‐hydroxy‐4,5‐dimethoxy­phenyl)‐3,6,7‐trimethoxy‐4H‐chromen‐4‐one], C₂₀H₂₀O₉, was isolated from the seeds of Cleom viscosa Linn. Two independent mol­ecules (A and B) are present in the asymmetric unit with almost similar conformations. The dihedral angles between the fused chromene ring system and the benzene ring bonded to it in mol­ecules A and B are 4.2 (1) and 12.7 (1)°, respectively. The hydroxy O atoms are involved in intra­molecular hydrogen bonding. The mol­ecules are linked by C—H⋯O and O—H⋯O inter­actions into chains of edge‐fused R₃³(22) rings. Aromatic π–π and weak C—H⋯π(arene) inter­actions are also observed.     

5‐Amino‐3‐tert‐butyl‐1‐(4‐nitro­phen­yl)‐1H‐pyrazole forms hydrogen‐bonded sheets of alternating R(20) and R(32) rings

Molecules of the title compound, C₁₃H₁₆N₄O₂, are linked by one N—H⋯O hydrogen bond [H⋯O = 2.47 Å, N⋯O = 3.326 (2) Å and N—H⋯O = 166°] and one N—H⋯N hydrogen bond [H⋯N = 2.19 Å, N⋯N = 3.063 (2) Å and N—H⋯N = 173°] into sheets containing alternating (20) and (32) rings, both types of which are centrosymmetric.     

2‐Amino‐4‐chloro‐6‐[N‐methyl‐N‐(4‐methylphenyl)amino]pyrimidine: formation versus fragmentation of hydrogen‐bonded chains of edge‐fused R22(8) rings in 4,6‐disubstituted 2‐aminopyrimidines

Molecules of the title compound, C₁₂H₁₃ClN₄, are linked by two independent N—H...N hydrogen bonds into a chain of edge‐fused R₂²(8) rings. The significance of this study lies in its attempt to rationalize the patterns of supramolecular aggregation in the title compound and in a range of analogous 4,6‐disubstituted 2‐aminopyrimidines.     

Hydrogen‐bonded sheets of R22(10) and R44(24) rings in 1‐deoxy‐1‐morpholino‐d‐fructopyranose

In the title compound, C₁₀H₁₉NO₆, both rings adopt almost perfect chair conformations and their mutual orientation is influenced by an intramolecular O—H...N hydrogen bond. The molecules are linked by three independent O—H...O hydrogen bonds into sheets containing equal numbers of R₂²(10) and R₄⁴(24) rings.     

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.     

Dimethyl 6‐[1,2‐bis(methoxycarbonyl)‐2‐(triphenyl‐λ5‐phosphanylidene)ethylideneamino]‐2‐methylsulfanyl‐3,4‐pyridinedicarboxylate forms a chain of hydrogen‐bonded rings

In the title compound, C₃₄H₃₁N₂O₈PS, the intramolecular distances provide evidence for polarization of the molecular–electronic structure. The molecules are linked into complex chains of rings by three independent C—H...O hydrogen bonds. The significance of this study lies in its finding that two of the four carbonyl O atoms play no role in the hydrogen bonding, despite the large excess of potential hydrogen‐bond donors present.     

The hydrogen‐bonded complex bis(tert‐butylammonium) 2,6‐dichlorophenolate 2,4‐dichlorophenol–2,4‐dichlorophenolate tetrahydrofuran disolvate containing a chiral R53(10) hydrogen‐bonded ring as a supramolecular synthon

A fixed hydrogen‐bonding motif with a high probability of occurring when appropriate functional groups are involved is described as a `supramolecular hydrogen‐bonding synthon'. The identification of these synthons may enable the prediction of accurate crystal structures. The rare chiral hydrogen‐bonding motif R₅³(10) was observed previously in a cocrystal of 2,4,6‐trichlorophenol, 2,4‐dichlorophenol and dicyclohexylamine. In the title solvated salt, 2C₄H₁₂N⁺·C₆H₃Cl₂O⁻·(C₆H₃Cl₂O⁻·C₆H₄Cl₂O)·2C₄H₈O, five components, namely two tert‐butylammonium cations, one 2,4‐dichlorophenol molecule, one 2,4‐dichlorophenolate anion and one 2,6‐dichlorophenolate anion, are bound by N—H…O and O—H…O hydrogen bonds to form a hydrogen‐bonded ring, with the graph‐set motif R₅³(10), which is further associated with two pendant tetrahydrofuran molecules by N—H…O hydrogen bonds. The hydrogen‐bonded ring has internal symmetry, with a twofold axis running through the centre of the 2,6‐dichlorophenolate anion, and is isostructural with a previous and related structure formed from 2,4‐dichlorophenol, dicyclohexylamine and 2,4,6‐trichlorophenol. In the title crystal, helical columns are built by the alignment and twisting of the chiral hydrogen‐bonded rings, along and across the c axis, and successive pairs of rings are associated with each other through C—H…π interactions. Neighbouring helical columns are inversely related and, therefore, no chirality is sustained, in contrast to the previous case.     

Hydro­gen bonding in C‐substituted nitro­anilines: a chain of R(12) rings in 2‐methane­sulfonyl‐4‐nitro­aniline

The title compound, C₇H₈N₂O₄S, exhibits a markedly polarized molecular–electronic structure. The mol­ecules are linked into a chain of edge‐fused (12) rings by two N—H⋯Ozdbnd;S hydrogen bonds [H⋯O = 2.10 and 2.21 Å, N⋯O = 2.900 (2) and 2.878 (2) Å, and N—H⋯O = 152 and 133°].     

(2,6‐Bis{1‐[4‐(dimethylamino)phenylimino]ethyl}pyridine)dichlorido(triphenylphosphine‐κP)ruthenium(II): a zigzag chain of fused centrosymmetric R22(12) rings

The title compound, [RuCl₂(C₂₅H₂₉N₅)(C₁₈H₁₅P)], a transfer hydrogenation catalyst, is supported by an N,N′,N′′‐tridentate pyridine‐bridged ligand and triphenylphosphine. The Ru^II centre is six‐coordinated in a distorted octahedral arrangement, with the two Cl atoms located in the axial positions, and the pyridine (py) N atom, the two imino N atoms and the triphenylphosphine P atom located in the equatorial plane. The two equatorial Ru—N_imino distances (mean 2.093 Å) are substantially longer than the equatorial Ru—N_py bond [1.954 (4) Å]. It is observed that the N_imino—M—N_py bond angle for the five‐membered chelate rings of 2,6‐bis(imino)pyridine‐based complexes is inversely related to the magnitude of the M—N_py bond. The title structure is stabilized by intra‐ and intermolecular C—H...Cl hydrogen bonds, as well as by intramolecular π–π stacking interactions between the aromatic rings belonging to the triphenylphosphine ligand and the dimethylaminophenyl fragment. The intermolecular hydrogen bonds form an R₂²(12) ring and a zigzag chain of fused centrosymmetric rings running parallel to the [100] direction.     

Methyl 4‐amino‐2,3‐dihydro‐6‐methoxy‐1,3‐dioxo‐1H‐pyrrolo[3,4‐c]pyridine‐7‐carboxylate forms hydrogen‐bonded sheets built from R22(8) and R66(42) rings

In the title compound, C₁₀H₉N₃O₅, which was formed by the reaction of 6‐amino‐2‐methoxy‐4(3H)‐pyrimidinone with di­methyl acetyl­enedi­carboxyl­ate, the mol­ecules are linked by N—H?O hydrogen bonds [N?O 2.8974 (15) and 3.0300 (15) Å, and N—H?O 165 and 174°] into planar sheets built from alternating R₂²(8) and R₆⁶(42) rings.