Hydro­gen‐bonding patterns in two structural isomers of 3,6‐bis(2‐chloro­phenyl)‐1,4‐di­hydro‐1,2,4,5‐tetrazine

Two structural isomers, 3,6‐bis(2‐chloro­phenyl)‐1,4‐di­hydro‐1,2,4,5‐tetrazine, (I), and 3,5‐bis(2‐chloro­phenyl)‐4‐amino‐1H‐1,2,4‐triazole, (II), both C₁₄H₁₀Cl₂N₄, form chain‐like structures in the solid state, stabilized by N—H⋯N and N—H⋯Cl hydrogen bonds. A contribution from weak interactions to the strong hydrogen‐bond network is observed in both structures. The secondary graph sets for intermolecular hydrogen bonds [(11) for (I) and (12) for (II)] indicate the similarity between the networks.     

1‐(2‐Hydroxy‐4,6‐di­methyl­phenyl)­ethanone

In the crystal of the title compound, C₁₀H₁₂O₂, there are two symmetry‐independent mol­ecules, which are essentially superimposable. Each mol­ecule exhibits an intramolecular O—H?O hydrogen bond, with O?O separations of 2.483 (4) and 2.468 (4) Å.     

Hydro­gen‐bonding patterns in cis‐4‐ammonio­cyclo­hexane­carboxyl­ate hemihydrate

In the title compound, C₇H₁₃NO₂·0.5H₂O, cis‐4‐amino­cyclo­hexane­carboxylic acid exists as a zwitterion and co‐crystallizes with water mol­ecules in a 2:1 amino acid–water ratio. The cyclo­hexane ring adopts a chair conformation, with the carboxyl­ate and ammonium groups in axial and equatorial positions, respectively. The basic motif in the crystal structure is a sandwich structure, formed by two amino acid units linked by head‐to‐tail hydrogen bonds. Hydro­gen bonds of the type N⁺—H⋯O—C—O⁻ link these motifs, forming helicoidally extended chains running along the c axis. The water molecule lies on a twofold axis and interacts with the chains by means of O—H⋯O hydrogen bonds.     

Hydro­gen bonding and π–π stacking in di­methyl­genistein

The title compound, 5‐hydroxy‐4′,7‐di­methoxy­isoflavone, C₁₇H₁₄O₅, is composed of a benzo­pyran­one moiety, a phenyl moiety and two methoxy groups. The benzo­pyran­one ring is not coplanar with the phenyl ring, the dihedral angle between them being 56.28 (3)°. The two methoxy groups are nearly coplanar with their corresponding rings, having C—C—O—C torsion angles of 2.9 (2) and 5.9 (2)°. The mol­ecules are linked by C—H·O hydrogen bonds into sheets containing classical centrosymmetric (8) rings. The sheets are further linked by aromatic π–π stacking interactions and C—H·O hydrogen bonds into a supramolecular structure.     

Hydro­gen‐bonded chains in N‐(2‐nitrophenyl)phenylamine

Molecules of the title compound, C₁₂H₁₀N₂O₂, are markedly non‐planar. There is an intramolecular N—H?O hydrogen bond, and the mol­ecules are linked into zigzag chains by a single C—H?O hydrogen bond. Comparisons are made with the supramolecular aggregation in isomeric amino–nitro derivatives, and in some N‐methylnitro­anilines.     

2‐(4‐Acetyl‐3,5‐di­hydroxy‐2‐methyl­phenoxy)‐4,6‐di­methoxy‐3‐methyl­benzoic acid

In the title compound, C₁₉H₂₀O₈, the benzene rings are nearly perpendicular to each other [dihedral angle 80.2 (2)°]. The carboxy group is twisted out while both the methoxy and acetyl groups are almost coplanar with their attached benzene rings. The hydroxy group is involved in an intramolecular O—H?O hydrogen bond with the acetyl O atom and the compound is connected through an intermolecular O—H?O contact to form a dimer. The crystal structure is stabilized by intermolecular O—H?O hydrogen bonds.     

Hydrogen‐bonding and π–π inter­actions in 2‐amino‐4,6‐dimethyl­pyrimidinium salicylate

In the crystal structure of the title compound, C₆H₁₀N₃⁺·C₇H₅O₃⁻, the asymmetric unit contains four crystallographically independent 2‐amino‐4,6‐dimethyl­pyrimidinium and salicylate ions (Z = 8). In each of these, one of the pyrimidine N atoms is protonated, and the carboxyl­ate group of the salicylate ion inter­acts with the pyrimidine group through a pair of N—H⋯O hydrogen bonds, forming an R₂²(8) motif. The pyrimidine cations also form base pairs via a pair of N—H⋯N hydrogen bonds (involving the amino group and the unprotonated ring N atom), forming another R₂²(8) motif. Three such R₂²(8) motifs, fused together, constitute a closed cyclic aggregate, and the linking of these aggregates, arranged in consecutive layers, can be analysed in terms of off‐face stacking inter­actions.     

(2‐Hydro­xy‐5‐methyl­phenyl)­di­phenyl­phosphine oxide

Pairs of individual mol­ecules of the title compound, C₁₉H₁₇O₂P, (I), containing tetrahedrally coordinated P atoms are connected across crystallographic inversion centres via complementary O—H?O=P hydrogen bonds.     

Supramolecular structures of 2‐cyano‐3‐di­methyl­amino‐N‐(4‐methyl­phenyl)­acryl­amide and 2‐cyano‐3‐di­methyl­amino‐N‐(2‐methoxy­phenyl)­acryl­amide

In the title compounds, C₁₃H₁₅N₃O, (I), and C₁₃H₁₅N₃O₂, (II), the dihedral angles between the planes of the phenyl ring and the amide group are 4.1 (1) and 20.7 (1)°, respectively. The mol­ecules adopt a fully extended conformation, aided by intramolecular interactions. The molecular structures of (I) and (II) display different crystal packing and hydrogen‐bonding networks.     

Hydro­gen bonding in 1‐carbamoyl­guanidinium methyl­phospho­nate monohydrate

The title compound, C₂H₇N₄O⁺·CH₄O₃P⁻·H₂O, crystallized with one carbamoyl­guanidinium cation, one methyl­phos­phonate anion and one water mol­ecule in the asymmetric unit. All H atoms of the carbamoyl­guanidinium ion are involved in a hydrogen‐bonded network. The CH₃PO₂(OH) anions, together with the water mol­ecules, build O—H⋯O hydrogen‐bonded ribbons around a 2₁ screw axis parallel to the b axis. Neighbouring ribbons are not directly connected via hydrogen bonding. The carbamoyl­guanidinium cations are linked to these ribbons by N—H⋯O bridges and build a slightly buckled layer structure, the interlayer distance being b/2.     

1‐Chloro‐3,6‐di­methoxy‐2,5‐di­methyl­benzene and 1‐chloro‐3,6‐di­methoxy‐2,4‐di­methyl­benzene

The title compounds, 1‐chloro‐3,6‐di­methoxy‐2,5‐di­methyl­benzene, (IIIa), and 1‐­chloro‐3,6‐di­methoxy‐2,4‐di­methyl­benzene, (IIIb), both C₁₀H₁₃ClO₂, were obtained from 2,5‐ and 2,6‐di­methyl‐1,4‐benzo­quinone, respectively, and are intermediates in the synthesis of ammonium quinone derivatives. The isomers have different substituents around the methoxy groups and crystallize in different space groups. In both mol­ecules, the methoxy groups each have different orientations with respect to the benzene ring. In both cases, one methoxy group lies in the plane of the ring and can participate in conjugation with the aromatic system, while the second is almost perpendicular to the plane of the aromatic ring. The C—O—C bond angles around these substituents are also different: 117.5 (4) and 118.2 (3)° in (IIIa) and (IIIb), respectively, when the methoxy groups lie in the plane of the ring, and 114.7 (3) and 113.6 (3)° in (IIIa) and (IIIb), respectively, when they are out of the plane of the ring.     

Intramolecular hydrogen bonding in derivatives of 3‐amino‐propenethial

Intramolecular H‐bonds existing for derivatives of 3‐amino‐propenethial have been studied using the B3LYP/6‐311++G** level of theory. The nature of these interactions, known as resonance assisted hydrogen bonds, has been discussed. The topological properties of the electron density distributions for N—H—S intramolecular bridges have been analyzed in terms of the Bader theory of atoms in molecules. Correlations between the H‐bond strength and topological parameters have been also studied. Furthermore, we obtained the exact value of the intramolecular hydrogen bond energies by the related rotamers method. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

2‐Hydro­xy‐1‐naphth­aldehyde 2‐methyl­thio­semicarbazone

The potentially tridentate O,N,S‐donor ligand, 2‐hydroxy‐1‐naphth­aldehyde 2‐methyl­thio­semicarbazone, C₁₃H₁₃N₃OS, has been structurally characterized and the mol­ecule is found to exhibit a distorted planar structure with the thio­semicarbazide moiety being twisted slightly out of the plane defined by the naphthyl ring.     

Hydrogen bonding in 2‐amino‐4,6‐dimethoxypyrimidine, 2‐benzylamino‐4,6‐bis(benzyloxy)pyrimidine and 2‐amino‐4,6‐bis(N‐pyrrolidino)pyrimidine: chains of fused rings and a centrosymmetric dimer

Molecules of 2‐amino‐4,6‐di­methoxy­pyrimidine, C₆H₉N₃O₂, (I), are linked by two N—H?N hydrogen bonds [H?N 2.23 and 2.50 Å, N?N 3.106 (2) and 3.261 (2) Å, and N—H?N 171 and 145°] into a chain of fused rings, where alternate rings are generated by centres of inversion and twofold rotation axes. Adjacent chains are linked by aromatic π–π‐stacking interactions to form a three‐dimensional framework. In 2‐­benzylamino‐4,6‐bis(benzyloxy)pyrimidine, C₂₅H₂₃N₃O₂, (II), the mol­ecules are linked into centrosymmetric R(8) dimers by paired N—H?N hydrogen bonds [H?N 2.13 Å, N?N 2.997 (2) Å and N—H?N 170°]. Molecules of 2‐amino‐4,6‐bis(N‐pyrrolidino)­pyrimidine, C₁₂H₁₉N₅, (III), are linked by two N—H?N hydrogen bonds [H?N 2.34 and 2.38 Å, N?N 3.186 (2) and 3.254 (2) Å, and N—H?N 163 and 170°] into a chain of fused rings similar to that in (I).     

2‐(Hydro­xy­methyl)­pyridinium di­hydrogenphosphate

The title compound, C₆H₈NO⁺·H₂PO₄⁻, consists of 2‐(hy­droxy­methyl)­pyridinium and di­hydrogen­phosphate ions. The di­hydrogen­phosphate moieties are linked into chains by pairs of P—O—H⃛O—P hydrogen bonds. The 2‐(hydroxy­methyl)­pyridinium cations are connected to the di­hydrogen­phosphate units by O—H⃛O and N—H⃛O hydrogen bonds. Weak π–π interactions help to determine the interchain packing.     

2‐(Acridin‐9‐yl­imino)‐3‐di­methyl­amino‐1,3‐thia­zolidin‐4‐one

In the title compound, C₁₈H₁₆N₄OS, prepared by the reaction of 4‐(acridin‐9‐yl)‐1,1‐di­methyl­thio­semicarbazide with methyl bromo­acetate, the acridine and thia­zolidine ring systems are both non‐planar and, because of steric requirements, almost perpendicular, with a dihedral angle between their planes of 99.69 (6)°. C—H·O and C—H·π(arene) hydrogen bonds stabilize the crystal structure in the solid state.     

2‐Chloro‐4,6‐di­methoxy‐1,3,5‐triazine

The mol­ecules of 2‐chloro‐4,6‐di­methoxy‐1,3,5‐triazine, C₅H₆ClN₃O₂, lie on a crystallographic mirror plane. There is a close contact of 3.180 (3) Å between one of the methyl C atoms and the N atom of a neighboring mol­ecule. Differential scanning calorimetry measurements show that methyl rearrangement does not take place in the solid state, despite the close proximity of the methyl group to the N atom.     

2‐Amino‐5‐methyl­pyridinium (2‐amino‐5‐methyl­pyridine)trichloro­zincate(II)

The title compound, (C₆H₉N₂)[ZnCl₃(C₆H₈N₂)], consists of one 2‐amino‐5‐methyl­pyridinium cation and one (2‐amino‐5‐methyl­pyridine)trichloro­zincate(II) anion, which are held together by N—H·Cl hydrogen bonds and π–π inter­actions. The cation and the pyridine ligand show similar geometric features, except for the N—C bond lengths. Mol­ecules of the title compound are connected by N—H·Cl hydrogen bonds to form chiral chains; these chains are associated further by C—H·Cl hydrogen bonds to form layers, which are in turn linked by π–π inter­actions.     

O‐(2‐tert‐Butyl‐6‐di­methyl­thio­carbamoyl‐4‐methylphenyl) N,N‐di­methyl­thiocarbamate di­chloro­methane solvate

In the title compound, C₁₇H₂₆N₂OS₂·CH₂Cl₂, the C=S distances are 1.650 (4) and 1.679 (3) Å, and the torsion angle between the planes of the thio­carbamate and carbono­thio­yl fragments is 54.4 (2)°. The steric and electronic effects that these substituents exert on one another determine the observed anti configuration with respect to the phenyl C atoms to which they are attached.     

Hydro­gen‐bonded dimers in N‐(2‐nitro­phenyl­thio)­saccharin

In the title compound, 2‐(2‐nitro­phenyl­thio)‐1,2‐benzo­thia­zol‐3(2H)‐one 1,1‐dioxide, 2‐O₂NC₆H₄S(C₇H₄NO₃S) or C₁₃H₈N₂­O₅S₂, the planes of the saccharin and nitro­phenyl­thiol­ate portions are almost orthogonal. The mol­ecules are linked by C—H?O=S hydrogen bonds [C?O 3.308 (3) Å, H?O 2.44 Å and C—H?O 155°] into cyclic centrosymmetric R²₂(16) dimers, reinforced by aromatic π?π stacking interactions between the nitrated aryl rings.