Head‐to‐head dimers in the zwitterion of 1‐hydroxy‐3‐(pyrrolidin‐1‐yl)pro­pyl­idene‐1,1‐bis­phospho­nic acid (EB 1053)

The title compound, 1‐hydroxy‐1‐phospho­no‐3‐(1‐pyr­rol­idin­io)­propyl­idene‐1‐phospho­nate, C₇H₁₇NO₇P₂, is a member of the bis­phospho­nate class of drugs. As a zwitterion, it possesses a negative charge on one of the PO₃ groups and a positive charge on the pyrrolidine N atom. A zwitterion makes a contact with a neighbouring ion through the hydroxyl O atom and two phospho­nyl O atoms, one each from two different PO₃ groups. Hydro­gen bonding involves O—H⋯O and N—H⋯O interactions; the former are involved in the formation of head‐to‐head dimers, while the latter join the dimers into a chain running along the crystallographic b axis.     

Ferrocene compounds. XXXIV. 1′‐(tert‐Butoxycarbonylamino)ferrocene‐1‐carboxylic acid

Heteroannularly substituted ferrocene derivatives can act as model systems for various hydrogen‐bonded assemblies of biomol­ecules formed, for instance, by means of O—H⋯O and N—H⋯O hydrogen bonding. The crystal structure analysis of 1′‐(tert‐butoxy­carbonyl­amino)­ferrocene‐1‐carbox­ylic acid, [Fe(C₁₀H₁₄NO₂)(C₆H₅O₂)] or (C₅H₄COOH)Fe(C₅­H₄NHCOOC(CH₃)₃, reveals two independent mol­ecules within the asymmetric unit, and these are joined into discrete dimers by two types of intermolecular hydrogen bonds, viz. O—H⋯O and N—H⋯O. The –COOH and –NHCOOR groups are archetypes for dimer formation via two eight‐membered rings. The O—H⋯O hydrogen bonds [2.656 (3) and 2.663 (3) Å] form a cyclic carboxylic acid dimer motif. Another eight‐membered ring is formed by N—H⋯O hydrogen bonds [2.827 (3) and 2.854 (3) Å] between the N—H group and an O atom of another carbamoyl moiety. The dimers are assembled in a herring‐bone fashion in the bc plane.     

π‐Stacked hydrogen‐bonded dimers in 2‐(2‐nitro­phenyl­amino­carbonyl)­benzoic acid,and hydrogen‐bonded sheets in orthorhombic and monoclinic polymorphs of 2‐(4‐nitro­phenyl­amino­carbonyl)­benzoic acid

Molecules of 2‐(2‐nitrophenylaminocarbonyl)benzoic acid, C₁₄H₁₀N₂O₅, are linked into centrosymmetric R(8) dimers by a single O—H⋯O hydrogen bond [H⋯O = 1.78 Å, O⋯O = 2.623 (2) Å and O—H⋯O = 178°] and these dimers are linked into sheets by a single aromatic π–π stacking interaction. The isomeric compound 2‐(4‐nitrophenylaminocarbonyl)benzoic acid crystallizes in two polymorphic forms. In the orthorhombic form (space group P2₁2₁2₁ with Z′ = 1, crystallized from ethanol), the mol­ecules are linked into sheets of R(22) rings by a combination of one N—H⋯O hydrogen bond [H⋯O = 1.96 Å, N⋯O = 2.833 (3) Å and N—H⋯O = 171°] and one O—H⋯O hydrogen bond [H⋯O = 1.78 Å, O⋯O = 2.614 (3) Å and O—H⋯O = 173°]. In the monoclinic form (space group P2₁/n with Z′ = 2, crystallized from acetone), the mol­ecules are linked by a combination of two N—H⋯O hydrogen bonds [H⋯O = 2.09 and 2.16 Å, N⋯O = 2.873 (4) and 2.902 (3) Å, and N—H⋯O = 147 and 141°] and two O—H⋯O hydrogen bonds [H⋯O = 1.84 and 1.83 Å, O⋯O = 2.664 (3) and 2.666 (3) Å, and O—H⋯O = 166 and 174°] into sheets of some complexity. These sheets are linked into a three‐dimensional framework by a single C—H⋯O hydrogen bond [H⋯O = 2.45 Å, C⋯O = 3.355 (4) Å and C—­H⋯O = 160°].     

(2S,RS)‐6‐Phenyl‐1‐(p‐tolyl­sulfinyl)­hexa‐3(E),5(E)‐dien‐2‐ol

The mol­ecule of the title compound, C₁₉H₂₀O₂S, corresponds to a chiral sulfinyldienol with two stereogenic centres, viz. the C atom susbtituted by the hydr­oxy group and the sulfinyl S atom. The mol­ecule displays a V‐shape in the solid state. The dihedral angle defined by the least‐squares planes of the aromatic rings is 72.9 (1)°. The packing pattern exhibits the following inter­molecular hydrogen bonds: one O—H⋯O [H⋯O = 1.98 Å, O⋯O = 2.785 (4) Å and O—H⋯O = 166°] and two C—H⋯O [H⋯O = 2.58 and 2.60 Å, C⋯O = 3.527 (5) and 3.347 (5) Å, and C—H⋯O = 164 and 134°]. These define a chain along b.     

O—H⋯O‐bridged dimers linked via C—H⋯O and C—H⋯π inter­actions in 4,6‐di‐O‐benzyl‐myo‐inositol 1,3,5‐orthoformate

The centrosymmetric O—H⋯O‐bonded head‐to‐head dimers of the title compound, C₂₁H₂₂O₆, are linked together via bifurcated C—H⋯O inter­actions along the a axis and via favourable C—H⋯π inter­actions along the b axis in the crystal structure.     

Hydro­gen‐bonded supramolecular motifs in 4,4′‐bipyridinium 8‐hydroxy‐7‐iodo­quinoline‐5‐sulfonate dihydrate

In the title compound, C₁₀H₉N₂⁺·C₉H₅INO₄S⁻·2H₂O, the 4,4′‐bi­pyridine mol­ecule is protonated at one of the pyridine N atoms. These moieties self‐assemble into a supramolecular chain along the a axis through N—H⋯N hydrogen bonds. The quinolinol OH group acts as a donor with respect to a sulfonate O atom [O—H⋯O(sulfonate)] and acts as an acceptor with respect to a C—H group of ferron [C—H⋯O(hydroxy)], forming a supramolecular chain along the b axis. These two types of supramolecular chains (one type made up of bi­pyridine motifs and the other made up of sulfoxine motifs) interact viaπ–π stacking, generating a three‐dimensional framework. These chains are further crosslinked by C—­H⋯O hydrogen bonds and O—H⋯O hydrogen bonds involving water mol­ecules.     

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.     

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.     

(R)‐N‐[(R)‐1‐(2‐Hydroxy‐5‐methyl­phenyl)‐2‐phenyl­ethyl]‐2‐methyl‐1‐phenyl­propyl­ammonium chloride

In the title compound, C₂₅H₃₀NO⁺·Cl⁻, the mol­ecules are linked by a combination of inter­molecular N—H⋯Cl and O—H⋯Cl hydrogen bonds and intra­molecular N—H⋯O hydrogen bonds. The absolute configuration of the new stereogenic centre (the C atom adjacent to the N atom on the phenol side) is determined to have an R configuration.     

4‐Amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one (metamitron) and 4‐amino‐6‐methyl‐3‐phenyl‐1,2,4‐triazin‐5(4H)‐one (isometamitron)

The title structures, both C₁₀H₁₀N₄O, are substitutional isomers. The N—N bond lengths are longer and the C=N bond lengths are shorter by ca 0.025 Å than the respective average values in the C=N—N=C group of asymmetric triazines; the assessed respective bond orders are 1.3 and 1.7. There are N—H⋯O and N—H⋯N hydrogen bonds in both structures, with 4‐­amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one containing a rare bifurcated N—H⋯N,N hydrogen bond. The structures differ in their mol­ecular stacking and the hydrogen‐bonding patterns.     

2‐[(2‐Hydro­xy‐4‐nitro­phenyl)­amino­methyl­ene]­cyclo­hexa‐3,5‐dien‐1(2H)‐one

The title compound, C₁₃H₁₀N₂O₄, adopts the keto–amine tautomeric form and displays an intramolecular N—H⋯O [N⋯O = 2.579 (2) Å] and three intermolecular O—H⋯O [O⋯O = 2.561 (2) Å] and C—H⋯O [C⋯O = 3.274 (2) and 3.318 (2) Å] hydrogen bonds. The keto–amine structure is favoured by through‐mol­ecule conjugation between the hydroxy O atom and imine N atom. The dihedral angle between the planes of the two aromatic rings is 10.79 (4)°.     

3,5‐Bis(4‐methoxy­benzyl­idene)‐1‐methyl‐4‐piperidone and 3,5‐bis(4‐methoxy­benzyl­idene)‐1‐methyl‐4‐oxopiperidinium chloride: potential biophotonic materials

In the title compound 3,5‐bis(4‐methoxy­benzyl­idene)‐1‐methyl‐4‐piperidone, C₂₂H₂₃NO₃, (I), the central heterocyclic ring adopts a flattened boat conformation, while in the related salt 3,5‐bis(4‐methoxy­benzyl­idene)‐1‐methyl‐4‐oxopiperidin­ium chloride, C₂₂H₂₄NO₃⁺·Cl⁻, (II), the ring exhibits a `sofa' conformation in which the N atom deviates from the planar fragment. The pendant benzene rings are twisted from the heterocyclic ring planes in both mol­ecules in the same direction, the range of dihedral angles between the ring planes being 24.5 (2)–32.7 (2)°. The dominant packing motif in (I) involves centrosymmetric dimers bound by weak intermolecular C—H⋯O hydrogen bonds. In (II), cations and anions are linked by strong N—H⋯Cl hydrogen bonds, while weak C—H⋯O and C—H⋯Cl hydrogen bonds link the cations and anions into a three‐dimensional framework.     

1‐Acetyl‐3‐ferrocenyl‐5‐methyl‐1H‐pyrazole and 1‐acetyl‐5‐ferrocenyl‐3‐(2‐pyrid­yl)‐1H‐pyrazole

Mol­ecules of 1‐acetyl‐3‐ferrocenyl‐5‐methyl‐1H‐pyrazole, [Fe(C₅H₅)(C₁₁H₁₁N₂O)], form a centrosymmetric dimer generated by a combination of one C—H⋯π(pyrazole) and one C—H⋯π(cyclo­penta­dienyl) inter­action. The dimers are linked by C—H⋯π inter­actions, involving the pyrazole rings as acceptors, into layers parallel to (10). Mol­ecules of 1‐acetyl‐5‐ferrocenyl‐3‐(2‐pyrid­yl)‐1H‐pyrazole, [Fe(C₅H₅)(C₁₅H₁₂N₃O)], are linked by C—H⋯O inter­actions into a chain running in the [010] direction. Two chains of this type passing through each unit cell are connected by O⋯π(pyridyl) inter­actions into an [010] double chain.     

Hydrogen bonding in nitroaniline analogues: hydrogen‐bonded sheets in 2‐amino‐4,6‐dimethoxy‐5‐nitropyrimidine and π‐stacked hydrogen‐bonded sheets in 4‐amino‐2,6‐dimethoxy‐5‐nitropyrimidine

In 2‐amino‐4,6‐di­methoxy‐5‐nitro­pyrimidine, C₆H₈N₄O₄, the mol­ecules are linked by one N—H⋯N and one N—H⋯O hydrogen bond to form sheets built from alternating R(8) and R(32) rings. In isomeric 4‐amino‐2,6‐di­methoxy‐5‐nitro­pyrimidine, C₆H₈N₄O₄, which crystallizes with Z′ = 2 in P, the two independent mol­ecules are linked into a dimer by two independent N—H⋯N hydrogen bonds. These dimers are linked into sheets by a combination of two‐centre C—H⋯O and three‐centre C—H⋯(O)₂ hydrogen bonds, and the sheets are further linked by two independent aromatic π–π‐stacking interactions to form a three‐dimensional structure.     

cis‐Diaqua­[(E)‐2‐(2‐oxidobenzyl­idene­amino‐κ2N,O)­benzoato‐κO]copper(II): tubes built from O—H⋯O hydrogen‐bonding, π–π and C—H⋯π inter­actions

In the title compound, [Cu(C₁₄H₉NO₃)(H₂O)₂], which crystallizes with Z = 18 in the space group R, pairs of complexes are linked into dimers by three O—H⋯O hydrogen bonds. Strong O—H⋯O hydrogen bonds link the dimers into one‐dimensional chains that further assemble into tubes through π–π and C—H⋯π inter­actions.     

4‐Amino‐7‐(2‐de­oxy‐2‐fluoro‐β‐d‐arabinofuranos­yl)‐5‐fluoro‐7H‐pyrrolo[2,3‐d]pyrimidine: a bis‐fluorinated analogue of 2′‐deoxy­tubercidin

The title compound, C₁₁H₁₂F₂N₄O₃, exhibits an anti glycosylic bond conformation, with a torsion angle χ = −117.8 (2)°. The sugar pucker is N‐type (C4′‐exo, between ³T₄ and E₄, with P = 45.3° and τ_m = 41.3°). The conformation around the exocyclic C—C bond is −ap (trans), with a torsion angle γ = −177.46 (15)°. The nucleobases are stacked head‐to‐head. The crystal structure is characterized by a three‐dimensional hydrogen‐bond network involving N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonds.     

Green chemistry synthesis: 2‐amino‐3‐[(E)‐(2‐pyridyl)methylideneamino]but‐2‐enedinitrile monohydrate and 5‐cyano‐2‐(2‐pyridyl)‐1‐(2‐pyridylmethyl)‐1H‐imidazole‐4‐carboxamide

The title compounds, C₁₀H₉N₅O·H₂O (L1·H₂O) and C₁₆H₁₂N₆O (L2), were synthesized by solvent‐free aldol condensation at room temperature. L1, prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 1:1 molar ratio, crystallized as a monohydrate. L2 was prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 2:1 molar ratio. By varying the conditions of crystallization it was possible to obtain two polymorphs, viz. L2‐I and L2‐II; both crystallized in the monoclinic space group P2₁/c. They differ in the orientation of one pyridine ring with respect to the plane of the imidazole ring. In L2‐I, this ring is oriented towards and above the imidazole ring, while in L2‐II it is rotated away from and below the imidazole ring. In all three molecules, there is a short intramolecular N—H...N contact inherent to the planarity of the systems. In L1·H₂O, this involves an amino H atom and the C=N N atom, while in L2 it involves an amino H atom and an imidazole N atom. In the crystal structure of L1·H₂O, there are N—H...O and O—H...O intermolecular hydrogen bonds which link the molecules to form two‐dimensional networks which stack along [001]. These networks are further linked via intermolecular N—H...N(cyano) hydrogen bonds to form an extended three‐dimensional network. In the crystal structure of L2‐I, symmetry‐related molecules are linked via N—H...N hydrogen bonds, leading to the formation of dimers centred about inversion centres. These dimers are further linked via N—H...O hydrogen bonds involving the amide group, also centred about inversion centres, to form a one‐dimensional arrangement propagating in [100]. In the crystal structure of L2‐II, the presence of intermolecular N—H...O hydrogen bonds involving the amide group results in the formation of dimers centred about inversion centres. These are linked via N—H...N hydrogen bonds involving the second amide H atom and the cyano N atom, to form two‐dimensional networks in the bc plane. In L2‐I and L2‐II, C—H...π and π–π interactions are also present.     

Ethyl 3‐amino‐6‐phenyl‐4‐tolylthieno[2,3‐b]pyridine‐2‐carboxylate

In the title compound, C₂₃H₂₀N₂O₂S, the central thieno­pyridine ring system is essentially planar, the dihedral angle between the planes of the two rings being 0.3 (2)°. The terminal ethyl carboxyl­ate group is twisted by 26.7 (3)° away from the central ring system. A short intramolecular hydrogen bond involving the amino N atom and the carbonyl O atom [N⋯O = 2.806 (4) Å] forms a pseudo‐six‐membered ring. Significant intermolecular C—H⋯N, C—H⋯O and C—H⋯π interactions contribute strongly to the stability of the structure, along with weak π–π‐stacking interactions.     

Dichloro­(O‐ethyl 3‐methyl­pyridine‐2‐carboximidic acid‐κ2N,N′)copper(II)

In the title compound, [CuCl₂(C₉H₁₂N₂O)], the Cu^II atom is coordinated by two Cl⁻ anions and two N atoms of one O‐ethyl 3‐methyl­pyridine‐2‐carboximidic acid mol­ecule in a slightly distorted square‐planar geometry, with Cu—N distances of 2.0483 (17) and 1.9404 (18) Å, and Cu—Cl distances of 2.2805 (10) and 2.2275 (14) Å. In addition, each Cu^II atom is connected by one Cl⁻ anion and the Cu^II atom from a neighbouring mol­ecule, with Cu⋯Cl and Cu⋯Cu distances of 2.9098 (13) and 3.4022 (12) Å, respectively, and, therefore, a centrosymmetric dimer is formed. Adjacent mol­ecular dimers are connected by π–π stacking inter­actions between pyridine rings to form a zigzag mol­ecular chain. The mol­ecular chains are also enforced by N—H⋯Cl and C—H⋯Cl inter­actions.     

2‐Formyl­benzonitrile

The title compound, C₈H₅NO, has an intra­molecular O⋯CN contact involving an O⋯C distance of 2.797 (2) Å and a C—C—N bond angle of 174.5 (2)°, both indicative of a weak nucleophilic attack of the aldehyde O atom on the electrophilic C atom in the nitrile group. Calculations at the B3LYP density functional level using the 6–31G* basis set support this inter­pretation; natural bond‐order analysis indicates an n_O1→π delocalization energy of 6.3 kJ mol⁻¹. Similar results were obtained from density functional calculations on three related mol­ecules. The 2‐formyl­benzonitrile mol­ecules pack in sheets as a consequence of C—H⋯N and C—H⋯O hydrogen bonds.