The perchlorate salt of the novel diprotonated dinucleating ligand 1,3‐bis­{[2‐(2‐pyridinio)eth­yl][2‐(2‐pyrid­yl)eth­yl]amino}benzene

In the title salt, 1,3‐bis­{[2‐(2‐pyridinio)eth­yl][2‐(2‐pyrid­yl)ethyl]amino}benzene diperchlorate dihydrate, C₃₄H₃₈N₆²⁺·2ClO₄⁻·2H₂O, the cation contains two ethyl­pyrid­yl and two ethyl­pyridinium pendant pairs anchored to the two N atoms of 1,3‐phenyl­enediamine. The pyrid­yl and pyridinium N atoms are flanked by a mol­ecule of water through strong hydrogen‐bonding inter­actions [N—H⋯O = 2.762 (6) and 2.758 (6) Å, and O—H⋯N = 2.834 (6) and 2.839 (6) Å]. The water mol­ecules have weak hydrogen‐bonding inter­actions with the perchlorate anions as well. One of the perchlorate anions is severely disordered.     

Dichloro­[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane]zinc(II) and di‐μ‐chloro‐bis­{chloro­[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane]cadmium(II)}

The Zn atom in dichloro­[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)­methane]zinc(II), [ZnCl₂(C₁₁H₁₆N₄)], (I), is tetra­hedrally coordinated by two N atoms from one bis­(3,5‐dimethyl­pyrazol­yl)methane ligand and two terminal Cl atoms. The mol­ecule has no crystallographic symmetry. One H atom of the CH₂ group of the bis­(3,5‐dimethyl­pyrazol­yl)methane ligand inter­acts with a Cl atom of an adjacent mol­ecule to yield inter­molecular C—H⋯Cl contacts, thereby forming a one‐dimensional zigzag chain extending along the b axis. On the other hand, in di‐μ‐chloro‐bis­{chloro­[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane]cadmium(II)}, [Cd₂Cl₄(C₁₁H₁₆N₄)₂], (II), each of the two crystallographically equivalent Cd atoms is penta­coordinated by two N atoms from one bis­(3,5‐dimethyl­pyrazol­yl)methane ligand, and by one terminal and two bridging Cl⁻ anions. The mol­ecule has a crystallographic centre of symmetry located at the mid‐point of the Cd⋯Cd line. One H atom of the CH₂ group of the bis­(3,5‐dimethyl­pyrazolyl)­methane ligand inter­acts with a Cl atom of an adjacent mol­ecule to produce pairwise inter­molecular C—H⋯Cl contacts, thereby affording chains of mol­ecules running along the c axis.     

Two hydrates of 2,6‐bis­(1H‐benzimidazol‐2‐yl)­pyridine

The structures of the mono‐ and sesquihydrates of 2,6‐bis(1H‐benz­imi­da­zol‐2‐yl)­pyridine (bbip) are reported. Phase (I), C₁₉H₁₃N₅·H₂O, has one water and one bbip mol­ecule in the asymmetric unit, while phase (II), C₁₉H₁₃N₅·1.5H₂O, has three water mol­ecules and two bbip mol­ecules in the asymmetric unit. The compounds exhibit very similar molecular geom­etries but different packing organizations, which result from intricate hydrogen‐bonding schemes.     

Tris(1H‐benzimidazol‐2‐yl­meth­yl)­amine–solvent adducts

The tris­(1H‐benzimidazol‐2‐yl­meth­yl)­amine (ntb) mol­ecule crystallizes in different solvent systems, resulting in two kinds of adduct, namely the monohydrate, C₂₄H₂₁N₇·H₂O or ntb·H₂O, (I), and the acetonitrile–methanol–water (1/0.5/1.5) solvate, C₂₄H₂₁N₇·C₂H₃N·0.5CH₄O·1.5H₂O or ntb·1.5H₂O·0.5MeOH·MeCN, (II). In both cases, ntb adopts a tripodal mode to form hydrogen bonds with a solvent water mol­ecule via two N—H⋯O and one O—H⋯N hydrogen bond. In (I), the ntb·H₂O adduct is further assembled into a two‐dimensional network by N—H⋯N and O—H⋯N hydrogen bonds, while in (II), a double‐stranded one‐dimensional chain structure is assembled via N—H⋯O and O—H⋯O hydrogen bonds, with the acetonitrile mol­ecules located inside the cavities of the chain structure.     

3,4‐Di‐2‐pyridyl‐1,2,5‐oxadiazole and its perchlorate salt

In 3,4‐di‐2‐pyridyl‐1,2,5‐oxadiazole (dpo), C₁₂H₈N₄O, each mol­ecule resides on a twofold axis and inter­acts with eight neighbours via four C—H⋯N and four C—H⋯O inter­actions to generate a three‐dimensional hydrogen‐bonded architecture. In the perchlorate analogue, 2‐[3‐(2‐pyrid­yl)‐1,2,5‐oxadiazol‐4‐yl]pyridinium perchlorate, C₁₂H₉N₄O⁺·ClO₄⁻ or [Hdpo]ClO₄, the [Hdpo]⁺ cation is bisected by a crystallographic mirror plane, and the additional H atom in the cation is shared by the two pyridyl N atoms to form a symmetrical intra­molecular N⋯H⋯N hydrogen bond. The cations and perchlorate anions are linked through C—H⋯O hydrogen bonds and π–π stacking inter­actions to form one‐dimensional tubes along the b‐axis direction.     

Picolinamidium squarate and di‐p‐toluidinium squarate dihydrate

The crystal structure determinations of picolinamidium squarate, C₆H₇N₂O⁺·C₄O₄⁻, (I), and di‐p‐toluidinium squarate dihydrate, 2C₇H₁₀N⁺·C₄O₄²⁻·2H₂O, (II), are reported. While salt formation occurs by donation of one H atom from squaric acid to the picolin­amide mol­ecule in (I), in compound (II), each squaric acid mol­ecule donates one H atom to the p‐toluidine N atom of two trans p‐toluidine molecules. In (I), the pyridine ring is coplanar with the squarate monoanion through imposed crystallographic mirror symmetry; in (II), the dihedral angle between the p‐toluidine moiety and the squarate dianion is 70.71 (1)°. In (I), a three‐dimensional structure is formed via van der Waals interactions between parallel planes of mol­ecules, with hydrogen‐bond interactions (N—H⋯O and O—H⋯O) acting within the planes; hydrogen bonds form a three‐dimensional network in (II).     

[2,6‐Bis(1H‐benzimidazol‐2‐yl‐κN3)­pyridine‐κN](di­methyl­form­amide‐κO)­(thio­sulfato‐κ2O,S)­nickel(II) mono­hydrate

The structure of the title compound, [Ni(ths)(bbip)(dmf)]·­H₂O [ths is thio­sulfate, S₂O₃; bbip is 2,6‐bis(1H‐benz­imidazol‐2‐yl)­pyridine, C₂₁H₁₃N₅; and dmf is di­methyl­form­amide, C₃H₇NO], is monomeric, with the nickel ion octahe­drally surrounded by an N,N′,N′′‐tridentate bbip mol­ecule, an S,O‐bidentate ths mol­ecule and an O‐monodentate dmf mol­ecule. The H atoms of the hydration water mol­ecule and the amino groups of bbip are involved in hydrogen bonding and determine a spatial organization of broad layers parallel to (001), which are connected by weak interactions.     

Three isomeric forms of hydroxyphenyl‐2‐oxazoline: 2‐(2‐hydroxyphenyl)‐2‐oxazoline, 2‐(3‐hydroxyphenyl)‐2‐oxazoline and 2‐(4‐hydroxyphenyl)‐2‐oxazoline

Crystal structures are reported for three isomeric compounds, namely 2‐(2‐hydroxy­phenyl)‐2‐oxazoline, (I), 2‐(3‐hydroxy­phenyl)‐2‐oxazoline, (II), and 2‐(4‐hydroxy­phenyl)‐2‐oxazoline, (III), all C₉H₉NO₂ [systematic names: 2‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (I), 3‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (II), and 4‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (III)]. In these compounds, the deviation from coplanarity of the oxazoline and benzene rings is dependent on the position of the hydroxy group on the benzene ring. The coplanar arrangement in (I) is stabilized by a strong intra­molecular O—H⋯N hydrogen bond. Surprisingly, the 2‐oxazoline ring in mol­ecule B of (II) adopts a ³T₄ (^C2T_C3) conformation, while the 2‐oxazoline ring in mol­ecule A, as well as that in (I) and (III), is nearly planar, as expected. Tetra­mers of mol­ecules of (II) are formed and they are bound together via weak C—H⋯N hydrogen bonds. In (III), strong inter­molecular O—H⋯N hydrogen bonds and weak intra­molecular C—H⋯O hydrogen bonds lead to the formation of an infinite chain of mol­ecules perpendicular to the b direction. This paper also reports a theoretical investigation of hydrogen bonds, based on density functional theory (DFT) employing periodic boundary conditions.     

Two rhod­amine derivatives: 9‐[2‐(ethoxycarbonyl)phenyl]‐3,6‐bis(ethyl­amino)‐2,7‐di­methyl­xanthyl­ium chloride monohydrate and 3,6‐di­amino‐9‐[2‐(methoxy­carbonyl)­phenyl]xanthyl­ium chloride trihydrate

The title compounds, C₂₈H₃₁N₂O₃⁺·Cl^?·H₂O (common name rhod­amine‐6g), (I), and C₂₁H₁₇N₂O₃⁺·Cl^?·3H₂O (common name rhod­amine‐123), (II), both have planar xanthene skeletons with a formal +1 charge on the amino N atoms delocalized through the π‐electron system so that the N—Csp² bond distances indicate significant double‐bond character. The substituted planar phenyl groups make angles of 63.29 (8) and 87.96 (11)° with the xanthene planes in (I) and (II), respectively. In both mol­ecules, the carbonyl bond vectors point toward the xanthene rings. The ethyl­amine groups in (I) are oriented similarly with their CH₂–CH₃ bond vectors pointing nearly perpendicular to the xanthene plane. The chloride ions and water mol­ecules are disordered in both structures. In (I), the chloride ion and water mol­ecule are disordered between two sites. One water and chloride alternately occupy the same site with occupancy factors of 0.5. The other 0.5‐chloride and 0.5‐water occupy two distinct positions separated by 0.747 (8) Å. In (II), the chloride ion is disordered between three sites and one of the waters is disordered about two other sites. Both crystal structures are stabilized by hydrogen bonds involving the chloride ions, amino groups and water mol­ecules, as well as by π–π stacking between xanthene planes.     

Hydrogen‐bonded one‐dimensional networks in 1:1 complexes of N,N′‐bis(2‐pyridyl)aryldiamines with anilic acid

The 1:1 complexes N,N′‐bis(2‐pyridyl)­benzene‐1,4‐di­amine–anilic acid (2,5‐di­hydroxy‐1,4‐benzo­quinone) (1/1), C₁₆H₁₄N₄·C₆H₄O₄, (I), and N,N′‐bis(2‐pyridyl)­bi­phenyl‐4,4′‐di­amine–anilic acid (1/1), C₂₂H₁₈N₄·C₆H₄O₄, (II), have been prepared and their solid‐state structures investigated. The component mol­ecules of these complexes are connected via conventional N—H?O and O—H?N hydrogen bonds, leading to the formation of an infinite one‐dimensional network generated by the cyclic motif R(9). The anilic acid molecules in both crystal structures lie around inversion centres and the observed bond lengths are typical for the neutral mol­ecule. Nevertheless, the pyridine C—N—C angles [120.9 (2) and 120.13 (17)° for complexes (I) and (II), respectively] point to a partial H‐atom transfer from anilic aicd to the bispyridyl­amine, and hence to H‐atom disorder in the OHN bridge. The bispyridyl­amine mol­ecules of (I) and (II) also lie around inversion centres and exhibit disorder of their central phenyl rings over two positions.     

Two phosphate–imidazole complexes with and without a hydrogen‐bonded guest mol­ecule

The mol­ecular structures of the complexes imidazolium 6,6′‐di‐tert‐butyl‐4,4′‐dimethyl‐2,2′‐thio­diphenyl phosphate, C₃H₅N₂⁺·C₂₂H₂₈O₄PS⁻, (I), and imidazolium 6,6′‐di‐tert‐butyl‐4,4′‐dimethyl‐2,2′‐thio­diphenyl phosphate diisopropyl hydrazo­dicarboxyl­ate hemisolvate, C₃H₅N₂⁺·C₂₂H₂₈O₄PS⁻·0.5C₈H₁₆N₂O₄, (II), have been determined. While (I) forms the expected hydrogen‐bonded chain utilizing the two imidazole N‐bound H atoms, in (II), the substituted hydrazine solvent mol­ecule inserts itself between the chains. Compound (I) exhibits a strong N—H⋯O hydrogen bond, with an N⋯O distance of 2.603 (2) Å. The hydrazine solvent molecule in (II) lies about a twofold axis and the N‐bound H atoms are involved in bifurcated hydrogen bonds with phosphate O atoms. A C‐bound H atom of the imidazolium cation is involved in a C—H⋯O inter­action with a carbonyl O atom of the hydrazine solvent mol­ecule.     

Supramolecular hydrogen‐bonded hexamers in two 5‐aryl‐3‐methyl‐1‐phenyl‐1,6,7,8‐tetra­hydro­pyrazolo­[3,4‐b][1,4]­diazepines

In both title compounds, i.e. 3‐methyl‐1,5‐di­phenyl‐1,6,7,8‐tetra­hydro­pyrazolo­[3,4‐b][1,4]­diazepine, C₁₉H₁₈N₄, (I), and 5‐(4‐chloro­phenyl)‐3‐methyl‐1‐phenyl‐1,6,7,8‐tetra­hydro­pyra­zolo­[3,4‐b][1,4]­diazepine, C₁₉H₁₇ClN₄, (II), an N—H?N hydrogen bond links six mol­ecules to form an R(30) ring. Compound (I) crystallizes in the R space group and (II) crystallizes in P with three mol­ecules in the asymmetric unit. The mol­ecule of (I) contains a disordered seven‐membered ring.     

1,1′‐Di(hydrazinocarbonylmethyl)‐2,2′‐biimidazole monohydrate and 1,1′‐di[2‐(hydrazinocarbonyl)ethyl]‐2,2′‐bi­imidazole

The crystal structures of the title compounds, alternatively called 2,2′‐(2,2′‐bi­imid­azole‐1,1′‐diyl)­diaceto­hydra­zide monohydrate, C₁₀H₁₄N₈O₂·H₂O, (I), and 3,3′‐(2,2′‐bi­imid­azole‐1,1′‐diyl)­dipropion­o­hydra­zide, C₁₂H₁₈N₈O₂, (II), respectively, have been determined. The mol­ecules consist of half‐mol­ecule asymmetric units related by a twofold rotation in (I) and by a center of inversion in (II). The imidazole rings of both mol­ecules crystallize in a nearly coplanar fashion [dihedral angles of 5.91 (3) and 0.0 (1)° for (I) and (II), respectively]. Both planar hy­dra­zinocarbonylalkyl substituents are essentially planar and assume the E orientation.     

The antiestrogen [2‐(4‐benzyl­phenoxy)­ethyl]­diethyl­ammonium chloride

The crystal structure of the title compound, C₁₉H₂₆NO⁺·Cl^? (common name: N,N‐diethyl‐2‐[(4‐phenyl­methyl)phenoxy]‐ethan­amine hydro­chloride), contains one mol­ecule in the asymmetric unit. The planes through the two phenyl rings are roughly perpendicular. Protonation occurs at the N atom, to which the Cl^? ion is linked via an N—H?Cl hydrogen bond. The mol­ecule adopts an eclipsed rather than extended conformation.     

Three 2‐amino­purine derivatives

The structure of 2‐amino‐6‐chloro­purine, C₅H₄ClN₅, (I), comprises a flat mol­ecule, with all possible strong hydrogen‐bond donors and acceptors involved in the hydrogen‐bonding network. The structures of 2‐amino‐6‐(4‐chloro­phenylsulfanyl)­purine hemihydrate, C₁₁H₈ClN₅S·0.5H₂O, (II), and 2‐amino‐6‐(4‐methylphenylsulfanyl)purine 0.33‐hydrate, C₁₂H₁₁N₅S·0.33H₂O, (III), have two and three unique mol­ecules, respectively, and one water mol­ecule in their asymmetric units. Both (II) and (III) exhibit elaborate hydrogen‐bonding networks that involve the S (for both) and Cl [for (II)] atoms in addition to the expected strong hydrogen‐bonding sites. Both structures also have offset‐stacking formations of the phenyl and purine rings.     

The proton‐transfer compounds of strychnine with achiral salicylic acids: strychninium 3,5‐dinitro­salicylate and the strychninium 5‐nitro­salicylate bis­(5‐nitro­salicylic acid) adduct

In the crystal structures of the proton‐transfer compounds of strychnine with 3,5‐dinitro­salicylic acid, namely strychninium 3,5‐dinitro­salicylate, C₂₁H₂₃N₂O₂⁺·C₇H₃N₂O₇⁻, (I), and 5‐nitro­salicylic acid, namely strychninium–5‐nitro­salicylate–5‐nitro­salicylic acid (1/1/2), C₂₁H₂₃N₂O₂⁺·C₇H₄NO₅⁻·2C₇H₅NO₅, (II), protonation of one of the N atoms of the strychnine mol­ecule occurs and this group is subsequently involved in inter­molecular hydrogen‐bonding inter­actions. In (I), this is four‐centred, the primary being with an adjacent strychninium carbonyl O‐atom acceptor in a side‐to‐side inter­action giving linear chains. Other inter­actions are with the phenolate and nitro O‐atom acceptors of the anionic species, resulting in a one‐dimensional polymer structure. In (II), the N⁺—H inter­action is three‐centred, the hydrogen bonding involving carboxyl O‐atom acceptors of the anion and both acid adduct species, giving unique discrete hetero‐tetramer units. The structure of (II) also features π‐bonding inter­actions between the two acid adduct mol­ecules.     

Layered structures in proton‐transfer compounds of 5‐sulfosalicylic acid with the aromatic polyamines 2,6‐diamino­pyridine and 1,4‐phenyl­ene­diamine

The crystal structures of two proton‐transfer compounds of 3‐carb­oxy‐4‐hydroxy­benzene­sulfonic acid (5‐sulfosalicylic acid) with the aromatic polyamines 2,6‐diamino­pyridine [namely 2,6‐diamino­pyridinium 3‐carb­oxy‐4‐hydroxy­benzene­sulfonate monohydrate, C₅H₈N₃⁺·C₇H₅O₆S⁻·H₂O, (I)] and 1,4‐phenyl­ene­diamine [namely 1,4‐phenyl­ene­diaminium 3‐carboxyl­ato‐4‐hydroxy­benzene­sulfonate, C₆H₁₀N₂²⁺·C₇H₄O₆S²⁻, (II)] have been determined. Both compounds feature extensively hydrogen‐bonded three‐dimensional layered polymer structures having significant inter­layer π–π inter­actions between the cation and anion species. In (I), the pyridine N atom of the Lewis base is protonated and forms a direct hydrogen‐bonding inter­action with the water mol­ecule, which together with the two amine groups of the cation and the carboxylic acid group of the anion also give additional inter­actions with O‐atom acceptors of the sulfonate group. In (II), a dianionic species results from deprotonation of both the sulfonic and the carboxylic acid groups, and all available O‐atom acceptors inter­act with all dication donors, which lie about inversion centres.     

Three 4‐amino­quinolines of anti­malarial interest

The structures of three compounds with potential anti­malarial activity are reported. In N,N‐diethyl‐N′‐(7‐iodo­quinolin‐4‐yl)ethane‐1,2‐diamine, C₁₅H₂₀IN₃, (I), the mol­ecules are linked into ribbons by N—H⋯N and C—H⋯N hydrogen bonds. In N‐(7‐bromo­quinolin‐4‐yl)‐N′,N′‐diethyl­ethane‐1,2‐diamine dihydrate, C₁₅H₂₀BrN₃·2H₂O, (II), two amino­quino­line mol­ecules and four water mol­ecules form an R₅⁴(13) hydrogen‐bonded ring which links to its neighbours to form a T5(2) one‐dimensional infinite tape with pendant hydrogen bonds to the amino­quinolines. The phosphate salt 7‐chloro‐4‐[2‐(diethyl­ammonio)ethyl­amino]quinolinium bis­(dihydrogen­phosphate) phospho­ric acid, C₁₅H₂₂ClN₃²⁺·2H₂PO₄⁻·H₃PO₄, (III), was prepared in order to establish the protonation sites of these compounds. The phosphate ions form a two‐dimensional hydrogen‐bonded sheet, while the amino­quino­line cations are linked to the phosphates by N—H⋯O hydrogen bonds from each of their three N atoms. While the conformation of the quinoline region hardly varies between (I), (II) and (III), the amino side chain is much more flexible and adopts a significantly different conformation in each case. Aromatic π–π stacking inter­actions are the only supramolecular inter­actions seen in all three structures.     

2‐Pyridone–tartronic acid (1/1), 3‐hydroxy­pyridinium hydrogen tartronate and 4‐hydroxy­pyridinium hydrogen tartronate

Tartronic acid forms a hydrogen‐bonded complex, C₅H₅NO·C₃H₄O₅, (I), with 2‐pyridone, while it forms acid salts, namely 3‐hydroxy­pyridinium hydrogen tartronate, (II), and 4‐hy­droxy­pyridinium hydrogen tartronate, (III), both C₅H₆NO⁺·C₃H₃O₅⁻, with 3‐hydroxy­pyridine and 4‐hydroxy­pyridine, respectively. In (I), the pyridone mol­ecules and the acid mol­ecules form R(8) and R(10) hydrogen‐bonded rings, respectively, around the inversion centres. In (II) and (III), the cations and anions are linked by N—H⋯O and O—H⋯O hydrogen bonds to form a hydrogen‐bonded chain. In each of (I), (II) and (III), an intermolecular hydrogen bond is formed between a carboxyl group and the hydroxyl group attached to the central C atom, and in (I), the hydroxyl group participates in an intramolecular hydrogen bond with a carbonyl group. No intermolecular hydrogen bond is formed between the carboxyl groups in (I), or between the carboxyl and carboxyl­ate groups in (II) and (III).     

7,8‐Dihydr­oxy‐4‐propyl‐1,2,3,4,4a,5,6,10b‐octa­hydro­benzo[f]quinolinium bromide monohydrate,a dopamine agonist

In the crystal structure of the title dopamine­rgic compound, C₁₆H₂₄NO₂⁺·Br⁻·H₂O, protonation occurs at the piperidine N atom. The piperidine ring adopts a chair conformation and the cyclo­hexene ring adopts a half‐chair conformation; together with the planar benzene ring, this results in a relatively planar shape for the whole mol­ecule. Classical hydrogen bonds (N—H⋯Br, O—H⋯Br and O—H⋯O) produce an infinite three‐dimensional network. Hydrogen bonds between water ­mol­ecules and Br⁻ anions create centrosymmetric rings throughout the crystal structure. Structural comparison of the mol­ecule with the ergoline dopamine agonist pergolide shows that it is the hydrogen‐bond‐forming hydr­oxy or imino group that is necessary for dopamine­rgic activity, rather than the presence of a phenyl or a pyrrole ring per se.