rac‐1‐Phenyl­ethyl­ammonium carboxy­methyl­phospho­nate(1–): hydrogen‐bonded anion sheets with pendent cations

In the title compound, C₈H₁₂N⁺·C₂H₄O₅P⁻, the anions are linked by two O—H⋯O hydrogen bonds [H⋯O both 1.75 Å, O⋯O = 2.5781 (15) and 2.5834 (15) Å, and O—H⋯O = 169 and 176°] into sheets built from alternating (8) and (32) rings. Each cation is linked to an anion sheet by three N—H⋯O hydrogen bonds [H⋯O = 1.88–2.04 Å, N⋯O = 2.7603 (16)–2.9334 (17) Å and N—H⋯O = 162–166°], such that all the cations pendent from one face of the sheet are of the R configuration, while all those pendent from the opposite face are of the S configuration.     

1‐[(4‐Chloro­benzoyl)­methyl]‐4‐(N,N‐di­methyl­amino)­pyridinium bromide sesquihydrate and 1‐[(4‐bromo­benzoyl)­methyl]‐4‐(N,N‐di­methyl­amino)­pyridinium bromide sesquihydrate

The title compounds, C₁₅H₁₆ClN₂O⁺·Br⁻·1.5H₂O and C₁₅H₁₆BrN₂O⁺·Br⁻·1.5H₂O, are isomorphous. The benzene ring is oriented nearly normal to the pyridine ring in both compounds. The molecular packing is mainly influenced by intermolecular O—H⋯O and O—H⋯Br interactions, as well as weak intramolecular C—H⋯O interactions. The H₂OBr⁻ units form an extended water–bromide chain, with a bridging water mol­ecule on a twofold axis.     

Isomorphous crystals of strychninium 4‐chloro­benzoate and strychninium 4‐nitro­benzoate

In strychninium 4‐chloro­benzoate, C₂₁H₂₃N₂O₂⁺·C₇H₄ClO₂⁻, (I), and strychninium 4‐nitro­benzoate, C₂₁H₂₃N₂O₂⁺·C₇H₄NO₄⁻, (II), the strychninium cations form pillars stabilized by C—H⋯O and C—H⋯π hydrogen bonds. Channels between the pillars are occupied by anions linked to one another by C—H⋯π hydrogen bonds. The cations and anions are linked by ionic N—H⁺⋯O⁻ and C—H⋯X hydrogen bonds, where X = O, π and Cl in (I), and O and π in (II).     

(R)‐1‐Phenyl­ethyl­ammonium 6‐amino‐5‐nitro­pyrimidine‐2,4(1H,3H)‐dionate (R)‐1‐phenyl­ethyl­amine hemisolvate: hydrogen‐bonded sheets of ions with pendent solvent mol­ecules

In the title compound, 2C₈H₁₂N⁺·2C₄H₃N₄O₄⁻·C₈H₁₁N, the anions are linked by paired N—H⋯N hydrogen bonds [H⋯N = 2.07 and 2.11 Å, N⋯N = 2.942 (3) and 2.978 (3) Å and N—H⋯N = 173 and 170°] and by paired N—H⋯O hydrogen bonds [H⋯O = 1.98 and 2.05 Å, N⋯O = 2.855 (3) and 2.917 (3) Å, and N—H⋯O = 173 and 167°] into chains of rings. These chains are linked into sheets by further N—H⋯O hydrogen bonds in which all of the donors are provided by the cations [H⋯O = 1.83–2.17 Å, N⋯O = 2.747 (3)–2.965 (3) Å and N—H⋯O = 141–168°]. The neutral amine molecule is pendent from the sheet and is linked to it by a single N—H⋯N hydrogen bond [H⋯N = 2.00 Å, N⋯N = 2.901 (3) Å and N—H⋯N = 175°].     

1‐((E)‐{(1R,2R)‐2‐[(E)‐(2‐Hydr­oxy‐1‐naphth­yl)methyl­eneamino]cyclo­hexyl}iminiometh­yl)naphthalen‐2‐olate: a Schiff base compound having both OH and NH character

The title Schiff base compound, C₂₈H₂₆N₂O₂, possesses both OH and NH tautomeric character in its mol­ecular structure. While the OH side of the compound is described as an inter­mediate state, its NH side adopts a predominantly zwitterionic form. The mol­ecular structure of the compound is stabilized by both N⁺—H⋯O⁻ and O—H⋯N intra­molecular hydrogen bonds. There are two weak C—H⋯O hydrogen bonds leading to polymeric chains of topology C(5) and C(13) running along the b axis of the unit cell. In addition, inter­molecular C—H⋯π inter­actions serve to stabilize the extended structure.     

Lamellar aggregation and hydrogen‐bonding motifs in 3‐(amino­carbon­yl)­pyridinium perchlorate and hydrogen oxalate

In the title compounds, C₆H₇N₂O⁺·ClO₄⁻, (I), and C₆H₇N₂O⁺·C₂HO₄⁻, (II), the carboxamide plane is twisted from the plane of the protonated pyridine ring. Lamellar or sheet‐like structural features are observed through N—H⋯O and O—H⋯O hydrogen‐bonded motifs of cations and anions in (I) and (II), respectively. These sheets are aggregated through C(4) and C(5) chain motifs in (I) and (II), respectively. R₁²(4) ring motifs in (I) and R₁²(5) motifs in (II) are formed via pyridine–anion bifurcated N—H⋯O inter­actions. In (II), carboxamide groups form N—H⋯O dimers around the inversion centres of the unit cell, with R₂²(8) ring motifs. A 2₁ screw‐related helical or ribbon‐like structure along the b axis is formed in (II) through carboxamide and pyridinium N—H⋯O hydrogen bonds with the oxalate anions.     

2‐Amino­benzimidazolium O‐ethyl malonate: eight independent N—H⋯O hydrogen bonds generate sheets

The title compound, C₇H₈N₃⁺·C₅H₇O₄⁻, crystallizes with Z′ = 2 in space group P2₁/c; eight independent N—H⋯O hydrogen bonds [H⋯O = 1.75–1.88 Å, N⋯O = 2.699 (2)–2.829 (2) Å and N—H⋯O = 147–179°] link the four inde­pendent ions into sheets.     

Solid‐state architecture of saccharin salts of some diamines

Hydrazinium saccharinate, N₂H₅⁺·C₇H₄NO₃S⁻, crystallizes in a 1:1 ratio, while ethyl­ene­diaminium bis­(saccharinate), C₂H₁₀N₂²⁺·2C₇H₄NO₃S⁻, and butane‐1,4‐diaminium bis­(sac­charin­ate), C₄H₁₄N₂²⁺·2C₇H₄NO₃S⁻, form in a 1:2 cation–anion stoichiometry. The structures contain many strong hydrogen bonds of the N⁺—H⋯N⁻, N⁺—H⋯O, N—H⋯O and N—H⋯N types, with auxiliary C—H⋯O inter­actions.     

Proton‐bifurcated C—H⋯(O,O) hydrogen bonds in 2,3‐dichloro‐6‐nitro­benzyl­aminium chloride

In the crystal structure of the title salt, C₇H₇Cl₂N₂O₂⁺·Cl⁻, the chloride anions participate in extensive hydrogen bonding with the aminium cations and indirectly link the mol­ecules through multiple N⁺—H⋯Cl⁻ salt bridges. There are two independent mol­ecules in the asymmetric unit, related by a pseudo‐inversion center. The direct inter­molecular coupling is established by C—H⋯O, C—H⋯Cl and C—Cl⋯Cl⁻ inter­actions. A rare three‐center (donor bifurcated) C—H⋯(O,O) hydrogen bond is observed between the methyl­ene and nitro groups, with a side‐on intra­molecular component of closed‐ring type and a head‐on inter­molecular component.     

2‐Amino­pyridinium–fumarate–fumaric acid (2/1/1)

The title complex, 2C₅H₇N₂⁺·C₄H₂O₄²⁻·C₄H₄O₄, contains cyclic eight‐membered hydrogen‐bonded rings involving 2‐­aminopyridinium and fumarate ions. The fumaric acid mol­ecules and fumarate ions lie on inversion centers and are linked into zigzag chains by O—H⋯O hydrogen bonds. The dihedral angle between the pyridinium ring and the hydrogen‐bonded fumarate ion is 7.60 (4)°. The fumarate anion is linked to the pyridinium cations by intermolecular N—H⋯O hydrogen bonds. The heterocycle is fully protonated, thus enabling amine–imine tautomerization.     

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.     

{4(S)‐(Piperidin‐1‐ylcarbonyl)‐4‐[3‐(trifluoro­methyl)phenylsulfon­amido]butyl}guanidinium chloride: a model of a graftable thrombin inhibitor

In the title compound, C₁₈H₂₇F₃N₅O₃S⁺·Cl⁻, the guanidine group forms N—H⋯Cl hydrogen bonds, with four N⋯Cl distances in the range 3.164 (3)–3.337 (4) Å. In the crystal packing, the cations are further linked by N—H⋯O and C—H⋯O inter­actions. The structure is compared with that of argatroban complexed with thrombin and is the subject of docking studies in the active site of thrombin.     

Berberine formate–succinic acid (1/1)

The title compound [systematic name: 9,10‐di­methoxy‐2,3‐methyl­ene­dioxy‐5,6‐di­hydro­dibenzo­[a,g]­quinolizinium form­ate–succinic acid (1/1)], C₂₀H₁₈NO₄⁺·CHO₂⁻·C₄H₆O₄, con­tains centrosymmetric pairs of almost planar berberine cations, and hydrogen‐bonded (C₄H₆O₄⋯HCOO⁻)₂ rings of succinic acid with formate anions, bonded by O—H⋯O hydrogen bonds with O⋯O distances of 2.4886 (15) and 2.5652 (16) Å. Pairs of cations and mol­ecules of succinic acid are connected by non‐conventional weak C—H⋯O hydrogen bonds, with C⋯O distances of 3.082 (2) and 3.178 (2) Å.     

N,N‐Di­methyl­anilinium 3‐cyano‐4‐(di­cyano­methyl­ene)‐5‐oxo‐4,5‐di­hydro‐1H‐pyrrol‐2‐olate

In the title compound, C₈H₁₂N⁺·C₈HN₄O₂⁻, the anion and cation lie on a crystallographic mirror plane and form planar ribbons via N—H⋯O [N⋯O = 2.933 (4) Å, H⋯O = 2.01 Å and N—H⋯O = 170°] and N—H⋯N [N⋯N = 3.016 (5) Å, H⋯N = 2.15 Å and N—H⋯N = 169°] hydrogen bonds. The ribbons are further linked via weak C—H⋯O and C—H⋯N hydrogen bonds. In adjacent planes, anions lie opposite cations; π–π interactions (separation a/2 = 3.520 Å) exist between the anions and the cations, and stacks are formed, running along the a axis. The cations are disordered over two interpenetrating sites, with occupancies of 0.833 (5) and 0.167 (5).     

N‐(2,4‐Dimethoxy­benzyl­idene­amino)­guanidinium dihydrogenphosphate

In the asymmetric unit of the title compound, C₁₀H₁₅N₄O₂⁺·H₂PO₄⁻, there are two protonated amino­guanidinium cations and two dihydrogenphosphate anions. The positive charge on the protonated amidine group is delocalized over the three C—N bonds in a manner similar to that found in guanidinium salts. The amino­guanidinium cations are found to be the E‐isomer structures. Intra­molecular inter­actions of the N—H⋯N type are observed, leading to the formation of five‐membered rings. Extensive networks of O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds stabilize the three‐dimensional network. In the crystal structure, π–π inter­actions between the benzene rings, with a distance of 3.778 (2) Å between the ring centroids, also affect the packing of the mol­ecules.     

N1‐(4‐tert‐Butyl­phenyl)‐N2‐hydroxy‐α‐oxo‐α‐phenyl­acet­amidine and N2‐hydroxy‐N1‐(4‐nitro­phenyl)‐α‐oxo‐α‐phenyl­acet­amidine hemihydrate

In the title compounds, C₁₈H₂₀N₂O₂, (I), and C₁₄H₁₁N₃O₄·0.5H₂O, (II), respectively, the oxime groups have an E configuration. In (I), the mol­ecules exist as polymers bound by intermolecular C—H⋯O and O—H⋯N hydrogen bonds around inversion centres. In (II), intermolecular OW—H⋯N, OW—H⋯O and O—H⋯OW interactions stabilize the molecular packing.     

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°].     

Ammonium O,O‐dicyclo­hexyl phosphoro­dithio­ate

The structure of the title compound, NH₄⁺·C₁₂H₂₂O₂PS₂⁻, consists of a polymeric arrangement of ammonium cations and O,O‐dicyclohexyl phosphorodithioate anions linked through N—H⋯O and N—H⋯S hydrogen bonds. These inter­actions result in the formation of (100) sheets.     

Secondary interactions in 3‐bromo­pyridinium tri­bromo­acetate

The title compound, C₅H₅BrN⁺·C₂Br₃O₂⁻, crystallizes with Z′ = 2. The residues pack in two distinct (but interconnected) types of layer, namely, layers parallel to (102), in which the residues are connected by classical N—H⋯O hydrogen bonds, C—H⋯O interactions and Br⋯Br contacts, and anion layers parallel to the ab plane, connected by Br⋯O interactions. The two formula units are topologically equivalent with respect to all these contacts.     

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.