2-Amino-6-methyl-pyridinium 2,2,2-tri-chloro-acetate

The crystal structures and Hirshfeld surface analysis of 6-(naphthalen-1-yl)-6a-nitro-6,6a,6b,7,9,11a-hexa-hydro-spiro-[chromeno[3',4':3,4]pyrrolo-[1,2-c]thia-zole-11,11'-indeno-[1,2-b]quinoxaline] and 6'-(naphthalen-1-yl)-6a'-nitro-6',6a',6b',7',8',9',10',12a'-octa-hydro-2H-spiro-[ace-naphthyl-ene-1,12'-chromeno[3,4-a]indolizin]-2-one

The crystal structures of the title spiro derivatives are described and the analysis of the inter­molecular contacts in the crystals using Hirshfeld surface analysis and two-dimensional fingerprint plots is reported.

The title compounds, 6-(naphthalen-1-yl)-6a-nitro-6,6a,6 b,7,9,11a-hexa­hydro­spiro­[chromeno[3′,4′:3,4]pyrrolo­[1,2-c]thia­zole-11,11′-indeno­[1,2-b]quinoxaline], C₃₇H₂₆N₄O₃S, (I), and 6′-(naphthalen-1-yl)-6a′-nitro-6′,6a′,6b′,7′,8′,9′,10′,12a′-octa­hydro-2H-spiro­[ace­naphthyl­ene-1,12′-chromeno[3,4-a]indolizin]-2-one, C₃₆H₂₈N₂O₄, (II), are new spiro derivatives, in which both the pyrrolidine rings adopt twisted conformations. In (I), the five-membered thia­zole ring adopts an envelope conformation, while the eight-membered pyrrolidine-thia­zole ring adopts a boat conformation. An intra­molecular C—H⋯N hydrogen bond occurs, involving a C atom of the pyran ring and an N atom of the pyrazine ring. In (II), the six-membered piperidine ring adopts a chair conformation. An intra­molecular C—H⋯O hydrogen bond occurs, involving a C atom of the pyrrolidine ring and the keto O atom. For both compounds, the crystal structure is stabilized by inter­molecular C—H⋯O hydrogen bonds. In (I), the C—H⋯O hydrogen bonds link adjacent mol­ecules, forming R₂²(16) loops propagating along the b-axis direction, while in (II) they form zigzag chains along the b-axis direction. In both compounds, C—H⋯π inter­actions help to consolidate the structure, but no significant π–π inter­actions with centroid–centroid distances of less than 4 Å are observed.

The crystal structures and Hirshfeld surface analyses of four 3,5-diacetyl-2-methyl-2,3-di-hydro-1,3,4-thia-diazol-2-yl derivatives

The crystal structures of four 3,5-diacetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl derivatives, viz. 4-phenyl benzoate, 4-phenyl isobutyrate, 4-phenyl propionate and 4-phenyl cinnamate, are described and the inter­molecular contacts in the crystals are analysed using Hirshfeld surface analysis and two-dimensional fingerprint plots.

The title compounds, 4-(5-acetamido-3-acetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl)phenyl benzoate, C₂₀H₁₉N₃O₄S (I), 4-(5-acetamido-3-acetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl)phenyl isobutyrate 0.25-hydrate, C₁₇H₂₁N₃O₄S·0.25H₂O (II), 4-(5-acetamido-3-acetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl)phenyl propionate, C₁₆H₁₉N₃O₄S (III) and 4-(5-acetamido-3-acetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl)phenyl cinnamate chloro­form hemisolvate, C₂₂H₂₁N₃O₄S·0.5CHCl₃ (IV), all crystallize with two independent mol­ecules (A and B) in the asymmetric unit in the triclinic P space group. Compound II crystallizes as a quaterhydrate, while compound IV crystallizes as a chloro­form hemisolvate. In compounds I, II, III (mol­ecules A and B) and IV (mol­ecule A) the five-membered thia­diazole ring adopts an envelope conformation, with the tetra­substituted C atom as the flap. In mol­ecule B of IV this ring is flat (r.m.s. deviation 0.044 Å). The central benzene ring is in general almost normal to the mean plane of the thia­diazole ring in each mol­ecule, with dihedral angles ranging from 75.8 (1) to 85.5 (2)°. In the crystals of all four compounds, the A and B mol­ecules are linked via strong N—H⋯O hydrogen bonds and generate centrosymmetric four-membered R⁴₄(28) ring motifs. There are C—H⋯O hydrogen bonds present in the crystals of all four compounds, and in I and II there are also C—H⋯π inter­actions present. The inter­molecular contacts in the crystals of all four compounds were analysed using Hirshfeld surface analysis and two-dimensional fingerprint plots.

The crystal structures and Hirshfeld surface analysis of N',N'''-((1E,1'E)-{[methyl-enebis(-oxy)]bis-(6-bromo-3,1-phenyl-ene)}bis-(methan-ylyl-idene))bis-(isonicotinohydrazide) dihydrate and N',N'''-((1E,1'E)-{[butane-1,4-diylbis(-oxy)]bis-(2,1-phenyl-ene)}bis-(methan-ylyl-idene))bis-(isonicotino-hydrazide) [+ solvent]

The title compounds, C27H20Br2N6O4·2H2O, (I), and C30H28N6O4·[+ solvent], (II), both crystallize with one half-mol-ecule in the asymmetric unit. The whole mol-ecule of (I) is generated by twofold rotation symmetry, with the twofold rotation axis bis-ecting the C atom of the -O-CH2-O- bridge. This results in a folded or U-shaped conformation of the mol-ecule. The whole mol-ecule of (II) is generated by inversion symmetry, with the central CH2-CH2 bond of the -O-(CH2)4-O- bridge being located about a center of inversion. This results in a step-like conformation of the mol-ecule. The central C(=O)N-N=C regions of the isonicotinohydrazide moieties in both compounds are planar and the configuration about the imine C=N bonds is E. In compound (I), the benzene and pyridine rings are inclined to each other by 37.60 (6)°. The two symmetry-related pyridine rings are inclined to each other by 74.24 (6)°, and the two symmetry-related benzene rings by 7.69 (6)°. In compound (II), the benzene and pyridine rings are inclined to each other by 25.56 (11)°. The symmetry-related pyridine rings are parallel, as are the two symmetry-related benzene rings. In the crystal of (I), a pair of water mol-ecules link the organic mol-ecules via Owater-H⋯O and Owater-H⋯N hydrogen bonds, forming chains along [001], and enclosing an R 4 2(8) and two R 1 2(5) ring motifs. The chains are linked by N-H⋯Npyridine hydrogen bonds, forming a supra-molecular framework. There are also a number of C-H⋯O hydrogen bonds, and C-H⋯π and offset π-π inter-actions [inter-planar distance = 3.294 (1) Å] present reinforcing the framework. In the crystal of (II), mol-ecules are linked by N-H⋯Npyridine hydrogen bonds, forming a supra-molecular framework. Here too there are also a number of C-H⋯O hydrogen bonds present, and a C-H⋯π inter-action, reinforcing the framework. For compound (II), a region of disordered electron density was corrected for using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] routine in PLATON. Their formula mass and unit-cell characteristics were not taken into account during refinement.

4-Methylanilinium trichloroacetate

The asymmetric unit of the title molecular salt, C7H10N+·C2Cl3O2−, consists of two cations and two anions. In the crystal, N—H...O hydrogen bonds link the components into [100] chains incorporatingR23(10) loops and weak π–π stacking [centroid-to-centroid distance = 3.865 (2) Å] is also observed.

2-Amino-4-methylpyridinium 2-(4-nitrophenyl)acetate

In the title molecular salt, C6H9N2+·C8H6NO4−, the cation is protonated at its pyridine N atom. In the crystal, the anions are connected by a pair of C—H...O contacts into [100] chains, which generateR22(11) loops and these chains are linkedviaanother C—H...O contact which encloses anR24(10) loop. Adjacent anions and cations are connected through N—H... O hydrogen bonds, generating anR22(8) loop. Two pairs of anions and cations are linked by N—H...O hydrogen bonds, forming a tetramer with anR22(8) loop motif. The packing also features weak C—H...π and π–π [centroid-to-centroid distances = 3.8972 (11) and 3.9549 (10) Å] interactions, which result in a three-dimensional network.

2-Amino-3-methylpyridinium 4-methoxybenzoate

In the title molecular salt, C6H9N2+·C8H7O3−, the cation is protonated at its pyridine N atom and is inclined by 3.39 (9)° to the benzene ring of the anion, which is deprotonated at the carboxyl group. The methoxy group is twisted with respect to the benzene ring to which it is attached, the methyl C atom deviating from the ring plane by 0.023 (2) Å. In the crystal, the anions and cations are linked by two N—H...O hydrogen bonds, forming anR22(8) ring motif. They are also linked by a weak offset π–π interaction [centroid-to-centroid distance = 3.890 (1) Å]. The anions and cations are further connected through N—H...O and C—H...O hydrogen bonds, forming slabs parallel to (001).

Crystal structure of 2-amino-5-nitro-pyridinium sulfamate

The title mol­ecular salt, obtained by the reaction of sulfamic acid with 2-amino-5-nitro­pyridine, is the result of a proton transfer from sulfamic acid to the N atom of the pyridine ring. In the crystal, the cations and anions are linked by a number of N—H⋯O and N—H⋯N hydrogen bonds, forming sheets lying parallel to (100).

The title mol­ecular salt, C₅H₆N₃O₂⁺ ·H₂NO₃S⁻, was obtained from the reaction of sulfamic acid with 2-amino-5-nitro­pyridine. A proton transfer from sulfamic acid to the pyridine N atom occurred, resulting in the formation of a salt. As expected, this protonation leads to the widening of the C—N—C angle of the pyridine ring, to 122.9 (3)°, with the pyridinium ring being essentially planar (r.m.s. deviation = 0.025 Å). In the crystal, the ion pairs are joined by three N—H⋯O and one N—H⋯N hydrogen bonds in which the pyridinium N atom and the amino N atom act as donors, and are hydrogen bonded to the carboxyl­ate O atoms and the N atom of the sulfamate anion, thus generating an R³₃(22) ring motif. These motifs are linked by further N—H⋯O hydrogen bonds enclosing R³₃(8) loops, forming sheets parallel to (100). The sheets are linked via weak C—H⋯O hydrogen bonds, forming a three-dimensional structure. The O atoms of the nitro group are disordered over two sets of sites with a refined occupancy ratio of 0.737 (19):0.263 (19).

Crystal structure of bis[4-(dimethylamino)pyridinium] bis(2-nitrobenzoate) trihydrate

The title salt, 2C7H11N2+·2C7H4NO4−·3H2O, crystallized with two anions and two cations in the asymmetric unit, together with three water molecules. Both 4-dimethylaminopyridinium cations are protonated at their pyridine N atoms with the plane of the N(CH3)2hetero atoms inclined to the pyridine ring by 4.5 (2) and 1.4 (2)°. In the 2-nitrobenzoate anions, the carboxyl and nitro groups are inclined to their respective benzene rings by 77.1 (3) and 20.0 (3)°, and 75.8 (2) and 20.9 (3)°. In the crystal, the anions are linkedviaO—H...O hydrogen bonds involving the water molecules, forming chains along [100]. The cations are linked to these chains by N—H...O hydrogen bonds. The chains are linkedviaC—H...O hydrogen bonds and C—H...π and π–π interactions [inter-centroid distances range from 3.617 (1) to 3.851 (1) Å], forming a three-dimensional structure.

2-Amino-6-methyl-pyridinium 4-methyl-benzene-sulfonate

In the asymmetric unit of the title salt, C₆H₉N₂⁺·C₇H₇O₃S⁻, there are two independent 2-amino-6-methyl­pyridinium cations and two independent 4-methyl­benzene­sulfonate anions. Both cations are protonated at their pyridine N atoms and their geometries reveal amine–imine tautomerism. In the 4-methyl­benzene­sulfonate anions, the carboxyl­ate groups are twisted out of the benzene ring planes by 88.4 (1) and 86.2 (2)°. In the crystal, the sulfonate O atoms of an anion inter­act with the protonated N atoms and the 2-amino groups of a cation via a pair of N—H⋯O hydrogen bonds, forming an R₂²(8) ring motif. These motifs are connected via N—H⋯O hydrogen bonds, forming chains running along the a-axis direction. Within the chains there are weak C—H⋯O hydrogen bonds present. In addition, aromatic π–π stacking inter­actions [centroid–centroid distances = 3.771 (2), 3.599 (2), 3.599 (2) and 3.497 (2) Å] involving neighbouring chains are also observed.

2-Amino-5-nitro-pyridinium hydrogen oxalate

In the cation of the title mol­ecular salt, C₅H₆N₃O₂⁺·C₂HO₄⁻, the dihedral angle between the aromatic ring and the nitro group is 3.5 (3)°; in the anion, the dihedral angle between the CO2 and CO₂H planes is 10.5 (2)°. In the crystal, the anions are linked into [100] chains by O—H⋯O hydrogen bonds. The cations cross-link the chains by way of N—H⋯O hydrogen bonds and the structure is consolidated by C—H⋯O inter­actions.