2‐Ethyl­phenyl acridine‐9‐carboxyl­ate and 2,5‐dimethyl­phenyl acridine‐9‐carboxyl­ate

The title compounds, 2‐ethyl­phenyl acridine‐9‐carboxyl­ate, C₂₂H₁₇NO₂, (I), and 2,5‐dimethyl­phenyl acridine‐9‐carboxyl­ate, C₂₂H₁₇NO₂, (II), form triclinic and monoclinic crystals, respectively. Related by a centre of symmetry, adjacent molecules of (I) are linked in the lattice via a network of C—H·π and non‐specific dispersive interactions. As a result, acridine moieties and independent phenyl moieties of (I) are parallel in the lattice. The molecules of (II), arranged in a `head‐to‐tail' manner and related by a centre of symmetry, form pairs stabilized via C—H·π interactions. These are linked in the crystal via dispersive interactions. Acridine and independent phenyl moieties lie parallel within the pairs, while adjacent pairs are perpendicular, forming a herring‐bone pattern.     

Form II of monoclinic methyl β‐carboline‐3‐carboxyl­ate

The crystal structure of the second monoclinic P2₁/c form of the β‐carboline‐3‐carboxyl­ate, C₁₃H₁₀N₂O₂, has been determined. Very small changes in the packing scheme lead to a different unit cell; the role of weak C—H?O hydrogen bonds seems to be crucial.     

2,6‐Di­phenyl­pyridine‐4‐carboxyl­ic acid

The distinctive feature of the crystal structure of 2,6‐di­phenyl­pyridine‐4‐carboxyl­ic acid, C₁₈H₁₃NO₂, is the formation of intermolecular O—H?O hydrogen bonds that lead to the formation of centrosymmetric cyclic dimers with R(8) topology. Molecules related by translation along the b axis exhibit strong π–π stacking of aromatic rings, with an average interplanar distance of 3.3 Å.     

tert‐Butyl 5‐methoxy‐3‐pentyl­indole‐1‐carboxyl­ate

The molecule of the title compound, C₁₉H₂₇NO₃, is essentially planar, with all non‐H atoms within 0.2 Å of the nine‐membered indole plane, except for the three tert‐butyl C atoms. The C₅ pentyl chain is in an extended conformation, with three torsion angles of 179.95 (13), 179.65 (13) and −178.95 (15)° (the latter two angles include the C atoms of the C₅ chain only). Three intramolecular C—H⋯Ozdbnd;C contacts are present (C⋯O < 3.05 Å and C—H⋯O > 115°), and an intermolecular C—H⋯Ozdbnd;C contact and π–π stacking complete the intermolecular interactions.     

Tetra­ammonium benzene‐1,2,4,5‐tetra­carboxyl­ate tetrahydrate

The anions in the title compound, 4NH₄⁺·C₁₀H₂O₈^4?·4H₂O, are held together by regular hydrogen bonds from the carboxyl­ate O atoms to the ammonium cations and water mol­ecules, forming a three‐dimensional network.     

Benzyl 5‐carboxy‐4‐ethyl‐3‐methyl­pyrrole‐2‐carboxyl­ate

In the title compound, C₁₆H₁₇NO₄, the benzyl­oxy­carbonyl group is anti to the pyrrolic N atom. The mol­ecules are joined into head‐to‐head dimers by hydrogen bonds involving the carboxyl­ic acid groups. There is orientational disorder of these groups over two positions with approximately equal occupancy. A weaker hydrogen bond between the pyrrolic N atom and the carbonyl O atom of the benzyl­oxy­carbonyl group joins the dimers into chains running parallel to the [110] direction.     

3‐Methyl 5‐isopropyl 2‐methoxy­imino­methyl‐6‐methyl‐4‐(3‐nitro­phenyl)‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate

The crystal structure of the title compound, C₂₀H₂₃N₃O₇, consists of relatively isolated mol­ecules. The substituted 1,4‐di­hydro­pyridine ring adopts a flattened boat conformation. Both ester groups, at positions 3 and 5, have cis,cis geometry. The phenyl ring is nearly planar and is approximately perpendicular to the 1,4‐di­hydro­pyridine ring (dihedral angle 87.70°).     

Three methoxy‐substituted diethyl 4‐­phenyl‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate compounds

Diethyl 4‐(2,5‐di­methoxy­phenyl)‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₁H₂₇NO₆, (I), diethyl 4‐(3,4‐di­methoxy­phenyl)‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₁H₂₇NO₆, (II), and diethyl 2,6‐di­methyl‐4‐(3,4,5‐tri­methoxy­phenyl)‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₂H₂₉NO₇, (III), crystallize with hydrogen‐bonding networks involving the H atom bonded to the N atom of the 1,4‐di­hydro­pyridine ring and carbonyl O atoms in (I) and (II). Unusually, (III) shows O atoms of methoxy groups serving as hydrogen‐bond acceptors.     

Ethyl 6‐amino‐2‐methoxypyridine‐3‐carboxyl­ate,interplay of molecular and supramolecular structure

The title compound, C₉H₁₂N₂O₃, crystallizes with two mol­ecules in the asymmetric unit. There is extensive hydrogen bonding which results in the formation of a two‐dimensional corrugated sheet. This supramolecular structure is determined by the formation of hydrogen‐bonded chains resulting from the presence of a 6‐amino group and an ethoxy­carbonyl group as substituents on a pyridine ring in relative para positions which constitute a π‐electron `push–pull' system.     

Sodium di­hydrogen tris­(cyclo­propane­carboxyl­ate)

The title acid salt, Na⁺·C₄H₅O₂^?·2C₄H₆O₂, contains finite anions in which two cyclo­propanoic acid mol­ecules are hydrogen bonded to a cyclo­propanoate residue. Each such anion interacts with four different Na⁺ cations.     

Di­methyl 9,10‐anthracenedi­carboxyl­ate: a centrosymmetric transoid molecule

In the crystal structure of the title compound, C₁₈H₁₄O₄, there are two independent mol­ecules, both of which are exactly centrosymmetric and therefore have a transoid arrangement of the ester substituents. The planes of these are inclined at 63.90 (4) and 61.02 (5)° to the anthracene central ring in the two mol­ecules because of steric interactions, preventing electronic delocalization. The observed conformation is in agreement with molecular‐modelling calculations for the isolated mol­ecule, indicating no major influence from crystal‐packing forces.     

Diethyl 1‐(4‐fluoro­phenyl)‐3‐(2‐furyl)‐5‐oxopyrrolidine‐2,2‐di­carboxyl­ate and diethyl 1‐(3,4‐di­chloro­phenyl)‐3‐(2‐furyl)‐5‐oxopyrrolidine‐2,2‐di­carboxyl­ate

The title compounds, C₂₀H₂₀FNO₆ and C₂₀H₁₉Cl₂NO₆, respectively, may exhibit bioactivity. In these compounds, the pyrrolidine ring adopts a conformation intermediate between envelope and half‐chair. Only one of the two ethoxy­carbonyl side chains is nearly planar. Centrosymmetric pairs are formed, and the crystal structure is stabilized by weak C—H⋯O hydrogen bonds and van der Waals interactions.     

Methyl 3‐para‐anisyl‐4‐(2‐hydroxy­benzoyl)­isoxazole‐5‐carboxyl­ate

The title compound, C₁₉H₁₅NO₆, contains a planar isoxazole ring. An intramolecular hydrogen bond is formed between the OH group attached to a phenyl ring and a carbonyl O atom.     

Polymeric μ‐bromo‐μ‐pyridine‐3‐carboxyl­ato‐κ3O,O′:N‐mercury(II)

The asymmetric unit of the title polymeric complex, [HgBr(C₆H₄NO₂)]_n or HgBr(nic), contains mercury coordinated via two Br atoms [Hg—Br = 2.6528 (9) and 2.6468 (9) Å], two carboxyl­ate O atoms, which form a characteristic four‐membered chelate ring [Hg—O = 2.353 (6) and 2.478 (7) Å], and an N atom [Hg—N = 2.265 (5) Å], in the form of a very irregular (3+2)‐coordination polyhedron. The pronounced irregularity of the effective Hg (3+2)‐coordination is a result of the rigid stereochemistry of the nicotinate ligand. According to the covalent and van der Waals radii criteria, the strongest bonds are Hg—Br and Hg—N. These covalent interactions form a two‐dimensional poly­mer. The puckered planes are connected by van der Waals interactions, and there are only two intermolecular C—H⋯O hydrogen bonds [3.428 (10) and 3.170 (10) Å].     

Ethyl 2‐amino‐4‐phenyl‐1,3‐thia­zole‐5‐carboxyl­ate

The structure of the title compound, C₁₂H₁₂N₂O₂S, (I), comprises mol­ecules that form dimers via N—H?N hydrogen‐bonding interactions and then construct the overall network through N—H?O associations. The dihedral angle between the phenyl and thia­zole rings is 42.41 (6)°.     

Chloro­(μ‐6‐methyl­pyridine‐2‐carboxyl­ato)bis­(6‐methyl­pyridine‐2‐carboxyl­ato)triphenyl­chromium(III)­tin(IV) chloro­triphenyl­tin(IV)

The title compound, [CrSn(C₆H₅)₃(C₇H₆NO₂)₃Cl][Sn(C₆H₅)₃Cl(CH₄O)], was obtained from the reaction of Ph₃SnCl with the complex [Cr(C₇H₆NO₂)₃] in methanol. The structure contains [Ph₃SnCl(MeOH)] (A) and [Ph₃SnClCr(C₇H₆NO₂)₃] (B) mol­ecules. In mol­ecule A, the Sn atom of Ph₃SnCl is coordinated by one methanol mol­ecule. In mol­ecule B, the Sn atom of Ph₃SnCl is coordinated by one carboxyl­ate O atom of [Cr(C₇H₆NO₂)₃]. Mol­ecules A and B are connected through an O—H⋯O hydrogen bond between a carboxyl­ate O atom and the methanol OH group. Weak C—H⋯Cl inter­actions and O—H⋯O hydrogen bonds extend the components of (I) into a two‐dimensional network.     

Ferrocene compounds. XXXVIII. Di­methyl ferrocene‐1,1′‐di­carboxyl­ate

In the title compound, [Fe(C₇H₇O₂)₂], the cyclo­penta­dienyl rings and the two attached methoxy­carbonyl groups, in an anti arrangement, form an extended π‐conjugated system. The Fe—C distances range from 2.035 (3) to 2.061 (3) Å and the average value of the C—C bond lengths in the two cyclo­penta­dienyl rings is 1.419 (5) Å. The rings are almost parallel to one another [1.0 (2)°] and are mutually twisted from an eclipsed conformation by only 1.8 (3)° (average value). The methoxy­carbonyl groups are twisted out of the plane of the cyclo­penta­dienyl rings by 6.5 (4) and 15.7 (4)°, respectively. The mol­ecules are joined into dimers by intermolecular C—H⃛O hydrogen bonds that form ten‐membered rings. The same types of hydrogen bonds form eight‐membered rings and infinite chains along the b axis.     

2‐Amino‐1,3‐benzo­thia­zole–ethyl coumarin‐3‐carboxyl­ate (1/1)

The title adduct, C₇H₆N₂S·C₁₂H₁₀O₄, is formed via N—H⋯O and N—H⋯N hydrogen‐bonding interactions, which gener­ate a tetrameric unit with a pseudo‐centre of symmetry. The tetramer further packs through parallel‐displaced π–π stacking interactions along the a direction.     

Diethyl 4‐(2,5‐di­methoxy­phenyl)‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate,conformational change with solvent of crystallization

The title compound, C₂₁H₂₇NO₆, has been crystallized from ethanol containing nitro­benzene and shows the phenyl ring, B, in an ap conformation. This structure may be compared with that of the mol­ecule crystallized from ethanol alone, in which the B ring is seen in an sp conformation. The isolation of this rotamer has implications for the understanding of the docking of calcium beta‐blocking di­hydro­pyridine mol­ecules with their receptor site.     

Diethyl 9,10‐di­hydro‐9,10‐ethano­anthracene‐11,12‐trans‐di­carboxyl­ate

The title compound, C₂₂H₂₂O₄, is the product of the Diels–Alder reaction of anthracene with fumaric acid diethyl ester. The molecular C₂ symmetry is nearly fulfilled in the crystal. Only the terminal torsion angles about the O—CH₂ groups show significant differences.