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.     

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.     

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.     

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.     

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.     

A comparison of 2,7‐di­hydro‐2,2,7,7‐tetra­methyl‐3,6‐di­phenyl‐1,4,5‐thiadiazepine and the corresponding 1,1‐­dioxide

The structures of the highly substituted title heterocycles, C₂₀H₂₂N₂S and C₂₀H₂₂N₂O₂S, have been determined at 123 (1) K. Both mol­ecules possess exact C₂ symmetry and the seven‐membered rings have very similar twist‐boat conformations. The magnitudes of the C—S—C bond angles, 107.13 (6) and 108.27 (7)°, respectively, are influenced significantly by the four substituent methyl groups on the seven‐membered rings.     

A substituted EDOT precursor: diethyl 3,4‐di­hydroxy­thio­phene‐2,5‐di­carboxyl­ate

The title compound, C₁₀H₁₂O₆S, has been obtained as dark‐yellow chunk‐shaped crystals, together with the expected thin white needles. The structures of the two phases are identical. Two independent mol­ecules compose the asymmetric unit: one mol­ecule is totally planar, whereas a methyl group of the second mol­ecule points out of the plane. Each mol­ecule participates in several intra‐ and intermolecular hydrogen bonds and short contacts. The overall structure can be regarded as parallel sheets of mol­ecules. Within a sheet, mol­ecules are connected to one another in an infinite network via numerous short intermolecular contacts. Sheets are connected via hydrogen bonds and short contacts, in particular involving the methyl groups.     

9,10‐Di­phenyl‐9,10‐epi­dioxy­anthra­cene and 9,10‐di­hydro‐10,10‐di­methoxy‐9‐phenyl­anthracen‐9‐ol

9,10‐Di­phenyl‐9,10‐epi­dioxy­anthracene, C₂₆H₁₈O₂, (I), was accidentally used in a photo­oxy­genation reaction that produced 9,10‐di­hydro‐10,10‐di­methoxy‐9‐phenyl­anthracen‐9‐ol, C₂₂H₂₀O₃, (II). In both compounds, the phenyl rings are approximately orthogonal to the anthracene moiety. The conformation of the anthracene moiety differs as a result of substitution. Intramolecular C—H⃛O interactions in (I) form two approximately planar S(5) rings in each of the two crystallographically independent mol­ecules. The packing of (I) and (II) consists of molecular dimers stabilized by C—H⃛O interactions and of molecular chains stabilized by O—H⃛O interactions, respectively.     

Sodium pyridine‐3‐carboxyl­ate

The title compound, also known as sodium nicotinate, Na⁺·C₆H₄NO₂⁻, consists of two unique Na atoms coordinated to two unique pyridine‐3‐­carboxyl­ate ligands through the N atoms and carboxylate groups. One Na atom and one pyridine‐3‐­carboxyl­ate ligand lie on a twofold axis. Extensive Na coordination results in a three‐dimensional array comprising infinite NaO₂CR chains linked by intrachain Na—N bonds.     

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)°.     

7,8‐Di­phenyl‐9‐di­methyl­sulfido‐10,11‐μ‐hydro‐7,8‐dicarba‐nido‐undecaborane(9)

In the title compound, C₁₆H₂₅B₉S, there are two crystallographically independent mol­ecules, and the conformations of the phenyl and SMe₂ substituents indicate some intramolecular steric crowding. The bridging H atom is asymmetrically disposed. The title compound is a precursor to a crowded vertex‐labelled nido carborane ligand important in establishing the mechanism of isomerization of icosahedral heteroboranes.     

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.     

4‐Acetyl‐5‐methyl‐2‐phenyl‐1,2‐di­hydro‐3H‐pyrazol‐3‐one hydrate

The title compound, C₁₂H₁₂O₂N₂·H₂O, is described. Although the keto–enol form of the ligand in solution is known, the compound crystallized in the orthorhombic space group P2₁2₁2₁ with only the monohydrated 1,3‐diketo form. The intermolecular hydrogen bond between the imino N—H group of the ligand and O atom of the water mol­ecule recorded an H?O distance of 1.73 (3) Å.     

Hydro­gen‐bonding patterns in two structural isomers of 3,6‐bis(2‐chloro­phenyl)‐1,4‐di­hydro‐1,2,4,5‐tetrazine

Two structural isomers, 3,6‐bis(2‐chloro­phenyl)‐1,4‐di­hydro‐1,2,4,5‐tetrazine, (I), and 3,5‐bis(2‐chloro­phenyl)‐4‐amino‐1H‐1,2,4‐triazole, (II), both C₁₄H₁₀Cl₂N₄, form chain‐like structures in the solid state, stabilized by N—H⋯N and N—H⋯Cl hydrogen bonds. A contribution from weak interactions to the strong hydrogen‐bond network is observed in both structures. The secondary graph sets for intermolecular hydrogen bonds [(11) for (I) and (12) for (II)] indicate the similarity between the networks.     

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 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.     

cis,cis,cis‐Tetra­methyl 1,2,4,5‐cyclo­hexane­tetra­carboxyl­ate

The title compound, C₁₄H₂₀O₈, was synthesized from the hydrogenation of tetra­methyl 1,4‐cyclo­hexa­diene‐1,2,4,5‐tetra­carboxyl­ate with a catalytic amount of palladium/carbon. All four carbonyl moieties of the methyl ester groups are on the same face of the chair‐conformed ring. The substantial ring distortion associated with the 1,3‐diaxial methoxycarbonyl substituents is reflected in the large difference between bond angles as well as torsion angles, respectively, that in undistorted cyclo­hexanes would be approximately the same.     

cis‐Bis(3,6‐di­hydro‐2H‐1,2‐oxazine‐N)­di­iodo­platinum(II) and cis‐bis(3,4,5,6‐tetra­hydro‐2H‐1,2‐oxazine‐N)­di­iodo­platinum(II)

The title complexes, [Pt(C₄H₇NO)₂I₂], (I), and [Pt(C₄H₉NO)₂I₂], (II), possess similar square‐planar coordination geometries with modest distortions from ideality. For (I), the cis‐L—Pt—L angles are in the range 87.0 (4)–94.2 (3)°, while the trans angles are 174.4 (3) and 176.4 (3)°. For (II), cis‐L—Pt—L are 86.1 (8)–94.2 (6)° and trans‐L—Pt—L are 174.4 (6) and 177.4 (5)°. One 3,6‐di­hydro‐2H‐1,2‐oxazine ligand in (I) is rotated so that the N—O bond is out of the square plane by approximately 70°, while the N—C bond is only ca 20° out of the plane. The other oxazine ligand is rotated so that the N—C bond is about 80° out of the plane, while the N—O bond is out of the plane by approximately 24°. In (II), the 3,4,5,6‐tetra­hydro‐2H‐1,2‐oxazine ligands are also positioned with one having the N—O bond further out of the plane and the other having the N—C bond positioned in that fashion. Both ligands, however, are rotated approximately 90° compared with their positions in (I). In both complexes, this results in an unsymmetrical distortion of the I—Pt—N bond angles in which one is expanded and the other contracted. These features are compared to those of reported cis‐di­amine­di­iodo­platinum(II) complexes.     

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.     

3‐Acetoxy­cyclo­hex‐4‐ene‐1,2‐di­carboxyl­ic anhydride

The title compound, C₁₀H₁₀O₅, was found to exist as the endo–cis isomer with a pair of enantiomers in the asymmetric unit. The cyclo­hexene ring is folded about the methyl­ene‐to‐CH(acetoxy) vector to give a boat conformation.