Polymorphism in bipodal O,O′‐dimeth­yl N,N′‐(m‐phenyl­ene­di­carbonyl)bis(thio­carbamate)

The title compound, C₁₂H₁₂N₂O₄S₂, crystallizes in white and yellow polymeric forms as a result of inter­esting anti–anti and syn–anti conformational isomerism of the thio­carbon­yl and carbon­yl moieties relative to one another. This work is the first reported X‐ray crystallographic structure determination of isomers of this class of bipodal ligand. The white form, anti–anti, (I), crystallizes with the benzene ring lying about a twofold rotation axis, resulting in both of the thio­carbon­yl and carbon­yl moieties being anti relative to each other. The yellow modification crystallizes as syn–anti, (II), with one thio­carbon­yl moiety syn and the other anti relative to the respective carbon­yl groups. The individual mol­ecules of both (I) and (II) are extensively linked through inter­molecular hydrogen bonds. Inter­molecular hydrogen bonding in (II) includes a network of bifurcated N—H⋯O and N—H⋯S hydrogen bonds, while mol­ecules of (I) include bifurcated C—H⋯O hydrogen bonds.     

4‐(4‐Chloro­phen­yl)‐3‐(4‐phenyl­pent‐4‐en­yloxy)‐1,3‐thia­zole‐2(3H)‐thione

The title compound, C₂₀H₁₈ClNOS₂, is a thia­zole‐derived thio­hydroxamic acid O‐ester. The value of Z′ is 3 and the asymmetric unit comprises three mol­ecules of identical helicity along the N—O bond. Two of these show an anti and the third a syn arrangement of substituents attached in positions 3 and 4 to the 1,3‐thia­zole nucleus.     

5‐Acetyl‐2‐amino‐6‐methyl‐4‐phenyl‐4H‐pyran‐3‐carbonitrile and 2‐amino‐5‐benzoyl‐6‐methyl‐4‐phenyl‐4H‐pyran‐3‐carbonitrile acetonitrile solvate

The syntheses, X‐ray structural investigations and calculations of the conformational preferences of the carbonyl substituent with respect to the pyran ring have been carried out for the two title compounds, viz. C₁₅H₁₄N₂O₂, (II), and C₂₀H₁₆N₂O₂·C₂H₃N, (III), respectively. In both mol­ecules, the heterocyclic ring adopts a flattened boat conformation. In (II), the carbonyl group and a double bond of the heterocyclic ring are syn, but in (III) they are anti. The carbonyl group forms a short contact with a methyl group H atom in (II). The dihedral angles between the pseudo‐axial phenyl substituent and the flat part of the pyran ring are 92.7 (1) and 93.2 (1)° in (II) and (III), respectively. In the crystal structure of (II), inter­molecular N—H⋯N and N—H⋯O hydrogen bonds link the mol­ecules into a sheet along the (103) plane, while in (III), they link the mol­ecules into ribbons along the a axis.     

2,3,4,5,6‐Penta­nitro­aniline 1,2‐dichloro­ethane disolvate: `push–pull' deformation of aromatic rings by intra­molecular charge transfer

The title compound, C₆H₂N₆O₁₀·2C₂H₄Cl₂, forms layered stacks of penta­nitro­aniline mol­ecules, which possess twofold symmetry. The voids between these stacks are occupied by dichloro­ethane mol­ecules, which reside near a 2/m symmetry element and display pseudo‐inversion symmetry. The C atoms in one of the two solvent mol­ecules are threefold disordered. In the penta­nitro­aniline mol­ecule, considerable distortion of the benzenoid ring, coupled with the short C—N(H₂) bond and out‐of‐plane NO₂ twistings, point to significant intra­molecular `push–pull' charge transfer at the amino‐ and nitro‐substituted (ortho and para) positions, as theoretically quantified by natural bond orbital analysis of the π‐electron density.     

3,4‐Di­hydro‐6‐methyl‐3‐β‐d‐ribo­furan­osyl‐4,5′‐cyclo‐9H‐imidazo[1,2‐a]­purin‐9‐one hydrate

In the title compound, C₁₃H₁₃N₅O₄·H₂O (4,5′‐cyclo­wyosine·H₂O), the cyclization forces a syn arrangement of the aglycon with respect to the sugar moiety. The ribo­furan­ose part of the mol­ecule displays a β‐d configuration with an envelope C1′‐endo pucker. The mol­ecules are arranged in columns along the short a axis and are linked to water mol­ecules through O—H?O and O—H?N hydrogen bonds.     

Supramolecular structures of 5‐[3‐(4‐methyl­phenyl)‐ and 5‐[3‐(4‐chloro­phenyl)‐2‐propenyl­idene]‐2,2‐di­methyl‐1,3‐dioxane‐4,6‐dione

2,2‐Di­methyl‐5‐[3‐(4‐methyl­phenyl)‐2‐propenyl­idene]‐1,3‐di­ox­ane‐4,6‐dione, C₁₆H₁₆O₄, crystallizes in the triclinic space group , with two mol­ecules in the asymmetric unit. These mol­ecules and a centrosymmetrically related pair, linked together by weak C—H?O hydrogen bonds, form a tetramer. 5‐[3‐(4‐Chloro­phenyl)‐2‐propenyl­idene]‐2,2‐di­methyl‐1,3‐dioxane‐4,6‐dione, C₁₅H₁₃ClO₄, also crystallizes in the triclinic space group , with one mol­ecule in the asymmetric unit. Centrosymmetrically related mol­ecules are linked together by weak C—H?O hydrogen bonds to form dimers which are further linked by yet another pair of centrosymmetrically related C—H?O hydrogen bonds to form a tube which runs parallel to the a axis.     

9(R)‐[6(R)‐Hydroxy­methyl‐1‐oxa‐4‐thia­cyclo­hexan‐2‐yl]hypoxanthine–water (4/3), a nucleoside analogue

The title compound, 9(R)‐[6(R)‐hydroxy­methyl‐1‐oxa‐4‐thia­cyclo­hexan‐2‐yl]‐1,9‐di­hydro‐6H‐purin‐6‐one–water (4/3), C₁₀H₁₂N₄O₃S·0.75H₂O, crystallizes in the triclinic space group P1 with four mol­ecules in the asymmetric unit and 0.75 waters of hydration per mol­ecule. The structure was refined to an R value of 0.072 for 3382 observed reflections. The four crystallographically independent mol­ecules are designated A, B, C and D. All four oxa­thia­ne rings adopt the chair conformation and the purine bases are in an anti orientation with respect to the sugar moieties. Molecules A and D and mol­ecules C and B are base paired by a single hydrogen bond of the type N—H?N. These base pairs are again hydrogen bonded to their translated pairs in the direction of a cell diagonal.     

Bis(1‐ferrocenylbutane‐1,3‐dionato‐κ2O,O′)copper(II) and bis­(1,3‐diferrocenylpropane‐1,3‐dionato‐κ2O,O′)­copper(II)

The title compounds, [CuFe₂(C₅H₅)₂(C₉H₈O₂)₂], (I), and [CuFe₄(C₅H₅)₄(C₁₃H₉O₂)₂], (II), are four‐coordinate square‐planar copper(II) complexes with two bidentate 1‐ferrocenylbutane‐1,3‐dionate or 1,3‐diferrocenylpropane‐1,3‐dionate ligands, respectively. The copper ion in (I) lies on an inversion centre, with one‐half of the mol­ecule in the asymmetric unit, while in (II), there are two independent half mol­ecules in the asymmetric unit, with the copper ions also situated on inversion centres. The ferrocene substituents in (I) are in an anti arrangement. The mol­ecules assemble in the crystal structure in layers with ferrocene groups at the surface. The pairs of ferrocene substituents on each ligand in complex (II) are syn and these adopt an anti arrangement with respect to the pair on the other diketonate ligand. As found in (I), complexes assemble in a layered structure with ferrocene‐coated surfaces.     

Tetrakis(2,2′‐bipyridine‐κ2N,N′)­tetrakis(μ‐salicyl­ato‐κ3O,O′:O′′)‐quadro‐tetrazinc(II) decahydrate

The title compound, [Zn₄(C₇H₄O₃)₄(C₁₀H₈N₂)₄]·10H₂O, crystallizes as a centrosymmetric tetranuclear cyclic complex containing four Zn^II atoms bridged by four carboxyl­ate groups from salicyl­ate ligands, with a syn–anti configuration. Each Zn^II atom has a distorted trigonal–bipyramidal coordination geometry, formed by two N atoms of a 2,2′‐bipyridine ligand and three O atoms from two salicyl­ate ligands. The complex is stabilized by intramolecular π–π interactions between pairs of bi­pyridine rings and a 16‐membered gear‐wheel‐shaped cyclic framework. The hydrogen‐bonding network is formed via the water mol­ecules.     

2′‐De­oxy‐5‐propynyl­cytidine: a nucleoside forming two solid‐state conformations

The title compound, 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythropentofuranosyl)‐5‐(prop‐1‐ynyl)pyrimidin‐2(1H)‐one, C₁₂H₁₅N₃O₄, shows two conformations in the crystalline state which differ mainly in the glycosylic bond torsion angle and the sugar pucker. Both mol­ecules exhibit an anti glycosylic bond conformation, with torsion angles χ = −135.0 (2) and −156.4 (2)° for mol­ecules 1 and 2, respectively. The sugar moieties show a twisted C2′‐endo sugar pucker (S‐type), with P = 173.3 and 192.5° for mol­ecules 1 and 2, respectively. The crystal structure is characterized by a three‐dimensional network that is stabilized by several inter­molecular hydrogen bonds between the two conformers.     

1‐Benzyl‐3,3‐dichloro‐1H‐indol‐2(3H)‐one

The title compound, C₁₅H₁₁Cl₂NO, was synthesized from N‐­benzyl­isatin. The compound crystallizes as stacks of mol­ecules running down the c axis. Mol­ecules within each of these stacks inter­act with each other through π–π and C—H⋯π inter­actions, and inter­act with neighbouring stacks through C—H⋯O inter­actions.     

A series of three bis­[2‐(methyl/tri­fluoro­methyl)‐4H‐3,1‐benzoxazin‐4‐one] compounds

Each of the three title compounds, namely 6,6′‐methyl­ene­bis­(2‐methyl‐4H‐3,1‐benz­oxazin‐4‐one), C₁₉H₁₄N₂O₄, 6,6′‐methyl­ene­bis­(2‐tri­fluoro­methyl‐4H‐3,1‐benz­oxazin‐4‐one), C₁₉H₈F₃N₂O₄, and 6,6′‐bi­(2‐tri­fluoro­methyl‐4H‐3,1‐benz­oxazin‐4‐one), C₁₈H₆F₆N₂O₄, contains two planar benz­ox­azin­one fragments. In the first two compounds, these planes are virtually perpendicular to each other, while the third compound is planar overall. The electronic effects of the substituent groups on the oxazine moiety result in distortion of the bond angles at the C atoms of the C=O and C=N bonds, and in redistribution of electronic density in the oxazine rings. The latter leads to different bond lengths within this ring in the three mol­ecules. All the mol­ecules form stacks in their crystals with distances of 3.2–3.6 Å between adjacent mol­ecules in a stack.     

1‐Methyl‐5,6,7,8‐tetra­hydro­quin­ox­alin‐2(1H)‐one

The title compound, C₉H₁₂N₂O, crystallizes in a triclinic unit cell, with two crystallographically independent mol­ecules in the asymmetric unit. The two independent mol­ecules adopt different modes of packing. One type of mol­ecule is arranged in infinite columns, while the other type packs as dimers, forming spacers between the parallel columns. Each type of mol­ecule is arranged in pairs related by inversion centers. The distances between potential reaction centers are 3.395 (2), 3.457 (2) and 3.522 (2) Å. As a result of the symmetry of the pairs and the close distances between the potential photoreactive centers, it is expected that the dimer will be the anti–trans isomer.     

2,2′‐Methyl­enebis(3‐hydroxy‐2‐cyclo­hexen‐1‐one)

In the title compound, C₁₃H₁₆O₄, the cyclo­hexene rings adopt a sofa conformation. Adjacent mol­ecules are connected by C—H?O intermolecular interactions. Each mol­ecule is characterized by O—H?O intramolecular hydrogen bonds. The anti arrangement of the enolic OH group and the carbonyl O atom in the solid state is similar to the anti arrangement of the NH and carbonyl groups in indigo.     

rac‐(Z)‐Ethyl 2‐bromo‐2‐[(3R,5R)‐3‐bromo‐5‐methyl­tetra­hydro­furan‐2‐yl­idene]acetate

In the title compound, C₉H₁₂Br₂O₃, a (tetra­hydro­furan‐2‐yl­idene)acetate, the double bond has the Z form. In the tetra­hydro­furan group, the relative configuration of the Br atom in the 3‐position and the methyl group in the 5‐position is anti. The compound crystallizes with two independent mol­ecules per asymmetric unit and, in the crystal structure, the individual mol­ecules are linked to their symmetry‐equivalent mol­ecules by C—H⋯O hydrogen bonds, so forming centrosymmetric hydrogen‐bonded dimers.     

3,3′‐Dihydr­oxy‐5,5,5′,5′‐tetra­methyl‐2,2′‐thio­dicyclo­hex‐2‐en‐1‐one

Mol­ecules of the title compound, C₁₆H₂₂O₄S, have twofold crystallographic symmetry and are stabilized by strong intra­molecular O—H⋯O hydrogen bonds and very weak inter­molecular C—H⋯O hydrogen bonds, forming layers normal to the c axis. The mol­ecular structure is compared with those of the Se‐ and CH₂‐bridged analogues.     

1,2,3‐Trimethoxy‐5,11‐dihydro­indolo[1,2‐b]isoquinoline‐5,11‐dione

The title compound, C₁₅H₁₉NO₅, crystallizes in the monoclinic space group P2₁/c with four mol­ecules in the asymmetric unit, which differ from each other in the orientation of their methoxy groups. Of the three methoxy groups in each molecule, one lies close to the plane of the mol­ecule and the other two have an out‐of‐plane conformation where they point in opposite directions. In the crystal structure, four different types of π‐stacks are observed and the mol­ecules pack in two different types of stacking sheets, with alternating mol­ecules A and B in one ribbon and alternating mol­ecules C and D in the other. The supramolecular structure is supported by C—H⋯O and π–π inter­actions.     

Ethyl 3,5‐dimethyl‐4‐phenyl‐1H‐pyrrole‐2‐carboxylate

In the title compound, C₁₅H₁₇NO₂, the ethoxy­carbonyl group is anti with respect to the pyrrole N atom. The angle between the planes of the phenyl and pyrrole rings is 48.26 (9)°. The mol­ecules are joined into dimeric units by a strong hydrogen bonds between pyrrole N—H groups and carbonyl O atoms. The geometry of the isolated mol­ecule was studied by ab initio quantum mechanical calculations, employing both molecular orbital Hartree–Fock (MO–HF) and density functional theory (DFT) methods. The minimum energy was achieved for a conformation where the angle between the planes of the phenyl and pyrrole rings is larger, and that between the ethoxy­carbonyl and pyrrole planes is smaller than in the solid‐state mol­ecule.     

N‐Propionyl‐1,2‐benzisoselenazol‐3(2H)‐one

The title compound, C₁₀H₉NO₂Se, crystallizes as flat mol­ecules linked by selenium–oxy­gen interactions [Se?O = 3.189 (4) Å] into a linear chain along the a axis of the triclinic cell. The bond dimensions that are derived from ab initio geometry optimization calculations are similar to those determined from the diffraction measurements.     

N,N′‐Di­methyl‐1,4‐dithiine‐1,2:4,5‐tetracarbox­imide and N,N′‐di­methyl‐1,4‐diselenine‐1,2:4,5‐tetracarbox­imide

The title compounds of sulfur, C₁₀H₆N₂O₄S₂, (I), and selenium, C₁₀H₆N₂O₄Se₂, (II), are isomorphous. The crystallographically centrosymmetric mol­ecules are planar. The bond distances and angles, except for those involving the S and Se atoms, are comparable. The mol­ecules are disposed in layers parallel to the bc plane. The molecular axes differ by 75° for (I) and by 80° for (II) from one layer to the next.