7‐Vinyl‐8‐aza‐7‐de­aza‐2′‐deoxy­adenosine monohydrate

In the title compound, 4‐amino‐1‐(2‐deoxy‐β‐d ‐eythro‐pento­furan­osyl)‐3‐vinyl‐1H‐pyrazolo­[3,4‐d]­pyrimidine monohydrate, C₁₂H₁₅N₅O₃·H₂O, the conformation of the gly­cosyl bond is anti. The furan­ose moiety is in an S conformation with an unsymmetrical twist, and the conformation at the exocyclic C—C(OH) bond is +sc (gauche, gauche). The vinyl side chain is bent out of the heterocyclic ring plane by 147.5 (5)°. The three‐dimensional packing is stabilized by O—H·O, O—H·N and N—H·O hydrogen bonds.     

2,5‐Dichloro‐2,5‐dihydro­thio­phene 1‐oxide: determinaton of the complete stereochemistry

The title five‐membered heterocycle, C₄H₄Cl₂OS, adopts an envelope conformation with the S atom at the tip of the flap. All three ring substituents, viz. the sulfoxide O atom and the two Cl atoms, are cis to each other. The two C atoms α to the sulfoxide group are also bonded to chlorine. The electron‐withdrawing chlorine substituents give rise to weak C—H·O hydrogen bonds with the sulfoxide O atom of a symmetry‐related mol­ecule [H·O = 2.44 (2) and 2.61 (2) Å, C·O = 3.143 (3) and 3.302 (2) Å and C—H·O = 129.9 (19) and 135.1 (19)°]. There is also a possible weak C—H·Cl inter­action. Chains of mol­ecules held together by these weak inter­actions run parallel to the a axis.     

2,6‐Dimethyl‐1,4‐benzoquinone 4‐monooxime

Mol­ecules of the title compound, C₈H₉NO₂, are linked into sheets by a combination of C—H·N, O—H·N and O—H·O hydrogen bonds and C—H·π inter­actions. The hydrogen bonds are arranged as described by the graph‐set ring notations R₂²(7) and R₃³(5), and a C8 chain motif. There are two planar symmetry‐independent mol­ecules in the asymmetric unit, with a dihedral angle of 19.24 (5)° between their least‐squares mean planes.     

2‐Amino‐5‐methyl­pyridinium (2‐amino‐5‐methyl­pyridine)trichloro­zincate(II)

The title compound, (C₆H₉N₂)[ZnCl₃(C₆H₈N₂)], consists of one 2‐amino‐5‐methyl­pyridinium cation and one (2‐amino‐5‐methyl­pyridine)trichloro­zincate(II) anion, which are held together by N—H·Cl hydrogen bonds and π–π inter­actions. The cation and the pyridine ligand show similar geometric features, except for the N—C bond lengths. Mol­ecules of the title compound are connected by N—H·Cl hydrogen bonds to form chiral chains; these chains are associated further by C—H·Cl hydrogen bonds to form layers, which are in turn linked by π–π inter­actions.     

Charge‐assisted N—H·I and C—H·I hydrogen bonding in (1R,2S)‐1‐(ferrocenylmethyl)‐2‐(methoxymethyl)pyrrolidinium iodide

In the title compound, [Fe(C₅H₅)(C₁₂H₁₉NO)]I, the ferrocene moiety has an eclipsed conformation, with mean Fe—C bond lengths of 2.031 (4) and 2.020 (6) Å for the substituted and unsubstituted cyclo­penta­dienyl rings. The pyrrolidinium heterocycle adopts an envelope conformation and has its 1‐ and 2‐substituents in a relative trans disposition. Strong (+/−)‐charge‐assisted N—H·I and C—H·I hydrogen bonds are present. The crystal structure is also stabilized by weak C—H·O interactions.     

Packing effects in 4,4′‐bis(4‐hydroxy­butyl)‐2,2′‐bi­pyridine and 4,4′‐bis(4‐bromo­butyl)‐2,2′‐bi­pyridine

Structure analyses of 4,4′‐bis(4‐hydroxy­butyl)‐2,2′‐bi­pyridine, C₁₈H₂₄N₂O₂, (I), and 4,4′‐bis(4‐bromo­butyl)‐2,2′‐bi­pyridine, C₁₈H₂₂Br₂N₂, (II), reveal intermolecular hydrogen bonding in both compounds. For (I), O—H·N intermolecular hydrogen bonding leads to the formation of an infinite two‐dimensional polymer, and π stacking interactions are also observed. For (II), C—H·N intermolecular hydrogen bonding leads to the formation of a zigzag polymer. The two compounds crystallize in different crystal systems, but both mol­ecules possess C_i symmetry, with one half mol­ecule in the asymmetric unit.     

N‐Cinnamo­ylsaccharin

The title compound [systematic name: 2‐cinnamoyl‐1,2‐benzisothiazol‐3(2H)‐one 1,1‐dioxide], C₁₆H₁₁NO₄S, contains both saccharin and cinnamo­yl groups. The mol­ecule is approximately planar in the solid state, and adjacent mol­ecules are connected by C—H·O and C—H·π(phen­yl) inter­actions. In the C—H·π inter­action, the C·CgA distance is 3.916 (4) Å (CgA is the non‐fused benzene ring centroid) and the C—H·π angle is 156 (2)°. A feature of the mol­ecular geometry is the narrow C—S—N angle of 92.51 (9)° in the five‐membered ring. This angle relieves strain from the ring and makes it possible for the whole saccharin group to become quite planar.     

4′‐Hydro­xy­bi­phenyl‐4‐carbo­nitrile

The title compound, C₁₃H₉NO, crystallizes with four mol­ecules in the asymmetric unit. Each of the four crystallographically independent mol­ecules forms a chain parallel to the a axis with symmetry‐equivalent mol­ecules. These chains are held together by similar O—H·NC hydrogen bonds, with approximately linear O—H·N angles and significantly bent H·N—C angles. The four different mol­ecules are related by strong elements of pseudosymmetry. To better describe the pseudosymmetry, the structure has been reported in the non‐standard space group .     

(E,E)‐2,5‐Di­methoxy‐1,4‐bis­[2‐(3,4,5‐tri­methoxy­phenyl)­ethenyl]­benzene

In the title compound, C₃₀H₃₄O₈, molecular symmetry is coincident with crystallographic inversion symmetry. A three‐dimensional network is generated containing both C—H·π and C—H·n(O) interactions. A comparison of the geometry of this mol­ecule and the structure of a number of 2,4,6‐tri­methoxy‐substituted analogues is provided.     

Two (+)‐α,4‐dimethyl‐2‐oxocyclo­hexaneacetic acids: hydrogen bonding in a terpenoid γ‐keto acid and in a diastereomeric lactol

The (+)‐(αS,1S,4R)‐diastereomer of the title structure, C₁₀H₁₆O₃, aggregates in the solid as non‐symmetric dimers with disorder in both carboxyl groups [O·O = 2.710 (5) and 2.638 (5) Å]. The two mol­ecules constituting the asymmetric unit pair around a pseudo‐twofold rotational axis and differ only slightly in their distances and angles, but one methyl group displays rotational disorder absent in the other mol­ecule. Five inter­molecular C—H·O close contacts exist, involving both ketone groups. The (+)‐(αR,1R,4R)‐diastereomer exists in the crystal in its closed‐ring lactol form, (3R,3aR,6R,7aR)‐2,3,3a,4,5,6,7,7a‐octa­hydro‐7a‐hydroxy‐3,6‐dimethyl­benzo[b]furan‐2‐one, C₁₀H₁₆O₃, and aggregates as hydrogen‐bonded catemers that extend from the hydroxyl group of one mol­ecule to the carbonyl group of a neighbor screw‐related along b [O·O = 2.830 (3) Å and O—H·O = 169°]. One close inter­molecular C—H·O contact exists involving the carbonyl group.     

8‐Aza‐7‐deaza‐7‐propynyladenosine methanol solvate

In the title compound, 4‐amino‐3‐propynyl‐1‐(β‐d ‐ribofur­anosyl)‐1H‐pyrazolo[3,4‐d]pyrimidine methanol solvate, C₁₃H₁₅N₅O₄·CH₃OH, the torsion angle of the N‐glycosylic bond is between anti and high‐anti [χ = −101.8 (5)°]. The ribofuranose moiety adopts the C3′‐endo (³T₂) sugar conformation (N‐type) and the conformation at the exocyclic C—C bond is +sc (gauche, gauche). The propynyl group is out of the plane of the nucleobase and is bent. The compound forms a three‐dimensional network which is stabilized by several hydrogen bonds (O—H·O and O—H·N). The nucleobases are stacked head‐to‐tail. The methanol solvent mol­ecule forms hydrogen bonds with both the nucleobase and the sugar moiety.     

Eth­yl 5‐isoprop­oxy‐4‐meth­yl‐β‐carboline‐3‐carboxyl­ate: structural determinants of benzodiazepine‐receptor antagonism

Mol­ecules of the title compound, C₁₈H₂₀N₂O₃, are linked into ribbons by N—H·O and N—H·N hydrogen bonds. Stereochemical comparison with Ro 15‐1788 (viz. eth­yl 8‐fluoro‐5,6‐dihydro‐5‐meth­yl‐6‐oxo‐4H‐imidazo[1,5‐a][1,4]benzodiazepine‐3‐carboxyl­ate) has identified three electronegative N and O atoms in the mol­ecule as features likely to be responsible for its activity as a benzodiazepine‐receptor antagonist.     

3,3′‐Dimethyl‐1,1′‐methyl­ene­di­imid­azolium tetrachloro­cobaltate(II)

The title compound, (C₉H₁₄N₄)[CoCl₄], a methyl­ene‐bridged bis‐imidazolium salt containing a tetrachloro­cobaltate anion, is one of the first examples where an alkyl‐bridged bis‐imidazolium compound could be structurally characterized. Short C—H·Cl contacts between the imidazolium C—H bonds and the Cl atoms of the counter‐anion build up a three‐dimensional network and indicate that the C—H bonds are strongly polarized.     

2‐(3‐Benzoyl‐1‐pyridinio)‐3,4‐dioxocyclo­butenolate

The title compound, C₁₆H₉NO₄, also known as the 3‐benzoyl­pyridinium betaine of squaric acid, exhibits a dipolar electronic ground‐state structure with a positively charged pyridinium fragment and a negatively charged squarate moiety. In the mol­ecule, the two aromatic rings are twisted by 56.03 (2)° relative to one another. The three‐dimensional packing of the mol­ecules is stabilized by C—H·O short contacts.     

Hydro­gen bonding and π–π stacking in di­methyl­genistein

The title compound, 5‐hydroxy‐4′,7‐di­methoxy­isoflavone, C₁₇H₁₄O₅, is composed of a benzo­pyran­one moiety, a phenyl moiety and two methoxy groups. The benzo­pyran­one ring is not coplanar with the phenyl ring, the dihedral angle between them being 56.28 (3)°. The two methoxy groups are nearly coplanar with their corresponding rings, having C—C—O—C torsion angles of 2.9 (2) and 5.9 (2)°. The mol­ecules are linked by C—H·O hydrogen bonds into sheets containing classical centrosymmetric (8) rings. The sheets are further linked by aromatic π–π stacking interactions and C—H·O hydrogen bonds into a supramolecular structure.     

N‐[(R)‐1‐(2‐Hydr­oxy‐5‐methyl­phen­yl)­eth­yl]‐N‐[(R)‐1‐(2‐meth­oxy‐5‐methyl­phen­yl)‐2‐phenyl­eth­yl]aminium chloride

The title compound, C₂₅H₃₀NO₂⁺·Cl⁻, has been synthesized, and the crystal structure shows that it is mainly stabilized through inter­molecular N—H·Cl and O—H·Cl and intra­molecular N—H·O hydrogen bonds. The absolute configuration of the new stereogenic center (the C atom adjacent to the N atom on the phenol side) was determined to have an R configuration.     

[μ‐N,N′‐Bis(2‐amino­ethyl)­oxamidato(2–)]­bis­[(4,5‐di­aza­fluoren‐9‐one)­perchloratocopper(II)] 4,5‐di­aza­fluoren‐9‐one disolvate

The title compound, [Cu₂(C₆H₁₂N₄O₂)(ClO₄)₂(C₁₁H₆N₂O)₂]·2C₁₁H₆N₂O, contains a dinuclear copper(II) complex which lies about a twofold axis at the mid‐point of the C—C bond of the ox­amide ligand that bridges the two Cu^II atoms. The Cu·Cu distance is 5.215 (2) Å and the Cu atoms have distorted octahedral coordination geometry. Intramolecular N—H·O and N—H·N hydrogen bonds and intermolecular C—H·O hydrogen bonds, together with π–π stacking interactions, dominate throughout the crystal structure.     

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.     

Di‐μ‐iodo‐bis{[1,1′‐methyl­enebis(3,5‐dimethyl‐1H‐pyrazole‐κN2)]copper(I)}

In the title compound, [Cu₂I₂(C₁₁H₁₆N₄)₂], each of the two crystallographically equivalent Cu atoms is tetrahedrally coordinated by two N atoms from one 1,1′‐methyl­ene­bis(3,5‐di­methyl‐1H‐pyrazole) ligand and two bridging iodide anions. The mol­ecule has a crystallographic center of symmetry located at the mid‐point of the Cu·Cu line. One H atom of the CH₂ group of the 1,1′‐methyl­ene­bis(3,5‐di­methyl‐1H‐pyrazole) ligand interacts with an iodide ion in an adjacent mol­ecule to afford pairwise intermolecular C—H·I contacts, thereby forming chains of mol­ecules running along the [101] direction.     

N‐Amidino‐4‐hydroxy‐l‐proline monohydrate and N‐amidino‐l‐methionine monohydrate

The title amidino‐amino acids (a‐Hpro), C₆H₁₁N₃O₃·H₂O, (I), and a‐Met, C₆H₁₃N₃O₂S·H₂O, (II), respectively, exist in the form of zwitterions. The five‐membered pyrrolidine ring in (I) adopts an envelope conformation, with the Cγ atom out of the plane defined by the rest of the ring atoms, and with the hydroxyl and carboxyl­ate groups in a trans configuration relative to the ring plane. The two crystallographically independent zwitterions in (II) reveal quite different conformations of their side chains and a slightly different orientation of the guanidine moiety with respect to the carboxyl­ate group. The crystal structures of both (I) and (II) are stabilized by extensive networks of O—H·O, N—H·O and C—H·O hydrogen bonds, the network being three‐dimensional in (I) and two‐dimensional in (II).