The complete molecule of the title compound, C₂₂H₂₆Si₂, is generated by a crystallographic centre of symmetry. The central benzene ring makes a dihedral angle of 26.7 (4)° with the 4-(dimethyl­silyl)phenyl ring. There are weak C—Hπ inter­actions in the crystal structure.

The mol­ecule of the title compound, C₂₂H₂₆Si₂, is centrosymmetric. The dihedral angle between the central benzene ring and its phenyl substituents is 67.7 (2)°. The crystal packing is stabilized by van der Waals forces.

In the structure of the title compound, C₁₇H₁₃BrN₄O₂S, the dihedral angle between the two benzene rings is 38.5 (1)°; the angle between the 4-bromo­benzene and thia­diazole rings is 1.3 (1)°. The conformations of the N—H and C=O bonds are anti with respect to each other. The structure displays inter­molecular N—HO and C—HO hydrogen bonding, with both interactions leading to inversion dimers.

The title compound (systematic name: 5,6β-dihy­droxy-1α,14α,16β-trimeth­oxy-4-methyl-7β,8-methyl­enedi­oxy-20-ethyl­aconitan-6-yl acetate acetone monosolvate), C₂₇H₄₁NO₈·C₃H₆O, was isolated from Delphinium bonvalotii Franch, and is a typical C₁₉-diterpenoid alkaloid. The mol­ecule has a lycoctonine carbon skeleton with four six-membered rings and three five-membered rings. Three six-membered rings adopt the chair conformations while the fourth adopts a boat conformation, while the five-membered rings have the envelope conformations. The solvent mol­ecule links with the organic mol­ecule via a classical O—HO hydrogen bond. Weak C—HO hydrogen bonding is present in the structure. An intra­molecular O—HO hydrogen bond also occurs.

The title mol­ecule, C₂₀H₂₄O₂, shows a Z configuration with respect to the C=C double bond. The crystal structure is stabilized by intra- and inter­molecular O—HO hydrogen bonds.

The title compound, C₂₀H₁₈, contains four approximately coplanar fused rings: three six- and one five-membered. In the crystal structure, mol­ecules form columnar stacks along the a axis. Mol­ecules in adjacent stacks along the [010] direction are oriented approximately perpendicular to each other, with a dihedral angle of 81.38 (3)°. There is a short inter­molecular C—HC contact of 2.72 Å between a methyl group and an aromatic ring.

In the title compound, C₂₀H₁₇ClN₄O₂S, the dihedral angle between the two benzene rings is 65.9 (1)°; the corresponding angle between the 4-chloro­phenyl and thia­diazole rings is 3.4 (8)°. The conformations of the N—H and C=O bonds are anti with respect to each other. The enone groups show a trans configuration. The structure displays intermolecular N—HO, C—HN, C—HS and C—HO hydrogen bonding.

The title compound (delgradine), C₄₁H₄₃NO₁₂, is a hetisine-type C₂₀-diterpenoid alkaloid, isolated from the roots of Aconitum carmichaeli Debx. In the crystal structure, the mol­ecule assumes an U-shaped conformation, the terminal benzene rings being approximately parallel and partially overlapped with each other. The mol­ecule contains eight alicyclic and heterocyclic rings. Cyclo­hexane rings A and B adopt similar chair conformations; the six-membered rings C, D and E form a bicyclo­[2.2.2]octane system with a boat conformation for each six-membered ring, the six-membered heterocyclic ring F has a screw-boat conformation and both of the five-membered rings G and H have envelope conformations. The crystal structure contains inter­molecular O—HO hydrogen bonding.

The asymmetric unit of the title compound, C₂₁H₂₀N₄O₃S, contains two independent mol­ecules. The dihedral angles between the two benzene rings are 47.6 (1) and 30.2 (1)°, the corresponding values between the p-methoxy­benzene and thia­diazol rings are 12.3 (1) and 24.7 (1)°, respectively, for the two mol­ecules. The conformations of the N—H and C=O bonds are anti with respect to each other. The enone groups show a trans configuration. The crystal structure is stabilized by N—HO and N—HN inter­actions. The absolute structure could not be determined from the X-ray data but the absolute configuration has been assigned by reference to an unchanging chiral centre in the synthetic procedure.

The title compound, C₁₅H₂₂O₄, obtained from the dehydration of dihydro­artemisinin, has retained the endoperoxide bridge of the parent compound along with the C=C bond. The six-membered rings exhibit chair, twist-boat and envelope conformations.

In the title complex, [Cd(C₈H₉N₂O₄)₂(H₂O)₂]·3.5H₂O, the Cd^II is coordinated by two water mol­ecules and N,O-chelated by two 5-carb­oxy-2-propyl-1H-imidazole-4-carboxyl­ate anions in a distorted octa­hedral geometry. The two imidazole rings are oriented to each other with a dihedral angle of 75.1 (2)°. Strong O—HO hydrogen bonds between protonated and deprotonated carboxyl­ate groups occur in the mol­ecular structure. In the crystal structure extensive O—HO and N—HO hydrogen bonds help to stabilize the three-dimensional supra­molecular framework. The propyl groups of anions are disordered over two sites with refined occupancies of 0.768 (6):0.232 (6) and 0.642 (8):0.358 (8).

In the title complex, [Zn(C₈H₉N₂O₄)₂(H₂O)₂]·3.5H₂O, the Zn^II ion is coordinated by two N,O-bidentate H₂pimda ligands (H₃pimda = 2-propyl-1H-imidazole-4,5-dicarb­oxy­lic acid) and two water mol­ecules in a distorted octa­hedral environment. In the crystal structure, extensive inter­molecular O—HO and N—HO hydrogen bonds stabilize the three-dimensional supra­molecular network. Intra­molecular O—HO hydrogen bonds between the carboxyl groups are also observed. The propyl groups of the two H₂pimda ligands are disordered each over two sites, with occupancy factors of 0.752 (5):0.248 (5) and 0.519 (7):0.481 (7). One of the water mol­ecules is half-occupied.

In the title complex, [Mn(C₈H₉N₂O₄)₂(H₂O)₂]·3.5H₂O, the Mn^II cation is six-coordinated by two N,O-bidentate H₂pimda⁻ ligands (H₂pimda⁻ = 5-carb­oxy-2-propyl-1H-imidazole-4-carboxyl­ate) and two water mol­ecules in a distorted octa­hedral environment. The complete solid-state structure can be described as a three-dimensional supra­molecular framework stabilized by a wide range of O—HO and N—HO hydrogen bonds. The propyl groups of H₂pimda⁻ are disordered over two sets of sites with refined occupancies of 0.759 (5):0.241 (5) and 0.545 (7):0.455 (7).

The title compound, [Ag(C₈H₁₀NO₃S)(H₂O)]·H₂O, has a mononuclear structure in which the Ag⁺ cation is two-coordinated by one N atom from a 2-amino-4,5-dimethyl­benzene­sulfonate anion and one water O atom in a nearly linear arrangement. A network of O—HO and N—HO hydrogen bonds helps to consolidate the crystal packing.

In the title compound, C₁₄H₁₆ClN₃O₂S, the dihedral angle between the 4-chloro­phenyl and 1,3,4-oxadiazole rings is 67.1 (1)° and the orientation of the amide N—H and C=O bonds is anti. In the crystal, mol­ecules are linked by N—HO and N—HS hydrogen bonds.

Two racemic pairs of stereoisomers of the title compound, C₁₇H₂₂O₈, were characterized by single-crystal X-ray analysis. Compound (Ia) has an r-1,2-cis, 3-trans configuration, while (Ib) has an r-1,2-cis, 3-cis configuration. The five-membered tetrahydrofuran rings of both isomers adopt envelope conformations with the substituted β-C atom as the flap.

The title compound, C₃₀H₄₆O₉, prepared from a mixture of α- and β-dihydro­artemisinin, has α- and β-arteether moieties linked via an –O– bridge, so that the mol­ecule is asymmetric about the bridge. The endoperoxide bridges of the parent compounds have been retained in each half of the ether-bridged dimer. The rings exhibit chair and twist–boat conformations.