Disorder in the anionic part of catena-poly[[(pyrazine-2-carboxyl-ato)copper(II)]-µ-pyrazine-2-carboxyl-ato].

The title compound, [Cu(C(5)H(3)N(2)O(2))(0.88)(C(6)H(4)NO(2))(1.12)](n), is characterized by disorder of the anion, resulting from a statistical occupation in a 0.44 (3):0.56 (3) ratio of pyrazine-2-carboxylate and pyridine-2-carboxylate. The compound was isolated during attempts to synthesize a mixed-ligand coordination polymer by solvothermal reaction between copper(II) nitrate and equimolar mixtures of pyrazine-2-carboxylic acid and pyridine-2-carb-oxy-lic acid in a mixture of water and EtOH. The difference in the two components of the compound is due to substitutional disorder of a CH group for one of the N atoms of the pyrazine ring which share the same site in the structure. In the crystal structure, the Cu(II) atom lies on an inversion centre and is six-coordinated in a distorted N(2)O(4) geometry. The carboxyl-ate group carbonyl O atoms are weakly coordinated to an equivalent Cu(II) atom that is translated one unit cell in the a-axis direction, thus forming a polymeric chain through carboxyl-ate bridges.

2-Phenyl-ethyl 1-thio-ß-d-galactopyran-oside hemihydrate.

The title compound, C(14)H(20)O(5)S·0.5H(2)O, crystallizes with two organic mol-ecules and a solvent water mol-ecule in the asymmetric unit. In both mol-ecules, the hexa-pyranosyl rings adopt a slightly distorted chair conformation ((5)C(2)) with four substituents in equatorial positions and one substituent in an axial position. The main difference between the organic mol-ecules is the dihedral angle between the phenyl ring and the best plane defined by the O-C(1)-C(2)-C(3) atoms (r.m.s deviations = 0.003 and 0.043 Å) of the hexa-pyranosyl rings [47.4 (4) and 86.5 (4)°]. In the asymmetric unit, mol-ecules are linked by two strong O-H⋯O hydrogen bonds. In the crystal, the components are linked by a total of 10 distinct O-H⋯O hydrogen bonds, resulting in the formation of a two-dimensional network parallel to the ab plane.

Diaqua-bis-(5-methyl-pyrazine-2-carboxyl-ato-κN,O)cadmium.

In the title compound, [Cd(C(6)H(5)N(2)O(2))(2)(H(2)O)(2)], the Cd(II) ion is coordinated in a severely distorted octa-hedral geometry. The N atoms are cis to each other, while the water O atoms and ligand O atoms are mutually trans. The crystal structure is stabilized by a network of O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distances = 3.730 (3) and 3.652 (3) Å] between the 5-methyl-pyrazine-2-carboxyl-ate ligands. The structure is isotypic with the manganese analog.

S-(4-Nitrophenyl) 4-nitrobenzenethiosulfonate.

The title compound, C(12)H(8)N(2)O(6)S(2), (I), is a positional isomer of S-(2-nitrophenyl) 2-nitrobenzenethiosulfonate [Glidewell, Low & Wardell (2000). Acta Cryst. B56, 893-905], (II). The most obvious difference between the two isomers is the rotation of the nitro groups with respect to the planes of the adjacent aryl rings. In (I), the nitro groups are only slightly rotated out of the plane of the adjacent aryl ring [2.4 (6) and 6.7 (7) degrees ], while in (II) the nitro groups are rotated by between 37 and 52 degrees , in every case associated with S-S-C-C torsion angles close to 90 degrees . Other important differences between the isomers are the C-S-S(O(2))-C torsion angle [78.39 (2) degrees for (I) and 69.8 (3) degrees for (II) (mean)] and the dihedral angles between the aromatic rings [12.3 (3) degrees for (I) and 28.6 (3) degrees for (II) (mean)]. There are two types of C-H...O hydrogen bond in the structure [C...O = 3.262 (7) A and C-H...O = 144 degrees ; C...O = 3.447 (7) A and C-H...O = 166 degrees ] and these link the molecules into a two-dimensional framework. The hydrogen-bond-acceptor properties differ between the two isomers.

(1R,3aR,5aS,6S,8aR,8bR,9aS)-1-Hydr-oxy-6-isopropyl-1,3a,5a-trimethyl-perhydro-cyclo-penta-[a]cyclo-propa[i]naphthalen-4-one.

The title compound (also know as azorellanone), C(20)H(32)O(2), is built up from three fused carbocycles, one five-membered ring and two six-membered rings. The five membered-ring has an envelope conformation, whereas the six-membered rings have a distorted half-chair and a twist-boat conformation. In the crystal, mol-ecules are linked by O-H⋯O inter-actions into zigzag chains with graph-set notation C(8) along [010]. The absolute configuration was assigned on the basis of earlier chemical studies.

Trithia-cyanuric acid: a second triclinic polymorph.

The title compound, C(3)H(3)N(3)S(3), is a triclinic modification. The other reported modification crystallizes with just one mol-ecule in the asymmetric unit, [Guo et al. (2006 ▶). Cryst. Growth Des.6, 846-848] and was solved by power X-ray diffraction data. The present modification has Z' = 2. In the crystal, mol-ecules are linked by strong intra-molecular N-H⋯S hydrogen bonds with set graph-motif R(2) (2)(8). In both mol-ecules, all of the N atoms and two of the S atoms are involved in hydrogen bonding, with an average H⋯S distance of 2.58 Šand N-H⋯S angles in the range 163-167°. π-π stacking inter-actions are not observed. In the solid state, the mol-ecules exist in the thione form. The mol-ecular and supra-molecular properties are similar in both polymorphs.

17-Acet-oxy-mulinic acid.

THE TITLE COMPOUND, [SYSTEMATIC NAME: 5a-acet-oxy-methyl-3-isopropyl-8-methyl-1,2,3,3a,4,5,5a,6,7,10,10a,10b-dodeca-hydro-7,10-endo-epidi-oxy-cyclo-hepta-[e]indene-3a-carb-oxy-lic acid], C(22)H(32)O(6) (I), is closely related to methyl 5a-acet-oxy-methyl-3-isopropyl-8-methyl-1,2,3,3a,4,5,5a,6,7,10,10a,10b-dodeca-hydro-7,10-endo-epidi-oxy-cyclo-hepta-[e]indene-3a-carboxyl-ate, (II) [Brito et al., (2008 ▶). Acta Cryst. E64, o1209]. There are two mol-ecules in the asymmetric unit, which are linked by two strong intra-molecular O-H⋯O hydrogen bonds with graph-set motif R(2) (2)(8). In both (I) and (II), the conformation of the three fused rings are almost identical. The five-membered ring has an envelope conformation, the six-membered ring has a chair conformation and the seven-membered ring has a boat conformation. The most obvious differences between the two compounds is the observed disorder of the acet-oxy-methyl fragments in both mol-ecules of the asymmetric unit of (I). This disorder is not observed in (II). The crystal structure and the molecular conformation is stabilized by intermolecular C-H⋯O hydrogen bonds. The ability to form hydrogen bonds is different in the two compounds. The crystal studied was a non-merohedral twin, the ratio of the twin components being 0.28 (1):0.72 (1).

Dimethyl 2,2'-[butane-1,4-diylbis(sul-fanediyl)]dibenzoate.

The title compound, C(20)H(22)O(4)S(2), was synthesized by the reaction of 1,4-dibromo-butene with methyl thio-salicylate. The aliphatic segment of this ligand is in an all-trans conformation. The bridging chain, -S-(CH(2))(4)-S-, is almost planar (r.m.s. deviation for all non-H atoms: 0.056 Å) and its mean plane forms dihedral angles of 16.60 (7) and 5.80 (2)° with the aromatic rings. In the crystal, the mol-ecules are linked by weak C-H⋯O inter-actions into chains with graph-set notation C(14) along [0 0 1]. The crystal studied was a racemic twin, the ratio of the twin components being 0.27 (9):0.73 (9).

1-Methyl-4-({5-[(4-methyl-phen-yl)sulfan-yl]pent-yl}sulfan-yl)benzene.

There are two independent mol-ecules in the asymmetric unit of the title compound, C(19)H(24)S(2). In both mol-ecules, the aliphatic segment of the ligand is in an all-trans conformation: the -S-(CH(2))(5)-S-bridging chain is almost planar (r.m.s. deviation for all non-H atoms = 0.0393 and 0.0796 Šin the two mol-ecules) and maximally extended. Their mean planes form dihedral angles of 4.08 (6)/20.47 (6) and 2.22 (6)/58.19 (6)° with the aromatic rings in the two mol-ecules. The crystal packing is purely governed by weak inter-molecular forces.