The crystal structure of dithallium carbonate, Tl2CO3 (C2/m, Z = 4), is stable to 5.82 GPa and does not undergo any phase transitions at lower pressures as reported previously. At higher pressures, the material undergoes a phase transition that destroys the single crystal.

The crystal structure of dithallium carbonate, Tl2CO3 (C2/m, Z = 4), was investigated at pressures of up to 7.4 GPa using single-crystal X-ray diffraction in a diamond anvil cell. It is stable to at least 5.82 GPa. All atoms except for one of the O atoms lie on crystallographic mirror planes. At higher pressures, the material undergoes a phase transition that destroys the single crystal.

The structure of Ba5Cl4(H2O)8(PVO5)8 consists of alternating anionic oxovanadium phosphate (VPO5) and cationic barium chloride hydrate, Ba5Cl4(H2O)8, layers. These layers are linked through Ba—O bonds, generating a three-dimensional framework.

The novel hydro­thermally synthesized title compound, penta­barium tetra­chloride octa­hydrate octa­kis(oxovanadium phosphate), Ba5Cl4(H2O)8(VPO5)8, crystallizes in the ortho­­rhom­bic space group Cmca with a unit cell containing four formula units. Two Ba2+ cations, two Cl− anions and the O atoms of four water mol­ecules are situated on the (100) mirror plane, while the third independent Ba2+ cation is on the inter­section of the (100) plane and the twofold axis parallel to a. Two phosphate P atoms are on twofold axes, while the remaining independent P atom and both V atoms are in general positions. The structure is characterized by two kinds of layers, namely anionic oxovanadium phosphate (VPO5), composed of corner-sharing VO5 square pyramids and PO4 tetra­hedra, and cationic barium chloride hydrate clusters, Ba5Cl4(H2O)8, composed of three Ba2+ cations linked by bridging chloride anions. The layers are connected by Ba—O bonds to generate a three-dimensional structure.

The ionic title complex, bis(μ-ethyl­ene glycol)-κ3 O,O′:O′;κ3 O:O,O′-bis[(ethyl­ene glycol-κ2 O,O′)(ethyl­ene glycol-κO)sodium] bis(ethyl­ene glycolato-κ2 O,O′)copper(II), [Na2(C2H6O2)6][Cu(C2H4O2)2], was obtained from a basic solution of CuCl2 in ethyl­ene glycol and consists of discrete ions inter­connected by O—H⋯O hydrogen bonds. This is the first example of a disodium–ethyl­ene glycol complex cation cluster. The cation lies about an inversion center and the CuII atom of the anion lies on another independent inversion center.

In 2,4-diamino-5-(4-chloro­phenyl)-6-ethyl­pyrimidin-1-ium (pyri­methaminium, PMNH) 4-methyl­benzoate, C12H14ClN4 +·C8H7O2 −, (I), pyrimethaminium 3-hydroxy­picolinate, C12H14ClN4 +·C6H4NO3 −, (II), and pyrimethaminium 2,4-dichloro­benzoate, C12H14ClN4 +·C7H3Cl2O2 −, (III), the PMNH cations inter­act with the carboxyl­ate groups of the corresponding anion via nearly parallel N—H⋯O hydrogen bonds, forming R 2 2(8) ring motifs. A description of the observed arrays of quadruple hydrogen bonds in (I) and (II) in terms of hydrogen donors and acceptors (the DA model), their graph-set motifs and the resulting supra­molecular ladder is given. In (III), supra­molecular chains along the b axis and helical chains along the a axis are formed via N—H⋯O hydrogen bonds involving the 2-amino and 4-amino groups of the PMNH cation, respectively. Weak Cl⋯Cl inter­actions are also found in (III).

The crystal structure of the title compound, C13H15N3O3·C3H7NO, was determined as part of a larger project focusing on creatinine derivatives as potential pharmaceuticals. The mol­ecule is essentially planar, in part because of intra­molecular hydrogen bonding. Inversion-related pairs of mol­ecules result from inter­molecular hydrogen bonding. The π systems of 2-amino-5-(3,4-dimethoxy­benzyl­idene)-1-methyl­imidazol-4(5H)-one and an inversion-related mol­ecule over­lap slightly, indicating a small amount of π–π stacking. Bond lengths, angles and torsion angles are consistent with similar structures, except in the imidazolone ring near the doubly bonded C atom, where significant differences occur.

The X-ray analyses of 2,3,4,6-tetra-O-acetyl-α-d-glucopyran­osyl fluoride, C14H19FO9, (I), and the corresponding maltose derivative 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl-(1→4)-2,3,6-tri-O-acetyl-α-d-glucopyran­osyl fluoride, C26H35FO17, (II), are reported. These add to the series of published α-glyco­syl halide structures; those of the peracetyl­ated α-glucosyl chloride [James & Hall (1969 ▶). Acta Cryst. A25, S196] and bromide [Takai, Watanabe, Hayashi & Watanabe (1976 ▶). Bull. Fac. Eng. Hokkaido Univ. 79, 101–109] have been reported already. In our structures, which have been determined at 140 K, the glycopyranosyl ring appears in a regular 4 C 1 chair conformation with all the substituents, except for the anomeric fluoride (which adopts an axial orientation), in equatorial positions. The observed bond lengths are consistent with a strong anomeric effect, viz. the C1—O5 (carbohydrate numbering) bond lengths are 1.381 (2) and 1.381 (3) Å in (I) and (II), respectively, both significantly shorter than the C5—O5 bond lengths, viz. 1.448 (2) Å in (I) and 1.444 (3) Å in (II).

The first structure report of trichlorido[4′-(p-tolyl)-2,2′:6′,2′′-terpyridine]iridium(III) dimethyl sulfoxide solvate, [IrCl3(C22H17N3)]·C2H6OS, (I), is presented, along with a higher-symmetry setting of previously reported bis­[4′-(p-tolyl)-2,2′:6′,2′′-terpyridine]iridium(III) tris­(hexa­fluorido­phosphate) acetonitrile disolvate, [Ir(C22H17N3)2](PF6)3·2C2H3N, (II) [Yoshikawa, Yamabe, Kanehisa, Kai, Takashima & Tsukahara (2007 ▶). Eur. J. Inorg. Chem. pp. 1911–1919]. For (I), the data were collected with synchrotron radiation and the dimethyl sulfoxide solvent mol­ecule is disordered over three positions, one of which is an inversion center. The previously reported structure of (II) is presented in the more appropriate C2/c space group. The iridium complex and one PF6 − anion lie on twofold axes in this structure, making half of the mol­ecule unique.

The structures of the three title monosubstituted ferrocenes, namely 1-chloro­ferrocene, [Fe(C5H5)(C5H4Cl)], (I), 1-bromo­ferrocene, [Fe(C5H5)(C5H4Br)], (II), and 1-iodo­ferrocene, [Fe(C5H5)(C5H4I)], (III), were determined at 100 K. The chloro- and bromo­ferrocenes are isomorphous crystals. The new triclinic polymorph [space group P , Z = 4, T = 100 K, V = 943.8 (4) Å3] of iodo­ferrocene, (III), and the previously reported monoclinic polymorph of (III) [Laus, Wurst & Schottenberger (2005 ▶). Z. Kristallogr. New Cryst. Struct. 220, 229–230; space group Pc, Z = 4, T = 100 K, V = 924.9 Å3] were obtained by crystallization from ethanolic solutions at 253 and 303 K, respectively. All four phases contain two independent mol­ecules in the unit cell. The relative orientations of the cyclo­penta­dienyl (Cp) rings are eclipsed and staggered in the independent mol­ecules of (I) and (II), while (III) demonstrates only an eclipsed conformation. The triclinic and monoclinic polymorphs of (III) contain nonbonded inter­molecular I⋯I contacts, causing different packing modes. In the triclinic form of (III), the mol­ecules are arranged in zigzag tetra­mers, while in the monoclinic form the mol­ecules are arranged in zigzag chains along the a axis. Crystallographic data for (III), along with the computed lattice energies of the two polymorphs, suggest that the monoclinic form is more stable.

The compounds tricarbonyl(η5-1-iodo­cyclo­penta­dienyl)­man­gan­ese(I), [Mn(C5H4I)(CO)3], (I), and tricarbonyl(η5-1-iodo­cyclo­penta­dienyl)rhenium(I), [Re(C5H4I)(CO)3], (III), are isostructural and isomorphous. The compounds [μ-1,2(η5)-acetyl­enedicyclo­penta­dienyl]bis­[tricarbonyl­manganese(I)] or bis­(cymantrenyl)acetyl­ene, [Mn2(C12H8)(CO)6], (II), and [μ-1,2(η5)-acetyl­enedicyclo­penta­dienyl]bis­[tri­carbonyl­rhenium(I)], [Re2(C12H8)(CO)6], (IV), are isostructural and isomorphous, and their mol­ecules display inversion symmetry about the mid-point of the ligand C C bond, with the (CO)3 M(C5H4) (M = Mn and Re) moieties adopting a transoid conformation. The mol­ecules in all four compounds form zigzag chains due to the formation of strong attractive I⋯O [in (I) and (III)] or π(CO)–π(CO) [in (I) and (IV)] inter­actions along the crystallographic b axis. The zigzag chains are bound to each other by weak inter­molecular C—H⋯O hydrogen bonds for (I) and (III), while for (II) and (IV) the chains are bound to each other by a combination of weak C—H⋯O hydrogen bonds and π(Csp 2)–π(Csp 2) stacking inter­actions between pairs of mol­ecules. The π(CO)–π(CO) contacts in (II) and (IV) between carbonyl groups of neighboring mol­ecules, forming pairwise inter­actions in a sheared anti­parallel dimer motif, are encountered in only 35% of all carbonyl inter­actions for transition metal–carbonyl compounds.

The title compound, C23H26F2N2O4, is a dipeptidic inhibitor of γ-secretase, one of the enzymes involved in Alzheimer’s dis­ease. The mol­ecule adopts a compact conformation, without intra­molecular hydrogen bonds. In the crystal structure, one of the amide N atoms forms the only inter­molecular N—H⋯O hydrogen bond; the second amide N atom does not form hydrogen bonds. High-resolution synchrotron diffraction data permitted the unequivocal location and refinement without restraints of all H atoms, and the identification of the characteristic shift of the amide H atom engaged in the hydrogen bond from its ideal position, resulting in a more linear hydrogen bond. Significant residual densities for bonding electrons were revealed after the usual SHELXL refinement, and modeling of these features as additional inter­atomic scatterers (IAS) using the program PHENIX led to a significant decrease in the R factor from 0.0411 to 0.0325 and diminished the r.m.s. deviation level of noise in the final difference Fourier map from 0.063 to 0.037 e Å−3.

In the title compound, C23H22N4O, there is evidence for some bond fixation in the aryl component of the quinolinone unit. Pairs of mol­ecules related by inversion are linked into R 2 2(8) dimers by almost linear N—H⋯O hydrogen bonds, and dimers related by inversion are linked into chains by a single aromatic π–π stacking inter­action.

The title compound, C40H64O12, crystallizes in a pseudo­merohedrally twinned primitive monoclinic cell with similar contributions of the two twin components. There are two symmetry-independent half-mol­ecules of nona­ctin in the asymmetric unit. Each mol­ecule has a pseudo-S 4 symmetry and resides on a crystallographic twofold axis; the axes pass through the mol­ecular center of mass and are perpendicular to the plane of the macrocycle. The literature description of the room-temperature structure of nona­ctin as an order–disorder structure in an ortho­rhom­bic unit cell is corrected. We report a low-temperature high-precision ordered structure of ‘free’ nona­ctin that allowed for the first time precise determination of its bond distances and angles. It possesses an unfolded and more planar geometry than its complexes with encapsulated Na+, K+, Cs+, Ca2+ or NH4 + cations that exhibit more isometric overall conformations.

Mol­ecules of the title compound, C16H13N5O2, have no inter­nal symmetry despite the symmetric pattern of substitution in the pyrimidine ring. The intra­molecular distances indicate polarization of the electronic structure. There are two intra­molecular N—H⋯O hydrogen bonds and mol­ecules are linked into centrosymmetric dimers by pairs of three-centre C—H⋯(O)2 hydrogen bonds. These dimers are linked into chains by means of a π–π stacking inter­action.

The pyrimidinone ring in the title compound, C12H13N5O3, is effectively planar, despite the presence of five substituents. The bond distances provide evidence for significant polarization of the electronic structure, with charge separation, and the mol­ecules are linked into sheets by a combination of N—H⋯O and N—H⋯π(arene) hydrogen bonds. Comparisons are made with the mol­ecular and supra­molecular structures of the precursor compound 2-amino-6-[meth­yl(phen­yl)amino]-5-nitro­pyrimidin-4(3H)-one.

The title compound, C14H11NS, crystallizes with Z′ = 0.75 in the space group C2/m. Two independent mol­ecules are present, one of which lies with all the non-H atoms on a mirror plane, while the other is fourfold disordered across a site of 2/m symmetry. The ordered mol­ecules are stacked such that they enclose continuous channels running along twofold rotation axes, and the disordered mol­ecules are positioned within these channels.

In (2RS,4SR)-7-chloro-2-exo-(2-chloro-6-fluoro­phen­yl)-2,3,4,5-tetra­hydro-1H-1,4-epoxy-1-benzazepine, C16H12Cl2FNO, (I), mol­ecules are linked into chains by a single C—H⋯π(arene) hydrogen bond. (2RS,4SR)-2-exo-(2-Chloro-6-fluoro­phen­yl)-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C16H13ClFNO, (II), is isomorphous with compound (I) but not strictly isostructural with it, as the hydrogen-bonded chains in (II) are linked into sheets by an aromatic π–π stacking inter­action. The mol­ecules of (2RS,4SR)-7-methyl-2-exo-(4-methyl­phenyl)-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C18H19NO, (III), are linked into sheets by a combination of C—H⋯N and C—H⋯π(arene) hydrogen bonds. (2S,4R)-2-exo-(2-Chloro­phen­yl)-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C16H14ClNO, (IV), crystallizes as a single enantiomer and the mol­ecules are linked into a three-dimensional framework structure by a combination of one C—H⋯O hydrogen bond and three C—H⋯π(arene) hydrogen bonds.

4,4′-(Phenyl­methyl­ene)bis­(6-allyl-3-chloro-2-methyl­aniline), C27H28Cl2N2, (I), and 4,4′-(2-thienylmethyl­ene)bis­(6-allyl-3-chloro-2-methyl­aniline), C25H26Cl2N2S, (II), adopt similar mol­ecular conformations, although the thienyl group in (II) exhibits orientational disorder over two sets of sites with occupancies of 0.614 (3) and 0.386 (3). The amino groups in both compounds are pyramidal. A single N—H⋯N hydrogen bond links the mol­ecules of (I) into cyclic centrosymmetric dimers. Mol­ecules of (II) are linked by an ordered C—H⋯π(arene) hydrogen bond to form cyclic centrosymmetric dimers, and these dimers are linked into statistically inter­rupted chains by a second C—H⋯π(arene) hydrogen bond involving a donor in the minor component of the disordered thienyl unit.

The mol­ecules of the title compound, C20H23N3O6, are almost completely planar, apart from the H atoms bonded to tetra­hedral C atoms. A combination of five hydrogen bonds, one of the N—H⋯O type and two each of the C—H⋯O and C—H⋯π(arene) types, links the mol­ecules into complex sheets.

The mol­ecules of (2RS,4SR)-2-exo-(5-bromo-2-thienyl)-7-chloro-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C14H11BrClNOS, (I), are linked into cyclic centrosymmetric dimers by C—H⋯π(thienyl) hydrogen bonds. Each such dimer makes rather short Br⋯Br contacts with two other dimers. In (2RS,4SR)-2-exo-(5-methyl-2-thienyl)-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C15H15NOS, (II), a com­bination of C—H⋯O and C—H⋯π(thienyl) hydrogen bonds links the mol­ecules into chains of rings. A more complex chain of rings is formed in (2RS,4SR)-7-chloro-2-exo-(5-methyl-2-thienyl)-2,3,4,5-tetra­hydro-1H-1,4-ep­oxy-1-benzazepine, C15H14ClNOS, (III), built from a combination of two independent C—H⋯O hydrogen bonds, one C—H⋯π(arene) hydrogen bond and one C—H⋯π(thienyl) hydro­gen bond.

A crystallographic investigation of the title compound, C22H28Cl2N4O4, using crystals obtained under different crystallization conditions, revealed the presence of two distinct polymorphic forms. The mol­ecular conformation in the two polymorphs is very different: one adopts a ‘C’ shape, whereas the other adopts an ‘S’ shape. In the latter, the molecule lies across a crystallographic twofold axis. The ‘S’-shaped polymorph undergoes a reversible ortho­rhom­bic-to-monoclinic phase transition on cooling, whereas the structure of the ‘C’-shaped polymorph is temperature insensitive.

7-Benzyl-3-tert-butyl-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C22H25N3O, (I), and 3-tert-butyl-7-(4-methyl­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C23H27N3O, (II), are isomorphous in the space group P21, and mol­ecules are linked into chains by C—H⋯O hydrogen bonds. In each of 3-tert-butyl-7-(4-methoxy­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C23H27N3O2, (III), which has cell dimensions rather similar to those of (I) and (II), also in P21, and 3-tert-butyl-1-phenyl-7-[4-(trifluoro­meth­yl)benz­yl]-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C23H24F3N3O, (IV), there are no direction-specific inter­actions between the mol­ecules. In 3-tert-butyl-7-(4-nitro­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C22H24N4O3, (V), a combination of C—H⋯O and C—H⋯N hydrogen bonds links the mol­ecules into complex sheets. There are no direction-specific inter­actions between the mol­ecules of 3-tert-butyl-7-(2,3-dimethoxy­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C24H29N3O3, (VI), but a three-dimensional framework is formed in 3-tert-butyl-7-(3,4-methyl­enedioxy­benz­yl)-1-phenyl-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C23H25N3O3, (VII), by a combination of C—H⋯O, C—H⋯N and C—H⋯π(arene) hydrogen bonds, while a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds links the mol­ecules of 3-tert-butyl-1-phenyl-7-(3,4,5-trimethoxy­benz­yl)-6,7-dihydro-1H,4H-pyrazolo[3,4-d][1,3]oxazine, C25H31N3O4, (VIII), into complex sheets. In each compound, the oxazine ring adopts a half-chair conformation, while the orientations of the pendent phenyl and tert-butyl substituents relative to the pyrazolo[3,4-d]oxazine unit are all very similar.

The syntheses of 3-[1-(4-sulfamoylphenyl)-5-p-tolyl-1H-pyra­zol-3-yl]propanoic acid, C19H19N3O4S, (I), and 3-[5-(4-bromo­phen­yl)-1-(4-sulfamoyl­phen­yl)-1H-pyrazol-3-yl]­propanoic acid–dichloro­methane–diethyl ether–water (2/0.72/1/1), 2C18H16BrN3O4S·0.72CH2Cl2·C4H10O·H2O, (II), are regio­specific. However, correct identification by spectroscopic techniques of the regioisomer formed is not trivial and single-crystal X-ray analysis provided the only means of unambiguous structure determination. Both structures make extensive use of hydrogen bonding and while compound (I) forms a straightforward unsolvated Z′ = 1 structure, compound (II) crystallizes as an unusual mixed solvate, with two crystallographically unique mol­ecules of the pyrazole derivative present in the asymmetric unit. The structure of (II) also features Br⋯Br inter­actions.

Reduction of carbon dioxide by a diiron(I) complex gives μ-carbonato-κ3 O:O′,O′′-bis­{[2,2,6,6-tetra­methyl-3,5-bis­(2,4,6-triisopropyl­phenyl)heptane-2,5-diiminate(1−)-κ2 N,N′]iron(II)} toluene disolvate, [Fe2(C41H65N)2(CO3)]·2C7H8, a diiron(II) species with a bridging carbonate ligand. The asymmetric unit contains one diiron complex and two cocrystallized toluene solvent mol­ecules that are distributed over three sites, one with atoms in general positions and two in crystallographic sites. Both FeII atoms are η2-coordinated to diketiminate ligands, but η1- and η2-coordinated to the bridging carbonate ligand. Thus, one FeII center is three-coordinate and the other is four-coordinate. The bridging carbonate ligand is nearly perpendicular to the iron–diketiminate plane of the four-coordinate FeII center and parallel to the plane of the three-coordinate FeII center.

Diastereoisomers of the title organophospho­rus compound, C12H19N4OPS, denoted R C S P, (I), and R C R P, (II), were structurally characterized and compared. Asymmetric phosphorus compounds are of interest with regard to the use of these systems as possible protein probes via the stereoselective delivery of an azide group tethered to the P atom into key protein regions. The diastereomers were produced in a 1:1 mixture and isolated by chromatography. Although both isomers crystallize in the same space group with superficially similar cell constants, conformational and packing differences are pronounced. Despite the conformational differences, strong inter­molecular hydrogen bonding links both isomers into chains parallel to the a axis [N⋯O = 2.8609 (18) and 2.966 (3) Å in (I) and (II), respectively], with C—H⋯π inter­chain inter­actions of ca 3.5 Å.

The synthesis of 3-[5-(4-chloro­phen­yl)-1-(4-methoxy­phen­yl)-1H-pyrazol-3-yl]propionic acid, C19H17ClN2O3, (I), and its corresponding methyl ester, methyl 3-[5-(4-chloro­phen­yl)-1-(4-methoxy­phen­yl)-1H-pyrazol-3-yl]propionate, C20H19ClN2O3, (II), is regiospecific. However, correct identification of the regioisomer formed by spectroscopic techniques is not trivial and single-crystal X-ray analysis provided the only means of unambiguous structure determination. Compound (I) crystallizes with Z′ = 2. The propionic acid groups of the two crystallographically unique mol­ecules form a hydrogen-bonded dimer, as is typical of carboxylic acid groups in the solid state. Conformational differences between the meth­oxy­benzene and pyrazole rings give rise to two unique mol­ecules. The structure of (II) features just one mol­ecule in the asymmetric unit and the crystal packing makes greater use than (I) of weak C—H⋯A inter­actions, despite the lack of any functional groups for classical hydrogen bonding.