Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

The present knowledge of the crystallographic and structural properties of phosphate tungsten bronzes is given. The building of this family of compounds, focused on the tilt phenomenon of the octahedra involving a great variety of structures with different symmetries as well as the existence of numerous twins, is described.

Ab initio determination of the valence electron distribution in the average structure of the incommensurately modulated calaverite AuTe₂

The chemical bonds and the valence electron density of the average structure of incommensurate AuTe₂ are analysed in the framework of density functional theory.

Experimental electron density in the triclinic phase of Co₂(CO)₆(μ-CO)(μ-C₄O₂H₂) at 120 K

The topological analysis of the experimental electron density, determined by fitting a multipole model to high-resolution X-ray diffraction data collected at 120 K, confirms the presence of a `closed-shell' Co—Co bond in the title compound.

A pentagonal cluster in certain approximants to decagonal quasicrystals

The occurrence of a pentagonal cluster in several approximants to decagonal quasicrystals is discussed. The cluster is the main constituent of the decagonal approximant structure types Al₃Mn, Al₆₀Mn₁₁Ni₄ and Ga₁₃₇Mn₁₂₃.

Charge distribution as a tool to investigate structural details. II. Extension to hydrogen bonds, distorted and hetero-ligand polyhedra

An extension of the charge distribution method is presented, which exploits the iterative calculation of the effective coordination number, a specific contraction parameter for the hydrogen bonds and iterative scale factors for hetero-ligand polyhedra. Iteration allows the analysis of rather distorted coordination polyhedra through their charge distribution. Applications to oxides of pentacoordinated cations are shown. A computer program is available.

Bulk modulus and non-uniform compression of Nb₃Te₄ and In_xNb₃Te₄ (x < 1) channel compounds

X-ray powder diffraction with synchrotron radiation is used to study the pressure dependences of the crystal structures of Nb₃Te₄ and In_xNb₃Te₄ (x = 0.54) between 0 and 40 GPa.

Disordered crystal structure of penta­methylcyclo­pentadienylsodium as seen by high-resolution X-ray powder diffraction

The crystal structure of pentamethylcyclopentadienylsodium (NaCp*) has been determined from high-resolution X-ray powder diffraction. The crystal structure consists of polymeric multidecker chains along the crystallographic a axis. The pentamethylcyclopentadienyl anions are coplanar with each other and show twofold rotational disorder.

Perchlorophenalenyl radical, C₁₃Cl₉: a modulated structure with nine threefold-symmetric molecules in the asymmetric unit

The strongly ruffled, odd-alternant radical C₁₃Cl₉ stacks along crystallographic threefold axes, but the intrastack spacing is too large for the material to be a good conductor. The spacing is determined by interstack interactions, which are also responsible for the structural modulations.

Determination of the structure of 2(benzene-1,3,5-tri­carboxylic acid)·1.5(pyrene)·2(methanol) and comparison with that of 2(benzene-1,3,5-tri­carboxylic acid)·pyrene·2(ethanol)

A detailed comparison is made of the structures of 2(benzene-1,3,5-tricarboxylic acid)·1.5(pyrene)·2(methanol) (new determination) and of 2(benzene-1,3,5-tricarboxylic acid)·pyrene·2(ethanol) (data from the literature).

Polymorphism of maleic hydrazide. I

The third polymorph of maleic hydrazine (MH3) is monoclinic, space group P2₁/n, with the same pattern of hydrogen-bonded lactam–lactim tautomers as the two previously studied polymorphs, the triclinic MH1 and the monoclinic MH2. The interplay between the distortions of the hydrogen-bonded aggregates, their arrangements and symmetries of the polymorphs is analysed.

Self-association and stereochemistry study of 2-methylthio-, 2-di­methylamino­cyclo­hexanone oximes and the parent cyclo­hexanone oxime

The crystal structures of two 2-substituted cyclohexanone oximes and of the parent cyclohexanone oxime are reported and discussed in terms of three different types of hydrogen-bond patterns along with the π_C=N/σ*_C—X orbital interaction which stabilizes the axial conformation of the 2-substituted oximes.

Studies of molecular structure parameters of 20-piperidin-2-yl-5α-pregnan-3β,20-diol and its N-methyl derivative: two inhibitors of Δ²⁴⁽²⁵⁾ sterol methyl transferase and Δ^24(24′) sterol methyl reductase of Trypanosoma cruzi

Molecular structural parameters of two potential drugs against Trypanosoma cruzi epimastigotes have been studied using a combination of a stereoselective route, spectroscopic characterization and single-crystal X-ray analysis.

Space-group changes: a revision to a revision

The space group for the entry under the reference codes FEBMUU and FEBMUU01 in the Cambridge Structural Database should be further corrected to space group C2/c rather than P1 (FEBMUU) or C2 (FEBMUU01).

The weak hydrogen bond in structural chemistry and biology