Erwin Parthé (1928–2006)

Obituary for Erwin Parthé.

Temperature-dependent crystal structure refinement and ⁵⁷Fe Mössbauer spectroscopy of Cu₂Fe₂Ge₄O₁₃

Temperature-dependent structural changes of the quasi-one-dimensional compound Cu₂Fe₂Ge₄O₁₃ were evaluated from powder and single-crystal X-ray data between 10 and 900 K. ⁵⁷Fe Mössbauer spectroscopy between 20 and 298 K provides supplementary data relating to the magnetic properties of the title compound.

Structures of incommensurate and commensurate composite crystals Na_xCuO₂ (x = 1.58, 1.6, 1.62)

The crystal structures of the composite-type compounds Na_xCuO₂ are compared for incommensurate, x = 1.58 and 1.62, and commensurate, x = 1.6, compositions.

Structural filiations in the new complex titanates SrLiMTi₄O₁₁ (M = Cr, Fe)

Two new non-isostructural titanates with the composition SrLiMTi₄O₁₁ (M = Cr, Fe) were discovered and their structures were determined using single-crystal X-ray and neutron powder diffraction. Both structures were described in terms of close-packed Sr—O compact planes and relationships between them were established.

Ab initio constrained crystal-chemical Rietveld refinement of Ca₁₀(V_xP_1 − xO₄)₆F₂ apatites

The constraining of crystal-chemical Rietveld refinements of vanadate phosphate fluorapatites for two oxygen–metal–oxygen angles extracted by ab initio modeling produces experimental results in agreement with quantum ones and residuals similar to unconstrained refinements. Expansion of the BO₄ tetrahedra and rotation of Ca–Ca–Ca triangular units is observed upon replacement of phosphorus by vanadium.

Multipole refinement and electron density analysis in natural borosilicate datolite using X-ray diffraction data

The topological analysis of the electron density in datolite, Ca[BOH(SiO₄)], was carried out using accurate X-ray diffraction data.

Structure of an aluminophosphate EMM-8: a multi-technique approach

The crystal structure of EMM-8, the calcined form of SSZ-51, was determined by the combined use of synchrotron powder diffraction, electron diffraction and solid-state NMR.

Structure of the novel ternary hydrides Li₄Tt₂D (Tt = Si and Ge)

The crystal structures of novel Li₄Tt₂D (Tt = Si and Ge) ternary hydrides were solved using neutron powder diffraction data. All hydrogen atoms were found to occupy Li₆-octahedral interstices.

Sensitive detection of mirror symmetry by CBED applied to LaAlO₃ and GdAlO₃

High sensitivity to the presence of mirror symmetry has been found in HOLZ reflections from convergent-beam electron diffraction patterns tilted away from the major zone axes. This sensitivity has been used to re-examine the space groups of LaAlO₃ and GdAlO₃ perovskites and has relevance for the more precise observation of screw and glide operators.

Structure determination of di-μ-hydroxo-bis­[(2-(2-pyridyl)phenyl-κ²N,C¹)palladium(II)] by X-ray powder diffractometry

X-ray powder diffractometry has been used in conjunction with IR spectroscopy, thermogravimetry and mass spectrometry to establish the solid-state structure of the [{Pd(μ-OH)(phpy)}₂] [phpy = 2-(2-pyridyl)phenyl] complex. It adopts a planar conformation forming trimers created by groups of parallel molecules.

Extended structures of polyiodide salts of transition metal macrocyclic complexes

Complex cations of transition metals with thioether macrocycles act as templates for the assembly of a wide range of polyiodide anions and their polyanionic networks.

Low-temperature enantiotropic k2 phase transition in the ionic 222-cryptand complex with LiClO₄

The 222-cryptand/LiClO₄ complex undergoes an orthorhombic unit-cell phase transition at 253 (2) K from the space group P2₁2₁2₁ below the transition to P2₁2₁2 (2c′ = c) above it. A detailed study of the dynamic positional disorder of the Li⁺ and ClO ions in the system in the temperature range 100–295 K is presented.

Three isomeric 1-(2-chloronicotinoyl)-2-(nitro­phenyl)hydrazines, including three polymorphs of 1-(2-chloronicotinoyl)-2-(2-nitro­phenyl)hydrazine: hydrogen-bonded supramolecular structures in two and three dimensions

In isomeric 1-(2-chloronicotinoyl)-2-(nitrophenyl)hydrazines, the molecules may be linked into supramolecular structures in two or three dimensions by various combinations of N—H⋯O, N—H⋯N, C—H⋯N and C—H⋯O hydrogen bonds, sometimes augmented by π⋯π stacking interactions.

In-situ high-pressure study of the ordered phase of ethyl propionate

Pressure freezing of ethyl propionate yields the ordered structure, with no group–subgroup symmetry relation with the disordered low-temperature phase.

Pitfalls of data mining: triclinic polymorph of 2,2-aziridinedicarboxamide revisited

Polymorph β of 2,2-aziridinedicarboxamide, originally described in the space group P1, with an exceptionally high Z = 16, has been redetermined in the space group (Z′ = 8). Comparisons of the structural models and their diffraction patterns have been applied as validation tests.

Halogen⋯halogen interactions in pressure-frozen ortho- and meta-di­chloro­benzene isomers

The high-pressure crystal structures of 1,2- and 1,3-dichlorobenzene isomers have been determined at room temperature and at 0.18 (5) and 0.17 (5) GPa, respectively. The non-planar association of molecules in these crystals can be rationalized by the electrostatic potential distribution on the molecular surfaces and electrostatic intermolecular interactions.

Analysis of structures with saturated hydrogen bonding

A method is presented to classify all structures with saturated hydrogen bonding. Examples are included from the CSD, as are five examples from this study.

Determination of covalent bond orders and atomic valence indices using topological features of the experimental electron density

Determination of covalent bond orders and atomic valence indices from the experimental electron density and its derivatives at the bond critical points in a series of organic compounds has been described.

Structural study of four complexes of the M-N₂S₂ type derived from di­ethylphenylazo­thioformamide and the metals palladium, platinum, copper and nickel

The crystal structures at low temperature of four electron-transfer complexes of the M-N₂S₂ type are reported. The nickel and copper complexes show an unusual tetrahedral coordination, whereas the palladium and platinum complexes show the more conventional square-planar coordination.

Cu₃MgCl₂(OH)₆ and the bond-valence parameters of the OH—Cl bond

The crystal structure of Cu₃MgCl₂(OH)₆ consists of sheets of edge-sharing Cu(OH)₄Cl₂ and Mg(OH)₆ octahedra, weakly linked by Cl—H bonds. Based on the structural data of similar compounds, the bond-valence parameters of hydroxychlorides have been redetermined.

Structures of mono-unsaturated tri­acylglycerols. II. The β₂ polymorph. Corrigendum

A corrigendum to the paper by van Mechelen et al. (2006), Acta Cryst. B62, 1131–1138.

Notes for authors 2007