Structural phase transition and related electronic properties in quasi-one-dimensional (NbSe₄)_10/3I

The real crystal structure of the (NbSe₄)_10/3I charge density wave (CDW) compound is studied by simulation of the X-ray diffuse scattering. The average structure of the low-temperature twinned phase is determined and the phase transition is attributed to the formation of a CDW.

A new complex intermetallic phase in the system Al–Cu–Ta with familiar clusters and packing principles

A new compound, hP386-Al_57.4Cu_3.6Ta_39.0, is described in detail by multiple approaches and compared with related structures.

Use of intensity quotients and differences in absolute structure refinement

Differences and quotients can be defined using Friedel pairs of reflections and applied in refinement to enable absolute structure to be determined precisely even for light atom crystal structures.

Hirshfeld surface analysis of new phosphoramidates

New phosphoric triamide structures having different segments [C(=O)NH]P(=O)[N]₂, [O]₂P(=O)[N] and [N]₂P(=O)OP(=O)[N]₂ have been analyzed using Hirshfeld surfaces and two-dimensional fingerprint plots, providing a detailed description of salient features in the crystal structures.

A high-pressure single-crystal to single-crystal phase transition in DL-alaninium semi-oxalate mono­hydrate with switching-over hydrogen bonds

The first example of a single-crystal diffraction study of a high-pressure phase transition in a crystalline amino acid salt hydrate is reported. The transition is accompanied by pronounced discontinuities in the cell parameters and volume versus pressure, although no radical changes in the molecular packing are induced.

The versatile role of the ethynyl group in crystal packing: an interaction propensity study

Analysis of 824 crystal structures containing the ethynyl group C—C≡C—H shows that it acts as a hydrogen-bond donor or acceptor in 87% of those structures, and makes key contributions to crystal packing.

Absolute structure of R-(−)-2-methylpiperazine and S-(+)-2-methylpiperazine

Absolute structure of 2-methylpiperazine by Flack, Parsons' Q and Hooft methods.

Structural characterization of some N-phenyl-4-oxo-4H-2-chromone carboxamides

The molecular geometries and conformations of N-phenyl-4-oxo-4H-2-chromone carboxamides appear to be dependent on the possibility of establishing intramolecular hydrogen bonds.

Crystallographic input data for (001), (110) and (111)-oriented superlattices. Corrigendum

Corrigendum to the data published in the article by Touaa & Sekkal [(2012), Acta Cryst. B68, 378–388].