Pseudoatoms and preferred skeletons in crystals

A generalization of the Zintl–Klemm concept (ZKC) explains the complex structures of alloys as well as the cation arrays of oxides. This generalization helps to establish a univocal link between chemical composition (in terms of Klemm's pseudoatoms) and the structures observed experimentally.

Structures of stable and metastable Ge₂Bi₂Te₅, an intermetallic compound in a GeTe–Bi₂Te₃ pseudobinary system

Ge₂Bi₂Te₅ in the GeTe–Bi₂Te₃ pseudobinary system has two single-crystalline phases: a metastable phase with an NaCl-type structure and a stable phase with a nine-layer trigonal structure. These two crystalline phases in Ge₂Bi₂Te₅ have atomic configurations identical to those found in the two corresponding phases of Ge₂Sb₂Te₅.

Crystal chemistry of borates: the classification and algebraic description by topological type of fundamental building blocks

A novel systematic classification and a convenient algebraic description of borates were proposed on the basis of the topological structure and polymerization of FBBs (fundamental building blocks) in the borate crystallographic frame. The current work gives an impetus to elucidate topological features in borate chemistry and provides some useful statistical information to design and search for novel borate structures.

On the polyhedral volume ratios V_A/V_B in perovskites ABX₃

We present the formulae for the calculation of polyhedral volume ratios V_A/V_B for perovskite-type structures ABX₃ in terms of atomic coordinates. The analysis of crystallographic data for approximately 1300 perovskite structures from the Inorganic Crystal Structure Database resulted in the estimated values of ratios at which phase transitions occur.

Superspace crystal symmetry of thermoelectric misfit cobalt oxides and predicted structural models

The superspace crystal symmetry of two new misfit lamellar thermoelectric cobalt oxides is described. Structural models are deduced from generalized metric considerations and from observed crystal symmetries.

In situ observation of the tetragonal–cubic phase transition in the CeZrO₄ solid solution – a high-temperature neutron diffraction study

The crystal structure of the ceria–zirconia solid solution CeZrO₄ is refined by Rietveld analysis of neutron diffraction data measured in situ over the temperature range 296–1831 K. The cubic-to-tetragonal phase transition between 1542 and 1831 K is accompanied by the displacement of oxygen atoms and elongation of the c axis.

Electron diffraction and microscopy study of the structure and microstructure of the hexagonal perovskite Ba₃Ti₂MnO₉

The space group of the hexagonal perovskite Ba₃Ti₂MnO₉ has been determined using convergent-beam electron diffraction (CBED) and the microstructure investigated using high-resolution electron microscopy (HREM).

LiNaSiB₃O₇(OH) – novel structure of the new borosilicate mineral jadarite determined from laboratory powder diffraction data

Owing to the absence of crystals suitable for single-crystal X-ray diffraction, the structure of a new mineral, jadarite, with the composition LiNaSiB₃O₇(OH), has been determined using laboratory powder diffraction data. Its novel architecture consists of lithium, silicon and two of the B atoms forming unbranched vierer single layers of corner-sharing tetrahedra, themselves decorated by triangular borate groups, and connected by distorted NaO₆ octahedra. The structure was validated using ab initio modelling because of the extreme difficulty in obtaining neutron diffraction data from such a boron-rich sample.

Synchrotron powder diffraction in a systematic study of 4′-[2-(tosylamino)benzyl­idene­amino]-2,3-benzo-15-crown-5 complexes

The crystal structures of four compounds – 4′-[2-(tosylamino)benzylideneamino]-2,3-benzo-15-crown-5 (HL), ZnL₂, CuL₂ and LiNCS·HL, two of which (CuL₂ and LiNCS·HL) being determined from synchrotron powder diffraction data – were used in DFT calculations to determine a possible reason for the different ionic selectivities of ZnL₂ and CuL₂ complexes.

Structural similarities in tetra­aryltins described by virtual non-crystallographic rotations or translations: Kitaigorodskii's morphotropism is revisited

The reinvestigation of tetraaryltins together with the semantic elucidation of morphotropism revealed that isostructural groups of crystals are occasionally linked by non-crystallographic rotations and/or translations.

Structures of artificial sweeteners – cyclamic acid and sodium cyclamate with other cyclamates

The crystal structures of cyclamic acid and sodium cyclamate together with other cyclamates have been determined in the course of a study on artificial sweeteners.

Rapid structure determination of the hydrogen-containing compound Cs₂C₂O₄·H₂O by joint single-crystal X-ray and powder neutron diffraction

An accurate and precise crystallographic description for all atom types has been obtained rapidly for a hydrogenous material by the combined analysis of single-crystal X-ray diffraction and powder neutron diffraction data.

Solid-state compounds of stereoisomers: cis and trans isomers of 1,2-cyclo­hexanediol and 2,3-tetralindiol

The structure of the 1:1 compound of cis- and trans-2,3-tetralindiol, the existence of which has been known for nearly a century, has finally been determined. The likelihood of compound formation between stereoisomers is discussed.

Tautomerism and hydrogen bonding in guaninium phosphite and guaninium phosphate salts

The crystal structures of three similar guaninium salts are described and compared. The investigation of the hydrogen-bond network in these guaninium salts reveals the existence of two ketoamine tautomers, the N9H form and an N7H form.

X-ray studies of crystalline complexes involving amino acids and peptides. XLIV. Invariant features of supramolecular association and chiral effects in the complexes of arginine and lysine with tartaric acid

The crystal structures of tartaric acid complexes of arginine and lysine provide insight into the invariant and variable features of supramolecular association involving amino acids. The structures also contribute to information about the effect of chirality on such an association.

The application of cluster analysis to identify conformational preferences in enones and enimines from crystal structural data

Cluster analysis using the program dSNAP has been applied to the conformational analysis of enones and enimines using data from the Cambridge Structural Database.

Ab initio structure determination of 5-anilino­methylene-2,2-di­methyl-1,3-dioxane-4,6-dione from laboratory powder data – a combined use of X-ray, molecular and solid-state DFT study

The structure of the title compound was solved from laboratory powder data in the space group . Refinement was carried out by restrained Rietveld refinement as well as by structure optimization by energy minimization in the solid state at the DFT level of theory.

Isostructuralism among `bridge-flipped' isomeric benzylideneanilines and phenylhydrazones

The crystal structures of three pairs of isomeric benzylideneanilines and one pair of isomeric phenylhydrazones are described. The pairs are `bridge-flipped' isomers, related by the reversal of the bridge of atoms connecting the major parts of the molecules; all pairs but one are isostructural.

Investigation of hydrogen-bond network in bis­(glycinium) oxalate using single-crystal neutron diffraction and spectroscopic studies

Single-crystal neutron diffraction studies showed that the short hydrogen bond between the glycinium cation and the oxalate anion in the title compound is asymmetric in nature with no hydrogen disorder.

Redetermination, invariom-model and multipole refinement of L-ornithine hydrochloride

The structure of L-ornithine hydrochloride was investigated by an invariom refinement and a full multipole refinement, and the resulting electron densities on a grid were compared. Cruickshank's diffraction-component precision index and the suitability factor of Stevens and Coppens are discussed with respect to core scattering and improvement in figures-of-merit by aspherical atom refinements.