The development and use of a crystallographic database

To scientists working with small-molecule or organometallic compounds, the Cambridge Structural Database constitutes an extremely important tool for reference to individual crystal structures and as a data source for statistical investigations. The article by Groom et al. provides updated information on the use, development and future of this database.

Expanding the usage of the Source Function to experimental electron densities

The Source Function provides unique information about chemical bonding in the solid state, from theory as well as from experiment. It is now established that the concept of electronic delocalization in aromatic systems can be accurately studied using X-ray derived electron densities, and even more importantly the contributions are transferable between similar systems.

The Cambridge Structural Database

This paper is the definitive article describing the creation, maintenance, information content and availability of the Cambridge Structural Database (CSD), the world's repository of small molecule crystal structures.

Source Function applied to experimental densities reveals subtle electron-delocalization effects and appraises their transferability properties in crystals

The Source Function (SF), enabling the electron density to be viewed at a point as determined by source contributions from the various atoms or group of atoms of a system, is defined in terms of observables and it is amenable to experimental determination from accurate X-ray diffraction data. The use of the SF tool to discuss chemical bonding in molecules and crystals is reviewed, ahead of demonstrating that such a tool is also able to detect electron-delocalization effects and to assess their transferability properties in a series of paradigmatic molecular crystals, starting from knowledge of only the X-ray derived crystal electron densities.

Structure modulations in nonlinear optical (NLO) materials Cs₂TB₄O₉ (T = Ge, Si)

Incommensurately modulated borate structures of a new type are featured with ordering of oxygen atoms in nonlinear optical (NLO) materials Cs₂TB₄O₉ (T = Ge, Si).

A novel polytype – the stacking fault based γ-MoO₃ nanobelts

γ-MoO₃ nanobelts were prepared by hydrothermal synthesis. The novel polytype crystal structure and morphology of the belts were studied by synchrotron radiation powder diffraction, scanning electron microscopy, transmission electron microscopy and selected area electron diffraction. Their nm dimensions, in particular in two crystallographic directions, have a profound influence on electrochemical properties during cycling as the cathode material in Li-coin cells. The crystal structure for the γ-MoO₃ nanobelts differs significantly from that of bulk α-MoO₃. The question of whether the disorder structure type of γ-MoO₃ nanobelts is the main reason for the increased charge capacity of MoO₃ nanobelts from 200 for bulk materials up to 340 mAh g⁻¹ for nanobelts remains open.

Melilite-like modulation and temperature-dependent evolution in the framework structure of K₂Sc[Si₂O₆]F

This paper describes the crystal structure of synthetic K₂Sc[Si₂O₆]F in superspace group P4₂/mnm(α,α,0)000s(−α,α,0)0000 with modulation wavevectors q₁ = 0.2982 (4)(a* + b*) and q₂ = 0.2982 (4)(−a* + b*). The structure is a mixed octahedral–tetrahedral framework composed of [ScO₄F₂] octahedra, [Si₄O₁₂] rings and K in variable coordination.

An exceptional 5:4 enantiomeric structure

The difficulty of obtaining crystals of a resolvable [RuL₃]²⁺ cation is consistent with the remarkably complex structure of its PF₆⁻ salt.

Molecular structure of di­ethylaminoalane in the solid state: an X-ray powder diffraction, DFT calculation and Raman spectroscopy study

The crystal structure of diethylaminoalane, [H₂Al—N(C₂H₅)₂]₂, was determined by X-ray powder diffraction, geometry optimization by density functional theory (DFT) and Raman spectroscopy. The DFT calculations were validated by calculating the ground state structures of two known aminoalanes while the Raman spectrum of diethylaminoalane was measured and compared to the simulated ones. Furthermore, the crystal structure of diethylaminoalane is compared with chemically and structurally similar compounds.

Geometry of trigonal boron coordination sphere in boronic acids derivatives – a bond-valence vector model approach

The bond-valence vector model is applied for the identification and analysis of subtle in- and out-of-plane distortions in three-coordinate boron in molecules containing a CBO₂ skeleton.

Quartz: structural and thermodynamic analyses across the α ↔ β transition with origin of negative thermal expansion (NTE) in β quartz and calcite

The structural analysis of quartz across the α ↔ β transition is satisfactorily modelled with Landau theory. Cation–cation contractions give rise to negative-thermal expansion (NTE) in quartz and calcite.

New polymorphs of an old drug: conformational and synthon polymorphism of 5-nitrofurazone

Two new polymorphic forms of 5-nitrofurazone (5-nitro-2-furaldehyde semicarbazone) have been synthesized and structurally characterized by single-crystal and powder X-ray diffraction methods, vibrational spectroscopy, thermal and Hirshfeld surface analysis.

Structural complexity and configurational entropy of crystals

Structural complexity measured as the Shannon information per atom represents a negative contribution to the configurational entropy of a crystalline solid.

Resolving the structure of TiBe₁₂

With the aid of atomic scale lattice dynamics simulations, the article resolves the long-standing controversy regarding the structure of TiBe₁₂. The structure is confirmed to be tetragonal, whilst the hexagonal sub-cell used in recent publications is found to be an inappropriate model.

Minerals: A Very Short Introduction

Transition Metal Compounds

Pyrite. A Natural History of Fool's Gold

Nanoparticles