issue contents
October 2014 issue
Cover illustration: Proposed mechanism for the structural evolution of -MnO2 with time. This mechanism helps understand the fate of the element in surfacial environmental studies [see Grangeon et al. [(2014), Acta Cryst. B70, 828-838].
scientific commentaries
This paper presents a pixel detector mounted on a commercial goniometer, equipped with a microfocus X-ray source, to generate high-resolution X-ray data, well suited for experimental charge density investigations.
research papers
Download citation
Download citation
It is shown that high-resolution X-ray diffraction data collection with a laboratory diffractometer equipped with a hybrid pixel detector gives excellent quality structure-factor amplitudes for charge density analysis.
CCDC reference: 1016354
Download citation
Download citation
Three crystal forms of the new Schiff base ligand, N,N′-bis(5-methylsalicylidene)-4-methyl-1,3-phenylenediamine, have been found in the course of the synthesis of its complexes with rare earth metals. These forms have different numbers of symmetry-independent molecules (Z′ = 1, 3 and 4); only weak intermolecular interactions are involved in the crystal structure as the strong hydrogen bond donors are engaged in relatively strong intramolecular O—H⋯N bonds.
VF3-type FeF3 is predicted to become unstable above 51 GPa, as the result of enhanced structural distortion caused by development of octahedral elongation along the a axis.
A theoretical study of CaMnO3 perovskite structures was performed combining various methods ranging from data mining to the ab initio local optimizations.
Download citation
Download citation
Open access
X-ray diffraction analyses for new pentamidine analogs are presented: 1,4-bis(4-cyanobenzyl)piperazine (1) crystallizes in the triclinic space group () and 1,4-bis(4-amidinobenzyl)piperazine tetrahydrochloride tetrahydrate (2) in the monoclinic space group (P21/n) revealing a complex system of hydrogen bonds for (2).
Synthetic vernadite was equilibrated at pH values ranging from 3 to 10 and its crystal structure elucidated using X-ray diffraction on fresh samples and on samples aged for up to 8 years. The main structural transformation with time is related to the migration of Mn3+ from the octahedral layer to the interlayer. For low pH samples, which initially contain a higher number of interlayer Mn3+, this transformation leads to a tunnel-like cryptomelane structure (2 × 2 tunnel size).
Download citation
Download citation
Dialkyl succinates with odd numbers of carbon atoms in the alkyl side chain exhibit higher melting points than the immediately adjacent analogues with even numbers. This melting point alternation is attributed to the molecular packing density differences and geometric factors.
Download citation
Download citation
The first charge density study using a Bruker AXS CMOS-type PHOTON 100 detector is reported. The analysis reveals high-quality X-ray diffraction data collected for the selected case of a complex organic crystal containing oxalic acid, ammonium oxalate and water molecules.
CCDC reference: 1017251
Download citation
Download citation
Open access
The most stable sorption site of dimethyl ether on silicalite-1 is the sinusoidal channel. The configuration of guest molecules (linear or bent) plays an important role in determining where the stable sorption site is situated.
CCDC reference: 1012728
Bond valence sum at mixed occupancy sites show the occurrence of systematic errors leading to apparent violations of the Valence Sum Rule as well as to erroneous bond strain values indicating underbonding or overbonding that actually does not exist.
Download citation
Download citation
The phase diagram of combined alkaline light-metal and heavy-metal borohydrides is explored and revealed to be surprisingly rich. The Li cation is revealed to be a versatile node, allowing for three- and fourfold connectivity in the same structure. Topologies of the Li-BH4 substructure range from isolated chains to three-dimensional frameworks as a function of Li content.
Download citation
Download citation
The structure of Cu3Sn is best understood as a compositional modulation of a simple hexagonal close packing. It is one member of a large family of such structures.
B-IncStrDB reference: 9792EkbCGH
The orientations of dispersoids of the cubic icosahedral quasicrystal approximation phase α-Al(Fe,Mn)Si in aluminium matrix have been studied by electron diffraction. The commonly observed orientation relationship is explained by an internal fixed orientation of the inner part Mackay icosahedron of the structure.
short communications
Download citation
Download citation
A new chloroauric acid with water of crystallization and ethanol is prepared and discussed.
CCDC reference: 1016070
Download citation
Download citation
This work reports on the structural study of a two-dimensionally stacked heterometallic compound built by hydrogen bonds which hosts a well resolved discrete dodecameric ring of water clusters in a chair conformation.
CCDC reference: 1022754