Structure of Ce₂RhIn₈: an example of complementary use of high-resolution neutron powder diffraction and reciprocal-space mapping to study complex materials

The crystal structure of Ce₂RhIn₈ is reported. It is disordered, exhibiting a complex interplay of planar defects, coexistence and segregation of polytypic phases (with slightly different tetragonal structures), mosaicity and non-uniform strain.

On the crystal structure of Cr₂N precipitates in high-nitrogen austenitic stainless steel. II. Order–disorder transition of Cr₂N during electron irradiation

During electron irradiation, the superlattice reflections characterizing the ordered Cr₂N superstructure gradually disappeared in regular sequence, indicating that the order–disorder transition (ODT) occurred. The redistribution of N atoms through the ODT is discussed based on the characteristics of superlattice reflections.

Description of Ba_1 + xNi_xRh_1 − xO₃ with x = 0.1170 (5) in superspace: modulated composite versus modulated-layer structure

Ba_1 + xNi_xRh_1 − xO₃ belongs to the family of trigonal compounds A_1 + xAB_1 − xO₃. Its structure at room temperature is refined applying the superspace approach and discontinuous atomic domains. It is on the one hand described as a modulated composite and on the other as a modulated-layer structure.

Crystal structure of the high-pressure phase of the oxonitridosilicate chloride Ce₄[Si₄O_3 + xN_7 − x]Cl_1 − xO_x, x ≃ 0.2

Crystal structures and compression mechanisms of the cubic low-pressure and orthorhombic high-pressure phase of a cerium oxonitridosilicate chloride were determined by in situ single-crystal synchrotron X-ray diffraction at pressures of 3.0, 8.5 and 8.6 GPa using the diamond–anvil cell technique. A spontaneous change of the crystal colour was observed at the phase transition between 8.5 and 8.6 GPa.

Temperature dependence of the silver distribution in the crystal structure of natural pearceite, (Ag,Cu)₁₆(As,Sb)₂S₁₁

The crystal structure of a natural pearceite crystal with the chemical composition (Ag_12.15Cu_3.84)_{Σ = 15.99}(As_1.18Sb_0.83)_{Σ = 2.01}S_11.00 has been solved and refined from X-ray single-crystal diffraction data at 300, 120 and 15 K. d¹⁰ silver-ion distribution over diffusion-like paths has been determined by means of a combination of a Gram–Charlier description of the atomic displacement parameters and a split-atom model.

Anions in metallic matrices model: application to the aluminium crystal chemistry

The localization and formation of anions in inorganic compounds are induced by the inhomogeneities of the electron density of the host metallic sub-lattices. This `anions in metallic matrices' model is supported by quantum-mechanical simulations of aluminium compounds.

Modulated structure of potassium sodium strontium barium niobates (KNSBN): harmonic solution

The modulated crystal structures of two compounds of the (K_1 − yNa_y)_2F − 2(Sr_xBa_1 − x)_2 − FNb₂O₆ family (KNSBN) have been solved by means of X-ray diffraction and the five-dimensional superspace approach.

Experimental charge-density study on the nickel(II) coordination complex [Ni(H₃L)][NO₃][PF₆] [H₃L = N,N′,N′′-tris­(2-hy­droxy-3-methylbutyl)-1,4,7-tri­aza­cyclononane]: a reappraisal

The charge density in the pendant-arm macrocylic nickel(II) coordination complex [Ni(H₃L)][NO₃][PF₆] [H₃L = N,N′,N′′-tris(2-hydroxy-3-methyl butyl)-1,4,7-triazacyclononane] has been re-examined. Unusual features of this charge density, which have been previously reported, are now shown to be artefacts due to a programming error.

Solvothermal synthesis, multi-temperature crystal structures and physical properties of isostructural coordination polymers, 2C₄H₁₂N⁺[M₃(C₈H₄O₄)₄]²⁻·3C₅H₁₁NO, M = Co, Zn

A Co-based ferromagnetic coordination polymer and the Zn-based nonmagnetic structural isomer have been synthesized and characterized.

Packing and polytypism in 1,10-phenanthrolin-1-ium (2-carboxyethyl)(2-carboxylato­ethyl)di­chloro­stannate(IV)

Triclinic crystals obtained from a 1:1 mixture of [SnCl₂(C₂H₄COOH)₂] and 1,10-phenanthroline were examined. Crystals of the accurately determined Z = 2 structure are generally twinned, and the twin-disorder mechanism suggests the structure for a Z = 6 triclinic modification, for which there is diffraction evidence but not a complete structure determination.

(Z,2R,3R,4aR,7R,12aS)-2,3,7,8,12,12a-Hexa­hydro-2,3-di­meth­oxy-2,3,7-tri­methyl-4aH-[1,4]dioxino[2,3-c]oxecin-5(11H)-one: a commensurate occupationally modulated structure revealing a condition for diffraction symmetry enhancement for non-parent reflections

(Z,2R,3R,4aR,7R,12aS)-2,3,7,8,12,12a-Hexahydro-2,3-dimethoxy-2,3,7-trimethyl-4aH-[1,4]dioxino[2,3-c]oxecin-5(11H)-one crystallizes in the space group P3₁ with Z = 9 and approximates the conditions necessary for the h − k ≠ 3N reflections to have 1m diffraction symmetry without twinning. The structure may be described as an occupancy modulation of a 1:1 disordered P3₁21 parent structure with Z = 3.

Spatial arrangement of molecules in homomolecular Z' = 2 structures

The analysis of homomolecular Z = 2 structures within the context of the Box Model has shown that the fundamentals of crystal packing are not dependent on Z.

Structure determination and phase transition behaviour of di­methyl sulfate

The crystal structures of phase I and phase II of dimethyl sulfate, (CH₃O)₂SO₂, have been determined using complementary high-resolution neutron powder and single-crystal X-ray diffraction techniques. Below its melting point of 241 K dimethyl sulfate crystallizes in an orthorhombic structure (I) in space group Fdd2, which transforms, below ∼175 K, to a monoclinic structure (II) in space group I2/a.

Single-crystal X-ray and neutron powder diffraction investigation of the phase transition in tetra­chlorobenzene

The polymorphic phase transition of 1,2,4,5-tetrachlorobenzene (TCB) has been investigated using neutron powder diffraction and single-crystal X-ray diffraction.

High-pressure polymorphism in L-cysteine: the crystal structures of L-cysteine-III and L-cysteine-IV

Compression of orthorhombic L-cysteine-I, which contains molecules in the g⁺ conformation, leads to the formation of a new orthorhombic phase (L-cysteine-III) with the molecules in the g⁻ conformation. Decompression of L-cysteine-III ultimately leads to L-cysteine-I, but this proceeds through an intermediate phase, L-cysteine-IV, which contains molecules in both g⁺ and g⁻ conformations.

Effect of pressure on the crystal structure of α-glycylglycine to 4.7 GPa; application of Hirshfeld surfaces to analyse contacts on increasing pressure

The effect of pressure up to 4.7 GPa on the crystal structure of the simplest dipeptide, glycylglycine, has been investigated. The structure is built of layers resembling the β-sheets of proteins. These layers are quite robust, with the main structural effect of pressure being to compress layers together

Structural investigations of phosphorus–nitrogen compounds. 7. Relationships between physical properties, electron densities, reaction mechanisms and hydrogen-bonding motifs of N₃P₃Cl_{(6 − n)}(NHBu^t)_n derivatives

The crystal structures of N₃P₃Cl₅(NHBu^t) and N₃P₃Cl₂(NHBu^t)₄ have been determined at 120 K, and those of N₃P₃Cl₆ and N₃P₃Cl₄(NHBu^t)₂ have been redetermined at 120 K. These are compared with the known structure of N₃P₃(NHBu^t)₆, which was studied at 150 K. Molecular parameters and hydrogen-bonding motifs are discussed and compared in the light of their chemical and physical properties.

Low-temperature structure of rubrene single crystals grown by vapor transport

The structure of rubrene single crystals grown by vapor transport has been studied in the temperature range 100–300 K and correlated with the electronic properties. In rubrene the electronic mobility, which is very high, changes rapidly near 175 K.

Crystal chemical information to be obtained from the bond-number equality concept

An equation is derived for anion complexes of normal valence compounds where the ratio of triangularly to tetrahedrally coordinated central atoms is correlated with the fractions of anions having one, two, three and four bonds to central atoms. The equation can be of help to formulate the crystal chemical formulae of compounds with unknown crystal structure.

Crystalline Molecular Complexes and Compounds