The charge-flipping algorithm in crystallography

The state-of-the-art charge-flipping algorithm is summarized, and its applications to various crystallographic problems connected with structure solution are reviewed.

The role of the coordination defect (CD) in the structures of anion-deficient, fluorite-related compounds

The many superstructure phases of rare-earth oxides M_nO_2n − 2 are rationalized in terms of the `coordination defect model'.

Structural transformations in the low-temperature grown GaAs with superlattices of Sb and P δ-layers

Structural transformations in superlattices of Sb and P δ-layers upon annealing were studied in low-temperature grown GaAs. The combination of Sb and P δ-layers appears to be an effective tool for spatial patterning of arsenic nanoinclusions and prevention of the defect formation in the GaAs matrix.

Electronic influence of β-diketonato-type ligands on the coordination of 1,5-cyclo­octadiene to palladium(II) as defined by `Venus fly trap' geometric parameters

The influence of inter- and intramolecular interactions in a range of palladium(II) β-diketonato complexes, as investigated by single-crystal X-ray crystallography, is presented in relation to solid-state packing modes, bond distances, hydrogen bonds and halogen interactions, while the `Venus fly trap' parameters of the 1,5-cyclooctadiene ligand are defined as a function of its bonding to the palladium(II) metal centre.

Weak intermolecular hydrogen and halogen interactions in an isomorphous halogen series of pseudoterpyridine Zn^II complexes

The structures of four halogen pseudoterpyridine Zn^II complexes are analysed for the influence of very weak intermolecular interactions on their crystal packings.

Structural and electronic aspects of hydrogen bonding in two polymorphs of butylene-N,N′-bis­(O,O′-di­arylphosphoramidate)

The solid-state and gas-phase structure of (C₆H₅O)₂P(O)NH(CH₂)₄NHP(O)(OC₆H₅)₂ are reported.

Entry point into new trimeric and tetrameric imide-based macrocyclic esters derived from isophthaloyl dichloride and methyl 6-aminonicotinate

The reaction of isophthaloyl dichloride with methyl 6-aminonicotinate yields `3 + 3' and `4 + 4' imide-linked macrocycles with the former representing a new macrocycle class (trezimide). The role of 2-aminopyridine in imide hinge formation and ultimately macrocyclization is pivotal to this one-step synthetic route into cyclic triimides (trezimides) and tetraimides (tennimides).

Thermodynamic and structural relationships between the two polymorphs of 1,3-di­methylurea

Polymorph (I) of dimethylurea (Fdd2) is the more stable modification at room temperature, where polymorph (II) (P2₁2₁2) is metastable; the thermodynamic transition temperature lies between 253 K and room temperature.

A high-pressure polymorph of chlorpropamide formed on hydrostatic compression of the α-form in saturated ethanol solution

The crystal structure of a high-pressure monoclinic polymorph (P2₁11) of chlorpropamide has been determined. It is formed at ∼ 2.8 GPa on hydrostatic compression of the orthorhombic stable α-polymorph (P2₁2₁2₁) in saturated ethanol solution.

On the shortest B^III—O bonds

For the crystal structures of oxoborates, the value of ∼ 1.2 Å can be regarded as the lower physical limit for B^III—O bond lengths. The oxoborate crystal structures with B^III—O bond lengths shorter than ∼ 1.2 Å have been found to be either doubtful or clearly erroneous.