Superstructure Ordering of Intermetallics: B8 Structures in the Pseudo-Cubic Regime

The class of B8-type compounds (structure types NiAs, Ni₂In and to some extent MnP and Co₂Si, and superstructures thereof) has attracted interest throughout the history of crystallography. Today, there is renewed interest in this topic from the point of view of modulated structures and structured diffuse scattering.

Structure Refinement of Monoclinic Astrophyllite

The crystal structure of monoclinic astrophyllite, whose chemical composition and crystal structure are different from astrophyllite (triclinic system), has been redetermined.

β-K₂SO₄-Type Isomorphs: Prediction of Structures and Refinement of Rb₂CrO₄

Using ionic radii and calculated Mulliken charge densities it is possible to predict cell parameters and atomic coordinates for members of an isostructural series. For the β-K₂SO₄ series, predictions agree well with experiment, except for an early structure determination of Rb₂CrO₄. New X-ray data give a structure in close accord with that predicted. Parameters are predicted for the, as yet, undetermined structures of Rb₂MnO₄ and Rb₂FeO₄.

Neutron and X-ray Diffraction Study of the Thermal Motion in K₂PtCl₆ as a Function of Temperature

The structure and atomic thermal motions of K₂PtCl₆ are studied as functions of temperature between 8 and 380 K with 11 neutron and X-ray single crystal and powder data sets.

Chain, Sheet and Framework Structures in the Adducts of Phenylphosphonic Acid with 4,4'-Bi­pyridyl (1/1), Piperazine (2/1) and 1,4-Di­azabi­cyclo[2.2.2]octane (2/1)

Phenylphosphonic acid forms a stem-and-leaves motif in its 1:1 adduct with 4,4'-bipyridyl, where the acid-dimer motif is retained; in its 2:1 adduct with piperazine, where sheets are formed, again the acid-dimer motif is retained. The 2:1 adduct with DABCO shows retention of the acid-chain motif in a three-dimensional framework structure.

Crystal Engineering Using Bis- and Tris-phenols. Adducts with 1,4,8,11-Tetra­aza­cyclo­tetra­decane (Cyclam): Isolated Ladders in the Adduct with 4,4'-Thiodiphenol, Tethered Ladders in the Adduct with 4,4'-Sulfonyldiphenol and Two Interwoven Three-Dimensional Networks in the Adduct with 1,1,1-Tris(4-hydroxyphenyl)ethane

The 2:1 adducts formed between 4,4'-thiodiphenol or 4,4'-sulfonyldiphenol with cyclam take the form of supramolecular ladders, with chains of diphenol anions forming the uprights and [cyclamH₂]²⁺ cations the rungs; with CH₃C(C₆H₄OH)₃, cyclam forms a three-dimensional interwoven structure without void spaces.

Formation of One-Dimensional Chains, Two-Dimensional Bilayers and a Three-Dimensional Diamondoid Architecture in Hydrogen-Bonded Adducts of 4,4'-Biphenol with 1,4-Di­azabi­cyclo[2.2.2]octane and 1,2-Di­amino­ethane

4,4^'-Biphenol forms simple chains in its 1:1 adduct with 1,4-diazabicyclo[2.2.2]octane, two-dimensional sheets in its methanol-solvated 2:1 adduct with 1,2-diaminoethane and a three-dimensional diamondoid architecture in its 1:1 adduct with 1,2-diaminoethane.

Pseudoacids. I. 4- and 5-Oxoacids

Pseudoacids are cyclic oxoacids or lactols formed in favorable cases by intramolecular reaction of carboxylic acid and aldehyde or ketone functions. The resulting nominal C-O bonds from the former aldehydo or keto carbon differ in length by ~0.08Å, based on disparities in oxyanion leaving-group basicities.

Low-Temperature Synchrotron Radiation Study of a Twinned Disordered Crystal of Bis(4,4'-bromo­phenyl)-61,61-diyl Methano Fullerene C₆₀

Combined use of synchrotron radiation and area-detector technology allows the structure of a twinned crystal containing two isomers of the title compound to be solved.

Hydrogen-Bonded Urea–Anion Host Lattices. 6. New Inclusion Compounds of Urea with Tetra-n-propylammonium Halides

The novel inclusion complex 2(n-C₃H₇)₄N⁺F⁻.7(NH₂)₂CO.- 3H₂O contains a channel framework built from urea ribbons that are bridged by fluoride ions, water molecules and other urea molecules. The complexes (n-C₃H₇)₄N⁺Cl⁻.y(NH₂)₂CO (y = 2, 3) feature layer and channel-type urea-chloride host lattices, respectively, whereas the isomorphous compounds (n-C₃H₇)₄N⁺- X⁻.3(NH₂)₂CO.H₂O (X = Br, I) exhibit a channel-type host lattice built of corrugated urea layers and centrosymmetric cyclic (H₂O–X⁻)₂ units.

Towards extinction-free experimental diffraction data on Al₂O₃

Virtually extinction-free 58 keV (0.214 Å) synchrotron radiation data on Al₂O₃ produce high-quality deformation electron density maps, which compare very well with theoretical maps.

Molecular Toxicology by P. D. Josephy