Search

To report the prevalence and topographic distribution of structural characteristics in study participants with age-related macular degeneration (AMD) and controls in the cross-sectional study part of the MACUSTAR study (ClinicalTrials.govIdentifier: NCT03349801). more...

Die Kristallstrukturen der Verbindungen Cs3CrCl6und Cs3Cr2Cl9werden auf der Basis von Röntgeneinkristalldaten bestimmt bzw. nachbestimmt. Cs3CrCl6kristallisiert in der orthorhombischen Raumgruppe Pnnm(Z= 6) mit den Gitterkonstanten a= 1115,6(2) pm, b= 2291,3(5) pm, c= 743,8(1) pm (Rf= 7,73%, 1025 symmetrieunabhängige Reflexe mit I> 2σ(I)). Die Struktur von Cs3CrCl6besteht aus zwei verschiedenen, isolierten CrCl6‐Oktaedern sowie fünf kristallographisch verschiedenen Caesiumionen. Die CrCl6‐Oktaeder bilden Stränge in Richtung [001]. Wegen einer Orientierungsfehlordnung der Cr(1)Cl6‐Oktaeder und der nur 50%igen Besetzung eines Teils der Cs+‐ und Cl–‐Lagen ist Cs3CrCl6in Richtung der Netzebene (020) stark fehlgeordnet. Die auf Grund der Fehlordnung erwartete Ionenleitfähigkeit ist jedoch mit 7,3 × 10–5Ω–1cm–1bei 740 K relativ niedrig. Die in der Literatur beschriebene Kristallstruktur von Cs3Cr2Cl9(P63/mmc, Z= 2; a= 721,7(2) pm und c= 1791,0(1) pm; Rf= 2,06%, 395 symmetrieunabhängige Reflexe mit I> 2,5σ(I)) wurde bestätigt. Die bei Raumtemperatur metastabile, mit Cs3CrCl6wahrscheinlich isotype Verbindung Cs3CrBr6konnte durch Abschrecken von 833 K dargestellt und röntgenographisch charakterisiert werden. more...

The nonstoichiometric compounds Rb0.75Cr5Se8and Cs0.76Cr5Se8crystallise in the monoclinic space group C2/m (Z = 2) being isostructural to KCr5S8(Rb0.75Cr5Se8: a = 1877.0(8) pm, b = 361.2(2) pm, c = 902.1(9) pm, b = 104.23(6)°, Rf= 0.0399, 826 unique reflections; Cs0.76Cr5Se8: a = 1885.3(9) pm, b = 362.7(2) pm, c = 910.9(3) pm, b = 104.27(4)°, Rf= 0.0524, 1280 unique reflections). The structures are build up by edge and face shared CrSe6octahedra forming one-dimensional channels parallel to the monoclinic b axis. In these channels, the alkali metal ions are located. Many compounds of the KCr5S8-structure type display significant enlargement of the U11or the U22 displacement parameters of the univalent metal ions. A model that can explain the enlargement of these parameters is presented. It is based on the relative size of the MIlattice sites including repulsions and M+ion deficiency phenomena. more...

The results of band structure (extended Hückel procedure) and cohesive energy calculations of spinel-type chromium oxides and sulfides, and of lithium vanadium chloride were presented. They confirm that the D3dto C3vsymmetry reduction of the octahedrally coordinated metal ions (Cr, V) of the respective oxides and of Li2VCl4(space group F-43m instead of Fd-3m) is caused by relatively strong metal-metal bonds with crystal orbital overlap populations (COOP) up to 10% of those of the metal-oxygen bonds despite M-M distances ≅300pm. In the case of spinel-type chromium sulfides, the Cr-Cr interactions are antibonding in nature and, hence, no symmetry reduction occurs. more...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. more...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. more...