Die Struktur von Cyclosporin C

The Structure of Cyclosporin C The structure of cyclosporin C ( 2 ), a minor antifungal metabolite from Trichoderma polysporum (Link ex Pers.) RIFAI has been elucidated. Hydrolytic cleavage and spectroscopic evidence show that cyclosporin C is a neutral oligopeptide of 11 amino acids linked together in a 33-membered ring. Cyclosporin C ( 2 ) differs from the main metabolite cyclosporin A ( 1 ) [2] [4] only by containing L-threonine in the place of L-α-aminobutyric acid as has been shown by the conversion of 2 into 1 . ¹³C-NMR. spectra and study of molecular models suggest that cyclosporin C ( 2 ) has the same molecular conformation as 1 , which is best described as a twisted β-pleated sheet held together in a conformationally stable form by intramolecular hydrogen bonding.     

Darstellung und Struktur von Ag2C4O4

Preparation and Structure of Ag₂C₄O₄ Ag₂C₄O₄ occurs in a yellow and a colourless modification. Both forms decompose to metallic silver upon heating. Ag⁺ is coordinated in two different fashions in the yellow Ag₂C₄O₄. Ag(1) shows distorted tetrahedral coordination, Ag(2) is coordinated in an unusual distorted square planar manner. The connection of Ag⁺ and C₄O₄^2? leads to a complicated three-dimensional framework. C₄O₄^2? is planar with C? O and C? C bonds lengths typical of complete delocalization of the π-electron system.     

Die Struktur von Panepoxydon und verwandten Pilzmetaboliten

The structure of panepoxydone ( 1 ) and some related products, produced by two species of Panus (basidiomycetes), are proposed on the basis of chemical transformations and physical measurements. The absolute configurations of the main products are deduced by the interpretation of CD. studies and compared with those of the structurally related compounds epoxydone ( 10 ), terreic acid ( 11 ) and terremutin ( 12 ).     

Die Herstellung und Untersuchung von Oxydkathoden von kolloider Struktur

Ohne Zusammenfassung Die erste Ver?ffentlichung über diesen Gegenstand: E. Patai, Matematikai és Fizikai Lapok35, 145 (1929) (ungarisch, mit Auszug in deutscher Sprache).     

Struktur und Bildung von RbCs11O3

Structure and Formation of RbCs₁₁O₃ Formation, crystal structure, and thermal analysis of the ternary suboxide RbCs₁₁O₃ are reported. RbCs₁₁O₃ crystallizes in the orthorhombic space group Pmn2₁? C (Z = 2) with lattic constants a = 1648.4(4), b = 1371.3(5) c = 913(1) pm. It melts incongruently at +10°C and consists of an (idealized) hexagonal close packed arrangement of Cs₁₁O₃ groups, the single Rb atom occupying the quasi tetrahedral holes of this arrangement. Structural relationships to CsCs₁₁O₃ and Cs₁₁O₃ are discussed.     

Die Struktur von HfP

Zusammenfassung HfP wird hergestellt und seine Struktur ermittelt. Diese erweist sich isotyp mit TiP und -ZrP.     

Zur Darstellung und Struktur von LaTa7O19 Röntgenographische und elektronenmikroskopische Untersuchungen

Preparation and Structure of LaTa₇O₁₉. X-Ray and Electronmicroscopic Investigations In the system La₂O₃/Ta₂O₅ a new ternary compound LaTa₇O₁₉ could be prepared by chemical transport in a temperature gradient T₂ → T₁ (1120 → 1020°C; Cl₂ was added). LaTa₇O₁₉ is hexagonal, space group P6 with the lattice constants a = 6.23₆ and c = 19.99₅ Å. In the structure double layers of pentagonal TaO₇-bipyramids are recognizable perpendicular to [001]-direction. They alternate with a single layer consisting of La? O and Ta? O coordination polyhedra. Images of the structure were made with high resolution transmission electron microscopy along the [001]-direction. Despite the length of the axis the computer simulation based on the multi-slice method agreed well with the experimental images.     

Die Struktur von Benzazarsol

Structure of Benzazarsole Benzazarsole crystallizes in the space group Pna2₁ with a = 8.283, b = 5.560, c = 14.647 Å and with 4 formula units per units cell. The structure was determined by X-ray structure analysis and refined to a final R value of R = 0.04. The arsenic atom has the coordination number 2 with significantly different bond lengths to the adjacent carbon atoms (1.82 and 1.92 Å). The estimated bond lengths and the strict planarity confirm the conclusion of benzazarsole being an aromatic molecule. The structure of benzazarsole is compared with the structures of benzimidazole and benzazaphosphole.     

Zur Darstellung und Struktur von LaTa3O9 Röntgenographische und elektronenmikroskopische Untersuchungen

Preparation and Structure of LaTa₃O₉. X-Ray and Electronmicroscopic Investigations In the system La₂O₃/Ta₂O₅ a new ternary compound LaTa₃O₉ could be prepared by chemical transport in a temperature gradient T₂ → T₁ (1100 → 1040°C; Cl₂ was added). LaTa₃O₉ is orthorhombic, space group Pnma–D with the lattice constants a = 6.59₅, b = 7.66₄, and c = 12.48₁ Å. In the structure ribbons of pentagonal TaO₇-bipyramids are recognizable parallel to the a-direction. These ribbons are connected with each other in the (010) plane by TaO₆-octahedra. The tunnels formed in this way are occupied by La atoms. High resolution transmission electron microscopy images of the structure were made along the [010] direction. They were interpreted by using images calculated on the basis of the multi-slice method.     

Die Struktur von TiAs

Zusammenfassung Die vor kurzem vonN. Schönberg aufgeklärten Strukturen von TiP, -ZrP, -TaP, MoP und WP werden bestätigt.Im System Ti–As treten mehrere intermediäre Phasen auf. Bei der ungefähren Zusammensetzung TiAs wurden zwei Phasen identifiziert. Eine der beiden kristallisiert im NiAs-Typ mit den Gitterkonstanten:a=3,63k X · E,c=6,14k X · E undc/a=1,69. Die zweite ist isotyp zu TiP und hat die Gitterkonstanten:a=3,64k X · E,c=12,2₈ k X · E undc/a=3,38. Ihr Aufbau steht in unmittelbarem Zusammenhang.     

Die Struktur von HfAl

Zusammenfassung HfAl kristallisiert rhombisch (D ₂ ⁵ ) mit den Gitterkonstantena=10,81;b=3,24₉;c=4,27₂kX. E. Die Struktur, offensichtlich ein eigener Typ, wird ermittelt und diskutiert.Mit 1 Abbildungen