Kristallstruktur und katalytische Wirksamkeit

Relationships between aspects of structure and catalytical activity are discussed for aluminas, X-ray amorphous alumina silicates, zeolites, active coals and metals, respectively.     

Die Molekül- und Kristallstruktur des N-Methyl-piperidinium-acet-para-brom-anilid-jodid

N-Methyl-piperidinium-acet-para-bromo-anilide-iodide crystallizes in the triclinic space group P 1 with two formula units C₁₄H₂₀N₂OBrJ and two H₂O molecules in the unit cell. The lattice constants are a = 8.950 Å, b = 14.721 Å, c = 7.440 Å, α = 80.19°, β = 112.57° and γ = 106.82°. The molecular structure of the compound was determined by the X-ray structure analysis and the interaction between the molecules in the crystal was investigated. Especially the influence of the water in the crystal on the form of the molecule was analysed.     

Die Molekül- und Kristallstruktur des N-Methylpiperidinium-acet-para-nitro-anilid-jodid

The compound N-methyl-piperidinium-acet-para-anilide-iodide crystallizes in the triclinic space group P1 with 2 molecules in the unit cell of dimensions a = 7.164, b = 16.818, c = 6.974 Å, α = 94.20, β = 102.95, γ = 86.15°. The accurate measurement of the intensities of the X-ray reflexions by an automatic four circle diffractometer allowed the determination of the positions of the hydrogen atoms in this heavy atom structure containing one iodine atom per molecule. The final R value is 0.097 for all 3033 reflexions.     

Die Molekül- und Kristallstruktur des N-Methyl-piperidinium-acet-ortho-methyl-anilid-jodids

The crystal structure of N-Methyl-piperidinium-acet-ortho-methyl-anilide-iodide is monoclinic, space group P2₁/c with 4 formula units C₁₅H₂₃N₂OJ in the unit cell. The lattice constants are a = 7.119, b = 18.932, c = 12.592 Å und β = 105.77°. As the intensities of the X-ray reflexions could by measured very accurately by an automatic four circle diffractometer, it was possible to determine also the positions of the hydrogen atoms in this heavy atom structure containing an iodine atom. The final R value for all 3157 reflexions was 0.042.     

Die Molekül- und Kristallstruktur des Morpholyl-pentamethin-merocyanins C9O2NH13

The morpholyl-pentamethine-merocyanine crystallizes within the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\frac{{{\rm 2}_{\rm 1} }}{{\rm a}} $\end{document} with the lattice constants being a = 13.269 Å, b = 15.232 Å, c = 4.513 Å, β = 94.05°. The bond lengths between the methine-carbon atoms within the pentamethine chain alternate significantly, and thus show a distinct polyenal course. Simultaneously, short C–N (1.339 Å) and short C–O bond lengths (1.224 Å) of the substituents N and O towards the pentamethine chain occur. As with open chained cyanines we also find with this merocyanine a distinct alternation of the valence angles at the methine-carbon atoms. Distances of substituents and alternation of valence angles point to a poylmethinic behaviour of the molecules. The presented merocyanine therefore takes a mean position between a polyenal and a polymethinic behaviour, sharply to be limited by X-ray crystal structure analysis. The experimentally determined geometry of the molecule is compared with quantum mechanical calculations and different structure chemical ideas. On the base of the resonance theory new limiting structures are introduced, the consideration of which enables to give an explanation of the molecule's geometry also in the formalism of mesomerism. The geometry of the chair formed morpholyl ring as well as the packing of the molecules in the crystal bond (intermolecular interaction) are discussed in detail.     

Zur Korrespondenz von Kristallstruktur und Habitus. Bestimmung der Molekülschwerpunkte in organischen Kristallen

Screw axes and glide planes lower the morphological importance of certain crystal faces. It has been demonstrated, that pseudosymmetry also influences crystal tracht. In case of organic crystals it is sometimes possible to determine the approximate molecule centres with aid of „morphological extinction tables”︁.     

Die Molekül- und Kristallstruktur von 1.1′-Bis-[phenyl-glyoxyloyl]-ferrocen

The 1.1′-Bis-[phenylglyoxyloyl]-ferrocen (PGF) crystallizes within the monoclinic space group P₁/c with the lattice constants a = 7,338 Å, b = 16,872 Å, c = 8,046 Å, β = 87,0°. The PGF belongs to metal-π-complexes. With the iron atom in the center of symmetry, both the heavy atom ligands are centrosymmetric-to each other. The two cyclopentadinyl rings linked to the iron atom are arranged in the sandwichtype with staggered conformation. The mean planes are separated by 3,32 Å. In a single phenyl-glyoxyloyl molecule exists an expanded Csp²–Csp² bondlength (1,528 Å). The two plane parts of the molecule are twisted around this bond. These two plane parts consist on the one hand of the carbon-5-ring and a C  O group and on the other hand of the carbon-6-ring and a C  O group. The dihedral angle is 62,5°. The expanded bond length mentioned is explained by Coulomb repelling forces of partially charged atoms. The packing of the molecules in the crystal lattice is discussed in detail.     

Die Kristallstruktur des N-Methyl-piperidinium-acet-meta-chlor-anilid-jodids

The crystal structure of N-Methyl-piperidinium-acet-meta-chloro-anilide-jodide is monoclinic, space group P2₁/c with 4 formula units C₁₄H₂₀N₂OClJ in the unit cell. The lattice constants are a = 6.931, b = 33.193, c = 7.280 Å and β = 104.01°. The crystal structure has been determined, including all H-atoms. The final R value was 0.049.     

Die Änderung der Molekül- und Kristallstruktur des N-Methyl-piperidinum-acet-meta-chlor-anilid-jodid durch Einlagerung von Wasser

N-Methyl-piperidinium-acet-meta-chloro-anilide-iodide crystallizes from water in the space group Pna2₁ with 4 formula units C₁₄H₂₀N₂OClJ and 4 H₂O molecules in the unit cell. The lattice constants are a = 12.413 Å, b = 19.798 Å and c = 6.919 Å. The change of the molecular conformation caused by water molecules was investigated by X-ray structure analysis.     

Die Verfeinerung der Kristallstruktur eines metamorphen Orthopyroxens

The atomic coordinates, the isotropic temperature factors and the site-occupancy factors of a metamorphic orthopyroxene Mg_1,56Fe_0,39Ca_0,05Si₂O₆ have been refined by the least-squares method using 1373 crystallographically independent reflections. Three-dimensional intensity data have been determined by integrated Weissenberg photographs. The final residual is 0.11. The site-occupancy factors M 1 = Mg_0,968 + Fe_0,032 and M 2 = Mg_0,589 + Fe_0,361 + Ca_0,050 reflect a high degree of order in the intracrystalline Mg, Fe distribution. The M 1, M 2 octahedra, the Si tetrahedra and the dependence of the means interatomic distances M  O on the Mg. Fe site occupancy are the subject of discussions.     

Zur Morphologie organischer Kristalle mit zwei Molekülen in der asymmetrischen Einheit. Ein Beitrag zur Korrespondenz von Kristallstruktur und Habitus

It has been demonstrated in an earlier publication, that pseudosymmetry influences crystal tracht of organic crystals. The morphological lattice of structures with two independent molecules in the unit cell corresponds with the lattice of the centers between the two molecules. This can be pointed out with aid of “morphological extinction rules”.     

Modelle und Eigenschaften von Korn- und Phasengrenzen

Models about the structure of grain boundaries in pure metals, alloys and of phase boundaries between two crystals of different elements are known. Geometrical and energetical interpretations of these models are discussed. It is tried to establish the structure of grain boundaries by an energetical method. With the results of these theoretical works you can better interpret the experimental results from oriented bicrystals. But the direct investigation of the influence of grain boundaries in polycrystals will be also necessary in future.     

Chemische Bindung und Struktur von Halbleitern und Isolatoren

Modern semiempirical substance and structure theories are very useful for the investigation of chemical trends of material properties of semiconductors and insulators. On the basis of the conception of the ionicity of mixed ionic-covalent chemical bonds, chemical trends of selected energetic, electric and elastic properties are described. The ionicity parameter, which can be derived from the static electronic dielectric constant or from valence band spectra, is built into models for different effects (e.g. the chemical shift of electronic binding energies). In this way chemical information is taken into account in an explicit manner and good agreement with experimental results is obtained. With the help of the ionicity and related parameters the separation of fourfold from sixfold coordinated crystal structures, the relative stability of the wurtzite and zincblende structure, and the problem of different bonding angles in different SiO₂ modifications are investigated. An extension of this conception with the help of the pseudopotential theory leads to some interesting conclusions concerning structural disorder effects in amorphous semiconductors     

Ein- und Mehrkristallspektrometrie und Fragen der Abbildung

Methods are discussed allowing to improve the resolving of the image and to make short time statements on the defect structure and characteristics of semiconductors. A monocrystal spectrometer method developed in 1970 by the author and afterwards the capacity of multi-crystal spectrometers are treated.     

Die Herstellung und einige Eigenschaften von reinen und dotierten BaTiO3-Einkristallen

Colourless BaTiO₃-monocrystals were prepared by slowly cooling down from 1300°C a mixture of BaTiO₃, Ba₂TiO₄ and BaCl₂ in a Pt-crucible under Ar-atmosphere. The crystals have a Curietemperature of 132°C. Partial substitution of Ti by Nb or V decreases the Curietemperature of BaTiO₃. The dependence of Curie-temperature from the concentration of the foreign ions was investigated.     

Die Löslichkeiten von GaP und GaAs in Sn und Bi

The pseudo-binary GaAs Bi, GaPs Bi and GaP Sn phase diagrams were investigated by Differential Thermal Analysis (DTA), and a theoretical analysis on the basis of the regular solution model for Ga GaAs Bi, Ga GaPs Bi and Ga GaP Sn has been presented. The solubilities of GaAs and GaP in Sn and Bi in the temperature range of 600–1200°C were determined. The solubility of the compounds decreases in the order Sn Ga Bi.