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  • 11
    Electronic Resource
    Electronic Resource
    Modulated structure of Ag2SnO3 studied by high-resolution electron microscopy (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 363-368 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The modulated structure of Ag2SnO3, disilver tin trioxide, was investigated by high-resolution electron microscopy and electron diffraction along four different directions. Electron diffraction showed an incommensurate one-dimensional modulated structure with a modulation wavevector of 1/6.4a*. High-resolution images showed a large number of superstructure domains with the size range 10–100 nm and orientations related by hexagonal rotation. The modulation was determined to be displacements along the c axis of the Ag atoms both in octahedral and linear coordination. An approximate structure model with a commensurate sixfold superstructure, with an orthorhombic cell (P212121, a = 2.922, b = 1.267, c = 0.562 nm), is proposed. Calculated images and electron diffraction patterns, based on this model, agree well with experimental observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768199013695
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  • 12
    Electronic Resource
    Electronic Resource
    Zinc cyanamide, Zn(CN2) (2001)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 347-348 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Single crystals of the title compound have been grown by annealing microcrystalline zinc cyanamide at 843 K in silver crucibles. Zn(CN2) crystallizes as colourless prisms. The crystal structure is composed of corner-linked ZnN4/2 tetrahedra. Carbon and nitrogen form (CN2)2− dumb-bells with the C atom on a twofold axis. Nitrogen is approximately trigonally planar, coordinated by two Zn atoms and one C atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270101000865
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  • 13
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of the cycloaddition product between maleic anhydride, cyclopentadiene, and 1,2-bis(dibromomethyl)benzene as DMF solvate (1∶2) (1993)
    Springer
    Journal of chemical crystallography 23 (1993), S. 55-60 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystal structure determination reveals that the unknown cycloaddition product between maleic anhydride, cyclopentadiene, and 1,2-bis(dibromomethyl)benzene has a nona-cyclic centrosymmetric structure. The compound was studied as DMF solvate (1∶2). There is no significant intermolecular interaction between the title molecule and the DMF. Packing is in layers for both molecular species. A possible mechanism of formation of the title compound is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01161288
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  • 14
    Electronic Resource
    Electronic Resource
    Zur Kenntnis von Cr2H2(As2O7)(As4O12) (1980)
    Springer
    Monatshefte für Chemie 111 (1980), S. 377-384 
    Details
    ISSN: 1434-4475
    Keywords: Crystal structure of Cr2H2(As2O7)(As4O12) ; Cyclo-tetraarsenate(V)-ion ; Diarsenate(V)-ion ; Magnetic susceptibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of Cr2H2(As2O7)(As4O12) has been determined by X-ray methods using single crystal diffractometer data (1,152 reflections,R=0.054, orthorhombic,Pmmn,a=1317.7 (7),b=1124.9 (6),c=494.3 (4) pm,Z=2). The crystal structure contains both diarsenate(V) and the hitherto unknown cyclo-tetraarsenate(V)-anions. The magnetic susceptibility follows theCurie-Weiss law (μ=3.86±0.01 μB/Cr3+, Θ=−31 K).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00903233
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  • 15
    Electronic Resource
    Electronic Resource
    Untersuchungen an Tetranatrium-cyclo-tetraphosphat(V) und seinen Hydraten (1983)
    Springer
    Monatshefte für Chemie 114 (1983), S. 699-709 
    Details
    ISSN: 1434-4475
    Keywords: Anhydrous sodium-cyclo-tetraphosphate(V) ; Crystal-structure ; Sodium-cyclo-tetraphosphate(V)-monohydrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A reinvestigation of the system (NaPo3)4/H2O has been carried out. Besides the already known tetra-hydrate and anhydrous form, a mono-hydrate in the temperature range 100–120°C exists. Single crystals were obtained by crystallization from aqueous solutions containing higher alcohols (e.g. ethyleneglycol) at ∼115°C. The crystal structure was solved by X-ray methods (orthorhombic;P212121;a=1365.4(2),b=1 347.5(3),c=629.1(3)pm;Z=4; 2774 diffractometer data;R=0.053). The cyclic anions exhibit point symmetryD 2d with all terminal oxygens in eclipsed conformation. With respect to the (NaPO3)4-part of structure, mono-hydrate and anhydrous forms are isostructural; lattice parameters of the latter area=1 380.8(2),b=1 363.3(2),c=602.7(2) pm. The transition mono-hydrate to anhydrous form occurs topochemically and is reversible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01134183
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  • 16
    Electronic Resource
    Electronic Resource
    [(Trichlorosilyl)dichloroboryl]ethane: Synthesis and Characterisation by Means of Experiment and Theory (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 75-81 
    Details
    ISSN: 1434-1948
    Keywords: TSDE ; Ceramics ; Theoretical IR-spectroscopy ; RI-MP2 ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new compound for the molecular synthesis route to high-demand Si/B/N/C ceramics has been found and is described in this work. We report on an elegant “one-pot” synthesis of [(trichlorosilyl)dichloroboryl]ethane (TSDE, Cl3Si-CH[(CH3)(BCl2)]) and its structural characterisation by means of nuclear magnetic resonance and (theoretical and experimental) infra-red spectroscopy. Density functional and Hartree-Fock calculations combined with a perturbational treatment of the electron correlation have been performed. Both methods yield good agreement of theoretical and experimental spectra, with the perturbational approach being slightly superior. In a similar way to the amino compound [(trichlorosilyl)amino]dichloroborane (TADB), TSDE exhibits a planar coordination of the dichloroboryl terminus but tetrahedral neighbourhoods for both carbon and silicon. The electronic structure has been investigated and a σ - n order of the frontier orbitals shall be discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    On the Geometry of the Fulleride Dianion C602- in Crystalline Fullerides - Syntheses and Crystal Structures of [M(NH3)6]C60 · 6 NH3 (M = Mn2+, Cd2+) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1183-1186 
    Details
    ISSN: 1434-1948
    Keywords: Fullerides ; Crystal structure analysis ; Jahn-Teller effect ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fullerides [M(NH3)6]C60 (M = Mn2+, Cd2+) have been synthesized by ion exchange in liquid ammonia and analyzed by X-ray single-crystal diffraction. With both complex cations the C602- units are in fixed orientations, and their geometries have been determined with good accuracy. An inspection of the fulleride dianions with respect to geometric deformations in the title compounds and three further independent determinations has led to the conclusion that no significant static Jahn-Teller distortion is present.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Die Kristallstruktur von As2O5, eine neue RaumnetzstrukturDem Andenken Professor Erich Thilos gewidmet (1978)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 441 (1978), S. 5-12 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of As2O5, a New Type of Framework StructureUsing high oxygen pressure, single crystals of As2O5 were obtained. According to an X-ray crystal structure analysis (space group: P212121; a = 864.6, b = 844.9, c = 462.6 pm) As2O5 exhibits a new type of framework structure consisting of corner sharing AsO4 tetrahedra and AsO6 octahedra. The mean distances As—O are 167.6 pm (As[4]) und 181.8 pm (As[6]).
    Notes: Einkristalle von As2O5 wurden unter Anwendung erhöhter Sauerstoffdrucke erhalten. Der Kristallstrukturanalyse zufolge (Raumgruppe: P212121; a = 864,6, b = 844,9, c = 462,6 pm) besitzt As2O5 eine bisher nicht beobachtete Raumnetzstruktur mit tetraedrisch und oktaedrisch koordiniertem Arsen. Die mittleren As—O-Abstände betragen 167,6 pm (As[4]) und 181,8 pm (As[6]).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19784410101
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  • 19
    Electronic Resource
    Electronic Resource
    Darstellung und Kristallstruktur von Na2Mn3O7 (1985)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 531 (1985), S. 177-182 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal-Structure of Na2Mn3O7Single crystals of Na2Mn3O7 have been grown hydrothermally applying high oxygen pressure (pO2 = 2 kbar). The new compound cystallizes triclinic; space group P1; a = 6.636(6) Å, b = 6.854(6) Å, c = 7.548(6) Å, α = 105.76(6)°, β = 106.86(6)°, γ = 111.60(6)°; Z = 2. The crystal structure has been solved and refined to R = 7.9% and Rw = 6.2% (diffractometer data, 1044 independent reflexions). The crystal structure consists of ∞2Mn3O72- anions with manganese coordinated octahedrally by oxygen. These layered anions are hold together by Na+ ions (coordination numbers 5 and 6).
    Notes: Einkristalle von bislang unbekanntem Na2Mn3O7 wurden hydrothermal unter hohem Sauerstoffdruck (pO2 = 2 kbar) erhalten, die Kristallstruktur unter Verwendung von Diffraktometerdaten aufgeklärt und verfeinert: P1; a = 6,636(6) Å, b = 6,854(6) Å, c = 7,548(6) Å, α = 105,76(6)°, β = 106,86(6)°, γ = 111,60(6)°; Z = 2; 1044 unabhängige Reflexe; R = 7,9% bzw. Rw = 6,2%. Es liegen im Sinne dichter Packungen angeordnete Sauerstoffdoppelschichten vor, deren Oktaederlücken zu 6/7 mit Mn unter Ausbildung eines ∞2Mn3O72--Anions besetzt werden. Na+ (Koordinationszahl 5 und 6) befindet sich zwischen diesen Schichtpaketen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19855311224
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  • 20
    Electronic Resource
    Electronic Resource
    Asymmetric Control of 1,3-Dipolar Cycloaddition Reactions with Azomethine Ylides by Means of Proline Esters as Chiral Auxiliary Groups (1995)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 1 (1995), S. 150-154 
    Details
    ISSN: 0947-6539
    Keywords: asymmetric syntheses ; azomethine ylides ; chiral auxiliaries ; cycloadditions ; pyrrolidines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Upon treatment with triethylamine or DBU in the presence of LiBr, aromatic and aliphatic imines of amino acid esters are converted to N-metalated azomethine ylides. These 1,3-dipoles undergo highly stereoselective cycloadditions with N-acryloyl-(S)-proline esters in THF at -78 to -40°C to afford highly substituted pyrrolidines with complete regiocontrol and good to excellent diastereomeric ratios. The chiral auxiliary groups can readily be removed from the cycloadducts by simple acid hydrolysis. To rationalize the observed stereoselectivity a transition-state model is proposed in which the lithium cation is coordinated to both the 1,3-dipole and the dipolarophile.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19950010209
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