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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 121 (1990), S. 505-509 
    ISSN: 1434-4475
    Keywords: Chevrel phases ; Crystal structure ; Phase transition ; X-ray analysis ; Rietveld refinement ; Powder diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Temperaturabhängigkeit der Gitterparameter und die Atomlagen der Tieftemperaturphase von SrMo6S8 wurden mittels Röntgenpulverdiffraktometrie bestimmt. Die rhomboedrische Hochtemperaturmodifikation (R $$\bar 3$$ ,a rh=6.5630(3)Å, αrh=88.9982(2)°,V rh=282.55(5)Å3,T=298 K) wandelt beiT 1=135(3) K in die trikline Tieftemperaturmodifikation (P $$\bar 1$$ ,a tr=6.481(1)Å,b tr=6.572(1)Å,c tr=6.611(1)Å, αtr=89.246(4)°, βtr=89.304(4)°, γtr=88.169(4)°,V tr=281.4(2)Å3,T=20 K) um. Die trikline Deformation ist stärker ausgeprägt als in der Ca-Verbindung und ähnlich jener der Ba- and Eu-Verbindung.
    Notes: Abstract Lattice parameters as a function of temperature for, and atomic coordinates of the low-temperature phase of, SrMo6S8 are reported from X-ray powder diffraction. The structure transforms atT 1=135(3) K from the rhombohedral high-temperature modification (R $$\bar 3$$ ,a rh=6.5630 (3) Å, αrh=88.9982(2)°,V rh=282.55(5)Å3 at 298 K) into the triclinic low-temperature modification (P $$\bar 1$$ ,a tr=6.481(1)Å,b tr=6.572(1)Å,c tr=6.611(1)Å, αtr=89.246(4)°, βtr=89.304(4)°, γtr=88.169(4)°,V tr=281.4(2)Å3 at 20K). The triclinic distortion is larger than in the Ca analogue, and similar to the Ba and Eu analogues.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 523-533 
    ISSN: 0009-2940
    Keywords: Hofman 1,6-elimination / Pyrazine derivatives / [2.2]Pyrazinophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds 1-3 and their methyl derivatives 4-7 were synthesized 2,11-dithia[3.3]pyrazinophanes 24-26 or by Hofmann 1,6-elimination of the appropriate [(5-methyl-2-pyrazinyl)methyl]trimethylammonium hydroxides followed by dimerization of the generated 2,5-dihydro-2,5-dimethylenepyrazines. α-Chlorination of the methylpyrazines 8-10 with N-chlorosuccinimide gave the required precursors 11, 12, 14, 17 and 18. The results of the X-ray structure determinations for 1-4 and 7 which indicate an unequivocal isomer assignment are discussed with regard to steric strain in these molecules. The electronic spectra of the pyrazinophanes 7-7 are reported and compared with those of the parent methylpyrazines.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 723-728 
    ISSN: 0009-2940
    Keywords: 1,8-Diaminonaphthalenes, X-ray structure analysis of, conformational barriers of, dynamic behavior of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds 2 and 3 have been synthesized from 1,8-diaminonaphthalene. The molecular structure of 2 has been determined by X-ray structure analysis and is discussed with regard to the arrangement of the peri-diphenylamino substituents in the crystalline state and the steric strain in the molecule. NMR studies of 3 reveal two conformational processes. Their nature is discussed and barriers are reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1885-1889 
    ISSN: 0009-2940
    Keywords: Pyrimidine derivatives ; Sulfur extrusion, photolytic ; Pyrimidinophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds 1 and 2 are synthesized by photolytic sulfur extrusion from the 2,11-dithia[3.3](2,5)pyrimidinophane 17. The molecular structures of 1 and 2 are determined by X-ray structure analysis and are discussed with regard to the steric strain in these molecules. Thermolysis of [(5-methyl-2-pyrimidinyl]methyl]- or [(2-methyl-5-pyrimidinyl)methyl]-trimethylammonium hydroxide (10 or 11) does not generate 1 and 2. α-Chlorination of 2,5-dimethylpyrimidine (3) with N-chlorosuccinimide provides the required precursors 4-6.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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