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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 18 (1994), S. 317-329 
    ISSN: 1573-1111
    Keywords: Crystal structure ; clathrate ; Werner complex ; isothiocyanate ; 4-methylpyridine ; Mg(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two clathrate modifications of the title host with 4-methylpyridine (4-CH3C5H4N) as a guest have been determined at −50°C. [Mg(4-CH3C5H4N)4(NCS)2] · 2/3(4-CH3C5H4N) · 1/3H2O is trigonal, space group $$R\bar 3$$ , witha=27.630(7),c=11.219(3) ÅV=7417(4) Å3,Z=9,D calc=1.171 g cm−3,μ(CuK α)=18.506 cm−1, finalR=0.064. [Mg(4-CH3C5H4N)4(NCS)2] · (4-CH3C5H4N) is tetragonal, space group I4l/a, witha=16.944(7),c=23.552(9)Å,V=6762(5) Å,Z=8,D calc=1.191 g cm−3, μ(CuK α)=18.200 cm−1, finalR=0.071. The structures consist of molecular packings of the same host complex units and the guest species. The Mg(II) cation is octahedrally coordinated to theN-atoms of four 4-methylpyridine and twotrans-coordinated isothiocyanato ligands in the host molecule. The conformations of the molecule are considerably different both in symmetry and in geometry in these two structures. The guest 4-methylpyridine molecules are disordered into channels which have different topology in these two clathrates resulting in different thermal stability.
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  • 2
    ISSN: 1573-1111
    Keywords: Werner clathrates ; X-ray structure ; packing of guest molecules ; guest disordering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Single crystal X-ray structures of clathrates of β-[Ni(NCS)2(4-methylpyridine)4] with furan, tetrahydrofuran, benzene + ethanol, methylene chloride, and methylcellosolve as guests molecules are reported. The location of the guest molecule in the partially decomposed clathrate with methylene chloride was defined by X-ray diffraction and compared with the fully occupied one. The host lattices of all clathrates studied are tetragonal (I41/a) and do not differ significantly from typical β-phase clathrates of [M(NCS)2(4-methylpyridine)4] (M = divalent metal cation). Arrangements of guest molecules represent different types of packing: one type of guest molecule occupies both possible types of positions, two different guest molecules occupy different positions, with only one type of positions occupied by one type of guest molecule. Possible stoichiometries of clathrates with β-type lattices are discussed.
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  • 3
    ISSN: 1573-1111
    Keywords: Werner clathrates ; sorption equilibria ; isosteric heats of sorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sorption equilibria have been studied in the systems solid β-[Ni(NCS)2(4-MePy)4] clathrate – gaseous guest (benzene, furan,tetrahydrofuran, propane, CH2Cl2, CH2Br2, methanol). Analysis of theexperimental data shows that the solid–gas equilibrium in this systemcannot be regarded as simple physical sorption by a rigid host lattice. Itwas found that the isosteric heats of guest sorption decrease withincreasing guest uptake in all systems studied. The observed phenomena areinterpreted as the result of a guest to host influence and guest–guest repulsion. The molecular model of guest sorption by theβ-[Ni(NCS)2(4-MePy)4] host was suggested on the basis of combinedanalysis of sorption isotherms and the dependence of the isosteric heat ofsorption on clathrate composition.
    Type of Medium: Electronic Resource
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