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  • 1
    ISSN: 0009-2940
    Keywords: cis-Stannyl-boryl-alkenes ; Sulfur diimide anions ; Multinuclear NMR ; 1,2,5-Azastannaboratoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 1,2,5-Azastannaborole Derivatives from Sulfur Diimide Anions and cis-Stannyl-boryl-alkenes - X-ray Crystallographic Study of Two 2,5-Dihydro-1-(imino-λ4-sulfanylidene)-1,2,5-azastannaboratoles(E)-3-(Diethylboryl)-2-(chlorodimethylstannyl)-2-pentene (1) reacts with the sulfur diimide anions 3 [R - NSN-K+, R=tBu (a), Me3Si (b), tBu2P (c)] in a 1:1 ratio, and with 4 (K+;-NSN-K+) in a 2:1 ratio, to give various heterocycles. The first products of the reaction between 1 and 3 [2,5-dihydro-1-(imino-λ4-sulfanylidene)-1,2,5-azastannaboratoles 5a, b, c] are isolated at -30°C and characterized by X-ray crystallography. The compounds 5a,b rearrange into the borole derivates 6a,b (with an additional N—Sn coordination) by transfer of an ethyl group from the boron to the sulfur atom. Ethylene is eliminated from compound 6a (not 6b) to give the diaminosulfane derivative 7a. The 2:1 reaction between 1 and 4 affords an unstable intermediate 8 with a fluxional structure, leading to 9 in which an EtS moiety bridges a borole ring (analogous to 6 but without the additional N - Sn coordination) and a boratole ring (analogous to 5). All compounds are characterized by 1H-, 11B-, 13C-, 15N- (in part), 29Si- and 119Sn-NMR spectra.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1235-1240 
    ISSN: 0009-2940
    Keywords: Phosphorus ; Phase transitions ; Molecular crystal ; Crystal growth ; Low-temperature crystal structure ; Librational motion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: White phosphorus occurs in three modifications. The α form, which exists at roomtemperature, transforms reversibly to the β form at -77°C. The α · β transformation may be strongly delayed. Quenching the α form to -185°C followed by slow warming results in an exothermic reactions with formation of the γ form which transforms into the β form at -120°C in an endothermic reaction. A transition β · γ is not observed. The γ form is characterized by its powder diagram. The structure of the β form is redetermined from a single crystal at -185°C (P., α = 547.88(5), b = 1078.62(11), c = 1096.16(11)pm, α= 94.285(8), β = 99.695(7), γ = 100.680(7)., V = 623.79(10) · 106 pm3, Z = 6 formula units per cell). The P4 molecules exhibit pronounced librational motion in spite of the low temperature of investigation. The arrangement of the centers of the tetrahedra corresponds to the atom positions in the γ-plutonium structure, which is discussed in relation to the bcc structure.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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