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1980 (2)
1Author    Uwe Klingebiel, Jutta NeemannRequires cookie*
 Title    .3-Silylgruppenwanderung und gehinderte Si-N-Bindungsrotation Aminofluorosilanes: 1,3-Migration of Silyl Groups and Si-N-Rotational Barrier  
 Abstract    with bulky amino groups are prepared by the reaction of bis-(organyl-trimethylsilyl)amino-difluorosilane8 with lithiated amines. A 1,3-migration of trimethylsilyl groups from bulky alkylamino substituents to arylamino substituents is observed in these reactions. Structural isomers of the new triaminofluorosilanes were isolated. The silyl group migration depends on steric and electronic effects. Further reactions of the triaminofluorosilanes with butyllithium and trifluoroorganylsilanes lead to the formation of difluorosilyl-substituted triaminofluorosilanes and LiF. The symmetric compounds show AB-systems for the fluorine atoms of the difluorosilyl groups in the low temperature 19 F NMR Spectra, due to hindered rotation about the Si-N-bond. The coalescence temperature depends on the bulkiness of the substituents and is observed at or about room temperature. 
  Reference    Z. Naturforsch. 35b, 1155—1161 (1980); eingegangen am 24. Januar/13. März 1980 
  Published    1980 
  Keywords    Aminofluorosilanes, Structural Isomers, Silyl Group Migration, Rotational Barrier, NMR Spectra Triaminofluorosilanes 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-1155.pdf 
 Identifier    ZNB-1980-35b-1155 
 Volume    35 
2Author    Joachim Firl, Heinz Braun, Anton Amann, Robert BarnertRequires cookie*
 Title    und Bindungsverhältnisse von Enaminosulfoniumsalzen Dynamic Behaviour, Conformation and Bonding of Enaminosulfonium Salts  
 Abstract    The rotational barriers about the C-N single bond of the enaminosulfonium salts 1-6 are measured. Their magnitudes are related to the jr-donor strength of the NR2 group. For the unsymmetrically substituted compounds 7-12 the rotational equilibria are determined. In the case of the monoalkyl compounds 7-10 the more crowded s-cis-rotamers turn out to be the more stable conformations. Furthermore, the 13 C chemical shifts of the sulfonium salts 1-16 are reported. The shift differences ö(s-cis-s-trans) for the a-carbons of the N-alkyl groups seem to depend on the dihedral angle between the vinyl group and the C-H(°-c > bonds. Moreover, the spectra reveal that enaminosulfonium salts posses a high degree of ylide character. 
  Reference    Z. Naturforsch. 35b, 1406—1414 (1980); eingegangen am 20. Juni 1980 
  Published    1980 
  Keywords    Enaminosulfonium Salts, 13 C NMR Spectra, Rotational Barriers, Rotational Equilibria, Ylide Character 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-1406.pdf 
 Identifier    ZNB-1980-35b-1406 
 Volume    35