Lineare tetrasilane mit mittelständigen substituenten—oligosilane mit optischer Aktivität
摘要:
The chiral tetrasilane 2,3-diphenyltetrasilane (2) is formed by the stepwise cleavage of Si-aryl bonds in appropriate aryltetrasilanes with HCl under pressure and subsequent reduction with LiAlH4. HPh2SiSiPh2SiPh2SiPh2H affords a mixture of conformers, whereas MeS2HSiSiPh2SiPh2SiHMeS2, which is accessible from MeS2HSiLi and Ph2SiCl2, only yields 2 because mesityl groups proved to be much more reactive towards HCl than towards phenyl groups. Further reaction of 2 with HCl or HBr affords 2,3-dichlorotetrasilane (7) and 2,3-dibromotetrasilane (8). The diastereomers that appear because of the presence of 2 asymmetric Si atoms in 2, 7 and 8, can be easily distinguished in NMR and GC/MS experiments.
Aminoderivate hydrierter Oligosilane: Darstellung, Charakterisierung und Eigenschaften
摘要:
Amino derivatives of linear and branched tri- und tetrasilanes R2N-H2Si(SiH2)SiH2-NR2 H3SiSiHNR2SiHNR2SiH3, R2N-H2SiSiH2SiH2SiH2-NR2 und (R2N-H2Si)2SiHSiH(SiH2-NR2)2 with R = Et, SiMe3 are formed by the reaction of the corresponding bromooligosilanes with suitable amines or alkali metal amides. Product distribution and yields are strongly influenced by the nucleophilicity of the amino reagent and by the structure of the SiSi-backbone. The structures proposed for the aminopolysilanes thus prepared are proved by Si-29-, H-1-NMR- and MS-investigations.