- Preparation of Silan- and Germanimines Me2E=NR (E = Si, Ge) from Sila- and Germadihydrotriazoles
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Sila- or germaethene Me2E=C(SiMe3)2 quantitatively react with azidoalkanes or -silanes RN3 nMe3-nSi, Ph3Si, (Me3Si)2NMe2E, Me2SiN3> at -78 deg C by cycloaddition to form sila- or germadihydrotriazoles 3 and 4, respectively.The latter decompose partly below (E = Si, R = silyl), partly at or above room temperature (E = Si, R = alkyl; E = Ge) in a first-order reaction by isomerization into diazomethane derivatives as well as by cycloreversion into (Me3Si)2C=N=N and silan- or germanimines Me2E=NR (rate constants: Table 1).The saturated compounds Me2E= NR are formed as short-lived intermediates.Their stabilization, as a rule, takes place by dimerization and, in exceptional cases, by reaction with the silan- or germanimine sources (R = SiMe3) or by intramolecular migration processes .
- Wiberg, Nils,Karampatses, Petros,Kim, Chung-Kyun
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p. 1203 - 1212
(2007/10/02)
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- Storage of Silan- and Germanimines Me2E=NR (E = Si, Ge) by Way of Sila- or Germadihydrotetrazoles
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Silan- and germanimines Me2E=NR (1, 2) ntBu3-n, SiPh3, EMe2N(SiMe3)2> react with azidoalkanes or -silanes R'N3 ntBu3-n, SiPh3, SiMe2N(SiMe3)2> by cycloaddition to form sila- or germatetrazoles 5, 6 (in addition, insertion products of Me2E=NR in the R'N bond of the azides and others are formed in some cases).The sila- or germadihydrotetrazoles decompose at raised temperatures in a first-order reaction, reversing their formation by cycloreversion into azides R'N3 or RN3 and imines Me2E=NR or Me2E=NR' (rate constants: Table 1).Consequently, azides operate as stores for silan- and germanimines.The unsaturated systems are formed only as short-lived intermediates.Their stabilization, as a rule, takes place by dimerization and/or insertion of the imines into the RN or R'N bond of the azides, formed as well by thermolysis of dihydrotetrazoles.
- Wiberg, Nils,Karampatses, Petros,Kim, Chung-Kyun
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p. 1213 - 1222
(2007/10/02)
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