- 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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- Adduct Formation and Reactivity of Silane- and Germaneimines Me2E=NR (E = Si, Ge)
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Silane- and Germaneimines Me2E=NR (E = Si, Ge; R = silyl), generated as reactive intermediates by thermal cycloreversion from cycloadducts of Me2E=C(SiMe3)2 or Me2E=NR with silyl azides RN3, combine with reactants a (e.g.NEtMe2) under addition (formation of adducts 7), with a-b under insertion into the a-b bond (formation 13-16), with a=b (e.g.RN=EMe2, O=CPh2) under cycloaddition (e.g. formation of 17, 18), with a=b=c (e.g.R'N=N=N) under cycloaddition (e.g. formation of 19, 20), and with a=b-c-H (e.g.CH2=CR-CH2-H, O=CMe-CH2-H) under ene reaction (formation of 21-24). cycloaddition of Me2Si=NR with organic 1,3-dienes (e.g.CH2=CR-CR=CH2, cyclopentadiene) is not observed.By comparison with ethenes Me2E=C(SiMe3)2, imines Me2E=NR have greater tendency for insertion and lesser tendency for cycloaddition; by comparison with silaneimines Me2Si=NR, germaneimines Me2Ge=NR are possibly less Lewis acidic.
- Wiberg, Nils,Preiner, Gerhard,Karampatses, Petros,Kim, Chung-Kyun,Schurz, Klaus
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p. 1357 - 1368
(2007/10/02)
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- Reactivity of the Germaethene Me2Ge=C(SiMe3)2
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Germaethene Me2Ge=C(SiMe3)2 (2), generated as a reaction intermediate by thermal elimination of LiX from Me2XGe-CLi(SiMe3)2 or by thermal cycloreversion from the adduct 2*Ph2CO, combines with reactants a-b (e. g.MeO-H) under insertion into the a-b bond (formation of 4), with a=b-c-H (e. g.CH2=CR-CH2-H; R = H, Me, CMe=CH2) under ene reaction (formation of 19 - 21), and with ab 3-nMenSi), O=N=N or CH2=CR-CR=CH2 (R = H, Me)> under , , and cycloaddition (formation of 6, 7 or 9 - 14 or 17, 18).By comparison with the silaethene Me2Si=C(SiMe3)2 (1), 2 is less Lewis acidic and its double bond is less polar.
- Wiberg, Nils,Kim, Chung-Kyun
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p. 2980 - 2994
(2007/10/02)
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