Synthesis and Reactivity of Base-Stabilized and Base-Free Silaimidoyl Bromides.

The reactivity of the base-free bromosilylene dtbp CbzSiBr ( dtbp Cbz = 1,8-bis(3,5-di- tert- butylphenyl)-3,6-di- tert -butylcarbazolyl) toward carbodiimides and azides was studied in order to generate base-stabilized and base-free silaimidoyl bromides, respectively. The steric bulk of carbodiimides and azides allows control over the reactivity. While with small substituents such as tert -butyl or adamantyl, the reactions cannot be stopped at the Si═N stage, with large substituents, they lead to C-H activation in the product. The Dipp substituent (Dipp = 2,6-diisopropylphenyl) allowed the isolation of the silaimidoyl bromide dtbp CbzSi(Br)NDipp and its CNDipp-coordinated analogue. The reactivity of the Si═N double bond species was studied with respect to cycloaddition and donor exchange reactions.