Facile B–H Bond Activation of Borane by Stable Carbenoid Species

Stable
nucleophilic carbene compounds have recently been shown
to be able to mimic in some instances the reactivity of metal fragments
in the reaction of unactivated E–H bonds (E = H, R3Si, NH2, R2P). However, the insertion into
a B–H bond of the strongly Lewis acidic BH3 molecule
has never been observed at a single C atom or even at a metal fragment.
Our results show that designed stable, highly electrophilic carbenoid
fragments in compounds 4 and 6 can achieve
this reactivity in a controlled manner. Density functional theory
calculations corroborated the experimental results on the presently
designed systems as well as the lack of reactivity on nucleophilic
carbenes.