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 <b>4</b> and <b>6</b> 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.