A Base-Stabilized Silylene-Promoted C(sp³)−H Borylation and H₂ Activation

Treatment of the amidinato amidosilylene [L{(Me₃Si)₂N}Si:] [1, L = PhC(NtBu)₂] with a slight excess of borane–tetrahydrofuran complex [BH₃·THF] in toluene at room temperature afforded the silylene–borane adduct [L{(Me₃Si)₂N}Si:→BH₃] (2). A triflate substituent was introduced on the boron center by reacting 2 with methyl triflate [MeOTf] (OTf = OSO₂CF₃) in toluene at room temperature to form [L{(Me₃Si)₂N}Si:→BH₂OTf] (3), with the elimination of CH₄ gas. The intramolecular C(sp³)–H borylation and H₂ elimination occurred by reacting complex 3 with 1 in refluxing toluene to form a C–B bond in the resulting silylene–boronium ion 5. Complex 5 activated H₂ gas or NH₃BH₃ at room temperature to form silylene–borane adduct 2 and [L{(Me₃Si)₂N}Si-H]OTf. Additionally, the reaction of 5 with H₂ was studied through density functional theory calculations.