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

Area of Science:

• Organometallic Chemistry
• Boron Chemistry
• Silicon Chemistry

Background:

• Amidinato amidosilylenes are versatile silicon-based compounds.
• Borane adducts are key intermediates in various chemical transformations.
• Understanding silylene-borane interactions is crucial for developing new synthetic methodologies.

Purpose of the Study:

• To synthesize and characterize a novel silylene-borane adduct.
• To investigate the reactivity of the silylene-borane adduct, including C-H borylation.
• To explore the activation of small molecules like H2 and NH3BH3 by the silylene-boronium ion.

Main Methods:

• Reaction of an amidinato amidosilylene with borane-tetrahydrofuran complex.
• Introduction of a triflate substituent on the boron center using methyl triflate.
• Intramolecular C(sp3)-H borylation reaction and subsequent studies using density functional theory (DFT).

Main Results:

• Successful synthesis of the silylene-borane adduct [L{(Me3Si)2N}Si:→BH3] (2).
• Formation of a silylene-boronium ion [L{(Me3Si)2N}Si:→BH2OTf]+ (5) via intramolecular C-H borylation.
• Demonstration of H2 and NH3BH3 activation by the silylene-boronium ion.

Conclusions:

• The synthesized silylene-borane adduct and its derivatives exhibit unique reactivity.
• The study highlights a novel pathway for intramolecular C-H borylation and small molecule activation.
• DFT calculations provide insights into the mechanism of H2 activation.