Silylene-Stabilized Neutral Dibora-Aromatics with a B═B Bond

Area of Science:

• Organometallic Chemistry
• Boron Chemistry
• Main Group Chemistry

Background:

• Silylene ligands offer unique stabilization for reactive main group elements.
• Dibenzodiboraoxepin and diboraphenanthrene scaffolds are of interest due to their electronic properties.

Purpose of the Study:

• To synthesize novel silylene-supported dibenzodiboraoxepin and diboraphenanthrene complexes.
• To investigate the reactivity of these complexes with small molecules like white phosphorus, ammonia, and carbon dioxide.
• To explore the potential for deoxygenation reactions mediated by these organoboron compounds.

Main Methods:

• Debromination of precursor compounds using potassium graphite (KC8).
• Thermal rearrangement reactions.
• Deoxygenation reactions using KC8 and N-heterocyclic carbenes (NHCs).
• Computational studies to confirm aromaticity.

Main Results:

• Synthesis of silylene-supported dibenzodiboraoxepin (2) and diboraphenanthrene complexes (6, 8).
• Activation of white phosphorus to form a B2P4 cage (3) and ammonia to form a diborane species (4) by complex 2.
• Thermal rearrangement of 2 to dihydro-diboraphenanthrene (5) via deoxygenation.
• Generation of aromatic diboraphenanthrenes (6, 8) through deoxygenation of 2.
• Monodeoxygenation of carbon dioxide by complex 8 to yield a CO-stabilized derivative (9).

Conclusions:

• Novel silylene-stabilized dibenzodiboraoxepin and diboraphenanthrene complexes have been successfully synthesized.
• These complexes exhibit remarkable reactivity, including the activation of small molecules and deoxygenation of CO2.
• The findings highlight the potential of silylene ligands in stabilizing and functionalizing unique organoboron frameworks.