An intermolecular FLP System derived from an NHC-coordinated trisilacyclopropylidene

Area of Science:

• Organosilicon Chemistry
• Frustrated Lewis Pair Chemistry
• Main Group Chemistry

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Trisilacyclopropylidenes are a unique class of silicon compounds.
• Frustrated Lewis pairs (FLPs) are Lewis acid-base pairs that do not associate due to steric hindrance, enabling unique reactivity.

Purpose of the Study:

• To investigate the reactivity of an NHC-coordinated trisilacyclopropylidene as a Lewis base in an FLP.
• To explore the dihydrogen cleavage capabilities of this novel FLP system.
• To study the reactions of the FLP with other small molecules like amines, ketones, and nitrous oxide.

Main Methods:

• Synthesis and characterization of the NHC-coordinated trisilacyclopropylidene.
• Formation of the FLP by combining the trisilacyclopropylidene with a Lewis acid, B(C6F4H)3.
• Reaction of the FLP with dihydrogen, diphenylamine, acetone, and nitrous oxide.
• Spectroscopic characterization (NMR, IR) and X-ray crystallography of the products.

Main Results:

• The FLP system demonstrated highly selective dihydrogen cleavage at room temperature, yielding an ionic compound in 90% yield.
• Reactions with diphenylamine and acetone produced corresponding adducts in 75% and 80% yields, respectively.
• Oxidation of the silylene center with N2O afforded a unique product in 53% yield, with its structure confirmed by X-ray crystallography.

Conclusions:

• NHC-coordinated trisilacyclopropylidenes can function as effective Lewis bases in FLP chemistry.
• The developed FLP exhibits significant reactivity towards small molecules, including H2 cleavage.
• This study expands the scope of FLP applications in main group chemistry and organosilicon reactivity.