Reversible formylborane/SO₂ coupling at a frustrated Lewis pair framework.

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Catalysis

Background:

• Frustrated Lewis pairs (FLPs) are reactive species that can activate small molecules.
• P/B FLPs offer unique reactivity due to the combination of a Lewis acidic boron center and a Lewis basic phosphorus center.
• Activation of small molecules like CO and SO2 is crucial for synthetic transformations.

Purpose of the Study:

• To investigate the reactivity of a P/B FLP with carbon monoxide (CO).
• To explore the subsequent reaction of the CO-activated intermediate with sulfur dioxide (SO2).
• To characterize the resulting FLP-stabilized formylborane and SO2 adducts.

Main Methods:

• Synthesis of the P/B FLP precursor, Mes2PCH2CH2B(C6F5)2.
• Reaction of the P/B FLP with carbon monoxide.
• Subsequent reaction with sulfur dioxide.
• Characterization of products using spectroscopic techniques (NMR, X-ray crystallography).

Main Results:

• The P/B FLP successfully reduced carbon monoxide to form an FLP-stabilized (η2-formyl)borane product.
• Sulfur dioxide insertion into the three-membered ring of the formylborane intermediate occurred.
• A P/B FLP coordinated SO2 adduct was isolated and characterized.

Conclusions:

• P/B FLPs are effective templates for the reduction of CO and subsequent SO2 activation.
• The study demonstrates a novel pathway for forming FLP-stabilized formylborane and SO2 adducts.
• This work expands the scope of small molecule activation by frustrated Lewis pairs.