Pt^II -N-Heterocyclic Carbene Complexes in Solvent-Free Alkene Hydrosilylation

Area of Science:

• Organometallic Chemistry
• Catalysis
• Materials Science

Background:

• Alkene hydrosilylation is a crucial reaction in organic synthesis.
• Platinum catalysts are widely used but often require high loadings and harsh conditions.
• N-heterocyclic carbene (NHC) ligands offer tunable electronic and steric properties for catalyst design.

Purpose of the Study:

• To synthesize and characterize novel platinum(II) pre-catalysts bearing NHC ligands.
• To investigate the catalytic activity of these pre-catalysts in alkene hydrosilylation.
• To establish structure-activity relationships and gain mechanistic insights into catalyst activation.

Main Methods:

• Synthesis and characterization of platinum(II)-NHC complexes.
• X-ray diffraction analysis for structural elucidation.
• Nuclear magnetic resonance (NMR) spectroscopy for electronic property investigation.
• Catalytic testing in alkene hydrosilylation reactions.

Main Results:

• A series of platinum(II)-NHC pre-catalysts were successfully synthesized and characterized.
• One complex exhibited outstanding catalytic activity, achieving a turnover number (TON) of 970,000 and turnover frequency (TOF) of 40,417 h⁻¹ at 1 ppm catalyst loading.
• A solvent-free, open-to-air protocol was developed, significantly reducing residual platinum levels from 582 ppm to 5.8 ppm.

Conclusions:

• The developed platinum(II)-NHC pre-catalysts are highly effective for alkene hydrosilylation.
• The study provides valuable structure-activity relationships and mechanistic understanding.
• The optimized protocol offers an efficient, sustainable, and practical method for alkene hydrosilylation with minimal platinum contamination.