N-Indolylsilylene Cobalt(I) Chloride: A Base Metal Catalyst for Alkene Hydrosilylation.

Area of Science:

• Organometallic Chemistry
• Catalysis
• Ligand Design

Background:

• Development of efficient catalysts for alkene hydrosilylation is crucial.
• Silylene ligands offer unique electronic and steric properties for transition metal catalysis.
• Cobalt complexes are increasingly explored for catalytic applications.

Purpose of the Study:

• To synthesize and characterize a new N-indolylsilylene ligand (L1).
• To prepare and evaluate N-indolylsilylene cobalt complexes as catalysts for alkene hydrosilylation.
• To investigate the catalytic mechanism and identify key intermediates.

Main Methods:

• Ligand synthesis and characterization.
• Preparation and isolation of cobalt complexes (1, 2, and 4).
• Catalytic testing for alkene hydrosilylation.
• Single-crystal X-ray diffraction for structural determination.

Main Results:

• Successful synthesis of N-indolylsilylene ligand L1.
• Preparation of cobalt complexes 1 (N-indolylsilylene cobalt(I) chloride) and 2 (N-indolyldiphenylphosphine cobalt(I) chloride).
• Complex 1 exhibited superior catalytic activity and selectivity in alkene hydrosilylation, producing Markovnikov products efficiently at 50 °C within 10 min.
• Isolation of a silyl dihydrido silylene Co complex (4) as a potential intermediate.

Conclusions:

• The N-indolylsilylene ligand L1 enables highly active cobalt catalysts for alkene hydrosilylation.
• Complex 1 is a highly efficient and selective catalyst, outperforming existing systems.
• N-Indolylsilylene cobalt(I) hydride is proposed as the active catalytic species.