Bulky aryloxide ligand stabilizes a heterogeneous metathesis catalyst

Area of Science:

• Organometallic Chemistry
• Materials Science
• Catalysis

Background:

• Bulky 2,6-diadamantyl aryloxide ligands are crucial for stabilizing reactive organometallic species.
• Silica-supported catalysts offer advantages in terms of handling and recyclability.
• Alkene metathesis is a fundamental transformation in organic synthesis.

Purpose of the Study:

• To synthesize and characterize a well-defined silica-supported tungsten alkylidene complex.
• To evaluate the catalytic performance of the new material in alkene metathesis reactions.
• To investigate the catalyst's activity and stability with various alkene substrates.

Main Methods:

• Reaction of a tungsten precursor with partially dehydroxylated silica.
• Full characterization of the resulting silica-supported complex.
• Testing the catalyst in alkene metathesis of internal and terminal alkenes, including homocoupling.

Main Results:

• Selective formation of a well-defined silica-supported alkylidene complex, [(≡SiO)W(=O)(=CHCMe2Ph)(dAdPO)].
• The catalyst exhibits high activity and stability, enabling low loadings (50 ppm) for internal alkene metathesis.
• Efficient catalysis of terminal alkene homocoupling with turnover numbers >75,000 under ethylene removal.

Conclusions:

• The developed silica-supported tungsten alkylidene complex is a highly effective and robust alkene metathesis catalyst.
• Low catalyst loadings are feasible, making the process more economical and sustainable.
• The catalyst's performance in terminal alkene homocoupling highlights its versatility.