Ruthenium Phosphinimide Complexes as Highly Active Olefin Metathesis Catalysts

Olefin metathesis is a chemical reaction in which two alkene compounds exchange alkylidene fragments, typically utilizing an organometallic catalyst. Phosphinimides are anionic ligands that have multiple potential binding modes; they can act as 2, 4, or 6 e- donors. Previously, they have been used to great effect in place of cyclopentadienyl ligands for metallocene catalysts in olefin polymerization reactions. In these cases, the phosphinimide ligands acted as 6 e- donors to help stabilize high oxidation state Ti(IV) and Zr(IV) complexes. One of the most significant benefits seen for these ligands over their cyclopentadienyl analogues was that they gave similar steric protection to the metal centers, but the bulkiness of the ligand was further removed from the active site due to the nitrogen spacer. This created more space directly at the metal, facilitating substrate binding and promoting higher catalytic activities.

Benefit

• The structures of these catalysts are different than known ruthenium-based olefin metathesis catalysts, particularly the phosphinimide ligands that are used.
• Unlike most known ruthenium-based olefin metathesis catalysts, these novel catalysts do not have an induction period.
• Increased catalyst structural diversity for tuning activities and selectivities for specific substrates.

Market Application

• Pharmaceuticals, Plastics, Chemicals, Petrochemicals