Silica-Supported Cationic Tungsten Imido Alkylidene Stabilized By An N-Heterocyclic Carbene Ligand Boosts Activity And Selectivity In The Metathesis Of Alpha-Olefins

A well-defined silica-supported cationic W imido alkylidene was prepared through surface organometallic chemistry. This catalyst shows preferential activity towards alpha- over internal olefins, which is atypical for W-based catalysts, but consistent with the strong sigma-donating ability of the NHC ancillary ligand. Complementing the studies on tungsten-based d(0) metathesis catalysts, the silica-supported cationic W imido alkylidene displays the highest activity among W imido catalysts for alpha-olefins and shows improved selectivity for this class of olefins compared to Mo-based catalysts.