New synthetic approach towards well-defined silica supported tungsten bis-oxo, active catalysts for olefin metathesis

Abstract

A well-defined bis-oxo bisiloxy tungsten surface species has been prepared by a new synthetic non-aqueous approach. The reaction of [W(O)(OtBu)4] with the silica surface dehydroxylated at 200 °C proceeds by WO cleavage with concomitant tBuOH release, leading to bigrafted [(SiO)2W(O)(OtBu)2]. Upon heating at 300 °C, it converts into the bis-oxo derivative [(SiO)2W(O)2]. Without co-catalyst, this material demonstrated high, sustained activity and selectivity in propene metathesis. This emphasizes the importance of the design of robust bis-oxo catalysts by Surface Organometallic Chemistry and represents a significant step to understand and mimic the active species of the industrial WO3/SiO2 system.