A Well-Defined, Silica-Supported Tungsten Imido Alkylidene Olefin Metathesis Catalyst

Abstract

The reaction of [W(NAr)(CHtBu)(CH2tBu)2] (1; Ar = 2,6-iPrC6H3) with a silica partially dehydroxylated at 700 °C, SiO2-(700), gives syn-[(⋮SiO)W(NAr)(CHtBu)(CH2tBu)] (2) as a major surface species, which was fully characterized by mass balance analysis, IR, NMR, EXAFS, and DFT periodic calculations. Similarly, complex 1 reacts with [(c-C5H9)7Si7O12SiOH] to give [(SiO)W(NAr)(CHtBu)(CH2tBu)] (2m), which shows similar spectroscopic properties. Surface complex 2 is a highly active propene metathesis catalyst, which can achieve a TON of 16 000 within 100 h, with only a slow deactivation.