A well-defined, silica-supported tungsten imido alkylidene olefin metathesis catalyst

Abstract

The reaction of [W(=NAr)(=CHtBu)(CH 2tBu) 2] (1; Ar = 2,6-iPrC 6H 3) with a silica partially dehydroxylated at 700 °C, SiO 2-(700)), gives syn-[(≡SiO)W(=NAr)(=CHtBu)(CH 2tBu)] (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-C 5H 9) 7Si 7O 12SiOH] to give [(SiO)W(=NAr)(=CHtBu)(CH 2tBu)] (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. © 2006 American Chemical Society.