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

The reaction of [W(=NAr)(=CHtBu)(CH(2)tBu)(2)] (1; Ar = 2,6-iPrC(6)H(3)) with a silica partially dehydroxylated at 700 degrees C, SiO2-(700), gives syn-[( SiO)W(=NAr)(=CHtBu)(=CH(2)tBu)] ( 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)(7)Si7O12SiOH] to give [(SiO)W(=NAr)(=CHtBu)(CH(2)tBu)] (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.