Reactivity of Tungsten-aryloxides with Hydrosilane Cocatalysts in Olefin Metathesis

the reactivity of the [wcl4(oar)2] (oar = o-2,6-c3h3cl2, o-2,6-c6h3f2 and o-c6h3me2) systems, plus the silicon compounds ph2sih2 and polymethylhydrosiloxane (pmhs), were studied in metathesis reactions. the olefins used were methyl-10-undecenoate and 1-hexene. the results showed that the [wcl4(oar)2]-silicon compound systems are active and selective when the aryloxide ligand contain electronegative groups. the silicon compound pmhs proved to be the best cocatalyst for metathesis, even with the [wcl4(o-2,6-c6h3me 2)2] compound, which has no electronegative substituents. because it is non-toxic, non-volatile, easy to handle and cheap, pmhs is a good alternative cocatalyst in metathesis reactions.