Synthesis and characterization of a homogeneous and silica supported homoleptic cationic tungsten(vi) methyl complex: application in olefin metathesis.

A method for the synthesis of a homogeneous cationic tungsten(vi)pentamethyl complex [(WMe)(CF)BMe] from neutral tungstenhexamethyl (WMe) and a silica supported cationic tungstentetramethyl complex [([triple bond, length as m-dash]Si-O-)WMe (CF)BMe] from a neutral silica supported tungstenpentamethyl complex [([triple bond, length as m-dash]Si-O-)WMe] is described. In both cases a direct demethylation using the B(CF) reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe)(CF)BMe] shows moderate activity whereas the supported cationic complex [([triple bond, length as m-dash]Si-O-)WMe(CF)BMe] exhibits good activity in olefin metathesis reactions.