Synthesis and structure of stable cis-dimethyl complex of oxotungsten(VI)

Oxotungsten(VI) complex cis-[WO(LtBu)Me2] (LtBu = methylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenolate) dianion) was prepared by the transmetallation reaction of [WO(LtBu)Cl2] (either cis or trans isomer) with methyl magnesium iodide. This unexpectedly stable dialkyl complex can be activated by Et2AlCl to catalyze the ring-opening metathesis polymerization of norbornene.