Synthesis and ROMP activity of aminophenol-substituted tungsten(VI) and molybdenum(VI) complexes

Air-stable tungsten(VI) and molybdenum(VI) complexes with tridentate aminobis(phenolate) and bidentate aminophenolate ligands catalyse ROMP of 2-norbornene derivatives when activated by Et2AlCl. Activity increases when coming from dichlorido complexes [MO(L1)Cl2] (L1 = methylamino-N,N-bis(2-methylene-4,6-dimethylphenolate)] to the trichlorido complexes [M(X)(L2)Cl3] (X = O, NPh; L2 = 2,4-di-tert-butyl-6-((dimethylamino)methyl)phenolate).