Facile in situ generation of highly active (arylimido)vanadium(v)-alkylidene catalysts for the ring-opening metathesis polymerization (ROMP) of cyclic olefins by immediate phenoxy ligand exchange.

Highly active catalysts for the ring-opening metathesis polymerization (ROMP) of cyclic olefins (norbornene, cyclopentene, cycloheptene) can be generated in situ by premixing V(CHSiMe3)(NC6F5)(O-2,6-iPr2C6H3)(PMe3)2 (1) with 1.0 equiv. of C6F5OH or C6Cl5OH via the immediate phenoxy exchange; the activity was affected by the kind of phenol added [activity (TOF) in the ROMPs of norbornene: 46 200 min-1 (upon addition of C6F5OH) vs. 37.3 min-1 (by 1)].