Studies on the nature of active species in W(CO)6/CCl4/hν system as applied to metathesis polymerisation reactions

Irradiation of W(CO)6 in CCl4 generates an ‘active species’ which has the ability to polymerise alkynes and strained cyclic olefins via a metathesis pathway. The precipitate formed after 2 h of irradiation is active for polymerisation. The involvement of metal carbene in the polymerisation of norbornene was proved by in situ 1H-NMR study and by the end-capping reaction. IR studies showed the presence of carbonyl and chlorine ligands around the tungsten centre.