Catalysis of olefin transformation by tungsten complexes, 5. Tungsten carbonyl carbenes activated by titanium tetrahalides as catalysts for the ring‐opening polymerization of cyclopentene

The reaction of TiCl4 with tungsten carbonyl carbene derivatives such as (CO)5W‐[C(OEt)R] affords catalysts which display a very high activity for the “methathetic” polymerization of cyclopentene. Thus, the equilibrium concentration of cyclopentene can be reached with a cyclopentene: W mole ratio of 106:1. The formation of the active species is thermally or photochemically assisted. A large excess of TiCl4 is needed during the polymerization process.