C1‐Symmetric Heterocyclic Zirconocenes as Catalysts for Propylene Polymerization, 2

Summary: Sixteen C1‐symmetric zirconocene and one hafnocene complexes bearing the 2,5‐R2‐7H‐cyclopenta[1,2‐b:4,3‐b′]dithiophene ligand (R = H, Me, Et, Ph) linked to a substituted indenyl ligand have been synthesized and tested in propylene polymerization. Most of the C1‐symmetric zirconocenes of this type are highly active in propylene polymerization at low MAO/Zr ratios and produce poly(propylene)s (PP) in a broad range of isotacticity and melting points. The molecular weight and crystallinity of the PPs are strongly dependent upon the type of substituents on the indenyl moiety: PPs with Tm between 75 and 156 °C and viscosity average molecular weights between 100 000 and 400 000 have been obtained at 50–70 °C in liquid propylene. General formula of the indenyl‐based zirconocenes. magnified image General formula of the indenyl‐based zirconocenes.