C1-symmetric heterocyclic zirconocenes as catalysts for propylene polymerization, 2 -: ansa-Zirconocenes with linked dithienocyclopentadienyl-substituted indenyl ligands

Sixteen C-1-symmetric zirconocene and one hafnocene complexes bearing the 2,5-R-2-7H-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 Cl-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 T-m between 75 and 156 degrees C and viscosity average molecular weights between 100000 and 400 000 have been obtained at 50-70 degrees C in liquid propylene.