[ETHYLIDENE(1-ETA-5-TETRAMETHYLCYCLOPENTADIENYL)(1-ETA-5-INDENYL)]DICHLOROZIRCONIUM - SYNTHESIS, MOLECULAR-STRUCTURE, AND POLYMERIZATION CATALYSIS

Anti (1) and syn (2) diastereomers of rac[ethylidene(1-eta5-indenyl)(1-eta5-2,3,4,5-tetramethyl-cyclopentadienyl)]dichlorozirconium were synthesized by the reaction of the dilithium derivative of 1-(1-indenyl)-1-(2,3,4,5-tetramethylcyclopentadienyl)ethane with zirconium tetrachloride, under different conditions. Both diastereomers were characterized by elemental analysis, H-1 NMR, and 2D H-1 NMR. Compound 1 crystallizes in the monoclinic space group P2(1)/n with a = 12.158(2) angstrom, b = 9.752(2) angstrom, c = 15.807(2) angstrom, beta = 104.26(2)-degrees, and Z = 4; the X-ray molecular structure is reported. The catalytic system 2/methylaluminoxane has exceedingly low activity for propylene polymerization, forming hemiisotactic polymer. The crystal structure of 1 showed a commodious environment at the catalytic center and a possibility for isomerization between sites with and without stereochemical control. This catalyst also has unusually low ethylene polymerization activity. The polyethylene it produces exhibits two melting endotherms, indicating the presence of two types of catalytic sites.