Diastereoselective Synthesis, Molecular Structure, and Solution Dynamics of meso- and rac-[Ethylenebis(4,7-dimethyl-η5-1-indenyl)]zirconium Dichloride Isomers and Chain Transfer Reactions in Propene Polymerization with the rac Isomer

The known rac -[ethylenebis(4,7-dimethyl-η 5 -1-indenyl)]ZrCl 2 ( 2r ) and its meso isomer ( 2m ) have been compared with the prototypal chiral isospecific rac -[ethylenebis(η 5 -1-indenyl)]ZrCl 2 ( 1r ) and its aspecific meso isomer 1m in terms of molecular structures, solution dynamics, and ligand substitution effect on polymerization performance. In liquid propene at 50 °C, 2r /MAO produces iPP with appreciably higher isotacticity but lower molecular weight and regiospecificity than 1r /MAO. The lower molecular weight obtained with 2r in liquid monomer is due to predominant chain transfer to the monomer after a secondary propene insertion, producing >90% cis -2-butenyl− end groups. At lower propene concentration, 2r /MAO allows both β-hydrogen transfer after a primary insertion and β-methyl transfer. The low-activity 2m /MAO catalyst produces low molecular weight aPP. The diastereoselective synthesis of 2r, m via the corresponding rac - and meso -bis(4,7-dimethyl-1-(trimethylsilyl)-3-indenyl)ethane is reported. The crystal and molecular structures of meso -bis(4,7-dimethyl-1-(trimethylsilyl)-3-indenyl)ethane, 2r, m, have been determined.