A Sterically Expanded “Constrained Geometry Catalyst” for Highly Active Olefin Polymerization and Copolymerization: An Unyielding Comonomer Effect

The 14 Å octamethyloctahydrodibenzofluorene moiety has been incorporated into a sterically expanded constrained geometry catalyst, Me2Si(η-C29H36)(η1-N-tBu)ZrCl2·OEt2 (1). The solid-state structure suggests that the activated olefin polymerization catalyst is quite spatially accessible, rationalizing its extraordinary reactivity toward α-olefins. 1/MAO (MAO = methylaluminoxane) can be more reactive toward α-olefins than toward ethylene and exhibit activities that are linearly and continuously proportional to 4-methyl-1-pentene or 1-octene concentration in their copolymerizations with ethylene.