meso-Norbornane-7,7-bis(indenyl)titanium Dichloride:  A Highly Active Catalyst for Ethylene−Styrene Copolymerization

The synthesis of the highly stereorigid meso-norbornane-7,7-bis(indenyl)titanium dichloride (meso-1) is described. The stereorigidity of this new ansa-metallocene is due to the inclusion of the norbornane skeleton as the bridge, since H-exoof norbornane hinders the rotation of the C7-indenyl bonds. meso-1shows very high activity in ethylene−styrene copolymerizations, yielding copolymers with unprecedented homogeneous chemical compositions. In addition, UHMWPE is obtained when a mixture of rac-1:meso-1 (2.8:1) is used as catalyst in ethylene homopolymerization reactions.