New Types of Constrained Geometry Catalysts Containing Silacycloalkyl Bridging Unit: Synthesis, Structure, and Polymerization Activity

New types of constrained geometry complexes comprising rigid silacycloalkyl group incorporated into the bridging position between cyclopentadienyl and amido functionalities were prepared. The catalytic activities of olefin polymerization were influenced by the change of exo-cyclic ring size on bridge-head silacycloalkyl unit. It has been noted that the activities of this unique series increase with increasing size of the silacycloalkyl bridge and reach the maximum in six-membered silacyclohexyl-bridged CGC complex. It is noteworthy that conformation of silacycloalkanes gives rise to enhanced catalytic activity of the titanium center although the cyclic ring and titanium center are far remoted from each other.