Synthesis, characterization and catalytic properties of metallacyclic zirconocene complexes

A series of 22 metallacyclic zirconocene complexes has been synthesized by the reaction of ω-phenyl-substituted zirconocene dichloride complexes with two equivalents of n-butyllithium via CH bond-activation reactions on the phenyl ring. After activation with methyl aluminoxane, these metallacycles are up to five times more active ethylene polymerization catalysts than the original metallocene dichloride complexes similarly activated.