Synthesis of ansa-Zirconocene/Rhodium Heterobimetallic Complexes:  Enhanced Catalytic Activity in Stereospecific Polymerization of α-Olefins

Novel heterobimetallic complexes that consist of zirconium and rhodium, LRh(η²-CH₂CH)₂Si(η⁵-C₅H₂-2,4-Me₂)₂ZrCl₂ (3a L = η⁵-C₉H₇, 3b η⁵-C₅H₅, 3c η⁵-C₅Me₅), were synthesized, and 3b was structurally characterized. The complexes have a “C₂-symmetric” ansa-zirconocene part and the rhodium metal on the bridge part. The complexes 3a−c in combination with methylaluminoxane catalyzed highly isospecific polymerization of α-olefins. Their catalytic activities were higher than that of the parent zirconocene complex, and the obtained polymer had a larger molecular weight.