A comparative study on the polymerization of alpha-olefins catalyzed by Salen and Salan zirconium complexes

摘要

A new Salan zirconium complex is synthesized and tested as a precatalyst for the polymerization of ethylene and higher alpha-olefins. Its catalytic behavior is compared to that of a previously reported and related Salen zirconium complex. Analysis of the produced polyolefins reveals that the two different catalytic systems produce polymers with the same microstructure: atactic polymers from propene versus highly isotactic polymers from higher alpha-olefins. The identification of the end groups indicates a prevailing primary regiochemistry of polyinsertion of the alpha-olefins for both Salan and Salen zirconium complexes. These observations strongly suggest the formation of very similar active species in both systems.