Synthesis and Characterization of Nitrogen-Functionalized Cyclopentadienylchromium Complexes and Their Use as Catalysts for Olefin Polymerization

Abstract

A series of nitrogen-functionalized cyclopentadienylchromium complexes ( 1 − 9 ) have been synthesized, characterized, and then tested as catalyst precursors for olefin polymerization. The structures of complexes 1 and 5 show the nitrogen atom coordinated to the chromium atom, which is confirmed by X-ray crystallography. In the presence of MAO, the complexes exhibited high catalytic activities for the homopolymerization of ethylene and its copolymerization with 1-hexene. It also turned out that both the activity of ethylene polymerization and the incorporation of 1-hexene into the copolymer were highly affected by the substituents on the cyclopentadienyl fragment and bridge group. The effects of temperature variation and Al/Cr ratio on catalytic activity were also studied.