Synthesis of pyrrole‐bridged constrained geometry complexes and their application for olefin polymerization

In this article, four constrained geometry complexes 4a [(η 5 ‐C 5 H 4 )CH 2 (α‐C 4 H 3 N)]Ti(NMe 2 ) 2 , 7a [(η 5 ‐C 9 H 6 )CH 2 (α‐C 4 H 3 N)]Ti(NMe 2 ) 2 , 4b [(η 5 ‐C 5 H 4 )CH 2 (α‐C 4 H 3 N)]Zr(NEt 2 ) 2 , 7b [(η 5 ‐C 9 H 6 )CH 2 (α‐C 4 H 3 N)]Zr(NEt 2 ) 2 with pyrrole‐bridged fragment were synthesized and characterized by 1 H NMR, 13 C NMR, MASS, and EA. When combined with MAO, complex 4b given the highest activity, the activity of copolymerizing ethylene and 1‐hexene reached 2.48 × 10 6 g polymer/mol·M·h. The effects of temperature, pressure, and ratio of Al/Metal on the polymerization reaction and properties of polymers had been investigated. The polymers with these complexes were characterized by 13 C NMR and DSC, and the results shown that polymer with 4a had the highest α‐olefin incorporation, the incorporation of 1‐hexene reached up to 9.81 mol%, and the 1‐octene was 8.84 mol%. Actually, there was no [HH] or [OO] sequence in the copolymer, according to the formula of reactivity ratio, rE • rH = 0, all these results suggested that the copolymerization mode is alternating copolymerization. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48620.