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

In this article, four constrained geometry complexes 4a [(eta(5)-C5H4)CH2(alpha-C4H3N)]Ti(NMe2)(2), 7a [(eta(5)-C9H6)CH2(alpha-C4H3N)]Ti(NMe2)(2), 4b [(eta(5)-C5H4)CH2(alpha-C4H3N)]Zr(NEt2)(2), 7b [(eta(5)-C9H6)CH2(alpha-C4H3N)]Zr(NEt2)(2) with pyrrole-bridged fragment were synthesized and characterized by H-1 NMR, C-13 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 x 10(6) g polymer/mol center dot M center dot 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 C-13 NMR and DSC, and the results shown that polymer with 4a had the highest alpha-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 center dot rH = 0, all these results suggested that the copolymerization mode is alternating copolymerization. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48620.