Thermo‐stable 2‐(arylimino)benzylidene‐9‐arylimino‐5,6,7,8‐tetrahydro cyclohepta<i>[b]</i>pyridyliron(II) precatalysts toward ethylene polymerization and highly linear polyethylenes

Abstract

ABSTRACT A series of 2‐(arylimino)benzylidene‐9‐arylimino‐5,6,7,8‐tetrahydrocyclohepta [b] pyridyliron(II) chlorides was synthesized and characterized using FT‐IR and elemental analysis, and the molecular structures of complexes Fe3 and Fe4 have been confirmed by the single‐crystal X‐ray diffraction as a pseudo‐square‐pyramidal or distorted trigonal‐bipyramidal geometry around the iron core. On activation with methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all iron precatalysts exhibited high activities toward ethylene polymerization with a marvelous thermo‐stability and long lifetime. The Fe4 /MAO system showed highest activity of 1.56 × 10 7 gPE·mol −1 (Fe)·h −1 at 70 °C, which is one of the highest activities toward ethylene polymerization by iron precatalysts. Even up to 80 °C, Fe3 /MAO system still persist high activity as 6.87 × 10 6 g(PE)·mol −1 (Fe)·h −1 , demonstrating remarkable thermal stability for industrial polymerizations (80–100 °C). This was mainly attributing to the phenyl modification of the framework of the iron precatalysts. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 830–842