Iron(III) complexes bearing 2-(benzimidazole)-6-(1-aryliminoethyl)pyridines: Synthesis, characterization and their catalytic behaviors towards ethylene oligomerization and polymerization

A series of iron(III) complexes ligated by 2-(benzimidazole)-6-(1-aryliminoethyl)pyridines was synthesized and examined by 1H NMR, ESI-MS, IR spectroscopic, elemental analysis and X-ray photoelectron spectroscopy (XPS). Activated with methylaluminoxane (MAO), all ferric complexes exhibited good activities (up to 5.38 × 106 g mol−1(Fe) h−1) of ethylene oligomerization and polymerization, and resultant oligomers and polyethylene waxes showed high α-olefin feature, meanwhile the distribution of oligomers mostly resembled Schulz–Flory rules. The various reaction parameters were investigated in detail, and the less bulky and electron-withdrawing substituents of ligands could enhance the catalytic activities of their ferric complexes. The observations explain the cause for unstable activities performed by stored iron(II) complexes.