Synthesis, characterization and catalytic behavior toward ethylene of cobalt(II) and iron(II) complexes bearing 2-(1-aryliminoethylidene)quinolines

A series of 2-(1-aryliminoethylidene)quinolines (L) were synthesized and used as bidentate N^N ligands in coordinating with metal (cobalt and iron) chlorides to form complexes of the type LMCl2, cobalt(II) (Co1–Co5) and iron(II) (Fe1–Fe5). All organic compounds and metal complexes were fully characterized, and the molecular structures of the representative complexes Co3·DMF and Fe4·DMF were confirmed as distorted bipyramidal geometry at the metal by single-crystal X-ray diffraction. Upon activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) under 10 atm ethylene, all complexes showed high activities in ethylene dimerization with activities of up to 1.82 × 106 g mol−1 (Co) h−1 and 5.89 × 105 g mol−1 (Fe) h−1, respectively.

Graphical abstractThe series of iron(II) and cobalt(II) complexes bearing 2-(1-aryliminoethylidene)quinolines were synthesized and characterized; when activated with MAO or MMAO, all pre-catalysts showed high activities in ethylene dimerization.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A series of 2-(1-aryliminoethylidene)quinolines were prepared as the bidentate ligands. ► The iron(II) and cobalt(II) complexes containing 2-(1-aryliminoethylidene)quinolines were synthesized and characterized. ► The molecular structures of metal complexes described as the distorted bipyramidal geometry at the metal. ► Upon activation with MAO or MMAO, all pre-catalysts showed high activities in ethylene dimerization.