Modulation of 2-imino-6,7-dihydroquinlin-8(5<i>H</i>)-imine-iron ethylene polymerization catalysts through (cyclo)alkyl, benzhydryl and halide substitution

<p dir="ltr">A direct one-pot assembly has been utilized for the preparation of 2-imino-6,7-dihydroquinlin-8(5H)-imine-ferrous chloride complexes, [2-(ArN[double bond, length as m-dash]CCH3)-8-(ArN)C9H8N]FeCl2 (Ar = 2-Me-4-(CHPh2)-6-(C5H9)C6H2 Fe1, 2-Me-4-(C5H9)-6-(CHPh2)C6H2 Fe2, 2-(C5H9)-4-Me-6-(CHPh2)C6H2 Fe3, 2-(C5H9)-4,6-(CHPh2)2C6H2 Fe4, 2-(C6H11)-4,6-(CHPh2)2C6H2 Fe5, 2-(C8H15)-4,6-(CHPh2)2C6H2 Fe6, 2-F-4,6-(CHPh2)2C6H2 Fe7, 2-Cl-4,6-(CHPh2)2C6H2 Fe8], disparate in the steric/electronic profile of their N-aryl groups. In addition to spectroscopic characterization, the structural properties of representative Fe3 and Fe5 have been determined by single crystal XRD. Under activation with MAO or MMAO, Fe1–Fe8 displayed very high catalytic activities for ethylene polymerization at 60 °C [up to 25.20 × 106 g (PE) per mol (Fe) per h for Fe2/MMAO]; even at temperatures as high as 100 °C the activity remained high [3.92 × 106 g (PE) per mol (Fe) per h]. Notably, the polymers generated using MMAO as activator showed distinctly lower molecular weight than those with MAO [Mw range: 1.36–62.41 kg mol−1 (MMAO) vs. 13.07–210.56 kg mol−1 (MAO)], with ortho-cycloalkyl-containing Fe4–Fe6 forming polymers at the lowest end of the Mw range and with the narrowest dispersity (Mw/Mn range: 1.6–2.3). Microstructural analysis of selected polymers highlighted the presence of both vinyl-terminated polymers and fully saturated polymers, the ratio of which could be influenced by not only the type of aluminum-alkyl activator but also by the run temperature and the N-aryl substitution pattern. Significantly, the molecular weights of many of these polyethylenes fall within the specification range for polyethylene waxes used in industrial applications.</p><p dir="ltr"><br></p><p dir="ltr"><br></p>