Reaction of 2,8-bis(o -hydroxyaryl)quinolines with group 4 metal alkyls resulting in three distinct coordination modes of the tridentate ligand. X-ray structure of complexes and performance as precursors in ethylene polymerization catalysis

A series of bis(o-hydroxyphenyl)quinolines have been prepared, starting from 2,8-dibromoquinoline. Reaction of these new ligand precursors with group 4 tetrabenzyl complexes MBn4 results in benzyl substitution of the azine fragment with the formation of amide complexes (M = Ti) or amine complexes with an N–H fragment coordinated to the metal (M = Zr, Hf). The third structural type—Zr complexes where the aromatic system of the precursor remains intact—can be prepared through the reaction of the bis(o-hydroxyphenyl)quinolones with 4 mol of methyllithium, followed by ZrCl4. The new complexes result in active polymerization catalysts when activated with MAO/borate cocatalysts on silica supports, resulting in polyethylene copolymers with very high molecular weights and multimodal MWDs.