Synthesis and olefin polymerization activity of (quinolin-8-ylamino)phenolate and (quinolin-8-ylamido)phenolate Group 4 metal complexes

New Zr and Hf complexes bearing either a tridentate monoanionic 2-tert-butyl-6-[(quinolin-8-ylamino)methyl]phenolate [N,N,O−] or a dianionic 2-tert-butyl-6-[(quinolin-8 ylamido)methyl]phenolate [N,N−,O−] ligand have been synthesized and characterized. The geometries of the zirconium complexes have been studied using DFT methods. The complexes were tested as catalysts in the polymerization of ethylene and α-olefins after activation with methylalumoxane, resulting in the production, with moderate activities, of high molecular weight linear polyethylene and prevailingly isotactic polypropylene, poly(1-butene), poly(1-pentene) and poly(1-hexene). The content of isotactic pentads of these poly(α-olefins) increases while the size of the monomer increases, ranging between 50% for polypropylene and 99% for poly(1-hexene).

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (115 K)Download as PowerPoint slideHighlights► New Zr and Hf complexes bearing [N,N,O−] or [N,N−,O−] ligand have been synthesized. ► The geometries of the Zr complexes have been studied using DFT methods. ► The complexes catalyze the polymerization of ethylene and α-olefins. ► High molecular weight linear PE and prevaingly isotactic poly(olefins) were obtained. ► Increasing the size of the monomer, the content of isotactic pentads increases.