1-octene polymerization catalyzed by titanium and zirconium complexes supported by [PN] or [NPN] ligands

Ligands in homogeneous complex polymerization catalysts are crucial not only for influencing polymerization activity but also for controlling the stereoselectivity of the resulting polymers. We designed ligands on the basis of the dibenzophosphole skeleton and investigated the structure and ethylene polymerization activity of titanium and zirconium complexes activated by dried modified methylaluminoxane. In this investigation, we selected 1-octene as an alpha-olefin monomer and polymerized it using five types of titanium and zirconium complexes. Then, we obtained information regarding the ligand structure, polymerization activity toward 1-octene, and tacticity control. The [NPN]-Zr complex, which exhibited the highest activity for ethylene polymerization, demonstrated negligible polymerization activity for 1-octene. Conversely, titanium and zirconium complexes with [PN] ligands as auxiliary ligands exhibited activity toward 1-octene, yielding isotactic-rich polyoctene.