Propylene Polymerization with Bis(phenoxy‐imine) Group‐4 Catalysts Using iBu3Al/Ph3CB(C6F5)4 as a Cocatalyst

The catalytic behavior of three bis(phenoxy‐imine) group‐4 transition‐metal complexes (M = Ti, Zr, Hf), with ⁱBu₃Al/Ph₃CB(C₆F₅)₄ cocatalyst systems towards propylene polymerization was investigated under atmospheric pressure at 25 °C. The Ti complex produced ultrahigh‐molecular‐weight atactic poly(propylene), whereas Zr and Hf complexes formed high‐molecular‐weight isotactic poly(propylene)s via a site‐control mechanism. The isotactic poly(propylene) obtained with the Hf complex displayed a high melting temperature of 123.8 °C.