Synthesis and Polymerization Activity of Phosphine‐Pyrrolido [PN] Titanium and Zirconium Complexes

Abstract

A monoanionic bidentate [PN]‐type ligand based on dibenzophosphole was synthesized, and its coordination properties toward titanium and zirconium were investigated. The complexes [PN]M (NR2)3 (M = Ti, R = Me; M = Zr, R = Et) were synthesized through the reaction of 4‐(1H‐pyrrole‐2‐yl)dibenzophosphole, [PN]H, with three equivalents of Ti (NMe2)4 or Zr (NEt2)4. Both titanium and zirconium complexes featuring the [PN] ligand were characterized by NMR and elemental analysis. Single‐crystal X‐ray crystallography unveiled the solid‐state structure of [PN]Zr (NEt2)3, with the pyrrolido group coordinated to the zirconium center in the η1‐mode. Ethylene polymerization at 0.4 MPa using these complexes and dried modified methylaluminoxane (dMMAO) as a cocatalyst yielded linear polyethylene (PE) with a melting point of 128°C–136°C; the polymerization activity reached up to 64 kg/mol (Zr)·h·bar at 70°C.