Vanadium(III) Complexes with Bidentate Ligands as Precatalysts for Ethylene Polymerization and Copolymerization

ABSTRACT Conventional vanadium(V) catalysts suffer from rapid deactivation above 30°C, limiting their industrial scalability. Readily accessible Schiff base ligands featuring N^N, S^N, or O^N bidentate coordination atoms were employed to synthesize vanadium(III) complexes that serve as effective precatalysts for olefin polymerization. These vanadium complexes incorporate three distinct types of bidentate ligands, differing in their steric and electronic properties. Activated by Et 2 AlCl as a cocatalyst, these complexes exhibited high catalytic activities for ethylene polymerization, reaching up to 7400 kg·mol V −1 h −1 at 4 atm ethylene pressure. Vanadium(III) catalysts designed with bulky substituents demonstrated good thermal stability in short polymerization time, maintaining significant activity (3100 kg·mol V −1 h −1 ) even at 100°C. For copolymerization with polar olefins such as 10‐undecen‐1‐ol (UOH) and methyl 10‐undecenoate ( MUA ), effective incorporation of the polar monomer into the polyethylene chain was achieved by pretreating the polar monomer with an equimolar amount of alkylaluminum cocatalyst. Notably, the incorporation level of MUA reached up to 1.11 mol%.