A Robust Vanadium(V) Tris(2-pyridyl)borate Catalyst for Long-Lived High-Temperature Ethylene Polymerization
Jin Qian, Robert J. Comito
Abstract
Soluble vanadium catalysts are highly coveted for their selectivity in olefin polymerization. However, their utility is limited by rapid deactivation, especially at scalable temperatures under which the polymer remains soluble (>100 °C). Reasoning that a highly σ-donating scorpionate ligand would stabilize the vanadium(V) against reductive deactivation, we developed vanadium tris(2-pyridyl)borate complexes and studied their reactivities in high-temperature homogeneous ethylene polymerization. Complex 1 shows exceptional ethylene polymerization longevity at high temperatures, with 1 h of activity at 105 °C. The low polydispersity, vinyl end groups, and concentration effects indicate single-site catalysis involving chain transfer to the monomer. These results provide a new platform for studying high-valent vanadium catalysts under demanding conditions.