Polymerization of ethylene using amido functional half‐sandwich complexes of group 4 metals

Abstract

AbstractLigands (C13H9)(2,6‐R2C6H3NH)SiPh2 [R = iPr (2a), Me (2b)] were synthesized by single deprotonation of the amino group in 2,6‐dialkylanilines with n‐BuLi at −78°C followed by reaction with fluorenyl diphenyl silyl chloride [FluSi(Ph2)Cl]. Single crystal X‐ray diffraction studies revealed different geometries around the nitrogen atom for the two compounds. Titanium and zirconium complexes (3a–3d) were prepared by double deprotonation of the ligands with n‐butyl lithium (n‐BuLi) followed by reaction with the respective metal chlorides, MCl4 (THF) 2. Polymerization of ethylene was performed using these complexes as catalyst precursors along with methylaluminoxane (MAO) as an activator at 5 bar pressure. Complexes 3a–3d/MAO exhibited moderate catalyst activities for polymerization of ethylene and resulted in high molecular weight linear poly(ethylene)s (Mv > 4 × 105 g/mol). Catalyst activities were much lower when compared to similar N‐alkyl substituted complexes presumably due to the resonance effect of the aromatic group on the amido nitrogen. POLYM. ENG.SCI., 2011. © 2011 Society of Plastics Engineers