Synthesis, structures, and catalytic properties for ethylene polymerization of bridged [η5,η1-C5H4CHPhArO]TiCl2 complexes

A number of bridged half-sandwich titanium complexes [η5:η1-2-C5H4CHPh-4-R1-6-R2C6H2O]TiCl2 [R1 = H (5), Me (6), tBu (7, 8); R2 = H (6, 7), tBu (5, 8)] were synthesized from the reaction of their corresponding trimethylsilyl substituted ligand precursors 2-Me3SiC5H4CHPh-4-R1-6-R2C6H2OSiMe3 [R1 = H (1), Me (2), tBu (3, 4); R2 = H (2, 3), tBu (1, 4)] with TiCl4 in hexane. All new complexes were characterized by 1H and 13C NMR spectroscopy. Molecular structures of complexes 5 and 8 were determined by single crystal X-ray diffraction analysis. Upon activation with AliBu3/Ph3CB (C6F5)4, complexes 5–8 exhibit reasonable catalytic activity for ethylene polymerization and copolymerization with 1-hexene, producing polyethylene and poly(ethylene-co-1-hexene) with moderate molecular weights.