Synthesis of Half-Titanocenes Containing Aryloxide Ligands Attached to the ROMP Polymer Chain End: Unique Catalyst Precursors for Ethylene (Co)polymerization

Abstract

Half-titanocenes containing aryloxide ligands immobilized on the chain end of ring-opened poly(norbornene)s, (C5Me5)TiMe2[O-2,6-R2C6H2-4-CH{CH-(1,3-cyclo-C5H8)-CH}nCHCMe2Ph] [R = H (1), Me (2), iPr (3)], prepared by living ring-opening metathesis polymerization (ROMP) by Mo(N-2,6-iPr2C6H3)(CHCMe2Ph)(OtBu)2, have been prepared and identified by 1H and 13C NMR spectra, elemental analysis, and X-ray photoelectron spectroscopy. These complexes showed high catalytic activities for ethylene polymerization in the presence of methylaluminoxane (MAO) cocatalyst, and the effect of the substituent on the aryloxide on both the activity and molecular weight of the resultant polymer was the same as that using nonsupported (C5Me5)TiCl2(O-2,6-R2C6H3) (R = H, Me, iPr). Complex 3 showed both notable catalytic activities and efficient 1-hexene incorporation with the same monomer reactivity ratio as nonsupported (C5Me5)TiCl2(O-2,6-iPr2C6H3) (3‘) for ethylene/1-hexene copolymerization in the presence of MAO.