Synthesis of phenoxy-ester titanium complexes with different R1 and R2 substituents and their catalytic properties

A series of phenoxy-ester ligated titanium complexes with different R1 and R2 substituents was synthesized. The structures of 3-silylsubstituted salicylate ligands and their corresponding titanium complexes were characterized using infrared spectrometer, nuclear magnetic resonance spectroscopy and mass spectrometer. The novel [O, O] bidentate coordination compounds with different R1 and R2 substituents were then used as the catalysts for ethylene-propylene copolymerization together with iBu3A1/Ph3CB(C6F5)4 as the cocatalysts in toluene. The correlations between R1, R2 substituents of titanium complexes and polymerization activity, polymer molecular weight were studied. The catalytic activity of titanium complex was observed to decline with increasing the size of R2, whereas the copolymers with higher molecular weight were synthesized using the titanium complex with larger R1 substituent. The ethylene propylene copolymers prepared using different titanium complex catalysts were all random copolymers.