Synthesis, structure and ethylene polymerization behavior of titanium phosphinoamide complexes

(Phosphinoamide)(cyclopentadienyl)titanium(IV) complexes of the type Cp*TiCl2(η2-Ph2PNR) [Cp*=C5Me5; R = t-Bu (2a), R = n-Bu (2b), R = Ph (2c)] have been prepared by the reaction of Cp*TiCl3 with the corresponding lithium phosphinoamides. The structure of Cp*TiCl2(η2-Ph2PNtBu) (2a) and Cp*TiCl2(η2-Ph2PNPh) (2c) have been determined by X-ray crystallography. These complexes exhibited moderate catalytic activities for ethylene polymerization in the presence of modified methylaluminoxane (MMAO). Catalytic activity of up to 2.5 × 106 g/(mol Ti h) was observed when activated by i-Bu3Al/Ph3CB(C6F5)4.