Synthesis of titanium(IV) complexes that contain the bis(silylamide) ligand of the type 1,8H₁₀NRM2- (R=SiMe₃; Si'BulVte, Si'Pr₃), and olefin polymerization catalyzed by the [WioHelNRfe] TWWXsCI, brcocatalyst system

[l,8-C,0H₆(NSi'BuMe₂)₂]TiBr₂ (4) has been prepared from dilithio salts [l,8-CinH₆(NR),]Li, (2) and TiBr₄ in Et₂O. This complex showed significant catalytic activity for ethylene polymerization in the presence of a cocatalyst, and the activity is the same as those obtained by using chloride analogues such as [1,8-C₁₀H₆(NR)₂] TiCl₂ (3: R = SiMe₃ Si'BuMe₂ Si'Pr,). The effective cocatalyst was, however, different between the chloride and the bromide complexes. [ArNCH₂CH₂CH₂NAr]TiCl₂ (5, Ar = 2,6-ⁱPr2C₆H₃), which has been known as an effective catalyst for polymerization of 1-hexene, showed lower activity under the same conditions. The broad molecular weight distributions (M_w/M_n for the resultant polymer can be attributed to the scission of titanium-nitrogen bond by cocatalyst, because the narrow MJM_nvalue (1.8) was observed if the polymerization was stopped at the initial stage (2 min) under the same reaction conditions.