Akio Imai

Synthesis of titanium(IV) complexes that contain the Bis(silylamide) ligand of the type [1,8-C10H6(NR)2]2−, and alkene polymerization catalyzed by [1,8-C10H6(NR)2]TiCl2-cocatalyst system

Abstract [1,8-C10H6(NR)2]TiCl2 (3; R=SiMe3, SiiBuMe2, SiiPr3) complexes have been prepared from dilithio salts [1,8-C10H6(NR)2]Li2 (2) and TiCl4 in diethyl ether in moderate yields (60–63%). These complexes showed significant catalytic activities for ethylene polymerization and for ethylene/1-hexene copolymerization in the presence of methylaluminoxane (MAO), methyl isobutyl aluminoxane (MMAO), AliBu3– or AlEt3–Ph3CB(C6F5)4 as a cocatalyst. The catalytic activities performed in heptane (cocatalyst MMAO) were higher than those carried out in toluene (cocatalyst MAO): 709 kg-PE/mol-Ti·h could be attained for ethylene polymerization by using [1,8-C10H6(NSiiBuMe2)2]TiCl2–MMAO catalyst system.

Synthesis of Titanium(IV) Complexes that Contain the Bis(silylamide) Ligand of the Type [1,8-C10H6(NR)2]2- (R=SiMe3, SitBuMe2, SiiPr3), and Olefin Polymerization Catalyzed by the [1,8-C10H6(NR)2] TiX2(X=Cl, Br)- cocatalyst System

Abstract [l,8-C 10 H 6 (NSi t BuMe 2 ) 2 ]TiBr 2 (4) has been prepared from dilithio salts [1,8-C 10 H 6 (NR) 2 ]Li 2 (2) and TiBr 4 in Et 2 O. 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-C 10 H 6 (NR) 2 ] TiCl 2 (3: R = SiMe 3 , Si t BuMe 2 , Si i Pr 3 ). The effective cocatalyst was, however, different between the chloride and the bromide complexes. [ArNCH 2 CH 2 CH 2 NAr]TiCl 2 (5, Ar = 2,6- i Pr 2 C 6 H 3 ), 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 M w /M n value (1.8) was observed if the polymerization was stopped at the initial stage (2 min) under the same reaction conditions.