164586-90-7Relevant academic research and scientific papers
[N,N′-bis(trimethylsilyl)benzamidinato]titanium and -zirconium compounds. Synthesis and application as precursors for the syndiospecific polymerization of styrene
Flores,Chien,Rausch
, p. 1827 - 1833 (2008/10/09)
Ti(O-i-Pr)3Cl reacts with Li[C6H5C(NSiMe3)2]·Et2O to give [η-C6H5C(NSiMe3)2]Ti(O-i-Pr)3 (1) in quantitative yield. Mild thermolysis of 1 promotes the elimination of C6H5CN to form Ti(O-i-Pr)3N(SiMe3)2 (2), which is also synthesized from the reaction of Ti(O-i-Pr)3Cl and Li[N(SiMe3)2]·Et2O. Treatment of the dimer {[η-C6H5C (NSiMe3)2]TiCl3}2 (3) with donor ligands produces the corresponding monomeric adducts [η-C6H5C(NSiMe3)2]TiCl3·L (L = THF (4); PMe3 (5)). Partial alkylation of the dimer 3 with 2 equiv of methyllithium gives {[η-C6H5C (NSiMe3)2]Ti(Me)Cl2 }2 (6); however, treatment with 6 equiv leads to the formation of the bis(benzamidinate) compound [η-C6H5C(NSiMe3)2]2TiMe2 (7). Compound 7 is synthesized in better yield by the reaction between [η-C6H5C(NSiMe3)2]2TiCl2 (8) and methyllithium. The same reaction but with the zirconium dichloride analog [η-C6H5(NSiMe3)2]2ZrCl2 (9) also gives [η-C6H5C(NSiMe3)2]2ZrMe2 (10) in good yield. The catalytic systems 1/methylaluminoxane (MAO), 3/MAO, 4/MAO, and 5/MAO are active for styrene polymerization, forming syndiotactic polymer in a highly stereospecific process. The systems 1/MAO, 3/MAO, 8/MAO, and 9/MAO show low activity as ethylene polymerization catalysts. The cationic systems 1/triisobutylaluminum (TIBA)/Ph3C+[B(C6F5)4]- (11) or 7,10/11 were not effective as olefin polymerization catalysts.
