| Abstract |
Neutral and cationic titanium and zirconium diamine bis(phenolate) complexes supported by chiral ligands L-1 and L-2 are described [L-1 = (R)-6,6 -\1-(dimethylamino)propan-2-ylazanediyl\bis(methylene)-bis(2,4 -di-tert-butylphenolate); L-2 = (S)-6,6 -\(1-ethylpyrrolidin-2-yl)methylazanediyl\bis-(methylene)- bis(2,4-di-tert-butylphenolate)]. Complexes [TiL(OiPr)(2)] [L = L-1 (1), L-2 (2)], [(TiLX)-X-2(OiPr)] [X = Cl (3), CH2Ph (4)], [TiL1(CH2Ph)(2)] (5), [ZrLCl2] [L = L-1 (6), L-2 (7)] and [ZrL(CH2Ph)(2)] [L = L-1 (8), L-2 (9)] are C-1-symmetric species readily prepared in moderate to high yields. Cationic compounds were obtained from complexes 5, 8 and 9 through reactions with B(C6F5)(3). The monocationic species reveal the eta(2)-binding character of the benzyl groups and noncoordinated [B(C6F5)(3)(CH2Ph)](-). Complexes 5-9 were tested in the polymerization of ethylene and propylene upon activation with modified methylaluminoxane (MMAO), B(C6F5)(3) or [NHMe2Ph](+) as cocatalysts. The [(ZrLCl2)-Cl-1]/MMAO and [ZrL1(CH2Ph)(2)]/B(C6F5)(3) systems revealed high activities in the polymerization of propylene (2.1 x 10(3) and 1.5 x 10(3) gpolmmol(cat)(-1)h(-1), respectively), leading to atatic polypropylene, whereas the titanium complexes showed no activity. |
