Tetrabenzo[a,c,g,i]fluorenyltitanium(III) and -(IV) complexes: Syntheses, reactions, and catalytic application

Reacting tetrabenzo[a,c,g,i]fluorenyllithium {TbfLi(THF)(4) (1)} with TiCl(3)(THF)(3) (2) leads to the formation of the eta(5)-tetrabenzo[a,c,g,i]fluorenyltitanium(III) derivative TbfTiCl(2)(THF) (3), which can be conveyed to the titanium(IV)complex TbfTiCl(3) (4) by oxidative chlorination with CCl(4). Subsequent reaction with various lithium phenoxides gives a series of titanium complexes of the type TbtTiCl(2)(OAr) (Ar = 4-(t)BUC(6)H(4) (5), 2,6-Me(2)C(6)H(3) (6), 2,4,6-Me(3)C(6)H(2) (7), 2,6-(i)PrC(6)H(3) (8), 2,6-Ph(2)C(6)H(3) (9)). Furthermore, 3 was reacted with radicals or radical-generating peroxides to form the complexes TbfTiCl(2)TEMPO (10) and TbfTiCl(2)O(t)Bu (11). All compounds were characterized by IR, MS, and NMR measurements and X-ray crystallography. Finally, compounds 6, 8, 9, and 10 were subjected to ethylene polymerization experiments using d-MAO. The activities increase in the following order [kG(PE)mol(Ti)(-1) h(-1) bar(-1)]: 6 (320) <8 (320) <10 (760) <9 (1000).