D. Van Leusen et al., Ethylene-bridged tetramethylcyclopentadienylamide titanium complexes: Ligand synthesis and olefin polymerization properties, ORGANOMETAL, 19(20), 2000, pp. 4084-4089
The N-alkyl-2(2,3,4,5-tetramethylcyclopentadienyl)ethylamines C5Me4H(CH2)(2
)NHR (R = i-Pr, t-Bu) were obtained from the reaction of 2,3,4,5-tetramethy
lcyclopent-2-enone with deprotonated imines LiCH2CH=NR followed by dehydrat
ion and reduction using LiAlH4. The parent compound with R = H was obtained
via a similar procedure using deprotonated acetonitrile and derivatized to
the R = Me species. The Ti(IV) complexes [C5Me4(CH2)(2)NR]TiCl2 (R = t-Bu,
i-Pr, Me) were prepared and tested for catalytic propene homopolymerizatio
n using methylaluminoxane (MAO) cocatalyst. Surprisingly, the catalysts wit
h R = i-Pr, t-Bu were found to be inactive, and only for R = Me was catalyt
ic formation of atactic polypropene observed. This is in marked contrast wi
th the analogous systems with ligands with a SiMe2-bridge that readily homo
polymerize propane under similar conditions.