P. Witte et al., Synthesis of unbridged bis(2-R-indenyl)zirconocenes containing functional groups and investigations in propylene polymerization, ORGANOMETAL, 18(20), 1999, pp. 4147-4155
Five new indenyl zirconium metallocenes with 2-alkyl and 2-aryl substituent
s were synthesized and characterized. For the synthesis of the ligand the d
i-Grignard reagent 1,2-bis(magnesiomethyl)benzene dichloride was explored a
s a synthon to 2-substituted indenes. This procedure provides access to a v
ariety of functionalized 2-indenylmetallocenes such as bis(2-ferrocenylinde
ne)zirconium dichloride and bis(2-adamantylindenyl)zirconium dichloride. Cr
ystallographic characterization of bis[2-(4-(dimethylamino)phenyl)indenyl]
zirconium dichloride revealed an anti conformation with a coplanar orientat
ion of the dimethylamino substituent to the aryl ring in the solid state. T
he polymerization behavior of all five zirconocene dichlorides in liquid pr
opylene was studied in the presence of MAO at various temperatures, and the
results were compared to those for the known catalyst system bis(2-phenyli
ndenyl)zirconium dichloride/MAO (M1/MAO). The productivity of the 2-arylind
ene metallocenes in propylene polymerization was on the order of 100-7000 k
g of PP/((mol of Zr) h). In contrast, the (2-adamantylindenyl)metallocenes
exhibited very low productivities of 6 kg PP/((mol of Zr) h) in propylene p
olymerization.