Wei Song, Keith Shackett, J. Chien
Oct 4, 1995
Citations
0
Influential Citations
14
Citations
Journal
Journal of Organometallic Chemistry
Abstract
Abstract Two new disiloxanyl-bridged bis(indenyl) Group 4 metallocenes, [ rac -1,3-bis( η 5 -indenyl)-1,1,3,3-tetramethyldisiloxane]dichlorotitanium ( 2 ) and -zirconium ( 3 ), have been synthesized from the corresponding ligand 1,1,3,3-tetramethyl-1,3-bis(indenyl)disiloxane ( 5 ), which in turn was obtained by the hydrolysis of (1-indenyl)chlorodimethylsilane ( 4 ). Both 2 and 3 exhibit unusual and unexpected catalysis behaviors for olefin polymerization. They polymerize ethylene only when activated by methyl aluminoxane (MAO) but not by Ph 3 C + B(C 6 F 5 ) 4 − -tri-isobutylaluminum ( 7 ). The Ti precursor 2 does not polymerize propylene with either cocatalyst, whereas the Zr precursor 3 exhibited moderate activity to produce atactic polypropylene, even though 3 is C 2 symmetric. The propylene polymerization activities of 3 -MAO increased strongly while that of 3–7 decreased slightly with the increase in T P . These catalytic behaviors may be the result of σ donation from oxygen atom of the siloxane bridge to metal center.