Catalyst/Cocatalyst Nuclearity Effects in Single-Site Polymerization. Enhanced Polyethylene Branching and -Olefin Comonomer Enchainm
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- 作者：Liting Li ; Matthew V. Metz ; Hongbo Li ; Ming-Chou Chen ; Tobin J. Marks ; Louise Liable-Sands ; and Arnold L. Rheingold
- 刊名：Journal of the American Chemical Society
- 出版年：2002
- 出版时间：October 30, 2002
- 年：2002
- 卷：124
- 期：43
- 页码：12725 - 12741
- 全文大小：473K
- 年卷期：v.124,no.43(October 30, 2002)
- ISSN：1520-5126
文摘
The binuclear "constrained geometry catalyst" (CGC) (
-CH2CH2-3,3'){(
5-indenyl )[1-Me2Si(tBuN)](ZrMe2)}2 [EBICGC(ZrMe2)2; Zr2] and the trityl bisborate dianion (Ph3C+)2[1,4-(C6F5)3BC6F4B(C6F5)3]2-(B2) have been synthesized to serve as new types of multicenter homogeneous olefin polymerizationcatalysts and cocatalysts, respectively. Additionally, the complex [1-Me2Si(3-ethylindenyl)(tBuN)]ZrMe2 (Zr1)was synthesized as a mononuclear control. For the bimetallic catalyst or bisborate cocatalyst, high effectivelocal active site concentrations and catalyst center-catalyst center cooperative effects are evidenced bybringing the catalytic centers together via either covalent or electrostatic bonding. For ethylene homopolymerization at constant conversion, the branch content of the polyolefin products (primarily ethyl branches)is dramatically increased as catalyst or cocatalyst nuclearity is increased. Moreover, catalyst and cocatalystnuclearity effects are approximately additive. Compared to the catalyst derived from monometallic Zr1 andmonofunctional Ph3C+B(C6F5)4- (B1), the active catalyst derived from bimetallic Zr2 and bifunctional B2produces ~11 times more ethyl branches in ethylene homopolymerization via a process which ispredominantly intradimer in character. Moreover, ~3 times more 1-hexene incorporation in ethylene +1-hexene copolymerization and ~4 times more 1-pentene incorporation in ethylene + 1-pentenecopolymerization are observed for Zr2 + B2 versus Zr1 + B1.
-CH2CH2-3,3'){(5-indenyl )[1-Me2Si(tBuN)](ZrMe2)}2 [EBICGC(ZrMe2)2; Zr2] and the trityl bisborate dianion (Ph3C+)2[1,4-(C6F5)3BC6F4B(C6F5)3]2-(B2) have been synthesized to serve as new types of multicenter homogeneous olefin polymerizationcatalysts and cocatalysts, respectively. Additionally, the complex [1-Me2Si(3-ethylindenyl)(tBuN)]ZrMe2 (Zr1)was synthesized as a mononuclear control. For the bimetallic catalyst or bisborate cocatalyst, high effectivelocal active site concentrations and catalyst center-catalyst center cooperative effects are evidenced bybringing the catalytic centers together via either covalent or electrostatic bonding. For ethylene homopolymerization at constant conversion, the branch content of the polyolefin products (primarily ethyl branches)is dramatically increased as catalyst or cocatalyst nuclearity is increased. Moreover, catalyst and cocatalystnuclearity effects are approximately additive. Compared to the catalyst derived from monometallic Zr1 andmonofunctional Ph3C+B(C6F5)4- (B1), the active catalyst derived from bimetallic Zr2 and bifunctional B2produces ~11 times more ethyl branches in ethylene homopolymerization via a process which ispredominantly intradimer in character. Moreover, ~3 times more 1-hexene incorporation in ethylene +1-hexene copolymerization and ~4 times more 1-pentene incorporation in ethylene + 1-pentenecopolymerization are observed for Zr2 + B2 versus Zr1 + B1.