TY - DATA T1 - Catalyst/Cocatalyst Nuclearity Effects in Single-Site Polymerization. Enhanced Polyethylene Branching and α-Olefin Comonomer Enchainment in Polymerizations Mediated by Binuclear Catalysts and Cocatalysts via a New Enchainment Pathway PY - 2002/10/03 AU - Liting Li AU - Matthew V. Metz AU - Hongbo Li AU - Ming-Chou Chen AU - Tobin J. Marks AU - Louise Liable-Sands AU - Arnold L. Rheingold UR - https://acs.figshare.com/articles/journal_contribution/Catalyst_Cocatalyst_Nuclearity_Effects_in_Single-Site_Polymerization_Enhanced_Polyethylene_Branching_and_-Olefin_Comonomer_Enchainment_in_Polymerizations_Mediated_by_Binuclear_Catalysts_and_Cocatalysts_via_a_New_Enchainment_Pathway/3640647 DO - 10.1021/ja0201698.s002 L4 - https://ndownloader.figshare.com/files/5729433 KW - BC KW - EBICGC KW - bifunctional B 2 KW - Ph 3 C KW - Zr 1 KW - Zr 2 KW - B 2 KW - cocatalyst nuclearity effects KW - monometallic Zr 1 KW - ethyl branches KW - bimetallic Zr 2 KW - New Enchainment Pathway KW - trityl bisborate dianion KW - ethylene homopolymerization KW - CGC KW - CH KW - Enhanced Polyethylene Branching KW - monofunctional Ph 3 C KW - olefin polymerization catalysts N2 - The binuclear “constrained geometry catalyst” (CGC) (μ-CH2CH2-3,3‘){(η5-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 polymerization catalysts 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 effective local active site concentrations and catalyst center−catalyst center cooperative effects are evidenced by bringing 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 cocatalyst nuclearity effects are approximately additive. Compared to the catalyst derived from monometallic Zr1 and monofunctional 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 is predominantly 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-pentene copolymerization are observed for Zr2 + B2 versus Zr1 + B1. ER -