2294-91-9Relevant articles and documents
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
Li, Liting,Metz, Matthew V.,Li, Hongbo,Chen, Ming-Chou,Marks, Tobin J.,Liable-Sands, Louise,Rheingold, Arnold L.
, p. 12725 - 12741 (2002)
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 Zrl and monofunctional Ph3C+B (C6F5)4- (B1), the active catalyst derived from bimetallic Zr2 and bifunctional B2 produces ～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.
A HAFNIUM COMPLEX; A SUPPORTED HAFNIUM COMPLEX; METHODS OF FORMING A POLYMER USING SUCH COMPLEXES
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Paragraph 0061; 0062, (2018/12/13)
Embodiments of the present disclosure are directed towards metal complexes that can be utilized to form polymers. As an example, the present disclosure provides a metal complex of Formula I: wherein each Me represents methyl.
A novel tandem [2 + 2] cycloaddition-Dieckmann condensation with ynolate anions. Efficient synthesis of substituted cycloalkenones and naphthalenes via formal [n + 1] cycloaddition
Shindo,Sato,Shishido
, p. 7818 - 7824 (2007/10/03)
A novel tandem [2 + 2] cycloaddition-Dieckmann condensation via ynolate anions is described. Ynolate anions are useful for the formation of reactive β-lactone enolates via a pathway not involving the enolization of the corresponding β-lactones. The [2 + 2] cycloaddition of ynolate anions with δ- or σ-keto esters, followed by Dieckmann condensation, gives bicyclic β-lactones, which are easily decarboxylated to produce synthetically useful 2,3-disubstituted cyclopentenones and cyclohexenones in one pot. This tandem reaction was applied to a novel, one-pot synthesis of highly substituted naphthalenes.
