Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
J Am Chem Soc. 2013 Jun 19;135(24):8830-3. doi: 10.1021/ja4039505. Epub 2013 Jun 4.
A heterobimetallic catalyst, {Ti--Cr}, consisting of a constrained-geometry titanium olefin polymerization center (CGC(Et)Ti) covalently linked to a chromium bis(thioether)amine ethylene trimerization center (SNSCr) was synthesized and fully characterized. In ethylene homopolymerizations it affords linear low-density polyethylene with molecular weights as high as 460 kg·mol(-1) and exclusively n-butyl branches in conversion-insensitive densities of ~18 branches/1000 carbon atoms, which are ~17 and ~3 times (conversion-dependent), respectively, those achieved by tandem mononuclear CGC(Et)Ti and SNSCr catalysts under identical reaction conditions.
一种异双核催化剂{Ti--Cr}，由一个约束几何钛烯烃聚合中心（CGC(Et)Ti）通过共价键连接到一个铬双（硫醚）胺乙烯三聚化中心（SNSCr）组成，已经被合成并进行了全面的表征。在乙烯均聚反应中，它可以得到分子量高达 460kg·mol(-1)的线性低密度聚乙烯，并且在转化率不敏感的密度下仅具有 n-丁基支链，约为 18 个支链/1000 个碳原子，这分别是在相同反应条件下使用串联单核 CGC(Et)Ti 和 SNSCr 催化剂时所达到的值的 17 倍和 3 倍（与转化率有关）。
