Role of the Counteranion in the Reaction Mechanism of Propylene Polymerization Catalyzed by a (Pyridylamido)hafnium(IV) Complex
Role of the Counteranion in the Reaction Mechanism of Propylene Polymerization Catalyzed by a (Pyridylamido)hafnium(IV) Complex
复制标题
抗衡阴离子在(吡啶酰胺基)铪(IV)配合物催化丙烯聚合反应机理中的作用
DOI：
10.1021/acs.organomet.7b00767
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发表时间：
2018
期刊：
影响因子：
2.8
通讯作者：
M. Nagaoka
中科院分区：
文献类型：
--
作者：
K. Matsumoto;M.Takayanagi;S. K. Sankaran;N. Koga;M. Nagaoka
研究了吡啶基胺基铪（IV）配合物离子对活性物种催化丙烯的立体选择性聚合。特别是，我们专注于抗衡阴离子（CA）的丙烯插入反应机理的作用，因为它从来没有从分子的角度进行了研究。首先，我们通过分子动力学方法和量子化学计算寻找了多种IP构型，并定位了丙烯插入的过渡态。通过比较CA结合的催化剂与孤立的，它揭示了能量有利的插入的方式是有趣的改变，由于CA的位置。接下来，我们表明CA是必不可少的，以确定在过渡态的Hf原子的配位结构。因此，可以得出结论，CA的作用对于精确控制聚合机理至关重要。最后，我们提出了一个合成实验，这将有利于提高催化剂的立体选择性的基础上，现有的聚合机理。
We studied the stereoselective propylene polymerization catalyzed by the ion pair (IP) active species of (pyridylamido)hafnium(IV) complex, the catalyst. In particular, we focused on the role of the counteranion (CA) for the reaction mechanism of propylene insertion because it had never been investigated from the molecular point of view. First, we searched for a variety of IP configurations by the molecular dynamics (MD) method and quantum chemical calculation, and located the transition states (TSs) of propylene insertion. By comparing the CA-bound catalysts with the isolated ones, it was revealed that the manner of energetically favorable insertion is interestingly altered due to the location of the CA. Next, we showed that the CA is essential to determine the coordination structures of the Hf atom at transition state. Therefore, it was concluded that the role of the CA is critical to accurately control the polymerization mechanism. Finally, we proposed a synthesis experiment which would be advantageous to increase the stereoselectivity of the catalyst on the basis of the present polymerization mechanism.