Alkyl Effects on the Chain Initiation Efficiency of Olefin Polymerization by Cationic Half-Sandwich Scandium Catalysts: A DFT Study
Alkyl Effects on the Chain Initiation Efficiency of Olefin Polymerization by Cationic Half-Sandwich Scandium Catalysts: A DFT Study
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DOI：
10.1021/acs.organomet.6b00081
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发表时间：
2016-03
期刊：
影响因子：
2.8
通讯作者：
Xiaohui Kang;Guangli Zhou;Xingbao Wang;Jingping Qu;Z. Hou;Yizhan Luo
中科院分区：
文献类型：
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作者：
Xiaohui Kang;Guangli Zhou;Xingbao Wang;Jingping Qu;Z. Hou;Yizhan Luo
用密度泛函方法研究了烷基对半夹心型稀土金属烷基配合物[（η5-C5 Me 5）ScR]+（R = CH_2SiMe_3，1; R = o-CH_2C_6H_4 NMe_2，2; R = η3-C_3H_5，3）催化乙烯、丙烯、1-己烯、苯乙烯、丁二烯和异戊二烯聚合链引发效率的影响。已经发现，具有最大空间要求的氨基苄基基团的2导致最低的引发效率，因此在所研究的三种催化剂中诱导期最长。相比之下，1与CH 2SiMe 3显示出最好的链引发能力，3与η3-烯丙基提供中等链引发活性，主要是由于最稳定的所得配位络合物。物种1和物种3在苯乙烯聚合链引发中具有比物种2更好的区域选择性。此外，1′（[（η5-C5 Me 5）Sc（CH 2SiMe 3）THF]+）在苯乙烯和异戊二烯聚合中具有比2更好的链引发效率，但也有一定的缺点。
The effect of alkyls on the chain initiation efficiency of ethylene, propene, 1-hexene, styrene, butadiene, and isoprene polymerizations catalyzed by the half-sandwich cationic rare-earth-metal alkyl complexes [(η5-C5Me5)ScR]+ (R = CH2SiMe3, 1; R = o-CH2C6H4NMe2, 2; R = η3-C3H5, 3) has been studied by using a DFT approach. It has been found that 2 with the largest sterically demanding aminobenzyl group results in the lowest initiation efficiency and thus longest induction period among the three catalysts investigated. In contrast, 1 with CH2SiMe3 displays the best chain initiation ability, and 3 with η3-allyl gives moderate chain initiation activity, mainly due to the most stable resulting coordination complex. Species 1 and 3 have better regioselectivity in the chain initiation of styrene polymerization than species 2. In addition, species 1′ ([(η5-C5Me5)Sc(CH2SiMe3)THF]+) with a THF ligand has better chain initiation efficiency in styrene and isoprene polymerizations than species 2 but is reasonably wor...