Guo Ge, Wu Xiaolu, Yan Xiangqian, Yan Li, Li Xiaofang, Zhang Shaowen, Qiu Nannan
Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081, China.
Analytical and Testing Center, Liangxiang Campus of Beijing Institute of Technology, Liangxiang East Road, Fangshan District, Beijing 102488, China.
Polymers (Basel). 2019 May 8;11(5):836. doi: 10.3390/polym11050836.
A series of fluorenyl-based constrained-geometry-configuration (CGC) allyl-type rare earth metal monoalkyl complexes bearing the divalent anionic η:η--butyl(dimethylfluorenylsilyl)amido (η:η-FluSiMeNBu) ligand (η:η-FluSiMeNBu)Ln(CHSiMe)(THF) (-) have been synthesized via the alkane elimination reaction between the FluHSiMeNHBu ligand and rare earth metal tri(trimethylsilylmethyl) complexes Ln(CHSiMe)(THF). Their structures are characterized by means of NMR spectrum, elemental analyses, and X-ray diffraction. These complexes - are isostructural and isomorphous, and each of them adopts a distorted-trigonal-bipyramidal configuration containing one η:η-FluSiMeNBu ligand, one CHSiMe ligand, and two THF molecules. Unlike traditional CGC allyl-type rare earth metal complexes showing no or low activity and regio-/stereoselectivity in styrene or MMA polymerization, these complexes - exhibit high catalytic activities and/or high regio-/stereoselectivities in the -1,4-polymerization of isoprene and myrcene or in the syndiotactic polymerization of styrene under the aid of different activators (borate or borane) and AlR. The in situ H NMR spectra suggest that the exchanges of chelating ligands such as alkyl groups and divalent anionic η:η-FluSiMeNBu ligands between rare earth metal centers and Al centers result in the formation of a heterobimetallic tetraalkylaluminate complex RAl(-R)Ln(R)(-R)AlR, which is activated by activators to form a divalent cationic species [Ln(-R)AlR] as a catalytically active species in the coordination-insertion polymerization of olefins.
通过芴基硅基氨基锂配体（η:η-FluSiMeNBu）与稀土金属三（三甲基硅基甲基）配合物Ln(CHSiMe)(THF)之间的烷烃消除反应，合成了一系列带有二价阴离子η:η-丁基（二甲基芴基硅基）氨基（η:η-FluSiMeNBu）配体的芴基基受限几何构型（CGC）烯丙基型稀土金属单烷基配合物（η:η-FluSiMeNBu）Ln(CHSiMe)(THF) (-)。通过核磁共振光谱、元素分析和X射线衍射对其结构进行了表征。这些配合物具有相同的结构和晶型，每个配合物都采用扭曲的三角双锥构型，包含一个η:η-FluSiMeNBu配体、一个CHSiMe配体和两个THF分子。与传统的在苯乙烯或甲基丙烯酸甲酯聚合中无活性或活性低且区域/立体选择性低的CGC烯丙基型稀土金属配合物不同，这些配合物在不同的活化剂（硼酸盐或硼烷）和AlR的帮助下，在异戊二烯和月桂烯的-1,4-聚合或苯乙烯的间同立构聚合中表现出高催化活性和/或高区域/立体选择性。原位1H NMR光谱表明，稀土金属中心和Al中心之间的螯合配体如烷基和二价阴离子η:η-FluSiMeNBu配体的交换导致形成异双金属四烷基铝酸盐配合物RAl(-R)Ln(R)(-R)AlR，该配合物被活化剂活化形成二价阳离子物种[Ln(-R)AlR]，作为烯烃配位插入聚合中的催化活性物种。
