点击次数：

发布时间：2019-03-09

论文类型：期刊论文

发表时间：2014-08-01

发表刊物：SCIENCE CHINA-CHEMISTRY

收录刊物：Scopus、EI、SCIE

卷号：57

期号：8

页面范围：1150-1156

ISSN号：1674-7291

关键字：scandium; 1,6-heptadiene; ethylene; cyclopolymerization; copolymerization

摘要：The cyclocopolymerization of 1,6-heptadiene (HPD) with ethylene (E) by a series of half-sandwich scandium alkyl catalysts bearing various auxiliary ligands have been examined. Significant ligand influence on the copolymerization activity and selectivity was observed. In combination with one equivalent of [Ph3C][B(C6F5)(4)], the half-sandwich scandium dialkyl complexes bearing a Lewis base THF (1) or an NHC side arm (2) yielded the copolymer products together with cross-linked polymers in the copolymerization of HPD with ethylene. In contrast, the THF-free complexes Cp'Sc(CH2C6H4NMe2-o)(2) (3: Cp' = C5H5; 4: Cp' = C5Me4SiMe3) and the phosphine oxide side-arm containing complex (C5Me4SiMe2CH2(O)PPh2)Sc(CH2SiMe3)(2) (5) showed excellent activity and selectivity for the cyclocopolymerization reaction, without giving cross-linked products. The H-1 and C-13 NMR analyses revealed that the resulting copolymers consist of E-E sequences and six-membered ring methylene-1,3-cyclohexane (MCH) and five-membered ring ethylene-1,2-cyclopentane (ECP) units. The HPD content in the copolymer products could be easily controlled by changing the feeding amount of HPD under 1 atm of ethylene.