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Indexed by:期刊论文

Date of Publication:2014-08-01

Journal:SCIENCE CHINA-CHEMISTRY

Included Journals:SCIE、EI、Scopus

Volume:57

Issue:8

Page Number:1150-1156

ISSN No.:1674-7291

Key Words:scandium; 1,6-heptadiene; ethylene; cyclopolymerization; copolymerization

Abstract: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.