Hits:

Indexed by:期刊论文

Date of Publication:2016-03-28

Journal:ORGANOMETALLICS

Included Journals:SCIE、EI

Volume:35

Issue:6

Page Number:913-920

ISSN No.:0276-7333

Abstract: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 [(eta(5)-C5Me5)ScR](+) (R = CH2SiMe3, 1; R = o-CH2C6H4NMe2, 2; R = eta(3)-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 eta(3)-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' ([eta(5)-C5Me5)Sc(CH2SiMe3)THF](+)) with a THF ligand has better chain initiation efficiency in styrene and isoprene polymerizations than species 2 but is reasonably worse than the analogue 1 without a THF ligand.