Isoprene polymerization with indolide-imine supported rare-earth metal alkyl and amidinate complexes
作者：Yang, Y ；Wang, QY，W；Cui, DM
關(guān)鍵字：catalysts， indole， rare-earth metal， selectivity， synthesis
論文來源：期刊
具體來源：http://onlinelibrary.wiley.com/doi/10.1002/pola.22855/abstract?systemMessage=Wiley+Online+Library+wi
發(fā)表時間：2008年
Reaction of 7-{(N-2,6-R)iminomethyl)}indole (HL1, R = dimethylphenyl; HL2, R = diisopropylphenyl) and rare-earth metal tris(alkyl)s, Ln(CH2SiMe3)3(THF)2, generated new rare-earth metal bis(alkyl) complexes LLn(CH2SiMe3)2(THF) [L = L1: Ln = Lu (1a), Sc (1b); L = L2: Ln = Lu (3a), Sc (3b)] and mono(alkyl) complexes L22Lu(CH2SiMe3) (4a). Treatment of alkyl complexes 1a and 4a with N,N′-diisopropylcarbodiimide afforded the corresponding amidinates L1Lu{iPr2NC(CH2SiMe3)NiPr2}2 (2a) and L22Lu{iPr2NC(CH2SiMe3)NiPr2} (5a), respectively. These new rare-earth metal alkyls and amidinates except 4a in combination with aluminum alkyls and borate generated efficient homogeneous catalysts for the polymerization of isoprene, providing high cis-1,4 selectivity and high molar mass polyisoprene with narrow molar mass distribution (Mn = 2.65 × 105, Mw/Mn = 1.07, cis-1,4 98.2%, ?60 °C). The environmental hindrance around central metals arising from the bulkiness of the ligands, the Lewis-acidity of rare-earth metal ions, the types of aluminum tris(alkyl)s and borate, and polymerization temperature influenced significantly on both the catalytic activity and the regioselectivity
