Quasi-Living trans-1,4-Polymerization of Isoprene by Cationic Rare Earth Metal Alkyl Species Bearing a Chiral (S,S)‑Bis(oxazolinylphenyl)amido Ligand

• Published in: Macromolecules 2013-05, Vol.46 (9), p.3257-3265
• Main Authors: Liu, Hui, He, Jianyun, Liu, Zhanxiong, Lin, Zhengguo, Du, Gaixia, Zhang, Shaowen, Li, Xiaofang
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma4005549

A series of chiral mononuclear dialkyl complexes [(S,S)-BOPA]Ln(CH2SiMe3)2 (1, 2) (BOPA = (S,S)-bis(oxazolinylphenyl)amido; Ln = Sc (1); Ln = Lu (2)) and binuclear alkyl complexes [ο-(S)-OPA–C6H4–(CH2SiMe3)CN–CH( i Pr)CH2–O]Ln(CH2SiMe3)}2 (3, 4) (OPA = (oxazolinylphenyl)amine; Ln = Y (3); Ln = Tm (4)) have been synthesized in moderate yields via one-pot acid–base reactions by use of the tris(trimethylsilylmethyl) rare earth metal complexes with the chiral tridentate (S,S)-bis(oxazolinylphenyl)amine ligand. In the presence of activator with or without a small amount of Al i Bu3, the dialkyl complexes 1 and 2 exhibit very high activities (up to 6.8 × 105 g molLn –1 h–1) and trans-1,4-selectivity (up to 100%) in the quasi-living polymerization of isoprene, yielding the trans-1,4-PIPs with moderate molecular weights (M n = (0.2–1.0) × 105 g/mol) and narrow molecular weight distributions (M w/M n = 1.02–2.66).