Rare-Earth Metal Bis(alkyl)s Supported by a Quinolinyl Anilido-Imine Ligand: Synthesis and Catalysis on Living Polymerization of ε-Caprolactone.

The tridentate ligand N-(2-((2,6-diisopropylphenylimino)methyl)phenyl)quinolin-8-amine ( HL) was prepared. Treatment of HLwith 1 equiv of Ln(CH 2SiMe 3) 3(THF) 2afforded the corresponding rare-earth metal bis(alkyl) complexes LLn(CH 2SiMe 3) 2(THF) n(Ln = Sc, n= 0 ( 1); Y, n= 1 ( 2); Lu, n= 0 ( 3)) in high yields. Variable-temperature 1H NMR spectral analysis showed that these complexes were fluxional at room temperature. Complexes 1and 3were THF-free, where the metal center adopted a square-pyramidal geometry, while in 2the metal center generated a distorted octahedral geometry owing to the coordination of a THF molecule. All these complexes catalyzed the ring-opening polymerization of ε-caprolactone with high activities in living fashion, among which the Lu complex was proved to be more active than its Sc and Y analogues. [ABSTRACT FROM AUTHOR]