Synthesis, structural characterization, and reactivity of organolanthanides derived from a new chiral ligand (S)-2-(pyrrol-2-ylmethyleneamino)-2′-hydroxy-1,1′-binaphthyl

Condensation of (S)-2-amino-2′-hydroxy-1,1′-binaphthyl with 1 equiv. of pyrrole-2-carboxaldehyde in toluene in the presence of molecular sieves at 70 °C gives (S)-2-(pyrrol-2-ylmethyleneamino)-2′-hydroxy-1,1′-binaphthyl (1H2) in 90% yield. Deprotonation of 1H2 with NaH in THF, followed by reaction with LnCl3 in THF gives, after recrystallization from a toluene or benzene solution, dinuclear complexes (1)3Y2(thf)2 · 3C7H8 (3 · 3C7H8) and (1)3Yb2(thf)2 · 3C6H6 (4 · 3C6H6), respectively, in good yields. Treatment of 1H2 with Ln[N(SiMe3)2]3 in toluene under reflux, followed by recrystallization from a benzene solution gives the dimeric amido complexes {1-LnN(SiMe3)2}2 · 2C6H6 (Ln = Y (5 · 2C6H6), Yb (6 · 2C6H6)) in good yields. All compounds have been characterized by various spectroscopic techniques, elemental analyses and X-ray diffraction analyses. Complexes 5 and 6 are active catalysts for the polymerization of methyl methacrylate (MMA) in toluene, affording syn-rich poly-(MMA)s.

Graphical abstractA new series of chiral organolanthanide amides have been prepared from the reaction between the ligand (S)-2-(pyrrol-2-ylmethyleneamino)-2′-hydroxy-1,1′-binaphthyl (1H2) and Ln[N(SiMe3)2]3. These amides can initiate the polymerization of MMA, leading to syn-rich poly(MMA)s.Figure optionsDownload full-size imageDownload as PowerPoint slide