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

Abstract

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 ( 1H 2) in 90% yield. Deprotonation of 1H 2 with NaH in THF, followed by reaction with LnCl 3 in THF gives, after recrystallization from a toluene or benzene solution, dinuclear complexes ( 1) 3Y 2(thf) 2 · 3C 7H 8 ( 3 · 3C 7H 8) and ( 1) 3Yb 2(thf) 2 · 3C 6H 6 ( 4 · 3C 6H 6), respectively, in good yields. Treatment of 1H 2 with Ln[N(SiMe 3) 2] 3 in toluene under reflux, followed by recrystallization from a benzene solution gives the dimeric amido complexes { 1-LnN(SiMe 3) 2} 2 · 2C 6H 6 (Ln = Y ( 5 · 2C 6H 6), Yb ( 6 · 2C 6H 6)) 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.