Syntheses, structures and catalytic activities of low‐coordinated rare‐earth metal complexes containing 2,2′‐pyridylpyrrolides

Abstract

Reactions of the ligand precursors 2‐(2′‐pyridyl)‐3,5‐Me2‐pyrrole (L1H) and 2‐(2‐pyridyl)‐3,4,5‐Me3‐pyrrole (L2H) with [(Me3Si)2N]3RE(μ‐Cl)Li(THF)3 in toluene afforded a series of low‐coordinated rare‐earth metal bis‐amido complexes L1RE[N(SiMe3)2]2 [RE = Y (1a), Dy (1b), Er (1c), Yb (1d)] and L2RE[N(SiMe3)2]2 [RE = Y (2a), Dy (2b), Er (2c), Yb (2d)]. With the ionic radius of rare‐earth metal increasing, the reaction of L1H and [(Me3Si)2N]3RE(μ‐Cl)Li(THF)3 gave dinuclear complexes (L1)2RE(μ‐Cl)(μ‐η5:η1:η1‐L1)RE(L1)[N(SiMe3)2]2 [RE = Sm (1e), Pr (1f)]; however, the reaction of L2H and [(Me3Si)2N]3Sm(μ‐Cl)Li(THF)3 afforded (L2)2Sm[N(SiMe3)2]2 (2e). Results indicated that the ionic radius of rare‐earth metal and subtle change in the ligands have substantial effects on the structure and bonding mode of complexes. The complexes showed a high catalytic activity for the ring‐opening reaction of cyclohexene oxide with amines to afford various β‐aminoalcohols under mild solvent‐free conditions.