Synthesis, characterization of some organolanthanide complexes containing 2-pyridylmethyl substituted fluorenyl ligand and catalytic activity of organolanthanide(II) complexes

A series of organolanthanide complexes with 2-pyridylmethyl substituted fluorenyl ligand were synthesized via reaction of [(Me3Si)2N]3LnIII(μ-Cl)Li(THF)3 (Ln = Yb, Eu, Nd, Y) with the functionalized fluorene compound. Treatment of [(Me3Si)2N]3LnIII(μ-Cl)Li(THF)3 (Ln = Yb, Eu) with 2 equiv. of C5H4NCH2C13H9 (1) at 60–80 °C in toluene afforded the corresponding organolanthanide(II) complexes with formula [η5:η1- C5H4NCH2C13H8]2Ln [Ln = Yb (2), Eu (3)] via tandem silylamine elimination/homolysis of the Ln–N bond reaction. Reaction of [(Me3Si)2N]3LnIII(μ-Cl)Li(THF)3 (Ln = Y, Nd) with 2 equiv. of C5H4NCH2C13H9 in toluene at 80 °C produced the corresponding organolanthanide(III) complexes with formula [η5:η1-C5H4NCH2C13H8]2LnCl [Ln = Y (4), Nd (5)]. Complexes 4 and 5 could also be prepared by treatment of 2 equiv. of lithium fluorenide [η5:η1-C5H4NCH2C13H8]Li(THF)2 (6) with corresponding LnCl3. All compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of complexes 4 and 6 were additionally determined by single-crystal X-ray analyses. The catalytic properties of the divalent organolanthanide complexes 2 and 3 on the ring-opening polymerization of ε-caprolactone (CL) have been studied. The temperatures, solvents effects on the catalytic activities of the complexes were examined.