Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with heterocyclic-functionalized fluorenyl ligands

Abstract

Two series of new organolanthanide(II) complexes with tetrahydro-2H-pyranyl- or N-piperidineethyl-functionalized fluorenyl ligands were synthesized via one-electron reductive elimination reaction. Treatments of [(Me 3Si) 2N] 3Ln III(μ-Cl)Li(THF) 3 with 2 equiv. of C 5H 9OCH 2C 13H 9 ( 1) or C 5H 10NCH 2CH 2C 13H 9 ( 2), respectively, in toluene at about 80 °C produced, after workup, the corresponding organolanthanide(II) complexes with formula [η 5:η 1-C 5H 9OCH 2C 13H 8] 2Ln II (Ln = Yb ( 3), Ln = Eu ( 4)) and [η 5:η 1-C 5H 10NCH 2CH 2C 13H 8] 2Ln II (Ln = Yb ( 5), Ln = Eu ( 6)) in good yields. All the compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of complexes 3, 4, and 6 were additionally determined by single-crystal X-ray analyses. It represents the first example of solvent-free organolanthanide(II) complexes with fluorenyl ligands. The catalytic properties of the organolanthanide(II) complexes on the polymerization of ε-caprolactone and methyl methacrylate have been studied. The temperatures, solvents and coordination effects on the catalytic activities of the complexes were examined.