Synthesis, characterization, and catalytic activity of divalent organolanthanide complexes with new tetrahydro-2H-pyranyl-functionlized indenyl ligands

Two series of new divalent organolanthanide complexes with the general formula [η5:η1-{1-R-3-(C5H9OCH2)C9H5}]2LnII (R = H, Ln = Yb (3); R = Me3Si, Ln = Yb (4); R = H, Ln = Eu (5); R = Me3Si, Ln = Eu (6)) were prepared by reactions of 2 equiv. of 1-R-3-(C5H9OCH2)C9H6 (R = H (1), R = Me3Si (2)) with the lanthanide(III) amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 (Ln = Yb, Eu) via a one-electron reductive elimination process. Recrystallization of 6 from n-hexane afforded [η5:η1-(C5H9OCH2C9H5SiMe3)]2EuII · (C6H14)0.5 (7). All compounds were fully characterized by elemental analyses, and spectroscopic methods. The structures of complexes 4 and 7 were additionally determined by single-crystal X-ray analyses. The catalytic activity of the complexes on methyl methacrylate and ε-caprolactone polymerization was studied, and the temperatures, substituents on the indenyl ring, and solvents effects on the catalytic activity of the complexes were examined.