Synthesis, Structure And Catalytic Activity Of Organolanthanide Complexes With N-piperidineethyl Substitued Cyclopentadienyl Ligands

All experiments were carried out under an atmosphere of dry argon with the rigid exclusion of air and moisture using standard Schlenk techniques.Reaction of C₅H₁₀NCH₂CH₂Cl with 1 equiv of CH₃C₅H₄Na in THF yielded C₅H₁₀NCH₂CH₂C₅H₄CH₃(1)in 53%yield.Treatment of 1 with 1 equiv of n-BuLi in THF at 0℃,followed by reaction with 2 equiv of Me₃SiCl yielded C₅H₁₀NCH₂CH₂C₅H₃(CH₃)(SiMe₃)(2)in 86%yield.Treatment of[(Me₃Si)₂N]₃Yb^â…¢(μ-Cl)Li(THF)₃ with 2 equiv of 1 and 2 in toluene at 80℃via a homolytic reaction,gave the corresponding ytterbium(â…¡)complexes[η⁵;η¹-(C₅H₁₀NCH₂CH₂C₅H₃CH₃)]₂Yb^â…¡(3)in 49% yield,and {η⁵;η¹-[C₅H₁₀NCH₂CH₂C₅H₂(CH₃)(SiMe₃)]}₂Yb^â…¡(5)in 42% yield.Treatment of[(Me₃Si)₂N]₃Eu^â…¢(μ-Cl)Li(THF)₃ with 2 equiv of 1 and 2 in toluene at room temperature via a homolytic reaction,gave the corresponding europium(â…¡)complexes[η⁵;η¹-(C₅H₁₀NCH₂CH₂C₅H₃CH₃)]₂ Eu^â…¡(4)in 56%yield and {η⁵;η¹-[C₅H₁₀NCH₂CH₂C₅H₂(CH₃)(SiMe₃)]}₂Eu^â…¡(6)in 52%yield.All the compounds were fully characterized by spectroscopic methods and elemental analyses.These results further certify the heteroatom coordination promoted homolytic reaction of the Ln-N(Ln=Yb,Eu)bond.This work further extends the new methodology to prepare organolanthanide(â…¡)complexes.At the same time,We have studied the catalytic activity of the organolanthanide(â…¡)complexes as single-component polymerization catalysts ofε-caprolactone.It was found that the catalysts above have catalytic activity in catalyzingε-CL polymerization.Studies also showed that the solvents,temperatures,the mole ratio of catalyst and monomer,the volume ratio of solvents and monomer have influences on activities of catalysts,the molecular weight and its distribution.