Synthesis, Structure And Catalytic Activity Of Organolanthanide Complexes With N-piperidineethyl Substituted Fluorenyl Ligands

All experiments were carried out under the dry and oxygen-free argon atmosphere by using standard Schlenk techniques.Reaction of C₅H₁₀NCH₂CH₂Cl with 1 equiv of C₁₃H₉Li in Et₂O at O^°C yielded C5_H10NCH₂CH₂C₁₃H₉(1)in 73%yield.Interaction of[(Me₃Si)₂N]₃Yb^â…¢(μ-Cl)Li(THF)₃ with 2 equiv of 1 in refluxing toluene for 24 hours,after recrystallization from toluene,gave an ytterbium(â…¡)complex[η⁵;μ¹-C₅H₁₀NCH₂CH₂C₁₃H₈]₂Yb^â…¡(2)in 64%yield.Interaction of[(Me₃Si)₂N]₃ Eu^â…¢(μ-Cl)Li(THF)₃ with 2 equiv of 1 in refluxing toluene for 24 hours,gave a europium(â…¡)complex[η⁵;η¹-C₅H₁₀NCH₂CH₂C₁₃H₈]₂Eu^â…¡(3)in 70%yield.Interaction of[(Me₃Si)₂N]₃Nd^â…¢(μ-Cl)Li(THF)₃ with 2 equiv of 1 in refluxing toluene for 24 hours,after recrystallization from toluene,gave a neodymium(â…¢)complex[η⁵;η¹- C₅H₁₀NCH₂CH₂C₁₃H₈]₂-Nd^â…¢Cl(4)in 47%yield;Interaction of 1 with 1 equiv ofn-BuLi in THF yielded C5_H10NCH₂CH2C₁₃H₅Li(THF)₂(5)in 81%yield;Reaction of 5 with 0.5 equiv of YCl₃ in THF yielded[η⁵;η¹-C₅H₁₀NCH₂CH₂C₁₃H₈]₂-y^â…¢Cl(6)in 62%yield.All the complexes were fully characterized by elemental and spectroscopic analyses.The structures of complexes 3 and 5 were determined by X-ray diffraction.On the basis of the above experimental results,these experiments further certify that the internal donor ligands coordination promoted homolytic reaction of the Ln-N bond,The activities of the ytterbium(â…¡) and europium(â…¡)complexes as single-component catalysts in catalyzing MMA andε-CL polymerization were examined.It was found that the activities of the catalysts,stereo-regularity of PMMA,and the molecular weight of polymers were dependent on the solvents,temperature and the central metal of the catalysts.