Synthesis, Characterization And Catalytic Activity Of Divalent Lanthanide Complexes With Furfuryl-and Tetrahydrofurfuryl-Functionalized Indenyl Ligands

All experiments were performed under an atmosphere of dry argon with the rigid exclusion of air and moisture using Schlenk techniques. Reaction of C4H7OCH2Cl or C4H3OCH2Cl with 1 equiv of C9H7Li in THF yielded C4H7OCH2C9H7 (1) and C4H3OCH2C9H7 (2) in 71% and 70% yield respectively. Treatment of 1 or 2 with 1 equiv of n-BuLi, respectively followed by reaction with 2 equiv of Me3SiCl in THF yielded C4H7OCH2C9H6SiMe3 (3) and C4H3OCH2C9H6SiMe3 (4) in 95% and 96% yield.Treatment of [(Me3Si)2N]3YbⅢ(μ-Cl)Li(THF)3 with 2 equiv of 1,2,3 and 4 in toluene at 80℃ via a reductive reaction, gave the ytterbium(Ⅱ) complexes [η5:η1-(C4H7OCH2C9H6)]2YbⅡ(5) in 43% yield, [η5:η1 -(C4H3OCH2C9H6)]2 YbⅡ(6) in 76% yield, [η5:η1 -(C4H7OCH2C9H5 SiMe3)]2YbⅡ(7) in 87% yield and [η5:η1-(C4H3OCH2C9H5 SiMe3)]2YbⅡ(8) in 67% yield. Treatment of [(Me3Si)2N]3EuⅢ(μ-Cl)Li (THF)3 and 2 equiv of 1,2,3 and 4 in toluene at 60℃ via a reductive reaction, afforded the europium(Ⅱ) complexes [η5:η1-(C4H7OCH2C9H6)]2EuⅡ(9) in 33% yield, [η5:η1-(C4H3OCH2C9H6)]2EuⅡ(10) in 21% yield, [η5:η1 -(C4H7OCH2C9H5SiMe3)]2EuⅡ(11) in 72% yield and [η5:η1-(C4H3O CH2C9H5SiMe3)]2 EuⅡ(12) in 64% yield. Treatment of [(Me3Si)2N]3 SmⅢ(μ-Cl)Li(THF)3 and 2 equiv of 1,2,3 and 4 in toluene at 100℃via a reductive reaction, gave the samarium(Ⅱ) complexes [η5:η1-(C4H7O CH2C9H6)]2SmⅡ(13) in 80% yield, [η5:η1-(C4H3OCH2C9H6)]2 SmⅡ(14) in 83% yield, [η5:η1-(C4H7OCH2C9H5SiMe3)]2SmⅡ(15) in 32% yield and [η5:η1-(C4H3OCH2C9H5SiMe3)]2 SmⅡ(16) in 41% yield. All the compounds were fully characterized by spectroscopic methods and elemental analyses. Complex (7) was additionally characterized by a single-crystal X-ray diffraction study. These results further certify the heteroatom coordination promoted homolytic cleavage reaction of the Ln-N(Ln = Yb,Eu,Sm) bond. This work further extends the new methodology to prepare organolanthanide (Ⅱ) complexes.At the same time, We have studied the catalytic activity of these organolanthanide(Ⅱ) complexes as single-component polymerization catalysts for Methyl methacrylate,ε-caprolactone,γ-butyrolactone. Studies showed that most of these complexes have high catalytic activity in catalyzing MMA polymerization, part of these complexes have high catalytic activity in catalyzing ε-CL polymerization, and these complexes show poor catalytic activity in catalyzing γ-BL polymerization. Studies also showed that the solvents,temperatures, the mole ratio of catalyst and monomer,the volume ratio of monomer and solvent have influenes on activities of catalysts,stereoregularity and the molecular weight distribution of polymer.