Study Of The Reaction Of Ytterbium Amides With Donor Ligands

All experiments were performed under an atmosphere of dry argon with the rigid exclusion of air and moisture using standard Schlenk techniques. Reaction of (CH2)2(C9H7)2 (1) with 2 equiv of n-BuLi in diethyl ether yielded (CH2)2(C9H6)2Li2 and then reaction with excess Me3SiCl yielded (CH2)2-[C9H6(SiMe3)]2(2) in 65% yield, Interaction between (1) and 1 equiv of [(Me3Si)2N]3YbIII(μ-Cl)Li(THF)3 in refluxed toluene gave, after recrystallization from n-hexane, an ytterbium(III) complex (CH2)2(C9H6)2YbN(SiMe3)2(3) in 68% yield ; Interaction between (1) and 1 equiv of [(Me3Si)2N]3YbIII(μ -Cl)Li(THF)3 in refluxed toluene for 8 hours, and THF (5ml) was added in, then refluxed for another 48 hours gave, after recrystallization from THF, an ytterbium(III) complex [(CH2)2(C9H6)2Yb(μ -Cl) (μ-O)Yb N(SiMe3)2(μ -Cl)Li(THF)4]2 (4) in 44% yield ; Treatment of (2) with 1 equiv of [(Me3Si)2N]3YbIII (μ -Cl)Li(THF)3 in refluxed THF gave, after recrystallization from n-hexane, an ytterbium(II) complex (CH2)2[C9H5(SiMe3)]2Yb(THF)2. (5) in 46% yield ; Treatment of (2) with 1 equiv of [(Me3Si)2N]3YbIII(μ -Cl)Li(THF)3 in refluxed DME gave, after recrystallization from toluene, an ytterbium(II) complex (CH2)2[C9H5(SiMe3)]2Yb.DME (6) in 55% yield ; Treatment of anhydrous DyCl3 with 3 equiv of (Me3Si)2NLi in refluxed THF produced, after recrystallization from hot toluene, a tetracoordinate Dysprodium(III) amide [(Me3Si)2N]3DyIII( μ -Cl)Li(THF)3. C7H8 (7) in 92% yield. All the complexes were characterized by IR , 1H-NMR , 13C-NMR and E.A.. 3, 4, 5 and 7 were also characterized by single-crystal X-ray diffraction study.Based on the above experimental result , we found that donor ligands can promoted homolysis of the Yb-N bond , and gave the final ytterbium(II) complexes. This work demonstrate that homolysis of the Yb-N bond provides a new route to obtain ytterbium(II) metallocenes.At the same time ,we also study the tetracoordinate Dysprosium amide [(Me3Si)2N]3DyIII(μ-Cl)Li(THF)3 . C7H8 . This complex can function as single-component MMA polymerization catalyst. It was found that the molecular weight and stereoregularity of PMMA were depended on the solvents, temperature, and the catalyst/MMA mole radios.