We have synthesized a new series of ytterbium(Ⅱ) and europium(Ⅱ) complexes by tandem silylamine elimination/homolysis of Ln−N (Ln=Yb, Eu) bonds. The interaction of 2 equiv. of C9H7CH2CH2CH2NMe2 (1) with [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 (Ln=Yb, Eu) in toluene under reflux produced lanthanide(Ⅱ) complexes [(η5:η1-C9H6CH2CH2CH2NMe2)2-Ln] [Ln=Yb (2), Eu(3)] in 67 and 74% yields, respectively. Treatment of 2 equiv. of Me2Si(Me2NCH2CH2C9H6)(NHtBu) with [(Me3Si)2N]3Eu(μ-Cl)Li(THF)3 in toluene at 80℃ afforded a europium(Ⅱ) complex [η5:η1-Me2Si(Me2NCH2-CH2C9H5)(NHtBu)]2Eu·(OC4H8)0.5 (4) in 46% yield. The interaction of 2 equiv. of Me2NCH2CH2C9H6SiMe3 with [(Me3-Si)2N]3Eu(μ-Cl)Li(THF)3 produced a europium(Ⅱ) compound [η5:η1-(Me2NCH2CH2C9H5SiMe3)]2Eu (5) in 49% yield. Treatment of 2 equiv. of Me2NCH2CH2C9H7 with [(Me3Si)2N]3Eu(μ-Cl)Li(THF)3 in toluene gave a europium(Ⅱ) complex (η5:η1-Me2NCH2CH2C9H6)2Eu (6) in 57% yield. All the compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of the complexes 4, 5, and 6 were determined by single-crystal X-ray analyses. The catalytic activities of organometallic complexes were examined; we found that all of the complexes can function as single-component MMA polymerization catalysts with good activity. We studied the effects of solvent and temperature on the catalytic activities and the stereochemistries of the polymers.

Summary: Treatment of Me2Si(C5H5)Cl with Li2C2B10H10 followed by hydrolysis gave the new versatile ligand Me2-Si(C5H5)(C2B10H11) in 79% isolated yield, which can be converted into the monoanion, dianion, and trianion, respectively. It makes possible the synthesis of a wide range of organometallic complexes.

Monofluorinated indolizines 4, benzo[d]indolizines 7 and 4H-pyrrolo[1,2-a]benzimidazoles 8 were synthesized in moderate yields by 1,3-dipolar reaction between fluorinated vinyl tosylates 2a and N-ylides of pyridinium, isoquinolinium and benzimidazolinium, generated in situ from their halides salts. When the same N-ylides were allowed to react with 2,3,3-trifluoro-1-propenyl tosylate 2b, the unexpected product formylated indolizines and their derivatives 9 were obtained. The reaction mechanism is also proposed.

Summary: Reaction of Me2Si(C9H7)(C2B10H11) with 4 equiv of NaNH2 in dry THF, followed by treatment with 1 equiv of LnCl3, gave unprecedented tetranuclear clusters of the general formula [{(η5-μ2-C9H6SiMe2NH)-Ln}2(μ3-Cl)(THF)]2(í4-NH)âTHF (Ln) Gd (1), Er (2)) in moderate yield. Their molecular structures have been confirmed by single-crystal X-ray analyses, which represent the first organometallic clusters containing a central μ4-imido group.