Two new indene compounds, C9H7CH2SiMe2NC4H8 (1) and C9H6-1-Me-3-CH2SiMe2NC4H8 (2), were synthesized by the reaction of C9H6RLi (R) H, Me) with ClCH2SiMe2Cl, followed by treatment with lithium pyrrolidinide C4H8NLi. The interaction of [(Me3Si)2N]3Eu(μ-Cl)-Li(THF)3 with 2 equiv of 1 in refluxing toluene produced, after workup, a novel triple-decker sandwich tetranuclear europium(Ⅱ) compound, [{η:5η:5η1-(C9H5CH2SiMe2NC4H8)2}Eu2(μ-Cl)]2-[μ-η3:η5:η1:η3:η5:η1-(C9H5CH2SiMe2NC4H8)2]âC7H8â(C6H6)0.5 (3), with a coupled indenyl ligand through tandem silylamine elimination, reduction of Eu3+ to Eu2+, and the C-C coupling reactions. To probe the formation pathway of complex 3, the interaction of C9H6-1-Me-3-CH2SiMe2NC4H8 (3) with [(Me3Si)2N]3Eu(μ-Cl)Li(THF)3 was studied. Treatment of [(Me3-Si)2N]3Eu(μ-Cl)Li(THF)3 with 2 equiv of 2 in refluxing toluene temperature or at 60℃ produced, after workup, a monomeric europium(Ⅱ) complex, (η5:η1-C9H5-1-Me-3-CH2SiMe2-NC4H8)2Eu (4), via tandem silylamine elimination/homolysis of the Eu-N bond reactions. The formation pathway for complex 3 was proposed. All the compounds were fully characterized by spectroscopic methods and elemental analyses, and the structures of complexes 3 and 4 were additionally determined by single-crystal X-ray diffraction analyses. It was found that complexes 3 and 4 can function as single-component MMA polymerization initiators, which represent the first examples of europium(Ⅱ) complexes as single-component MMA polymerization catalysts. The solvents and temperature effects' on the activities of the catalysts were also discussed.