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II (6) in 62% yield, which provides an alternate method for the preparation of 6. Treatment of 3 with 2 equiv of indene(C 9 H 8 ) produced the ytterbium(III) complex (η 5 -C 9 H 7 ) 2 Yb III N(SiMe 3 ) 2 (7). Treatment of 3 with 1 equiv of 1,2-bis(indenyl)ethane also produced the ytterbium(III) complex meso-[ethylenebis(η 5 -indenyl)ytterbium III bis(trimethylsily)amide ((EBI)Yb III N(SiMe 3 ) 2 ) (8). All the compounds were fully characterized by spectroscopic methods and elemental analyses. Complexes 3, 4, 5, 6, and 8 were additionally characterized by a single-crystal X-ray diffraction study. The formation pathway for the ytterbium(II) complexes is proposed. The study showed that ytterbuim(II) complexes 4, 5, and 6 can function as single-component MMA polymerization catalysts with good activity.