The development of efficient catalysts for the copolymerization of nonpolar monomers with polar monomers remains a great challenging task in polymer synthesis. A one-pot reaction of anhydrous LnCl with pyridyl-methylene-functionalized octamethylfluorenyl lithium OctFlu-CHPyLi in a 1:1 molar ratio, followed by alkylation with 2 equiv of LiCHSiMe in THF afforded the fluorenyl-ligated rare-earth metal bis(alkyl) complexes (OctFlu-CHPy)Ln(CHSiMe)(THF) [Ln = Sc (1), Y (2)]. Both complexes were isolated as neutral species and were characterized by NMR spectrum and elemental analysis. Complex 2 was subjected to single-crystal X-ray diffraction, which showed that the whole modified fluorenyl ligand was coordinated to Y in the η/κ mode to form a constrained geometry configuration. In the presence of excess AlBu, and on activation with 1 equiv of [PhC][B(CF)] in toluene, complexes 1 and 2 became active for both styrene (St) and -methoxystyrene (MOS) polymerization, giving polymers with high syndiotacticity (rrrr > 99%) without solvent extraction. Moreover, the ternary catalyst system composed of complex 2/AlBu/[PhC][B(CF)] was highly effective for the syndiospecific copolymerization of styrene with MOS, producing random copolymers with high molecular weights and narrow molecular weight distributions. The contents of MOS in the copolymers could be easily tuned in a wide range (11-93 mol %) by simply changing the MOS-to-St feed ratios.
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