Unique dual function of La(C5Me5)[CH(SiMe3)2]2(THF) for polymerizations of both nonpolar and polar monomers

A half‐metallocene‐type complex, La(C₅Me₅)CH(SiMe₃)₂]₂tetrahydrofuran (THF) 1 , showed the dual function of performing the controlled polymerizations of nonpolar monomers such as ethylene and styrene as well as polar monomers like methyl methacrylate, hexyl isocyanate, and acrylonitrile in high yields. On the other hand, the metallocene‐type rare‐earth metal complexes, (C₅H₄SiMe₃)₂Y(μ‐Me)]₂ 2 and (C₅Me₅)₂YMe(THF) 3 , showed relatively low catalytic activity. The structure of complex 2 was characterized by X‐ray analysis. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1382–1390, 2001