Synthesis, characterization, and styrene polymerization catalysis of pyridyl-functionalized indenyl rare earth metal bis(silylamide) complexes

• Mono(indenyl) rare earth metal bis(amide) complexes were synthesized.
• Mono(indenyl) rare earth metal bis(amide) complexes were employed as precatalysts.
• Syndiospecific polymerization of polystyrene was realized.

Amine elimination of rare earth metal tris(silylamide) complexes Ln[N(SiHMe2)2]3(THF)2 with 1 equiv of the pyridyl-functionalized indenyl ligand C9H7CMe2CH2C5H4N-α afforded the neutral mono-indenyl-ligated rare earth metal bis(silylamide) complexes (C9H6CMe2CH2C5H4N-α)Ln[N(SiHMe2)2]2 (Ln = Sc (1), Y (2), Nd (3)) in 70–82% isolated yields. These complexes were characterized by elemental analysis, FT-IR, NMR, and X-ray single crystal structural diffraction. X-ray determination showed that the metal centers are coordinated by one indenyl ring, one nitrogen atom from the pendent pyridyl group, and two amide groups to form a distorted tetrahedral geometry. In the presence of excess AliBu3 and on activation with 1 equiv of [Ph3C][B(C6F5)4] in toluene, 1–3 became active for syndiospecific polymerization of styrene in toluene at room temperature.

In the presence of excess AliBu3 and on activation with 1 equiv of [Ph3C][B(C6F5)4], the mono-indenyl-ligated rare earth metal bis(silylamide) complexes (C9H6CMe2CH2C5H4N-α)Ln[N(SiHMe2)2]2 showed activity toward syndiospecific polymerization of styrene in toluene at room temperature.Figure optionsDownload as PowerPoint slide