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.

Graphical abstractIn 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 full-size imageDownload as PowerPoint slide