Synthesis of Half-Titanocenes Containing Pyrrolides and their Use as Olefin Polymerization Catalysts

摘要

Nonbridged half-metallocenes containing anionic ancillary donor ligand of type, Cp/M(L)X2 (Cp' = cyclopentadienyl group; M = Ti, Zr, Hf; L = anionic donor ligand such as aryloxo, amide, anilide, ketimide etc.; X = halogen, alkyl), have recently emerged as new promising catalysts for precise olefin polymerization, because these complexes display unique characteristics that are different from ordinary metallocenes as well as linked (constrained geometry type) half-metallocenes. We have demonstrated that nature of anionic donor ligands (L) in the half-titanocenes, [Cp'Ti(L)X2], strongly affects both the catalytic activity and the monomer reactivity in the copolymerization of ethylene with α-olefins, cyclic olefins, styrene, non-conjugated dienes etc; this means that effective catalysts for the desired copolymerization can be tuned by modification of the anionic donor ligand employed. Since the study concerning effect of anionic ancillary ligand beyond aryloxo ligand will open a way for finding the new efficient catalysts, in the present study, new half-titanocenes containing pyrrolide and its derivatives as anionic ancillary ligands were synthesized and identified. We have also explored a possibility to use these complexes as catalyst precursors for olefin polymerization.