Synthesis and structural analysis of half-titanocenes containing 1,3-imidazolidin-2-iminato ligands: Effect of ligand substituents in ethylene (co)polymerization

• Synthesis and structural identification of (tBuC5H4)TiCl2(L) complexes.
• Unique ligand effects in ethylene polymerization and ethylene (living) copolymerization.
• Application as the catalysts for olefin polymerization.

A series of half-titanocenes containing 1,3-imidazolidin-2-iminato ligands of type, (tert-BuC5H4)TiCl2[1,3-R2(CH2N)2CN] [R = tBu (2a), cyclohexyl (Cy, 2b), C6H5 (2c), 2,6-Me2C6H3 (2d), 2,6-iPr2C6H3 (2e)] have been prepared and structures of 2a–d have been determined by X-ray crystallography. Complex 2a showed higher catalytic activity than the Cp analogue (1a) for ethylene polymerization but showed low catalytic activity in ethylene/1-hexene copolymerization under the similar conditions; the 2,6-Me2C6H3 analogue (2d) showed moderate catalytic activity for the ethylene/1-hexene copolymerization. The copolymerization with styrene proceeded in a living manner under certain conditions, whereas the other complexes (2a–c) including the Cp analogues, CpTiCl2[1,3-R2(CH2N)2CN] (1a–d), showed low catalytic activities and/or afforded a mixture of polymers (copolymer, and homopolymers) under the similar conditions.

Synthesis and structural analysis of half-titanocenes containing 1,3-imidazolidin-2-iminato ligands have been explored. (tert-BuC5H4)TiCl2[1,3-tBu2(CH2N)2CN] showed higher activity than the Cp analogue for ethylene polymerization, whereas (tert-BuC5H4)TiCl2[1,3-(2,6-Me2C6H3)2(CH2N)2CN] was effective for the copolymerization with 1-hexene and the copolymerization with styrene proceeded in a living manner.Figure optionsDownload as PowerPoint slide