Dinuclear titanium complexes with methylphenylsilylene bridge between cyclopentadienyl rings. Synthesis, characterization and reactivity towards ethylene

The new ansa-titanocene dichloride [{(SiMePh)(η5-C5H4)2}TiCl2] (1) was prepared by one pot reaction, whereas synthesis of its methylated analogue [{(SiMePh)(η5-C5Me4)2}TiCl2] (3) was performed in two steps with isolation of corresponding silane intermediate SiMePh(HC5Me4)2 (2). The reaction of 1 and 3 with TiCl4 afforded the dinuclear complexes [(SiMePh){(η5-C5R4)TiCl3}2] (R = H (4) and R = Me (5)). The catalysts formed from 4 and 5 after their activation with excess MAO exhibited a modest activity in ethylene polymerization. The polymer products consisted of high molar mass linear polyethylenes with a broad molar mass distribution. The presence of three paramagnetic titanium species in the mixture 4/MAO was revealed by EPR spectroscopy. All new prepared compounds 1–5 were characterized by multinuclear NMR, EI-MS, IR, and solid-state structures of 1, 3 and 5 were determined by X-ray single crystal diffraction.

Graphical abstractSynthesis of new dinuclear titanium hexachloro complexes bearing methylphenylsilylene bridge between cyclopentadienyl rings is described. Activation of complexes by an excess of MAO leads to catalytic systems polymerizing ethylene to linear polymers with broad MWD.Figure optionsDownload full-size imageDownload as PowerPoint slide