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.