Dinuclear titanium complexes with methylphenylsilylene bridge between cyclopentadienyl rings. Synthesis, characterization and reactivity towards ethylene
Abstract
The new ansa-titanocene dichloride [{(SiMePh)(eta(5)-C5H4)(2)}TiCl2] (1) was prepared by one pot reaction, whereas synthesis of its methylated analogue [{(SiMePh)(eta(5)-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){(eta(5)-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.