Synthesis, structures and catalytic properties of stable oxo-bridged half-sandwich titanium complexes

Hydrolysis of 1,2-diphenyl-4-R-cyclopentadienyl titanium trichloride (R = Me (1), n-Bu (2)) affords the corresponding oxo-bridged monocyclopentadienyl titanium compounds (1,2-Ph2-4-R-CpTiCl2)2(μ-O) (R = Me (3), n-Bu (4)), new dinuclear species. The molecular structures of complexes 3 and 4 have been confirmed by single-crystal X-ray diffraction. Both complexes have been characterized by elemental analysis, 1H and 13C NMR spectroscopy. When activated with Al(iBu)3 and Ph3C+B(C6F5)4-, complexes 3 and 4 show reasonable catalytic activity for ethylene polymerization, producing polyethylenes with moderate molecular weights, and upon activation with methylaluminoxane (MAO), complexes 3 and 4 exhibit high catalytic activity and syndiospecificity for the polymerization of styrene.

Graphical abstractThe oxo-bridged monocyclopentadienyl titanium complexes (1,2-Ph2-4-R-CpTiCl2)2(μ-O) (R = Me (3), n-Bu (4)), have been synthesized and structurally characterized. Both complexes show moderate catalytic activity for ethylene polymerization when activated with Al(iBu)3 and Ph3C+B(C6F5)4-, and those catalyst systems produces polyethylenes with moderate molecular weights and melting transition temperatures. The 3 or 4/MAO systems also show good catalytic performance for styrene polymerization in terms of catalytic activity and syndiotacticity.Figure optionsDownload full-size imageDownload as PowerPoint slide