Synthesis, characterization and applications in ethylene polymerization of asymmetric ansa-titanocene complexes. Molecular structure of [Ti{Me2Si(η5-C5Me4)(η5-C5H3iPr)}Cl2]

The ansa-titanocene complexes, [Ti{Me2Si(η5-C5Me4)(η5-C5H3R)}Cl2] (R = Me (5), iPr (6), tBu (7), SiMe3 (8)), were obtained from the reaction of Li2{Me2Si(C5Me4)(C5H3R)} (R = Me (1), iPr (2), tBu (3), SiMe3 (4)) with [TiCl4(THF)2], respectively. Compounds 5–8 have been tested as catalysts in the polymerization of ethylene and compared with the ansa-titanocene complexes [Ti{Me2Si(η5-C5H4)2}Cl2] and [Ti{Me2Si(η5-C5Me4)(η5-C5H4)}Cl2]. The resulting polyethylene showed molecular weights of about 200 000 g mol−1 and polydispersity values of approximately 3. In addition, the molecular structure of 6 has been determined by single crystal X-ray diffraction studies.