Half-Sandwich Group 4 Metal Siloxy and Silsesquioxane Complexes: Soluble Model Systems for Silica-Grafted Olefin Polymerization Catalysts

Abstract

The cuboctameric hydroxysilsesquioxane (c-C5H9)7Si8O12(OH) (2), obtained after hydrolysis of (c-C5H9)7Si8O12Cl (1), and triphenylsilanol have been applied as model supports for silica-grafted olefin polymerization catalysts. The ligands were introduced on group 4 metals by either chloride metathesis or protonolysis. Treatment of Cp‘ ‘MCl3 (M = Ti, Zr; Cp‘ ‘ = 1,3-C5H3(SiMe3)2) with silsesquioxane and siloxylithium or -thallium salts, [(c-C5H9)7Si8O13]M‘ (M‘ = Tl (3), Li (4), Li·TMEDA (5)) or Ph3SiOTl gave either the dichloride complexes Cp‘ ‘[(c-C5H9)7Si8O13]MCl2 (M = Ti (6a), Zr (7a)) and Cp‘ ‘[Ph3SiO]TiCl2 (8a) or the monochloride species Cp‘ ‘[(c-C5H9)7Si8O13]2MCl (M = Ti (6b), Zr (7b)) and Cp‘ ‘[Ph3SiO]2MCl (M = Ti (8b), Zr (9)). Similarly, protonolysis of Cp‘ ‘MR3 with the silanols 2 and Ph3SiOH yielded the corresponding silsesquioxane bis(alkyl) complexes Cp‘ ‘[(c-C5H9)7Si8O13]TiR2 (R = CH2Ph (10a), Me (10b)) and triphenylsiloxy bis(alkyl) compounds Cp‘ ‘[Ph3SiO]MR2 (M = Ti, R = CH2Ph (11a), Me (11b...