Silsesquioxane-bonded zirconocene complexes; soluble models for silica-tethered olefin polymerization catalysts

Silsesquioxane tethered fluorene ligands [R7Si8O12X]-9-Flu(H)(R =c-C6H11, X =-(1); R =c-C5H9, X = CH2(2), (CH2)3(3), C6H4CH2(4)), (c-C5H9)7Si8O12CH2-9-Flu(9-EMe3)(E = Si (5a), Sn (5b)) and zirconium dichlorides Cp" [(c-C5H9)7Si8O12CH2-9-Flu]ZrCl2(6b, Cp"= 1,3-C5H3(SiMe3)2), Cp*[(c-C5H9)7Si8O12-X-9-Flu]ZrCl2(X = CH2(6a), (CH2)3(7), C6H4CH2(8)) and [(c-C5H9)7Si8O12CH2-9-Flu]2ZrCl2 (9) have been applied as models for silica-tethered ancillary ligands and silica tethered-zirconocenes. Immobilization of zirconocenes containing a pendant anchorable functionality, Cp"[Me2(EtO)SiCH2Flu]ZrCl2(10) and Cp[C5Me4SiMe2OEt]ZrCl2(11) was considerably hampered by competitive Zr-Cl and Si-OEt bond splitting. When activated with MAO (methylalumoxane), 6-9 yield active ethylene polymerization systems.