Silsesquioxane-bonded zirconocene complexes as 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.