Synthesis of zirconocene silsesquioxane complexes and their ethene polymerization activity in systems with methylaluminoxane
Abstract
Protocols for obtaining defined zirconocene complexes with polyhedral oligomeric silsesquioxanes with mono-, di-, and trisilanol functionality (SIPOSS, DIPOSS, and TRIPOSS) were established. The TRIPOSS silanolates binding one zirconocene and one chlorozirconocene moiety, [{(c-C5H9)(7)Si7O9O3}Zr2Cl(eta(5)-C5H4R)(4)] (1, R = Bu; 2, R = H), were obtained by reacting the silanol with the respective zirconocene dichloride and triethylamine in CH2Cl2 in a 1.0:3.0:3.0 molar ratio, an excess of the zirconocene dichloride being required to suppress intramolecular dehydration of TRIPOSS.
The related SIPOSS complex, [{(c-C5H9)(7)Si8O12O}(2)Zr(eta(5)-C5H4Bu)(2)] (3), was prepared similarly at the stoichiometric ratio of [ZrCl2(eta(5)-C5H4Bu)(2)]/ SIPOSS/NEt3 equal to 1.0:2.0:2.0. When employed in the 1.0:1.0:1.0 ratio, the same reagents afforded only the impure complex [{(c-C5H9)(7)Si8O12O}ZrCl(eta(5)-C5H4Bu)(2)] (4), contaminated with 3 and unreacted [ZrCl2(eta(5)-C5H4Bu)(2)].