Three-Coordinate Aluminum is not a Prerequisite for Catalytic Activity in theZirconocene-Alumoxane Polymerization of Ethylene

摘要

In spite of the importance of alkylalumoxanes, in particular the methylderivative (methylalumoxane, MAO), as highly active catalysts and co-catalysts for the polymerization of a wide range of organic monomers, their structure and mode of catalytic activity remained ambiguous. The structual picture commonly proposed for alkylalumoxanes, involving Al-O chain and cyclic structures (e.g., I and II) were inconsistent with the aluminum-oxygen compounds. Furthermore, compounds containing three-coordinate aluminum, assumed to be vital for catalytic activity, are rare, only existing in compounds in which oligomerization is sterically hindered by bulky ligands. jg p.5.