The role of non‐coordinating anions in homogeneous olefin polymerization

We present an overview of homogeneous olefin polymerization catalysts in which chain initiation and propagation involves a metallocenium ion (e.g. Cp2ZrMe+) that can be produced by equilibrium or irreversible CH3− transfer. The Kaminsky catalyst is an example of the former. Complexes of (C6F5)3B with water, alcohols, mercaptans, silanols and oximes are strong acids which can protonate dialkylmetallocenes to produce weakly‐coordinated metallocenium salts that are hydrocarbon soluble and which produce high molecular weight poly‐1‐olefins. Polymer molecular weight is correlated with the steric and electronic effects of the ligands attached to the metal.