ABSTRACT
Many academic and industrial researchers have probed the utility of group 3 and group 4 metallocenes as catalyst precursors for the polymerization of ethylene and α-olefins such as propylene.1-4 In particular, much emphasis has been placed on the use of an interannular bridge, or linking group, between the two cyclopentadienyl rings in these metallocenes. These complexes are known as ansametallocenes, a term that Brintzinger introduced in his landmark work in this field.5 The term ansa (Latin, for “bent handle”) may be used to describe metallocenes with either one or two interannular bridges (Figure 4.1).
