Metallocenes based on group 4 metals were first synthesized by Wilkinson et al. in 1953;1 however, the great utility of these compounds as catalyst precursors for the stereoselective polymerization of α-olefins was not realized until the mid-1980s when two key discoveries were made. The first of these was the discovery that alkyl substituents placed on the cyclopentadienyl framework of the metallocene can significantly influence the performance and behavior of the catalyst.2 The second was the discovery that enantioselectivity in the insertion step of an α-olefin polymerization could result if one made metallocene catalysts with the appropriate chirality and stereorigidity.3