Metallocene compositions

This invention relates to metallocene compositions and their use in the preparation of catalyst systems for olefin polymerization, particularly propylene polymerization. The metallocene compositions may be represented by the formula: ##STR1##

wherein R³ are identical or different and are each a halogen atom, a C₁-C₁₀ alkyl group which may be halogenated, a C₆-C₁₀ aryl group which may be halogenated, a C₂-C₁₀ alkenyl group, a C₇-C₄₀-arylalkyl group, a C₇-C₄₀ alkylaryl group, a C₈-C₄₀ arylalkenyl group, a NR₂, SR, OR, OSiR₃ or PR₂ radical, wherein R is one of a halogen atom, a C₁-C₁₀ alkyl group, or a C₆-C₁₀ aryl group, and R⁹ and R¹¹ are identical or different and are a Group 14 radical having from 1 to 20 carbon atoms or are each primary, secondary or tertiary butyl groups, aryl groups, isopropyl groups, fluoroalkyl groups, trialkyl silyl groups, or other groups of similar size.