Metallocenes which comprise indene systems are well known .alpha.-olefin polymerization catalysts. Substitution patterns in such indene systems significantly influence poly-.alpha.-olefin properties, including tacticity and molecular weight.
Spaleck, et al., Organometallics (1994) 13:954-963 describes bridged zirconocene catalysts including indene systems illustrated by Compound 4 of "Scheme 1" (p. 955) which yield highly isotactic polypropylene when used with methylaluminoxane as a cocatalyst. As shown by "Scheme 2", Compound 10, Spaleck's synthesis requires an expensive 2-(bromomethyl) biphenyl starting material.
This invention provides a more cost effective synthesis of metallocene catalysts which comprise indene systems.