A process for the preparation of a compound of the formula III ##STR1## comprising, deprotonating a solution or suspension of an indene of the formula I ##STR2## in a solvent or solvent mixture containing a base to give a suspension of a metallated product of the compound of formula I, adding to the suspension of the metallated product a compound of the formula II and reacting the suspension of the metallated product and compound of the formula II.

The invention relates to a metallocene compound of the formula I ##STR1## where the two indenyl ligands have substitution patterns different from one another. The metallocene compound can be used as catalyst component for olefin polymerization.

Transparent cycloolefin copolymers having a high tensile strength are obtained by polymerization of a polycyclic olefin, ethylene and, if desired, an acyclic olefin and/or a monocylcic olefin in the presence of a catalyst system which comprises a cocatalyst and an asymmetrical metallocene compound of the formula ##STR1## in which R.sup.16 is cyclopentadienyl and R.sup.17 is indenyl.

The present invention relates to a polynuclear metallocene compound of the formula I ##STR1## a process for their preparation and their use as a catalyst for olefin polymerization.

The invention relates to a metallocene compound of the formula I ##STR1## where the two indenyl ligands have substitution patterns different from one another. The metallocene compound can be used as catalyst component for olefin polymerization.