Process for preparing a carbon-bridged biscyclopentadiene compound

A process for preparing a carbon-bridged cyclopentadienyl metallocene comprising the steps of:

• a) reacting one or two cyclopentadiene compounds, of which at least one cyclopentadiene compound is a substituted cyclopentadiene compound, with a carbonyl compound in the presence of at least one base and at least one phase transfer catalyst to give a carbon-bridged biscyclopentadiene compound, and
• b) reacting the carbon-bridged biscyclopentadiene compound obtained in step a) with a metal compound M.sup.1 X.sub.p, where M.sup.1 is an element of group IIIb, IVb, Vb or VIb of the Periodic Table of the Elements, X is a C.sub.1 -C.sub.40 -radical and or NR.sup.13.sub.2, where R.sup.13 is a C.sub.1 -C.sub.20 -hydrocarbon radical or C.sub.6 -C.sub.16 -aryl, a halogen or a pseudohalogen and p is an integer from 0 to 4, under conditions under which the carbon-bridged biscyclopentadiene compound obtained in step a) is complexed to give the carbon-bridged biscyclopentadienyl metallocene.