Abstract: The present invention relates to a process for preparing a metallocene, which comprises reacting a ligand starting compound with an adduct of the formula (I), M1XnDa ??(I) where M1 is a metal of group III, IV, V or VI of the Periodic Table of the Elements or an element of the lanthanide or actinide series, preferably titanium, zirconium or hafnium, particularly preferably zirconium, X are identical or different and are each halogen, C1–C10-alkoxy, C6–C10-aryloxy, C1–C10-alkylsulfonate such as mesylate, triflate, nonaflate, C6–C10-arylsulfonate such as tosylate, benzenesulfonate, C1–C10-alkylcarboxylate such as acetate, formate, oxalate or 1,3-dicarbonylate such as acetylacetonate or fluorinated 1,3-dicarbonylate, in particular chlorine, bromine, particularly preferably chlorine, n is an integer and is 2,3,4,5 or 6 and corresponds to the oxidation number of the metal M1, a is an integer or fraction and 0<a?4 and a is preferably in the range from 0.5 to 2.5 and is in particular 1, 1.
