The present invention relates to a process for preparing ruthenium(0)-olefin complexes of the (arene)(diene)Ru(0) type by reacting a ruthenium starting compound of the formula Ru(+II)(X) p (Y) q (in which X = an anionic group, Y = an uncharged two-electron donor ligand, p = 1 or 2, q = an integer from 1 to 6), with a cyclohexadiene derivative or a diene mixture comprising a cyclohexadiene derivative, in the presence of a base. In this process, the arene bound in the (arene)(diene)Ru(0) complex is formed from this cyclohexadiene derivative by oxidation. Suitable ruthenium(II) starting compounds are, for example, RuCl 2 (acetonitrile) 4 , RuCl 2 (pyridine) 4 or RuCl 2 (DMSO) 4 . The bases used are inorganic or organic bases. The ruthenium(0)-olefin complexes prepared by the process according to the invention have a high purity and can be used as precursors for homogeneous catalysts, for preparation of functional ruthenium- or ruthenium oxide-containing layers and for therapeutic applications.
