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, RuCl2(acetonitrile)4, RuCl2(pyridine)4 or RuCl2(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.
