Abstract: Phosphenium compounds with the general formula I: in which R1, R2, R3 and R4 are identical or different and represent a linear or branched C1-C6-alkyl radical, which can optionally be substituted, or R1 and R2 and/or R3 and R4 are bonded to one another with the formation of a ring, R5 and R6 stand for a saturated or unsaturated and linear or branched alkyl group, alkenyl group or aryl group, which can have suitable substituents, even heteroatoms as substituents, or a heteroatom-comprising hydrocarbon group, which can have suitable substituents, and the R5 and R6 radicals can form a ring which can be 4- to 20-membered, saturated or unsaturated and alicyclic or heteroalicyclic and can exhibit suitable substituents, X? represents an anion, a process for the preparation thereof, and also the use of these compounds in metal complexes which can be used as catalysts in organic synthesis, are claimed.