AbstractThe synthesis of cobalticenium (triphenylphosphine)trihalogenocobaltates(II), [Cp2‐Co][Co(PPh3)X3] (X = Cl,Br,I), which were first found as by‐products in the reaction of cobaltocene with triphenylphosphonium halides, is reported. The nature of the green complexes was derived from analytical and spectroscopic data and confirmed by X‐ray analysis of the iodo complex. Oxidation of solutions of the iodo complex by oxygen gives the compound [Cp2Co][Co(OPPh3)I3].[Cp2Co][Co(PPh3)I3] is cubic (a = 18.272 Å), space group Pa3, with eight formula units in the cell. The structure consists of discrete ions [Ph3PCoI3]−and [CpCoCp]+, both lying on a threefold axis. The apparent threefold symmetry of the cobalticenium cations is due to disorder of the π‐cyclopentadienyl ligands about the threefold axes. The substituents of P and Co in the [Ph3PCoI3]−anion are in staggered configuration; the metal atom is approximately tetrahedrally surrounded by 3 I (at 2.557 Å) and 1 P (at 2.368 Å), the latter distance being larger than in other phosphinec