M. V. Akker, R. Olthof, F. Bolhuis
Sep 2, 2010
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Recueil des Travaux Chimiques des Pays-Bas
Abstract
The 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 A), 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 A) and 1 P (at 2.368 A), the latter distance being larger than in other phosphinecobalt complexes.