We report an improved synthesis as well as a spectroscopical, structural, and electrochemical characterization of decabromoferrocene (FeC 10 Br 10 ) and relevant side products. Oneelectron oxidation of decabromoferrocene (E 1/2 = 1.095 V vs FeCp 2 0/+ ) was achieved by AsF 5 in liquid SO 2 . The crystal structure of decabromoferrocenium hexafluoroarsenate, [FeC 10 Br 10 ][AsF 6 ], represents the first example of an isolated and structurally characterized perhalogenated ferrocenium salt.

The permercuration of ferrocene was achieved by reacting ferrocene with 10 equivalents of mercury(II) butyrate Hg(O2CC3H7)2 in a facile one‐pot reaction in multi‐gram scale and high yields. The butyrate groups in FeC10(HgX)10 (X=O2CC3H7) can be exchanged by treatment with trifluoro‐ or trichloroacetic acid (X=O2CCF3, O2CCCl3). Substitution of the trifluoroacetate groups by halides (X=Cl, F) proceeds easily in aqueous THF. The completeness of metalation was confirmed by NMR and vibrational spectroscopy, mass spectrometry, as well as elemental analysis. Additionally, the first crystal structures of permetallated metallocenes are presented: FeC10(HgX)10 (X=Cl, O2CCF3, O2CCCl3).