Since [FeC10(HgTHT)10][SbF6]10 can be regarded as a ferrocene with ten cationic [Hg(THT)] + substituents the oxidation potentials of the metallocene are expected to be higher than in unsubstituted ferrocene as similar observations were reported for a series of acceptor substituted metallocenes. For example, Sundermeyer et al. observed increasing oxidation potentials of up to ΔE = 474 mV per cationic group {SR2 + } group. The electrochemical properties of the compounds 1 and 2b,c were determined by cyclic voltammetry. Unfortunately, the metallocene 1 decomposed upon oxidation preventing the determination of the oxidation potentials. The measurements of the soluble decacationic THT and MeCN complexes 2b and 2c were performed in acetonitrile and referenced against the FcH/FcH + redox couple (Fig. ). Both compounds exhibit a reversible oneelectron oxidation of the redox couple Fe +II/+III at E1/2 THT = 0.522 V and E1/2 MeCN = 0.713 V as well as irreversible oxidations above Ea > 1.3 V (Fig. , S19, ESI). The comparison of the Fe +II/+III potentials with the starting material FeC10(HgTFA)10 (E1/2 = 0.450 V) shows increasing oxidation potentials depending on the coordination strength of the ligand (TFA > THT > MeCN). Therefore, [FeC10Hg10(NC5F5)n][SbF6]10, is expected to exhibit the highest oxidation potential in the series TFA < THT < MeCN < NC5F5 although its insolubility prevented its electrochemical characterization. A similar trend was already observed in Ag(I) compounds which vary enormously in oxidation potentials depending on the ligands at the metal center or simply the solvation ability of the solvents. The surprisingly low potentials of the 10+/11+ redox couple are probably a consequence of the large size and effective solvatization of these highly charged species as in multicationic ferrocenyl dendrimers. To realise the chemical oxidation of the permercurated ferrocene decacations we used different moderate oxidants in liquid SO2 which allow solely oxidation to the desired ferrocenium compounds. The oxidations were tested with Ag[SbF6], NO[BF4], NO2[SbF6] as well as MoF6. Unfortunately, the presence of coordinating ligands seemed to reduce the reactivity of silver salts as no reaction of none of the compounds was observed with AgSbF6. Moreover, [FeC10Hg10(NC5F5)n][SbF6]10 showed no reaction with NO + but with NO2 + indicating high oxidation potentials which perfectly fits to the correlation between ligand strength and redox potential. Reactions with NO2 + and MoF6 were successful in all cases. Single crystals of 2c[MoF6] ‧ 10 HF ‧ 2 SO2 were obtained upon recrystallisation from HF/SO2 at -74 °C. The compound crystallized in the space group P1 ̅ . The asymmetric unit consists of one {FeC5(HgMeCN)5} moiety with a center of inversion located at the iron atom. The oxidation of the iron center is indicated by an elongated iron-cyclopentadienyl distance of 1.738(1) Å which is in the same order of magnitude as other substituted ferrocenium salts but significantly longer than those of non-substituted ferrocenium cations. The metallocene cation is again fully solvated by 10 HF molecules with Hg-F HF distances of 2.817(5)-2.956(4) Å within the inner-sphere of the metallocene framework in a similar fashion as discussed for compound 2b triggering a staggered conformation with torsion angles in the range of 31.1(1) to 35.9(1) . However, the structure features several additional Hg-F cation-anion interactions of 2.824(5)-3.090(5) Å length yielding a coordination number of four to six for all mercury atoms (Fig. ). The Hg-F contacts to the [SbF6] -counter anions are present due to the low solvation of the undecacation in HF, in contrast to the THT complex 2b which was recrystallized from acetonitrile. A detailed discussion of the packing motif of the deca-(2b) and undecacation (2c[MoF6]) can be found in the supplementary information.