In order to reduce cation anion interactions, we introduced more weakly coordinating anions by protonation of the TFA anions with protonated pentafluoropyridine [C5F5NH][SbF6] (pKa ≈ -11 estimated in H2O ) in liquid SO2 (Eq. 4) yielding [FeC10Hg10(NC5F5)n][SbF6]10 (2a) quantitatively as an insoluble orange solid whereas trifluoroacetic acid can be removed in vacuum. The completeness of the protonation was confirmed by the absence of TFA vibrations in the corresponding IR as well as Raman spectra (Figure ). Instead, additional Sb-F bands are present at ṽ = 660 and 633 cm -1 in the infrared spectrum as well as C-C and C-F vibrations in the Raman and infrared spectrum which could be assigned to C5F5N indicating coordination to the metal center. Protodemercuration is negligible as neither v(Cp-H) in the 3100 cm -1 region nor (intense) δ(Cp-H) vibrations in the 1100 cm -1 region are visible in both spectra which again confirms the stability of the Cp-Hg bonds. Unfortunately, the total composition could not be determined by elemental analysis due to the sensitivity of the compound. Substitution of the C5F5N ligands (Eq. 5) improves the solubility of the corresponding compounds considerably and enables the full characterization of the compounds [FeC10(Hg solv.)10][SbF6]10 (solv. = THT 2b, MeCN 2c). Both metallocenes show similar features in the vibrational spectra as discussed for compound 2a. The C Cp signals in the C NMR spectra (δ = 111.8 (2b) and 97.7 ppm (2c)) are again low field shifted in comparison to the signal of FeC10(HgTFA)10 as shown for compound 1, previously.