Persilylation of Ferrocene: The Ultimate Discipline in Sterically Overcrowded Metal Complexes

We report the preparation and structural characterization of the first persilylated metallocene via metalation of decabromoferrocene. Whereas Grignard conditions turned to be insufficient due to steric and electronic effects of the silyl groups causing a decreased nucleophilicity of the metalated intermediates, stepwise lithium-halogen exchange yields complex mixtures of polysilylated compounds FeC10DMSnH10−n (n = 10, 9, 8) including the targeted decasilylated ferrocene. Those mixtures were successfully separated allowing a systematic study on silylation effects on ferrocene by XRD, CV, NMR and UV/vis spectroscopy supported by DFT calculations. The findings were used to develop a high-yielding and preparative simple way to generate a perfunctionalized and overcrowded ferrocene, FeC10DMS8Me2.