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

Abstract

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.

Persilylation of ferrocene: the ultimate discipline in sterically overcrowded metal complexes

“…The focus of this work was to find appropriate methods for the generation of highly silylated ferrocenes to investigate the effects of steric overload and charge stabilization by the silyl groups. 48 Reactions were carried out by metalation of bromoferrocenes [FeC 10 Br 10 ] and [FeC 10 Br 8 Me 2 ] followed by quenching with DMSCl. We observed that the introduction of silyl groups inhibits further silylation yielding only a mixture of polysilylated compounds [FeC 10 DMS n H 10− n ] ( n = 10, 9, 8) containing the targeted decasilylated ferrocene in low yields.…”