So far, only one transition metal complex with a pentakis(dimethylsilyl) substituted Cp ligand is known in the literature. Sünkel and Hofmann prepared [Mn(CO)3(C5DMS5)] by iterative lithiation and silylation of [Mn(CO)3(C5Br5)] (Scheme 1, top). Although the preparation of [C5DMS5] -by reaction of C5DMS6 with MeLi has been reported it has never been used for follow-up chemistry. Here, the corresponding C5DMS6 was prepared by reaction of C5Br6 with Mg and DMSCl. Claims in the Russian literature regarding the preparation of C5TMS6 were not reproducible. In contrast, the synthesis of [C5TMS3H2] -is well established and the ligand is easily coordinated in reactions with metal halides. However, the synthetic challenge becomes more demanding for metallocenes due to repulsion of the sterically crowded Cp ligands in the "sandwich" structure. Okuda achieved high silylation degrees by reaction of iron(II) halides with tris(1,2,4-TMS)cyclopentadienyllithium to yield 1,1',2,2',4,4'hexakis(trimethylsilyl)ferrocene. As a consequence of the steric demand a distorted structure of the silylated Cp ligands is observed. Butler et al. reported an alternative approach for hexakis(trimethylsilyl)ferrocene including a lithium-halogen exchange of 1,1',2,2',3,3'hexabromoferrocene followed by silylation with TMSCl. Recently, some of us reported an improved synthetic protocol for decabromoferrocene by bromination of [FeC10(Hg(O2CC3H7)10]. The reaction pathway emerging from perbrominated ferrocene is supposed to be a promising route to persilylation.