The synthesis of the mixed rhodocenium issues and decomposition at temperatures above -20 °C, it was not possible to obtain single crystals of [1]. A second quasi-reversible reduction process was observed at E1/2 = -1.46 V (vs Fc +/0 ) and likely corresponds to the Rh +II /Rh +I one electron reduction towards the rhodocene anion. Compared to other substituted rhodocenium derivatives, [1] + [BF4] -revealed substantial increases of redox potentials of up to 1.0 V for both the first and second reduction. Similar to the introduction of an indenyl ligand [C9H7], the [C5(CF3)5] -ligand enhances the stability of the neutral and anionic rhodocene through increased redox potentials, resulting from a strong electron withdrawing effect, as well as a facilitated η 5 /η 3 -ring slippage, which results in a 18 electron rather than 20 electron complex. Based on the observed reduction potential towards the rhodocene anion and the relative position towards the oxidation potential of decamethylcobaltocene [Co(C5(CH3)5)2], the latter was assumed to be a suitable reducing agent. , confirming the cationic nature of the cobaltocene species. The η 3 -coordination of the [C5(CF3)5] -ligand in [1] -is most notable. It is perfectly reproduced in quantum chemical calculations at the r 2 SCAN-3c level (see SI). As the reduced π-donor ability of [C5(CF3)5] -coincides with smaller M-Cp interaction energies, which facilitates a η 5 /η 3 ring slippage, the η 3 -coordination effectively reduces the Pauli repulsion between the Rh(I) center and the [C5(CF3)5] -ring originating from the population of antibonding orbitals upon reduction (see Table in SI) and thereby stabilizes the anionic species. This also lowers the symmetry of the system, avoiding a low-spin 20 electron metallocene, resulting in a more stable 18 electron system. While the terminal positions (C2, C5) of the [C5(CF3)5] -allylic binding motive exhibit an average Rh-CCp bond length of 2.198( ) Å, the central position (C1) has a significantly shortened Rh-CCp bond length of 2.007(7) Å (Figure , right). These substantially divergent bond lengths are a consequence of the ring slippage, moving the center of the Cp ligand away from the metal center and thereby shortening the distance towards the central allylic position. Consequently, the adjacent CF3 substituent is significantly bent out of plane, with an angle of 24.09(66)°, and the [C5(CH3)5] - coligand is tiltied out of plane ( .89(50)°), minimizing the steric clash between adjacent CH3 and CF3 substituents. Furthermore, the uncoordinated C3-C4 C=C double bond is bent out of plane formed by the allylically bound C5-C1-C2 moiety by an angle of 23.94(56)°. The C1-C2 and C1-C5 bond lengths of 1.482( ) Å and 1.476( ) Å respectively, only differ by 0.006 Å which falls within the error intervals of both bonds, indicating a complete electron delocalization across the allylic system. As a consequence of the allylic structure, the CCp-CCp bond length of the unbound positions are significantly shortened and close to those of unconjugated C=C double bonds, at 1.355(10) Å. We further analyzed the reduction of [1] + to [1] -quantum chemically by means of energy decomposition analyses (see Table in SI). Adding two electrons to [1] + populates the e*1g orbitals (in D5d notation) of the metallocene. This reduces the π-bonding interaction between ring and metal center by half (lowering ΔEOrb.Int., see Tables and in SI) and increases Pauli repulsion (ΔEPauli), leading to a significantly reduced interaction energy (ΔEInt). Slippage of the ring then results in both a symmetry reduction (avoiding near degeneracies in the overall singlet state) and a reduction in Pauli repulsion. At the same time, the orbital interaction is increased significantly. This can be traced back to a strong π back-bonding interaction from the Rh(I) center to the LUMO of the slipped [C5(CF3)5] -ring (see Table in SI), which is located mostly at the allylic part and is completely absent in [1] + . The interaction is enhanced by a sizable decrease of the LUMO energy (from -0.59 eV to -2.23 eV) upon distortion. As a result of the structural relaxation, the overall computed interaction energy with the [C5(CF3)5] - ligand becomes very similar for the Rh(III) and Rh(I) complexes.