Regioselective Coordination of Re<sub>2</sub>(CO)<sub>10</sub> to Y@C<sub>2v</sub>(9)‑C<sub>82</sub>: An Unprecedented η<sup>1</sup> Complex Stabilized by Intramolecular Electron Transfer XieYun-Peng PanChangwang BaoLipiao SlaninaZdenek AkasakaTakeshi LuXing 2019 The prototypical η<sup>1</sup>-coordinated complexes of endohedral metallofullerenes (EMFs) have never been reported because of their low stability. Herein, we have developed a highly efficient radical-coupling strategy by performing a regioselective photochemical reaction of a rhenium complex (<b>1</b>) with the paramagnetic Y@C<sub>2v</sub>(9)-C<sub>82</sub> to form an unprecedented η<sup>1</sup>-coordinated complex with high stability: namely, Re­(CO)<sub>5</sub>-η<sup>1</sup>-Y@C<sub>2v</sub>(9)-C<sub>82</sub> (<b>2</b>). X-ray results demonstrate that the rhenium moiety coordinates to a [5,6,6]-carbon atom on the cage via a single Re–C σ bond. Vis–NIR results suggest that <b>2</b> displays an absorption curve that is identical with the monoanion of metallofullerene [Y@C<sub>2v</sub>(9)-C<sub>82</sub>]<sup>−</sup>, confirming unambiguously that one electron is transferred from the rhenium center to Y@C<sub>2v</sub>(9)-C<sub>82</sub>. This is also confirmed by an ESR study showing the diamagnetic properties of <b>2</b>. Surprisingly, our electrochemical results reveal that <b>2</b> possesses a redox behavior similar to that of pristine Y@C<sub>2v</sub>(9)-C<sub>82</sub>. Thus, we have presented a useful methodology for the synthesis of EMF-based molecular building blocks with the same electrochemical properties but different electronic configurations (e.g., open shell versus closed shell).