Stephen Hill, Jun-Liang Liu, Andrei Rogalev, Samuel M. Greer, Itziar Oyarzabal, Jeffrey R. Long, Rodolphe Clérac, Fabrice Wilhelm, Kasper S. Pedersen, Alain Tressaud, Etienne Durand, Abhishake Mondal, Centre de Recherche Paul Pascal (CRPP), Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Technical University of Denmark [Lyngby] (DTU), National High Magnetic Field Laboratory (NHMFL), Florida State University [Tallahassee] (FSU), Department of Physics, European Synchrotron Radiation Facility (ESRF), Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry, University of California, Berkeley, Department of Chemical & Biomolecular Engineering [Berkeley] (CBE), University of California [Berkeley], University of California-University of California, Lawrence Berkeley National Laboratory [Berkeley] (LBNL), the Danish Research Council for Independent Research for a DFF‐Sapere Aude Research Talent grant (4090‐00201), the University of Bordeaux, the ANR, the CNRS, the Region Nouvelle Aquitaine, the MOLSPIN COST action CA15128 and the GdR MCM‐2. Research at the University of California, Berkeley was supported by NSF Grant CHE‐1800252 to J.R.L. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by the NSF Cooperative Agreement (DMR‐1644779) and the state of Florida. R.C and J.R.L. are grateful to the France‐Berkeley Fund and the CNRS (PICS N°06485) for funding. Support from the NSF Graduate Research Fellowship Program (DGE‐1449440). Support from the NSF (DMR‐1610226 to S.H.) is also acknowledged. I.O. and R.C. are grateful to the Basque Government for a postdoctoral grant of I.O. The X‐ray spectroscopy experiments were performed at the European Synchrotron Radiation Facility (ESRF, Grenoble, France). Dr. D. Sadhukhan is acknowledged for helpful discussions about the synthesis., Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Facultad de Quimica de San Sebastian, Universidad del Pais Vasco, Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], and K.S.P. and R.C. thank the Danish Research Council for Independent Research for a DFF‐Sapere Aude Research Talent grant (4090‐00201), the University of Bordeaux, the ANR, the CNRS, the Region Nouvelle Aquitaine, the MOLSPIN COST action CA15128 and the GdR MCM‐2. Research at the University of California, Berkeley was supported by NSF Grant CHE‐1800252 to J.R.L. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by the NSF Cooperative Agreement (DMR‐1644779) and the state of Florida. R.C and J.R.L. are grateful to the France‐Berkeley Fund and the CNRS (PICS N°06485) for funding. S.M.G. acknowledges support from the NSF Graduate Research Fellowship Program (DGE‐1449440). Support from the NSF (DMR‐1610226 to S.H.) is also acknowledged. I.O. and R.C. are grateful to the Basque Government for a postdoctoral grant of I.O. The X‐ray spectroscopy experiments were performed at the European Synchrotron Radiation Facility (ESRF, Grenoble, France). Dr. D. Sadhukhan is acknowledged for helpful discussions about the synthesis.