Mixed‐Valence Compounds as Polarizing Agents for Overhauser Dynamic Nuclear Polarization in Solids

Herein, we investigate a novel set of polarizing agents—mixed‐valence compounds—by theoretical and experimental methods and demonstrate their performance in high‐field dynamic nuclear polarization (DNP) NMR experiments in the solid state. Mixed‐valence compounds constitute a group of molecules in which molecular mobility persists even in solids. Consequently, such polarizing agents can be used to perform Overhauser‐DNP experiments in the solid state, with favorable conditions for dynamic nuclear polarization formation at ultra‐high magnetic fields.