Monodisperse Au ₂₅L ₁₈ ⁰ (L = S(CH ₂) ₂Ph) and [n-Oct ₄N ⁺][Au ₂₅L ₁₈ ^-] clusters were synthesized in tetrahydrofuran. An original strategy was then devised to oxidize them: in the presence of bis(pentafluorobenzoyl) peroxide, the neutral or the negatively charged clusters react as efficient electron donors in a dissociative electron-transfer (ET) process, in the former case yielding [Au ₂₅L ₁₈ ⁺][C ₆F ₅CO ₂ ^-]. As opposed to other reported redox methods, this dissociative ET approach is irreversible, easily controllable, and clean, particularly for NMR purposes, as no hydrogen atoms are introduced. By using this approach, the -1, 0, and +1 charge states of Au ₂₅L ₁₈ could be fully characterized by ¹H and ¹³C NMR spectroscopy, using one- and two-dimensional techniques, in various solvents, and as a function of temperature. For all charge states, the NMR results and analysis nicely match recent structural findings about the presence of two different ligand populations in the capping monolayer, each resonance of the two ligand families displaying distinct NMR patterns. The radical nature of Au ₂₅L ₁₈ ⁰ is particularly evident in the ¹H and ¹³C NMR patterns of the inner ligands. The NMR behavior of radical Au ₂₅L ₁₈ ⁰ was also simulated by DFT calculations, and the interplay between theory and experiments revealed a fundamental paramagnetic contribution coming from Fermi contact shifts. Interestingly, the NMR patterns of Au ₂₅L ₁₈ ^- and Au ₂₅L ₁₈ ⁺ were found to be quite similar, pointing to the latter cluster form as a diamagnetic species.