Nitrogen-centred radicals (NCRs) offer a very versatile toolkit in organic chemistry. Thanks to their varying degree of stability and multiple generation schemes, 2 they have found a wide range of applications as intermediates in novel synthetic pathways, platforms for obtaining persistent high-spin (poly)radicals, frustrated Lewis pairs, and frustrated radical pairs. Moreover, their relevance goes well-beyond chemistry, extending to medicine with NCRs being key drug components, and chemical biology, where reactive nitrogen species participate in a number of metabolic processes. Among NCRs, nitroarene radicals, with the unpaired electron centred in a nitro group that delocalises in the π-system of an arene, are species of particular importance in multiple chemical transformations. For instance, they are involved as transient species in hydrogen atom transfer reactions, trans-annulation processes, photoinduced, electrochemical, and redox organic transformations, polymerizations, and metabolic processes with potential biological applications. As an example of their versatility, nitroarenes also support the formation of diradical transient species generated with visible light, that can be used as anaerobic oxidants for obtaining carbonyl and imine and alkene derivatives, and to promote oxygen atom transfer, C-H hydroxylation of aliphatic systems, C-C bond cleavage of olefins, and hydroxylation of olefins through C-N bond cleavage. The simplest nitroarene example is nitrobenzene ( [1]), where the arene group is a bare phenyl ring. Nitrobenzene radical anion ([1 •-] or nitrobenzenide) has received extensive attention in the past decades. The first stable [1 •-] was reported by Weissman and co-workers via sodium metal reduction and characterised using electron paramagnetic resonance (EPR), where they report "a spectrum of at least ten peaks, covering about 25 oersteds", but no assignment was performed. This work showed that the nitro group could act as a Lewis acid, opening the possibility to host unpaired electrons and enact radical chemistry in a commonly found organic molecule. Ever since, efforts have focused on understanding the electronic structure of [1 •-] in different conditions, mainly by means of EPR. An early example of the sensitivity of [1 •-] EPR spectra is Rieger's computational study, who demonstrated that the solvent, in this case dimethylformamide and acetonitrile, plays a significant role in the hyperfine coupling constants (HFCs) of [1 •-]. Some years later, Geske and Maki reported the in situ electrochemical formation and EPR characterisation of [1 •-] via cathodic reduction in acetonitrile with n-Pr 4 N + ClO 4 -as buffer in a mercury pool electrode. They were able to model the EPR spectra considering a monoradical (𝑔 = 2.0032) experiencing HFCs to one nitrogen, and two ortho, two meta and one para hydrogen atoms (|𝐴 𝑁 | = 10. -] can also be formed using Na and K metals as reducing agents in 1,2 dimethoxy ethane (DME), and that the spectra obtained with potassium was comparable to Geske' electrochemical data. Continuing with the use of metals as reducing agents, Ling and Gendell first reported the formation of contact ion pairs [1 where the HFCs to the nuclear spins of the alkali metals (I=3/2 for Li, Na and 39 K, I=7/2 for 133 Cs) were resolved. They found sizeable variations of all HFCs with temperature and a combination of separated and contact ion pairs in mixed solutions of DME and dimethyl sulfoxide (DMSO). Smentowski then reported [1 •-] formation using Lithium, Sodium and Potassium in liquid ammonia solution at -50 °C, whose HFCs were comparable to those measured in other solvents electrochemically. Gross et al., performed a detailed study of the effect of the solvent polarity on the contact (separated) ion pair formation and the HFCs of [ -][X + ] (X = Li, Na, K, Rb, Cs). They conclude that the measured EPR linewidths are directly proportional to the ionic radius of the alkali counterion and again found large variations depending on the media used. This is consistent with what was found by Stevenson and Echegoyen, who used the very polar hexamethyl phosphoramide solvent and found that it favours separated ion pair formation. Structural characterisation was advanced by Mason et al., who reported the principal values of the g-and 𝐴 𝑁 tensors in co-crystallisation studies. Along these lines, Kochi et al., resolved the single crystal structures of [1 •-][X + ] (X = K, Rb, Cs) using metal reduction of [1] and 18-crown-6 and [2.2.2] cryptand as chelating ligands -hyperfine coupling constants to all nuclear spin active atoms were assigned, clearly correlating structure to either separated or contact ion pair formation and its impact on EPR spectra. For clarity and from now on, the possibility of having separated or contact ion pairs is denoted as