How can breaking a nitrogen-nitrogen bond form a free radical?

In chemistry, a free radical is a molecule containing at least one unpaired electron. Most radicals are formed through the cleavage of normal electron-pair covalent bonds, where the bond breaks to produce two separate entities, each retaining one electron from the original shared pair.1

The formation of free radicals via the breaking of a nitrogen-nitrogen (N–N) bond occurs in specific chemical structures, such as aromatic hydrazines (general structure $R_{2}N–N{R}_2$) or the central N–N bond in aromatic tetrazanes ($R_{2}N–RN–NR–N{R}_2$). When these bonds undergo cleavage, the shared electron pair is split, resulting in the formation of two radicals, each with an unpaired electron on a nitrogen atom.21

While many simple radicals are highly reactive and short-lived, certain radicals formed from N–N bond cleavage can be stabilized through structural features like resonance, which allows for the delocalization of the unpaired electron and increases the molecule's stability.12