Aminoxyl radical
Aminoxyl radicals are chemical species containing the R2N–O• functional group. They are also known as nitroxyl radicals and nitroxides, however IUPAC discourages the use of these terms, as they erroneously suggest the presence of a nitro group. They are radicals and are structurally related to aldoximes (hydroxylamines) and N-oxoammonium salts, with which they can interconvert via a series of redox steps.
Sterically hindered aminoxyls such TEMPO and TEMPOL are persistent (stable) radicals and find use in a range of oxoammonium-catalyzed oxidations. They are also present as transitory species in hindered amine light stabilizers.
...
Wikipedia