A stable radical within a N-Co-N core.

A N-Co-N core is embedded within [Co(CNC) 2 ] 2+ (1) supported by two bis(4-methyl-2-(3-methyl-imidazolium)phenyl)amine (CNC) ligands. This species reveals a stable S = 1/2 state and its spin density is significantly delocalized within the N-Co-N core via parallel π-bonding interaction. Interestingly, it displays unusual stability towards O 2 and water, proving that the core is well protected. Upon reduction, compound 1 was converted to its reduced diamagnetic species [Co(CNC) 2 ] + (2) having two amide donors and a low-spin Co(III) ion, which can be oxidized by air to regenerate 1.