A stable radical within a N–Co–N core

Abstract

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 O₂ 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.