The redox properties of Ni complexes bound to a new ligand, [DMC-nit](+), where a N-heterocyclic nitrenium group is anchored on a 1,4,8,11-tetraazacyclotetradecane backbone, have been examined using spectroscopic and DFT methods. Ligand-based [(DMC-nit)Ni](2+/+) reduction and. metal-based [(DMC-nit)Ni](2+/3+) oxidation processes have been established for the [(DMC-nit)Ni](+/2+/3+) redox series, which represents the first examples of nitrenium nitrogen (N-nit)-bound first-row transition-metal complexes. An unprecedented bent binding mode of N-nit in [(DMC-nit)Ni](2+) is observed, which possibly results from the absence of any N-nit -> Ni sigma-donation. For the corresponding (DMC-nit)Ni(F)](2+) complex, sigma-donation is dominant, and hence a coplanar arrangement at N-nit is predicted by DFT. The binding of the triazolium ion to Ni enables new chemistry (formate oxidation) that is not observed in a derivative that lacks this functional group. Thus the N-heterocyclic nitrenium ligand is a potentially useful and versatile reagent in transition-metal-based catalysis.