While recent spectroscopic studies have established the presence of an interstitial carbon atom at the center of the iron–molybdenum cofactor (FeMoco) of MoFe-nitrogenase, its role is unknown. We have pursued Fe–N₂ model chemistry to explore a hypothesis whereby this C-atom (previously denoted as a light X-atom) may provide a flexible trans interaction with an Fe center to expose an Fe–N₂ binding site. In this context, we now report on Fe complexes of a new tris(phosphino)alkyl (CP^iPr₃) ligand featuring an axial carbon donor. It is established that the iron center in this scaffold binds dinitrogen trans to the C_alkyl-atom anchor in three distinct and structurally characterized oxidation states. Fe–C_alkyl lengthening is observed upon reduction, reflective of significant ionic character in the Fe–C_alkyl interaction. The anionic (CP^iPr₃)FeN₂^– species can be functionalized by a silyl electrophile to generate (CP^iPr₃)Fe–N₂SiR₃. (CP^iPr₃)FeN₂^– also functions as a modest catalyst for the reduction of N₂ to NH₃ when supplied with electrons and protons at −78 °C under 1 atm N₂ (4.6 equiv NH₃/Fe).