Decay of Iron(V) Nitride Complexes By a NN Bond‐Coupling Reaction in Solution: A Combined Spectroscopic and Theoretical Analysis

Cryogenically trapped Fe V nitride complexes with cyclam‐based ligands were found to decay by bimolecular reactions, forming exclusively Fe II compounds. Characterization of educts and products by Mössbauer spectroscopy, mass spectrometry, and spectroscopy‐oriented DFT calculations showed that the reaction mechanism is reductive nitride coupling and release of dinitrogen (2 Fe V N→Fe II ‐NN‐Fe II →2 Fe II +N 2 ). The reaction pathways, representing an “inverse” of the Haber–Bosch reaction, were computationally explored in detail, also to judge the feasibility of yielding catalytically competent Fe V (N). Implications for the photolytic cleavage of Fe III azides used to generate high‐valent Fe nitrides are discussed.