Abstract
A monomeric iron Fe(η(2)-N(2)H(3)) species has been prepared, and exposure to oxygen yields a diiron complex that features five-coordinate iron centers and an activated bridging diazene ligand (NH=NH). Combined structural, theoretical, and spectroscopic data for the redox pair of complexes [Fe(2)(μ-N(2)H(2))](2+/1+) are consistent with 4-center, 4-electron π-delocalized bonding picture across the Fe-NH-NH-Fe core that finds analogy in butadiene and the butadiene anion.