A µ‐Phosphido Diiron Dumbbell in Multiple Oxidation States

Reaction of the ferrous complex [LFe(NCMe)2](OTf)2 (1) containing a macrocyclic tetracarbene as ligand with Na(OCP) generates OCP− ligated complex [LFe(PCO)(CO)]OTf (2) together with dinuclear μ‐phosphido complex [(LFe)2P](OTf)3 (3) featuring an unprecedented linear Fe‐(μ‐P)‐Fe motif and a "naked" P‐atom bridge that appears at +1480 ppm in the 31P NMR spectrum. 3 is shown to exhibit rich redox chemistry, and both singly and doubly oxidized species 4 and 5 could be isolated and fully characterized. X‐ray crystallography, UV‐vis, EPR and 57Fe Mößbauer spectroscopies in combination with DFT computations provide a comprehensive electronic structure description and evidence that the Fe‐(μ‐P)‐Fe core is highly covalent and structurally invariant over the series of oxidation states that are formally described as ranging from FeIIIFeIII to FeIVFeIV. 3 – 5 now add a higher homologue set of complexes to many systems with Fe‐(μ‐O)‐Fe and Fe‐(μ‐N)‐Fe core structures that are prominent in bioinorganic chemistry and catalysis.