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Free keywords:
electronic structure; iron complex; N-heterocclic carbenes; phosphido complexes; redox series
Abstract:
The reaction of the ferrous complex [LFe(NCMe)2](OTf)2 (1), which contains a macrocyclic tetracarbene as ligand (L), with Na(OCP) generates the OCP−‐ligated complex [LFe(PCO)(CO)]OTf (2) together with the dinuclear μ‐phosphido complex [(LFe)2P](OTf)3 (3), which features an unprecedented linear Fe‐(μ‐P)‐Fe motif and a “naked” P‐atom bridge that appears at δ=+1480 ppm in the 31P NMR spectrum. 3 exhibits rich redox chemistry, and both the singly and doubly oxidized species 4 and 5 could be isolated and fully characterized. X‐ray crystallography, spectroscopic studies, in combination with DFT computations provide a comprehensive electronic structure description and show 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 the many systems with Fe‐(μ‐O)‐Fe and Fe‐(μ‐N)‐Fe core structures that are prominent in bioinorganic chemistry and catalysis.
