"Reaching New Heights in Weightlifting"
Iron, the fourth most abundant element on earth, is vital to countless biological processes due to its ability to participate in redox reactions. Its prevalence in biological systems is primarily due to its abundance and its ability to cycle between its most common oxidation states, Fe(II) and Fe(III). However, iron can also be found in higher oxidation states in enzyme active sites, such as the heme cofactor or directly attached to the protein framework in nonheme iron enzymes, where it can access high-valent oxidation states of +4 or greater.
High-valent iron-oxo species have garnered significant attention due to their importance in both biological and synthetic catalysis. These species are often challenging to isolate, owing to their intrinsically reactive nature. Nevertheless, the past twenty-five years have seen an explosion in the number of structurally characterized nonheme iron(IV) and iron(V) complexes. These complexes typically feature axial π-donors, such as oxo (O2−), imido (NR2−), and nitrido (N3−) ligands, which stabilize high oxidation states via iron-ligand multiple bonds.
In their latest study, Meyer, Munz, DeBeer, and co-workers have synthesized the newest member of the Fe(VI) family – an octahedral nitrido complex supported by a tris(carbene)amine ligand (1 in Fig. 1a) (ref. 12). Even more remarkably, the team has demonstrated that this complex undergoes one-electron oxidation to yield an Fe(VII) complex (2). Although 2 is metastable and needs to be generated at temperatures below -50°C, the researchers were able to characterize the 'super-oxidized' complex with multiple spectroscopic techniques.
The significance of this achievement cannot be overstated, as the synthesis and characterization of a bona fide Fe(VII) complex represents a major step forward in the decades-long quest to prepare iron complexes with ever-higher oxidation states. The team's work brings us one step closer to the oxidation limit of iron by preparing an Fe(VIII) complex with an empty set of 3d orbitals.
This breakthrough hints that iron(VII)–nitrido complexes like 2 are potent oxidants, and future efforts will seek to direct this reactivity towards productive ends, such as enabling organic transformations. The team's success in synthesizing 2 also demonstrates the power of nitrido complexes, further expanding the potential of this versatile ligand in coordination chemistry.
This study highlights the importance of pushing the boundaries of chemistry and the potential that lies within the exploration of high-valent iron complexes. With the successful synthesis and characterization of a long-sought iron(VII) complex, the potential for future discoveries in the field of iron chemistry is vast and exciting.
Source:
Fiedler, A. T., & Devkota, L. (2024). Lifting iron higher and higher. Nature Chemistry, 1-2. <https://doi.org/10.1038/s41557-024-01484-2>
Comments
Post a Comment