Uranium Coordination Chemistry and Reactivity

Uranium coordination chemistry explores how uranium ions bind to molecular frameworks and how these interactions govern reactivity patterns across multiple oxidation states. With accessible oxidation states ranging from II to VI, uranium exhibits versatile redox behaviour that underpins small‐molecule activation, catalysis and nuclear fuel processing. The 5f and 6d orbitals contribute to bonding in ways that blend ionic and covalent character, challenging classical views of f‐element chemistry. Ligand design—especially those incorporating π‐acceptors or redox‐active motifs—enables stabilisation of low‐valent uranium species and promotes selective transformations such as nitride formation, carbonylation or C–H bond activation. Conversely, high‐valent uranyl complexes feature strong oxo ligands that mediate reduction pathways. Understanding the balance between metal‐ligand covalency, orbital participation and steric control is crucial for advancing applications in actinide separations, environmental remediation and emerging catalytic processes. Recent advances reveal that perturbation of the electronic structure via tailored ligands or transition‐metal partners can unlock new reactivity trajectories, bridging fundamental studies and practical deployment in areas ranging from energy to materials science.

Research from Nature Portfolio

Recent studies have reported a series of uranium complexes supported by a tripodal tris(amido)arene ligand that collectively span oxidation states II–VI. Controlled one‐ and two‐electron redox interconversions demonstrate how uranium–arene interactions can act either as δ‐acceptors or π‐donors, stabilising both low‐ and high‐valent centres and enabling small‐molecule activation. In a foundational work on the inverse‐trans‐influence, tetravalent bis(carbene) complexes of uranium and cerium revealed that strong donor ligands adopt trans positions to reinforce metal–ligand bonds. This discovery unifies principles of trans‐influence across f‐elements and suggests broader applicability to mid‐range oxidation states, informing ligand design strategies for stabilising unusual bonding geometries.

Uranium Coordination Chemistry and Reactivity publication trend

The graph below shows the total number of articles in uranium coordination chemistry and reactivity across all publications each year (not limited to Nature Index journals).

Technical terms

Ligand: An atom or molecule that donates electrons to a central metal to form a coordination complex.

Oxidation state: The formal charge of a metal in a complex, indicating electron count changes in redox processes.

Redox: Chemical reactions involving electron transfer, here referring to changes in uranium valence.

Arene interaction: Binding between a metal and an aromatic ring that can accept or donate electron density.

Inverse‐trans‐influence: A phenomenon where strong donor ligands prefer trans arrangement, strengthening adjacent metal–ligand bonds.

Covalency: Sharing of electron density between metal and ligand, contrasting purely ionic interactions.

References

1. Accessing five oxidation states of uranium in a retained ligand framework. Nature Communications (2023).
2. A Route to Stabilize Uranium(II) and Uranium(I) Synthons in Multimetallic Complexes. Angewandte Chemie International Edition (2023).
3. The inverse-trans-influence in tetravalent lanthanide and actinide bis(carbene) complexes. Nature Communications (2017).
4. Metal–Metal Bonding in Uranium–Group 10 Complexes. Journal of the American Chemical Society (2016).