Isolation of uranocenium, the bis-[8]annulene uranium cation
Abstract
Uranocene, [U IV (η ⁸ -C ₈ H ₈ ) ₂ ], is the actinide equivalent to ferrocene. While ferrocene is readily oxidised to the ferrocenium cation, higher oxidation states of uranocene are unknown. Here we report the elusive uranocenium cation, [U V (η ⁸ -C ₈ H ₈ ) ₂ ] ⁺ , and demonstrate using electron paramagnetic resonance spectroscopy and magnetometry that this formal U(V) complex has a 5 f ¹ ground state. Enhanced uranium 5 f and 6 d mixing into filled δ-symmetry bonding orbitals in uranocenium, compared to uranocene, amplifies interorbital electron–electron repulsion, and counteracts bond length contraction, which minimises structural change. This manifests in solution where the uranocene/uranocenium redox couple exhibits near-ideal electrochemical reversibility, and in the solid-state where X-ray diffraction studies show minimal U–C bond length change upon oxidation. This demonstrates a case where actinide covalency governs molecular structure and physical properties across both solid and solution phases.
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BibTeX
@article{deakin2026isolation,
title = {{Isolation of uranocenium, the bis-[8]annulene uranium cation}},
author = {Cameron N. Deakin and Iulia Turcas and Benjamin L. L. Réant and Liam P. Griffin and John A. Seed and Adam Brookfield and David Collison and Eric J. L. McInnes and Andrew Kerridge and Conrad A. P. Goodwin},
journal = {Nature Communications},
year = {2026},
month = oct,
doi = {10.1038/s41467-026-77066-2},
url = {https://www.nature.com/articles/s41467-026-77066-2},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Isolation of uranocenium, the bis-[8]annulene uranium cation
AU - Cameron N. Deakin
AU - Iulia Turcas
AU - Benjamin L. L. Réant
AU - Liam P. Griffin
AU - John A. Seed
AU - Adam Brookfield
AU - David Collison
AU - Eric J. L. McInnes
AU - Andrew Kerridge
AU - Conrad A. P. Goodwin
PY - 2026
DA - 2026/10/23
JO - Nature Communications
DO - 10.1038/s41467-026-77066-2
UR - https://www.nature.com/articles/s41467-026-77066-2
AB - Uranocene, [U IV (η ⁸ -C ₈ H ₈ ) ₂ ], is the actinide equivalent to ferrocene. While ferrocene is readily oxidised to the ferrocenium cation, higher oxidation states of uranocene are unknown. Here we report the elusive uranocenium cation, [U V (η ⁸ -C ₈ H ₈ ) ₂ ] ⁺ , and demonstrate using electron paramagnetic resonance spectroscopy and magnetometry that this formal U(V) complex has a 5 f ¹ ground state. Enhanced uranium 5 f and 6 d mixing into filled δ-symmetry bonding orbitals in uranocenium, compared to uranocene, amplifies interorbital electron–electron repulsion, and counteracts bond length contraction, which minimises structural change. This manifests in solution where the uranocene/uranocenium redox couple exhibits near-ideal electrochemical reversibility, and in the solid-state where X-ray diffraction studies show minimal U–C bond length change upon oxidation. This demonstrates a case where actinide covalency governs molecular structure and physical properties across both solid and solution phases.
SN - 2041-1723
ER -