Plate Nº 79 · recorded October 2, 2026
Chemistry & MaterialsReported finding
Chemists Isolate First Uranium Compound with a Rare Carbon Triple Bond
Chemists in Germany and the U.K. have isolated the first stable uranium compound featuring a rare carbon triple bond, solving a longstanding challenge in heavy-element chemistry.
By Nathan Brooks4 min read719 words
In brief
- An international team including University of Manchester chemists synthesized the first isolable uranium Fischer-type carbyne, published in Nature Chemistry (2026).
- Quantum crystallography confirmed a uranium–carbon triple bond despite an unusually long distance of 2.379(15) Å between the atoms.
- The team built the compound using a new carbon-atom transfer reagent; until now, similar uranium species existed only at extreme cold or trapped in fullerene cages.
Chemists in Germany and the U.K. have synthesized and fully characterized what they describe as the first isolable uranium Fischer-type carbyne — a compound in which carbon forms an unusual triple-bond interaction with uranium. The study, published in Nature Chemistry, was carried out by an international team that includes researchers from The University of Manchester.
The result gives scientists a clear, stable example of uranium forming multiple bonds with carbon. It also offers a new reference point for comparing the chemistry of actinides — the row of heavy, radioactive elements that includes uranium — with the more familiar behavior of transition metals such as iron or chromium.
A bond chemists have chased for years
Metal-carbon triple bonds are old news in transition-metal chemistry. Chemists have made and studied them for decades. But building an equivalent uranium compound stable enough to isolate and examine on the bench has proved far harder.
Until now, related uranium examples existed only under highly specialized conditions — at extremely low temperatures, or trapped inside hollow carbon molecules known as fullerene cages. Those setups allow fleeting observations, not detailed study of a stable, isolable substance.
The Manchester-led team — including professor Stephen Liddle, John Seed, Ashley Wooles, Floriana Tuna and Adam Brookfield — took a different route. They combined a uranium precursor with a recently developed carbon-atom transfer reagent, a chemical that delivers a single carbon atom to a target metal. This new synthetic strategy let them build the compound and, crucially, keep it around long enough to study in detail.
To confirm what they had made, the researchers used single-crystal X-ray diffraction (a technique that reveals the arrangement of atoms in a crystal), spectroscopy, magnetometry and advanced computational analysis. Together, these methods showed the new compound carries the key features expected of a Fischer-type carbyne.
"This work addresses a longstanding challenge in f-element chemistry," said Liddle, professor of inorganic chemistry and co-director of the Centre Radiochemistry Research at Manchester. "By isolating and studying this compound in detail, we have been able to show that uranium can support a Fischer-type carbyne interaction that is related to, but distinct from, those previously established for transition metals."
"The result expands our understanding of how uranium engages in multiple bonding with carbon and provides a foundation for exploring new areas of actinide chemistry," he added.
A triple bond that breaks the usual rules
One detail stands out. The team's measurements put the uranium and carbon atoms 2.379(15) Å apart — a distance that, by conventional thinking, looks too long for a triple bond, since multiple bonds usually demand shorter distances between atoms.
To resolve the puzzle, the researchers turned to quantum crystallography, which combines X-ray diffraction data with quantum mechanical modeling. That analysis visualized and confirmed the uranium–carbon triple-bond interaction despite the longer-than-expected distance.
The bonding itself is unusual. It works through two-way electron sharing: carbon donates two electrons to uranium, while uranium donates electrons back to carbon through two so-called orthogonal one-electron bonds — two bonds oriented at right angles to each other. This is a rare arrangement in chemistry.
The compound also behaved as chemists would expect. It proved relatively unreactive, a hallmark of this type of Fischer carbyne. When the team chemically reduced it — adding electrons — they found the bonding changed, providing further evidence for how the compound's electrons are arranged.
Why it matters
The immediate significance is fundamental rather than applied. The findings sharpen the picture of how uranium bonds to carbon, and they help place actinide chemistry within a broader understanding of how elements behave across the periodic table.
The work also showcases the power of modern carbon-atom transfer reagents. These tools can build compounds that were previously difficult or impossible to access, and they may open the door to future studies of uranium–carbon bonding and related actinide systems.
As with any single-compound study, the results represent one well-characterized example rather than a general map of actinide bonding. But for a field long limited to fleeting, low-temperature observations, a stable, isolable uranium carbyne marks a genuine step forward.
Publication details: John A. Seed et al., "A crystalline uranium Fischer-type carbyne," Nature Chemistry (2026). DOI: 10.1038/s41557-026-02260-0.
via Phys.org Chemistry (Source)
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