The purple/blue solution in this vial contains crystals of the berkelocene “sandwich.” (Credit: Alyssa Gaiser/Berkeley Lab)
via UC Berkeley
Scientists have made a remarkable discovery: an organometallic molecule containing berkelium (Bk), one of the rarest and heaviest elements, bonded to carbon. They’ve named it berkelocene, and it looks like a tiny “sandwich,” with the berkelium atom snugly placed between two carbon rings .
The team used a tiny 0.3 milligrams of berkelium-249, one of the most radioactive elements, and every step had to be done inside airtight, high-security gloveboxes. Even with such a tiny amount, they managed to use X-rays to see the molecule’s structure, confirming that the berkelium was perfectly “sandwiched” between the two carbon rings.
The results surprised everyone. Berkelium turned out to be in a +4 state and formed strong covalent bonds with the carbon rings. Scientists had expected it to behave more like terbium, a related element that usually forms weaker, more “lazy” bonds.
The discovery is important, Understanding how heavy elements like berkelium bond helps scientists figure out nuclear waste storage and could open doors to exploring the chemistry of other superheavy elements. A tiny molecule with a huge impact on chemistry .
Reference:
Barton, B. E., Ryan, J. L., Kozimor, S. A., Hunter, B. A., Marquardt, T. R., Abergel, R. J., & Soderholm, L. (2025). Berkelium–carbon bonding in a tetravalent berkelocene. Science, 387(6648), 1234–1238. https://doi.org/10.1126/science.adr3346
