Ring of Five Bismuth Atoms Synthesized
Researchers from the Karlsruhe Institute of Technology (KIT) from Helmholtz Information have, for the first time, successfully synthesized a molecule composed of five bismuth atoms, the Bi₅⁻ ring, and stabilized it within a metal complex. With this discovery, they close a significant gap in chemistry and lay the foundation for new applications in materials science, catalysis, and electronics. The team reports their findings in Nature Chemistry. (Source: Karlsruhe Institute of Technology – Press Releases)
“With the successful synthesis of the Bi₅⁻ ring, we have answered a longstanding question in fundamental research. This molecule could play a crucial role in the development of new materials and chemical processes in the future,” explains Professor Stefanie Dehnen from the Institute of Inorganic Chemistry at KIT and head of the research group on cluster-based materials. She highlights that the Bi₅⁻ ring has a structure similar to the cyclopentadienyl (C₅H₅)⁻ molecule, which is already widely used in industry. However, the Bi₅⁻ ring differs due to its greater mass and unique electronic properties.
A Chemical Puzzle Solved After Decades
For decades, researchers have been searching for heavy analogs of the cyclopentadienyl ring—molecular variants in which the original carbon and hydrogen atoms are replaced by heavier elements. These analogs offer potentially interesting and attractive properties for catalyzing chemical reactions or for materials used in electronic components. The analog composed of atoms from the element bismuth—the heaviest yet non-toxic metal—remained unexplored until now, despite predictions that the ring should exhibit similar aromatic properties, meaning stable and widely delocalized electrons, as (C₅H₅)⁻. The isolation of the Bi₅⁻ ring now demonstrates that even the heaviest variants can be incorporated into stable compounds and utilized in chemical reactions.
High-precision analytical methods, applied in collaboration with the research groups of Professor Florian Weigend from the Institute for Quantum Materials and Technologies (IQMT) at KIT and Professor Wolfgang Wernsdorfer from KIT’s Institute of Physics, provided detailed insights into the unique electronic and magnetic properties of the [{IMesCo}₂Bi₅] product. As expected, the molecule showed particularly promising potential for applications in catalysis and electronics.
Professor Stefanie Dehnen and her team achieved the synthesis through a combination of experience, intuition, and modern synthetic techniques. A key factor, she explains, was the use of a specialized solvent. Professor Dehnen, who recently received the IUPAC Distinguished Women in Chemistry or Chemical Engineering Award, emphasizes that this recognition honors outstanding achievements by women in chemistry and chemical engineering worldwide.
Sustainable Technologies Could Benefit
The research group’s work demonstrates the importance of fundamental research in achieving scientific breakthroughs. Their findings are not only a milestone in chemistry but could also serve as a foundation for the development of more efficient and environmentally friendly technologies. The project was funded by the German Research Foundation (DFG) and the European Research Council (ERC). The team plans to investigate further compounds based on the Bi₅⁻ ring to fully explore its potential for chemical reactions and applications in materials science.
In the future, machine learning methods will also be employed to optimize synthesis pathways and accelerate research. “We hope that our work inspires other researchers to pursue this direction further and explore new applications,” says Dehnen. To achieve this, she and her team also aim to collaborate with interested companies and research institutions.
KIT/M. Heidelberger, 05.02.2025
Note: The article has been translated from German to English. It is based on a press release from KIT.
The original press release can be found at:
Ring aus fünf Bismut-Atomen hergestellt (only in german)
The original publication can be found at (Open Access):
Julia Rienmüller, Benjamin Peerless, Sagar Paul, Florian Bruder, Wolfgang Wernsdorfer, Florian Weigend and Stefanie Dehnen: Isolation of a planar π-aromatic Bi5–ring in a cobalt-based inverse-sandwich-type complex. Nature Chemistry. DOI: 10.1038/s41557-024-01713-8
Localization in Helmholtz Information:
Helmholtz Information, Program 3: Materials Systems Engineering
Contact:
Prof. Dr. Stefanie Dehnen
Institute of Nanotechnology
Karlsruhe Institute of Technology (KIT)
Phone: +49 721 608-28940
E-Mail: stefanie.dehnen@kit.edu
Contact for this press release:
Dr. Martin Heidelberger
Press Officer
Karlsruhe Institute of Technology (KIT)
Phone: +49 721-608-41169
E-Mail: martin.heidelberger@kit.edu
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