For more than six decades, chemists have tried to isolate a group of molecules containing an unusual triple bond between boron and oxygen. Several experiments had detected these compounds under extreme conditions, but obtaining stable samples that could be isolated and studied in a laboratory remained a challenge. An international research team has now achieved that, with computational support from researchers at Assam's Tezpur University.

The study, led by Professor Holger Braunschweig at Germany's University of Würzburg, reports the synthesis and isolation of three stable oxoboranes. Professor Ashwini K. Phukan and his research group at Tezpur University contributed computational work to the study, which was published in Nature Chemistry on October 27, 2026.

The discovery addresses a longstanding question in inorganic chemistry: can boron and oxygen form a stable triple bond in an isolable molecule?

What are oxoboranes?

Oxoboranes are molecules characterised by a triple bond between a boron atom and an oxygen atom. In their organic form, they contain a boron-oxygen unit attached to an additional chemical group.

A triple bond involves three shared pairs of electrons between two atoms. Such bonds are familiar in chemistry, including the carbon-carbon triple bond found in compounds such as acetylene. Boron, however, presents a different challenge. It is an electron-deficient element and does not readily form triple bonds in the way carbon does.

This makes the synthesis of compounds containing boron triple bonds particularly difficult. Although chemists had established evidence for oxoboranes through earlier experiments, their high reactivity and instability made it difficult to prepare stable examples for detailed study.

Researchers had managed to detect or trap these molecules under extreme conditions, but these observations did not provide the same opportunity to examine an isolated compound under laboratory conditions.

Professor Braunschweig's group at the University of Würzburg has spent more than 15 years investigating unusual bonding involving boron. In 2012, the team reported the first molecule containing a boron-boron triple bond. In 2025, it reported the first neutral molecule with a boron-carbon triple bond. The isolation of stable oxoboranes marks another advance in this research.

How did the researchers make the discovery?

The breakthrough emerged from experiments involving a compound called diboracumulene and a group of chemicals known as ketones.

Ketones are organic compounds containing a carbonyl group, in which a carbon atom is double-bonded to an oxygen atom. They are widely used in organic synthesis and serve as starting materials in several chemical reactions.

Two doctoral researchers at the University of Würzburg, Lukas Lubczyk and Christian Markl, independently investigated reactions between diboracumulene and different ketones. Instead of producing the outcomes they had anticipated, their experiments yielded unusual orange and yellow solids.

Further analysis revealed that oxoboranes had formed as the main products.

“The discovery was a pleasant surprise. I never thought the diboracumulene would react the way it did, let alone with multiple different, simple substrates. And when Christian came to me with his compound, I knew we were onto something,” Lubczyk said.

The result was unexpected because the researchers had considered several other reaction pathways more likely. Instead, the oxoboranes formed spontaneously and remained stable long enough to be isolated and examined.

Using this approach, the team successfully prepared three different oxoboranes. The fact that the reaction worked with multiple starting materials gives researchers a method to investigate whether other members of this molecular family can also be produced.

Professor Braunschweig described the surprise within the research community, saying, “Nearly everybody in the field had given up on oxoboranes, as they were thought to be just too unstable to be isolated. So we were stunned to see them spontaneously form in these reactions and stick around long enough that we could study them.”

What was Tezpur University's contribution?

The research brought together experimental chemistry at the University of Würzburg and computational chemistry expertise from Professor Phukan's group at Tezpur University.

Experimental chemistry involves carrying out reactions and examining the resulting substances in the laboratory. Computational chemistry uses mathematical models and computer-based calculations to investigate molecular structures, electronic properties, chemical bonding and reaction behaviour.

Such calculations help researchers interpret experimental observations and assess whether a proposed molecular structure is consistent with its predicted properties. In this study, the Tezpur University group provided computational support to the German team's experimental work.

Professor Phukan is a faculty member in the Department of Chemical Sciences at Tezpur University. His research interests include the chemistry of main-group elements, metal-free activation of small molecules and bio-organometallic chemistry. His group has worked on theoretical investigations of compounds involving boron and other main-group elements.

The study's authors include Lukas Lubczyk, Christian Markl, Mudit Jain, Sourav Kar, Thomas Kupfer, Rian D. Dewhurst, Ashwini K. Phukan and Holger Braunschweig.

The research received funding from the German Research Foundation, the German Academic Exchange Service and India's Department of Science and Technology.

What could the discovery lead to?

The immediate significance is giving chemists access to stable oxoboranes that can be isolated and studied. Their molecular structures and bonding properties can now be examined in greater detail, allowing researchers to investigate how boron forms unusual chemical bonds with other elements.

The researchers are also examining how widely the new synthetic method can be applied. Since the approach has produced three different oxoboranes, they are investigating whether it can be extended to prepare additional compounds of this type and potentially other difficult-to-isolate molecules.

However, the discovery does not yet establish a practical industrial or commercial application. Further research will be needed to determine how these compounds behave, what reactions they can undergo and whether their properties could prove useful in other areas of chemistry.

For now, the work provides experimental access to a class of molecules that chemists had pursued since the early 1960s, while adding a contribution from an Indian research group to an international effort in fundamental chemical science.