Chemists Isolate Crystals of a Boron-Oxygen Triple Bond Stable at Room Temperature

Chemists at the University of Würzburg in Germany have made three oxoboranes, molecules built around a triple bond between a boron atom and an oxygen atom, and isolated them as crystals that are stable at room temperature. Their report appeared Oct. 27, 2026, in Nature Chemistry. The team writes that until now, no oxoborane free of stabilizing add-on groups had been isolated, or, to its knowledge, detected by spectroscopy at or near room temperature.

The authors note that boron's chemistry is dominated by its bonds to oxygen: boron-oxygen compounds are workhorses of organic synthesis and feature in a young boron-based drug chemistry, while the triple-bonded form had stayed out of synthetic reach. They write that oxoboranes that can be stored and handled open the way to exploring a chemistry that the difficulty of making them had kept closed.

The paper records documented attempts to pin these molecules down going back to at least the early 1960s. Those reached detection in the gas phase or trapping in a frozen solid, evidence that oxoboranes form briefly during reactions, and the isolation of relatives whose boron-oxygen bonds are weaker than a triple bond.

The new route is one step. Lukas Lubczyk, Holger Braunschweig and colleagues stirred a highly reactive molecule carrying two boron atoms with reagents that hold a carbon-oxygen double bond, among them benzophenone, at room temperature. The authors report more than 50% isolated yield of an orange or yellow solid from each of the three reactions, and X-ray measurements that put the boron-oxygen bonds at 1.208 to 1.217 ångströms, which they describe as exceptionally short and strong.

They attribute the stability to the group bonded to the neighboring boron atom, which is rich in electrons and lowers the positive charge on the oxoborane's boron, leaving it less open to attack. Stable does not mean inert: in first tests, amines, a common family of nitrogen compounds, added across the triple bond.