The parent oxoborane, H–B=O, has so far only been detected in the gas phase or in low-temperature matrices. Difficult-to-isolate species such as this can sometimes be stabilized using a donor/acceptor approach, i.e., using an electron-donating group on one side and an electron-accepting group on the other side.

Sakya S. Sen, CSIR-National Chemical Laboratory, Pune, India, and Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India, and colleagues have synthesized a rare acid-stabilized neutral derivative of the parent oxoborane (pictured). The compound has a strongly electron-donating N-heterocyclic carbene (NHC), i.e., 6-SIDipp (1,3-di(2,6-diisopropylphenyl) tetrahydropyrimidine-2-ylidene) on one side and GaCl₃ as an electron-accepting Lewis acid on the other side. The team first synthesized an unusual boron gallium compound via a reaction of 6-SIDipp·BH₃ with GaCl₃.

The resulting boron gallium compound was reacted with water as an oxygen source to form the desired stabilized oxoborane. H₂ was eliminated during this reaction. According to the researchers, the product can be considered as an acid-stabilized parent oxoborane, containing an unusual H(B=O) linkage. Adding more water to this oxoborane derivative leads to the release of another molecule of H₂ and gives a hydroxy oxoborane derivative.

• Taming the parent oxoborane,
  Sakya Singha Sen, Gargi Kundu, P. R. Amrutha, K. Vipin Raj, Srinu Tothadi, Kumar Vanka,
  Chem. Sci. 2023.
  https://doi.org/10.1039/D3SC01544K