Taming the parent oxoborane

• Published in: Chemical science (Cambridge) 2023-06, Vol.14 (22), p.5894-5898
• Main Authors: Kundu, Gargi, Amrutha, P. R, Raj, K. Vipin, Tothadi, Srinu, Vanka, Kumar, Sen, Sakya S
• Format: Article
• Language: English
• Subjects: Boron compounds; Chemistry; Crystallography; Density functional theory; Gallium chloride; Hydrogen bonds; Water chemistry
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d3sc01544k

Despite recent advancements in the chemistry of multiply bound boron compounds, the laboratory isolation of the parent oxoborane moiety, HBO has long remained an unsolved and well-recognized challenge. The reaction of 6-SIDipp·BH 3 [6-SIDipp = 1,3-di(2,6-diisopropylphenyl)tetrahydropyrimidine-2-ylidene] with GaCl 3 afforded an unusual boron-gallium 3c-2e compound ( 1 ). The addition of water to 1 resulted in the release of H 2 and the formation of a rare acid stabilized neutral parent oxoborane, LB(H)&z.dbd;O ( 2 ). Crystallographic and density functional theory (DFT) analyses support the presence of a terminal B&z.dbd;O double bond. Subsequent addition of another equivalent of water molecule led to hydrolysis of the B-H bond to the B-OH bond, but the 'B&z.dbd;O' moiety remained intact, resulting in the formation of the hydroxy oxoborane compound ( 3 ), which can be classified as a monomeric form of metaboric acid. Addition of water to a 3c-2e boron gallium hydrido compound results in capturing of the parent oxoborane moiety, B(H)&z.dbd;O. The latter reacts with another molecule of water to give a boracarboxylic acid derivative.