Heats of formation for the boronic acids R-B(OH)2 and boroxines R3B3O3 (RÂ =Â H, Li, HBe, H2B, H3C, H2N, HO, F, and Cl) calculated at the G2, G3, and G4 levels of theory

► Heats of formation (HOF) of various aliphatic boronic acids/boroxines are calculated. ► Current computational procedures can yield substantially different HOF values. ► Dehydrations of boronic acids forming boroxines are typically endothermic.