Bis(pinacolato)diboron is a covalent compound containing two boron atoms and two pinacolato ligands. It has the formula [(CH)COB]; the pinacol groups are sometimes abbreviated as "pin", so the structure is sometimes represented as Bpin. It is a colourless solid that is soluble in organic solvents.  It is a commercially available reagent for making pinacol boronic esters for organic synthesis. Unlike some other diboron compounds, Bpin is not moisture-sensitive and can be handled in air.