Bis(pinacolato)diboron
Introduction '''Bis(pinacolato)diboron''' is a covalent compound containing two boron atoms and two pinacolato ligands. It has the formula (CH3)4C2O2B2; the pinacol groups are sometimes abbreviated as "pin", so the structure is sometimes represented as B2pin2.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, B2pin2 is not moisture-sensitive and can be handled in air.
Preparation and structure This compound may be prepared by treating tetrakis(dimethylamino)diboron with pinacol in acidic conditions. The B-B bond length is 1.711(6) Å.Dehydrogenation of pinacolborane provides an alternative route::2(CH3)4C2O2BH → (CH3)4C2O2B-BO2C2(CH3)4 + H2
Reactions 110pxThe B-B bond adds across alkenes and alkynes to give the 1,2-diborylated alkanes and alkenes. Using various organorhodium or organoiridium catalysts, it can also be installed onto saturated hydrocarbons::CH3(CH2)6CH3 + pinB2 → pinBH + CH3(CH2)7BpinThese reactions proceed via boryl complexes.Bis(pinacolato)diboron can also be used as reducing agent for example in transition metal catalyzed hydrogenations of alkenes and alkynes.
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