9-Borabicyclononane

9-Borabicyclo[3.3.1]nonane or 9-BBN is an organoborane compound and used in organic chemistry as a hydroboration reagent. It can be prepared from 1,5-cyclooctadiene and a borane-dimethyl sulfide complex, using dimethoxyethane as the reaction solvent. 9-BBN is more stable than other boranes in the pure state, but not in solution. This is due to the formation of hydride-bridged dimers in the solid state. The compound is commercially available as a solution in tetrahydrofuran and as a solid. 9-BBN is especially useful in Suzuki reactions.