9-Borabicyclo nonane dimer

Wang, K. K., Scouten, C. G., Brown, H. C. Hydroboration kinetics. 3. Kinetics and mechanism of the hydroboration of alkynes with 9-borabicyclo[3.3.1]nonane dimer. Effect of structure on the reactivity of representative alkynes. J. Am. Chem. Soc. 1982,104, 531-536. 

Borabicyclo[3.3.1]nonane dimer 9-Borabicyclo[3.3.1]nonane, dimer... 

In contrast to trialkylboranes BR3, the mono- and dialkylboranes R2BH and RBH2 are dimers with structures related to diborane(6) i.e., they are alkyldiboranes. With a few exceptions (borolane dimers and 9-borabicyclo[3.3.1]nonane dimer) they may also be in equilibrium at room temperature with small amounts of monomer. Characteristically there is rapid R/H exchange. Hence alkyldiboranes are in most cases mixtures of boranes in various degrees of alkylation. Tetraalkyldiboranes are therefore mixtures of alkyldiboranes and trialkylboranes, and the mixtures have mean compositions corresponding to a tetraalkylated diborane ... 

John A. Soderquist and Alvin Negron 169 9-BORABICYCLO[3.3.1]NONANE DIMER... 

Many metal (cyclooctane-1,5-diyl)dihydroborates(l-) can be prepared by reaction of the easily prepared 9-borabicyclo [3.3.1]nonane dimer (9-BBN)5,6 with metal-organic compounds.7 The reactions of 9-BBN with alkali metal hydrides in ethers are particularly smooth. 

The preparations of lithium and sodium (cyclooctane-1,5-diyl)dihydro-borates(l-) in tetrahydrofuran proceed via isolable, stable etherates. These can be made solvent-free simply by heating under vacuum. 9-Borabicyclo[3.3.1 ]-nonane dimer (9-BBN) can easily be prepared from cycloocta-1,5-diene2 by reaction with tetraethyldiborane(6), tetrahydrofuran-borane8,9 or dimethyl sulfide-borane.10 The synthesis of alkali metal (cyclooctane-1,5-diyl)dihydroborates is achieved by addition of 9-BBN to a suspension of the alkali metal hydride in tetrahydrofuran. Lithium hydride reacts more slowly than sodium or potassium hydride. The reactions are brought to completion by heating under reflux. 

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