Hydrogen bonds boron compounds

Hydroboration is a reaction m which a boron hydride a compound of the type R2BH adds to a carbon-carbon bond A carbon-hydrogen bond and a carbon-boron bond result... 

A potential way to avoid the formation of undesired side products, like in 7.2., is the use of such boron compounds that have only one transferable group. In most cases boronic acids are the compounds of choice, as they are easy to prepare, insensitive to moisture and air, and usually form crystalline solids. In certain cases, however the transmetalation of the heteroaryl group might be hindered by the formation of stable hydrogen bonded complexes. In such cases the use of a boronate ester, such as in equation 7.4., provides better yields. For example pyridine-2-boronic acid dimethylester coupled readily with a bromoquinoline derivative under conditions similar to 7.3. (potassium hydroxide was used as base and tetrabutylammonium bromide as phase transfer catalyst).6... 

The location of the catalyst is a problem in all attempts at kinetic measurement in these systems. It is well known that boron fluoride forms 1 1 complexes with most oxygenated compounds and 1 2 complexes when hydroxyl groups are present. The ternary complexes are to be regarded as a form of oxonium salt in which the third molecule is held by hydrogen bonding, so in the present reaction mixtures, equilibria of the type... 

The exchange equilibrium of Eq. (75) is also catalyzed by compounds containing boron-hydrogen bonds, such as (CH3)4B2H2 (140,141). 

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