Properties of Some Diboration Products

The addition of diboron tetrahalides to olefins provides a convenient route to vicinal bis(dihaloboryl)alkanes, which in general show most of the reactions to be expected of organoboron dihalides. The simplest member of this class of compounds, l,2-bis(dichloroboryl)ethane is also the most extensively studied. 

Like the parent subhalide, l,2-bis(dichloroboryl)ethane may function as a dibasic Lewis acid, forming stable 1 2 complexes with trimethylamine (53) or dimethyl or diethyl ether (92). 

The trimethylamine complex is stable to water, methanol, and hydrogen chloride at room temperature. Heating with HCl in a sealed tube leads to the uptake of two molecules of the hydrogen halide, suggesting formation of an ionic product (53). 

Formation of a 1 1 diethyl etherate has been mentioned this compound is said to decompose via elimination of ethyl chloride to form the heterocycle (XI) (iOJ). 

Reaction of trimethylamine with all four boron atoms of 1,2,4,5-tetrakis-(dichloroboryl)cyclohexane was observed by Saha et al. (91). With the 

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