The complexing equilibria of aqueous benzeneboronate ion with several polyols have been studied and the measured constants compared with those of borate. The results indicate that the anion has the formula CtH6B(OH)8_ with tetrahedral coordination about boron; this is consistent with a steric effect, previously cited, on the acid-base equilibria of ortho substituted benzeneboronic acids. Examination of the data on complexing equilibria requires modification of an earlier assumption that only anionic complexes are formed.

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and in that of aldehydes by the aprotic donors. Anyway, the relative strength of the coordinating power of hydrogen donors and hydrogen acceptors is one of the important factors to control the reaction mechanisms of transfer hydrogenations.