The rates of solvolysis of trimethylamine-monohaloboranes in aqueous dioxane at 25'increase in the series (CHa) &BHsCI<(CH8) 8NBHiBr<(CHs) JTBH21. The diiodoborane adduct reacts more slowly than the monoiodo compound but faster than trimethylamine- borane. Only a very slight retardation in rate is observed on substitution of deuterium for hydrogen on boron in the diiodo derivative (kH/kD= 1.1); however, a noticeable solvent ...