Highly Efficient Colloidal Cobalt- and Rhodium-Catalyzed Hydrolysis of H3N·BH3 in Air

The compound H3N. BH3 (1) is currently attracting considerable attention as a potential hydrogen storage material. Group 9 catalysts which rapidly and conveniently hydrolyze aqueous 1 in air are described. When treated with 1 mol % Rh (mu-Cl) (1, 5-cod) 2 (cod=cyclooctadiene) in air, aqueous 1 undergoes rapid hydrolysis to afford the ionic species NH4BO2 in approximately 40 s. Higher catalyst loadings (3 mol %) result in a reduction in reaction time to 10 s. Quantification of the hydrogen evolved revealed that, on average, 2. 8 of a maximum possible 3. 0 equivalents (93%) were generated during the course of the reaction. Rh (0) species (e. g. , Rh black, Rh stabilized on alumina, aqueous Rh colloids) were also found to be active hydrolysis catalysts, and evidence for a heterogeneous mechanism is provided. Significantly, although Ir (0) colloids are less active, aqueous Co (0) colloids are also effective catalysts for this process. This result is particularly important as Co, a first-row metal, is considerably more economical than the precious metal catalysts typically employed.