Our laboratory’s studies on catalytic AB dehydrogenation
have been focused on the reactivity of Shvo’s catalyst (12,
Scheme 1)15 and its relatives. By analogy to the established
mechanism for alcohol oxidation with 12, we presumed that the
coordinative saturation of the reduced form of the Shvo system
would preclude coordination of aminoborane, NH2BH2, to the
catalyst, and thus disfavor the formation of insoluble oligomers,
[NH2BH2]n, which limits the hydrogen production of some
catalysts7,8 for ammonia−borane dehydrogenation to 1 equiv.16
Although this proposal seems to hold true,9 the catalyst begins
to deactivate after ca. 25% conversion in the first pass, which
renders this system irrelevant to practical implementation