Exploring the Limits of Catalytic Ammonia–Borane Dehydrogenation Using a Bis(N-heterocyclic carbene) Iridium(III) Complex

Ammonia borane dehydrogenation can be catalyzed by a number of organometallic species. [Ir(kappa(2)-(IBu)-Bu-t)(2)][PF6] ((IBu)-Bu-t = 1,3-bis(tert-butyl)imidazol-2-ylidene) is the most active catalyst for this process that has been reported to date. We explore herein the absolute limits of the use of this and related complexes, including [Ir(kappa(2)-(IBu)-Bu-t)(2)][BAr4F], [Ir(H)(2)((IBu)-Bu-t)(2)]-[BAr4F], and [Ir(kappa(2)-(IBu)-Bu-t)(2)(NH3)][BAr4F] (BAr4F = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate).