Air‐Stable (CAAC)CuCl and (CAAC)CuBH₄ Complexes as Catalysts for the Hydrolytic Dehydrogenation of BH₃NH₃

The first stable copper borohydride complex [(CAAC)CuBH 4 ] [CAAC=cyclic(alkyl)(amino)carbene] bearing a single monodentate ligand was prepared by addition of NaBH 4 or BH 3 NH 3 to the corresponding [(CAAC)CuCl] complex. Both complexes are air‐stable and promote the catalytic hydrolytic dehydrogenation of ammonia borane. The amount of hydrogen released reaches 2.8 H 2 /BH 3 NH 3 with a turnover frequency of 8400 mol mol cat −1 h −1 at 25 °C. In a fifteen‐cycle experiment, the catalyst was reused without any loss of efficiency.