Stoichiometric reactions and catalytic dehydrogenations of amine–boranes with calcium aryloxide†
Catalysis with the main-group metal calcium conventionally relies on σ-bond metathesis to initiate the reactions. Here, we report a calcium aryloxide based on the tridentate β-diketiminato ligand, which shows transition-metal-like reactivity with dialkylamine–boranes H3B·NHR2 (R = CH3, Cy, C6H5CH2, and iPr) to afford unprecedented amine–borane coordinated complexes through Ca⋯H interactions. This calcium aryloxide was also an active catalyst in dehydrogenation of amine–boranes, and gave aminoboranes H2BNR2, as the sole product. The initiating species was a calcium amine–borane complex rather than the traditional calcium amidoborane complex formed by σ-bond metathesis.