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 CaH interactions. This calcium aryloxide was also an active catalyst in dehydrogenation of amine-boranes, and gave aminoboranes H2B[double bond, length as m-dash]NR2, 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.