Stoichiometric reactions and catalytic dehydrogenations of amine–boranes with calcium aryloxide

Abstract

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.