Co@CoO-catalyzed reductive amination driven by hydride-like NH₂^- species

Owing to the wide application of primary amines, their selective production via reductive amination has become a crucial research topic. Various metal-supported catalysts (Pt, Ru, Rh, Ir, Co, Ni, etc.) have been investigated, and metallic species have been recognized as active sites in recent years. Herein, we reveal for the first time that CoO species containing oxygen vacancies within a core-shell-structured Co@CoO catalyst accelerate the ammonolysis of Schiff bases, key intermediates in reductive amination, through NH3 dissociation to hydride-like NH2 delta- species, delivering an excellent reductive amination performance. The catalyst is highly stable and was utilized in 10 catalytic cycles for the amination of biomass-derived cyclopentanone (CPO) to cyclopentylamine (CPA) without deactivation. Various computational models in combination with spectroscopic measure-ments indicated that this catalyst not only drives the dissociation of H-2 to the active H delta- species, but also enables the homolytic cleavage of NH3 to NH2 delta-. D-2 isotopic tracing experiments provided fur-ther evidence of the direct involvement of hydride-like NH2 delta- species in Schiff base ammonolysis. Theoretical calculations verified the stable co-adsorption of H delta- and NH2 delta-, which allows the Schiff base to move freely on the surface of the CoO shell and participate extensively in molecular collisions, resulting in exceptional catalytic activity. This is the first study that demonstrates the potential of metal oxide catalysts for the production of primary amines via reductive amination. (c) 2023, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.