ИСТИНА

Catalytic dehydrogenation of amine-boranes (RR'NHBH3; R, R' = H, Alk) and other chemical storages of hydrogen is a key element for hydrogen energetics. Our group have previously shown that structurally simple Mn(I) complexes are capable of amine-boranes dehydrogenation, enabling active hydrogen evolution with TONs being superior to all known 3d metal derivatives. In-depth investigation of the reaction mechanism revealed the activation of N–H and B–H bonds in amine-boranes is achieved by a simultaneous action of cationic metal species and hydride derivative spontaneously formed in the presence of bifunctional substrate. Proton transfer was found to be the rate-determining step, that can be facilitated via tuning of reaction centers in catalytic system. Herein we present a targeted optimization of this catalytic reaction defined by discovered mechanistic features. The use of bisNHC Mn(I) complex with simple tertiary amines (R"N; R" = Et, nBu) as basic co-catalysts led to remarkable acceleration of hydrogen evolution rate (TOFmax 23000 h–1) and further increase of TON to 40000 even for non-purified solvent and substrate. The variation of amine and catalyst loadings at different temperature regimes has been demonstrated to exert full control over the hydrogenation rate and the amount of evolved hydrogen. The access to inexpensive, robust and highly active manganese catalysts capable of producing hydrogen from amine-boranes in a perfectly controllable manner allows imagining for the first time potential technological applications for chemical hydrogen storage.