Structural and thermochemical investigation of 1,3-bis(λ4-boraneyl)-1λ4,3λ4-imidazolidine adduct for chemical hydrogen storage.

ABSTRACT

The structure, thermochemical properties and reaction pathways of a cyclic amine diborane complex (1,3-bis(λ4-boraneyl)-1λ4,3λ4-imidazolidine) were investigated using quantum chemical calculations. Structural and thermochemical analysis revealed that the simultaneous and spontaneous elimination of both hydrogen molecules from this complex is predicted to occur under thermoneutral conditions. This observation is further supported by the investigation of the BH3-catalysed dehydrogenation pathway. The calculated thermochemical parameters indicate that the energy requirements for hydrogen release from this complex are minimal, suggesting efficient hydrogen release capability under suitable conditions. Additionally, the activation barriers, ∼75 and ∼20 kJ mol-1 for the first and second dihydrogen release from the catalysed dehydrogenation reactions of this compound exhibit moderate kinetics, confirmed by kinetic studies. These findings and the ability of the system to easily release two molecules of dihydrogen emphasize the potential of 1,3-bis(λ4-boraneyl)-1λ4,3λ4-imidazolidine as a highly effective hydrogen storage material.