Structural and thermochemical studies of pyrrolidine borane and piperidine borane by gas electron diffraction and quantum chemical calculations

Abstract

The gaseous structures, thermochemical properties and dehydrogenation reaction energy profiles of the borane complexes of pyrrolidine and piperidine have been investigated using gas electron diffraction (GED) and state-of-the-art computational methods. These complexes are of interest because of their potential as hydrogen storage materials for future onboard transport applications. A comparative structural and thermochemical analysis revealed structures with a slight difference in the essential B-N bond length, with the piperidine borane having a longer bond even though it has a stronger B-N bond according to predicted bond dissociation energies, a trend common with amine boranes. To identify the most favourable dehydrogenation pathway, BH3-catalysed and uncatalysed dehydrogenation channels have been explored, where the former has been shown to be the favourable process for both complexes. The energy requirements for the hydrogen release reactions are expected to be minimal as evidenced from the calculated dehydrogenation reaction energies, implying their suitability for onboard chemical hydrogen storage.

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

“…20 PPZBB could be a more efficient chemical hydrogen storage material due to the release of two equivalents of H 2 per PPZBB molecule than the previously studied cyclic amine borane complexes with only one BH 3 group. 21,22 The main scope of this work is to investigate the structural parameters of the various conformers of 1,3-bis(l 4 -boraneyl)-1l 4 ,3l 4 -imidazolidine (IMBB) via ab initio electronic structure calculations. The structures of the possible conformers and stereoisomers of IMBB are shown in Fig.…”

“…20 PPZBB could be a more efficient chemical hydrogen storage material due to the release of two equivalents of H 2 per PPZBB molecule than the previously studied cyclic amine borane complexes with only one BH 3 group. 21,22…”