Proton transfer reactions of hydrazine‐boranes |
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Authors: | Aiko Adamson Jean‐Claude Guillemin Peeter Burk |
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Institution: | 1. Institute of Chemistry, University of Tartu, Estonia;2. Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, Rennes, France |
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Abstract: | Hydrazine‐borane and hydrazine‐diborane contain, respectively, 15.4 and 16.9 wt% of hydrogen and are potential materials for hydrogen storage. In this work we present the gas‐phase complexation energies, acidities, and basicities of hydrazine‐borane and hydrazine‐bisborane calculated at MP2/6‐311 + G(d,p) level. We also report the release of dihydrogen from both protonated complexes (ΔGhydrazine‐borane = ?20.9 kcal/mol and ΔGhydrazine‐bisborane = ?27.2 kcal/mol) which is much more exergonic than from analogues amine‐boranes. The addition of the first BH3 to the hydrazine releases 17.1 kcal/mol, and the second addition releases 15.8 kcal/mol. The attachment of BH3 also increases the N―H acidity of hydrazine by 46.3 kcal/mol. It was found that the B―H deprotonation leads to intramolecular rearrangement. The basicity values for hydrazine‐borane and ‐bisborane are 180 and 172.8 kcal/mol, respectively. For both complexes the protonation centres are located at the boron moiety. The protonated structure of hydrazine‐bisborane is cyclic and can be described as H2 captured between a negatively charged B―H hydrogen and positive boron (B―H??H2??B). Atoms in molecules analysis are used to investigate bond paths in concerning structures. Copyright © 2015 John Wiley & Sons, Ltd. |
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Keywords: | ab initio calculations gas phase hydrazine borane complex acidity basicity dihydrogen |
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