Proton transfer reactions of hydrazine-boranes
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 (Ghydrazine-borane = –20.9 kcal/mol and Ghydrazine-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 is used to investigate bond paths in concerning structures.
Domains
Chemical Sciences
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