Dihydrogen Generation from Amine/Boranes: Synthesis,FT‐ICR,and Computational Studies |
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| Authors: | Prof Dr José‐Luis M Abboud Dr Balázs Németh Prof Dr Jean‐Claude Guillemin Prof Dr Peeter Burk Aiko Adamson Eva Roos Nerut |
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| Institution: | 1. Instituto de Química Física Rocasolano, CSIC, C/Serrano, 119. E‐28006 Madrid (Spain), Fax: (+34)?91‐5645557;2. Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR, 6226, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7 (France), Fax: (+33)?2‐23‐81‐08;3. Institute of Chemistry, University of Tartu, 4a Ravila St., 50411 (Estonia), Fax: (+372)?737 5570 |
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| Abstract: | A Fourier transform ion cyclotron resonance spectrometry (FT‐ICR) study of the gas‐phase protonation of ammonia‐borane and sixteen amine/boranes R1R2R3N? BH3 (including six compounds synthesized for the first time) has shown that, without exception, the protonation of amine/boranes leads to the formation of dihydrogen. The structural effects on the experimental energetic thresholds of this reaction were determined experimentally. The most likely intermediate and the observed final species (besides H2) are R1R2R3N? BH4+ and R1R2R3N? BH2+, respectively. Isotopic substitution allowed the reaction mechanism to be ascertained. Computational analyses (MP2/6‐311+G(d,p)] level) of the thermodynamic stabilities of the R1R2R3N? BH3 adducts, the acidities of the proton sources required for dihydrogen formation, and the structural effects on these processes were performed. It was further found that the family of R1R2R3N? BH4+ ions is characterized by a three‐center, two‐electron bond between B and a loosely bound H2 molecule. Unexpected features of some R1R2R3N? BH4+ ions were found. This information allowed the properties of amine/boranes most suitable for dihydrogen generation and storage to be determined. |
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| Keywords: | ab initio calculations amines boranes ion– molecule reactions structural effects |
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