Formation and Unimolecular Dehydrogenation of Gaseous Alkaline‐earth Metal Amidoboranes M(NH2BH3)2 (M = Be – Ba): Comparative Computational Study |
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| Authors: | Anna S Lisovenko Alexey Y Timoshkin |
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| Institution: | Institute of Chemistry, Saint Petersburg State University, St. Petersburg, Russia |
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| Abstract: | Formation of alkaline‐earth metal amidoboranes M(NH2BH3)2 (M = Be, Mg, Ca, Sr, Ba) and unimolecular dehydrogenation reactions were computationally studied at the B3LYP/def2‐TZVPPD level of theory. Formation of M(NH2BH3)2 from ammonia borane and MH2 is exergonic, but subsequent unimolecular dehydrogenation reactions are endergonic at room temperature. In contrast to alkali metal amidoboranes, for M(NH2BH3)2 the nature of M significantly affects their reactivity. Activation energies for the dehydrogenation of first and second hydrogen molecules decrease from Be to Ba. In case of Be compounds, intramolecular M ··· H–B contacts play an important role, whereas for heavier analogs such contacts are much less pronounced. |
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| Keywords: | Alkaline‐earth metal amidoboranes Dehydrogenation Reaction mechanisms Quantum‐chemical calculations Density functional calculations |
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