Trimeric cluster of lithium amidoborane—the smallest unit for the modeling of hydrogen release mechanism

A detailed first‐principle DFT M06/6‐311++G(d.p) study of dehydrogenation mechanism of trimeric cluster of lithium amidoborane is presented. The first step of the reaction is association of two LiNH 2 BH 3 molecules in the cluster. The dominant feature of the subsequent reaction pathway is activation of H atom of BH 3 group by three Li atoms with formation of unique Li 3 H moiety. This Li 3 H moiety is destroyed prior to dehydrogenation in favor of formation of a triangular Li 2 H moiety, which interacts with protic H atom of NH 2 group. As a result of this interaction, Li 2 H 2 moiety is produced. It features N − H + H − group suited near the middle plane between two Li + in the transition state that leads to H 2 release. The transition states of association and hydrogen release steps are similar in energy. It is concluded that the trimer, (LiNH 2 BH 3 ) 3 , is the smallest cluster that captures the essence of the hydrogen release reaction. © 2016 Wiley Periodicals, Inc.