Unveiling the dehydrogenation mechanism of dihydrogen‐bonded phenol‐borane‐dimethylamine complex in the ground and excited states

Abstract

AbstractIn this work, the density functional theory (DFT) and time‐dependent density functional theory (TDDFT) methods were adopted to explore the dehydrogenation mechanism of phenol‐borane‐dimethylamine (phenol‐BDMA) complex in ground (S0) and excited (S1) states. The analysis of the geometric parameters and infrared (IR) vibrational spectra indicate that the dihydrogen bond H1···H2is significantly strengthened in S1state and the dehydrogenation process may occur along the dihydrogen bond H1···H2. Upon photo‐excitation, the electronic density of phenol‐BDMA complex is redistributed and the redistribution of the electronic density can provide driving force for the dehydrogenation process in S1state. The potential energy curves reveal that the dehydrogenation process in S1state is easier than that in S0state. The charge redistribution in S1state is beneficial to the dehydrogenation process. Furthermore, it has been found that the dihydrogen bond can promote the dehydrogenation process, while the hydrogen bond can hinder the dehydrogenation process. In addition, the dehydrogenation mechanisms were described in detail. First, the H1and H2atoms gradually approach each other, and the O and H3atoms are also getting closer to each other. Subsequently, the O‐H1and B‐H2bonds break, and the H1and H2atoms dissociate from the O and B atoms, respectively. Hydrogen molecular is formed by combing the H1and H2atoms after crossing the energy barrier hopping point. In the meantime, the H3atoms dissociate from the N atom and transfer to the O atom.