Advanced hydrogen adsorption on benzene: Cation-π interaction effects

Abstract

Interactions between hydrogen and benzene are weak as they are mainly based on the dispersion forces. In this work, we report the advanced hydrogen interactions with the cation–π bound systems. MP2 and SAPT2+ calculations have established that the interaction energy (Eint) between the monovalent cation–π systems (−0.60 and −0.71 kcal/mol for Na+ and Li+, respectively) and the hydrogen molecule is slightly larger than that for pure benzene (−0.55 kcal/mol), whereas the divalent cation–π systems produce stronger interactions (−1.61 and −1.76 kcal/mol for Mg2+ and Zn2+, respectively). The SAPT2+ analysis have revealed that in all the studied cases the dispersion forces are dominating, however, the induction interactions are responsible for the stabilization of hydrogen at divalent cation–π species. AIMD simulations have validated the stability of the studied Mg2+ and Zn2+ complexes at low temperatures. Our investigations establish the potential of divalent cation–π complexes for the usage in systems for H2 storage.