Temperature-dependent nature of interaction between hydrogen and copper(II) acetate confined in nanoporous carbon

Sixty years ago, cupric acetate was proposed as one of the first homogeneous, heterolytic hydrogen activation catalysts. Later on, it was demonstrated that dihydrogen complexation is unequivocally the first step preceding HH bond cleavage. In this study, using a home-made, high-pressure adsorption setup working at different temperatures, we examined the carbon-nanoconfined counterparts of the former in order to elucidate the nature of H2-metal complex interaction inside the nanosized space provided by the porous support. In this regard, we found that by lowering temperature from 100 °C to room temperature, a marked alteration would take place in the nature of interaction. By doing so, we moved from what appeared to be (H2)CuH2, a dihydride-dihydrogen complex, to a Kubas compound releasing H2 in a fully reversible manner. The nanoconfined metal complex discussed here may serve either as a prototypical, room-temperature hydrogen storage medium with optimum heat of interaction, or as a solid-phase hydrogen activation catalyst operating under mild conditions.