Generation of Hydroxyl Radicals in the Reaction of Dihydrogen with AuNbO 4 + Cluster Cations

A molecular‐level insight into the nature of reactive oxygen species involved in dihydrogen (H 2 ) dissociation is of great importance to understand gold catalysis. In this study, laser ablation generated and mass‐selected AuNbO 4 + oxide cluster cations could dissociate H 2 in an ion‐trap reactor. The reaction has been characterized by time‐of‐flight mass spectrometric experiments and density functional calculations. The lowest energy isomer of AuNbO 4 + contains two lattice oxygen (O 2− ) and one superoxide (O 2 .− ) species. The gold atom anchors the H 2 molecule in the first step and then delivers one hydrogen atom to the O 2− ion in H 2 dissociation. At the same time, O 2 .− is reduced into a peroxide unit that can accept the second hydrogen atom of H 2 with the generation of a hydroxyl radical as the main product. In this study, the important roles of the O 2 .− unit in the dissociation of H 2 have been identified.