Electronic Origin of the Competitive Mechanisms in the Thermal Activation of Methane by the Heteronuclear Cluster Oxide [Al2ZnO4].+

The thermal gas‐phase reactions of [Al₂ZnO₄]^.+ with methane have been explored by using FT‐ICR mass spectrometry complemented by high‐level quantum chemical calculations. Two competitive mechanisms, that is, hydrogen‐atom transfer (HAT) and proton‐coupled electron transfer (PCET) are operative. Interestingly, while the HAT process is influenced by the polarity of the transition structure, both the ionic nature of the metal–oxygen bond and the structural rigidity of the cluster oxide affect the PCET pathway. As compared to the previously reported homonuclear [Al₂O₃]^.+ and [ZnO]^.+, the heteronuclear oxide [Al₂ZnO₄]^.+ exhibits a much higher chemoselectivity towards methane. The electronic origins of the doping effect have been explored.