Methane activation by gold-doped titanium oxide cluster anions with closed-shell electronic structures

The reactivity of closed-shell gas phase cluster anions AuTi(3)O(7)(–) and AuTi(3)O(8)(–) with methane under thermal collision conditions was studied by mass spectrometric experiments and quantum chemical calculations. Methane activation was observed with the formation of AuCH(3) in both cases, while the formation of formaldehyde was also identified in the reaction system of AuTi(3)O(8)(–). The cooperative effect of the separated Au(+) and O(2–) ions on the clusters induces the cleavage of the first C–H bond of methane. Further activation of the second C–H bond by a peroxide ion O(2)(2–) leads to the formation of formaldehyde. This study shows that closed-shell species on metal oxides can be reactive enough to facilitate thermal H–CH(3) bond cleavage and the subsequent conversion.