C-H bond activation by aluminum oxide cluster anions, an experimental and theoretical study

Aluminum oxide cluster anions are produced by laser ablation and reacted with n-butane in a fast flow reactor. A reflectron time-of-flight mass spectrometer is used to detect the cluster distribution before and after the reactions. Aluminum oxide clusters Al2O4,6- and Al3O7- can react with n-C4H10 to produce Al2O4,6H- and Al3O7H-, respectively, while cluster Al3O6- reacts with n-C4H10 to produce both the Al3O6H- and Al3O6H2-. The theoretical calculations are performed to study the structures and bonding properties of clusters Al2O4,6- and Al3O6,7- as well as the reaction mechanism of Al2O4- + n-C4H10. The calculated results show that the mononuclear oxygen-centred radicals (O-center dot) on Al2O4,6- and Al3O7-, and oxygen-centred biradical on Al3O6- are the active sites responsible for the observed hydrogen atom abstraction reactivity. Furthermore, mechanism investigation of the O-center dot generation in Al3O7- upon O-2 molecule adsorption on un-reactive Al3O5- is performed by theoretical calculations.