Gas Phase Dioxygen Activation by Binuclear Manganese Clusters

Binuclear manganese oxide cations, Mn2O2 (1) and Mn2O (2), have been prepared in the gas phase by a chemical route by using the reaction of O2 with the ions formed from the ionization of [Mn2(CO)10]. Their reactivity towards selected neutrals has been probed by Fourier Transform Ion Cyclotron Resonance spectrometry (FT-ICR), and insights into the structure of the reagent ions and of ionic reaction intermediates have been obtained by collision- induced dissociation and by the outcome of ion ±molecule reactions. Whereas dihydrogen proved to be unreactive, the hydrides H2O, H2S, and NH3 react by exchange, addition, and oxidation pathways. Oxidative features are displayed also in the reactions of 1 and 2 with model organic molecules, such as methanol, acetaldehyde, and unsaturated hydrocarbons, which undergo dehydrogenation, O-atom transfer, and homolytic cleavage processes. Potentially catalytic cycles are indicated, based on the regeneration of 1 by ligand exchange of end product ions with O2 .