Electrospray ionization as a convenient new method for the generation of catalytically active iron-oxide ions in the gas phase

Electrospray ionization (ESI) of aqueous iron(III) nitrate solutions can be used as an easy route for the generation of bare iron-oxide and hydroxide cations such as FeO+, FeOH+, and Fe(OH)2+ in the gas phase. Analysis of the ESI mass spectra obtained under variable conditions in combination with complementary collision experiments suggest that the iron-oxo species are formed by collision-energy driven replacements of nitrato-ligands by water stemming from the sprayed solution. It is demonstrated that the gas-phase reactivity of methane with the iron-oxide cation FeO+ generated via ESI is in good agreement with the well-documented literature data for this reaction.