Interaction of FeO− with water: anion photoelectron spectroscopy and theoretical calculations

Abstract

The interactions of FeO⁻ with water molecules were studied by using photoelectron spectroscopy and density functional theoretical calculations. It is found that a dihydroxyl species, Fe(OH)₂^−/0, can be formed when FeO^−/0 interacts with the first water molecule. The complexes formed via the interactions between FeO^−/0 and n water molecules can be viewed as Fe(OH)₂(H₂O)_n−1^−/0, in which (n − 1)H₂O molecules interact with a Fe(OH)₂ core. For Fe(OH)₂^−/0 and Fe(OH)₂(H₂O)⁻, the Fe(OH)₂ unit has two conformers with the two OH groups oriented differently. The vertical detachment energies (VDEs) of FeO₂H₂(H₂O)_n−1⁻ (n = 1–4) are measured to be 1.25 ± 0.04, 1.66 ± 0.04, 2.06 ± 0.04, and 2.37 ± 0.04 eV, respectively, by experiment. It is also worth mentioning that in the FeO₂H₂(H₂O)⁻ anion the water molecule interacts with the Fe(OH)₂ core by forming a hydrogen bond with one of the OH groups, while in neutral FeO₂H₂(H₂O), the water molecule interacts with the Fe atom of the Fe(OH)₂ core via its O atom.