Ligand effects on single-electron transfer of isolated iron atoms in the gaseous complexes [(OC)mFe(OH2)n]+ (m, n = 0–2, m + n = 1, 2)

The properties of neutral and monocationic complexes of iron with one and two water or carbonyl ligands (i.e. FeCO0/+, Fe(OH2)0/+, (OC)Fe(OH2)0/+, and (H2O)Fe(OH2)0/+) are studied by means of wave-function based ab initio theory. Not surprisingly, the addition of ligands to the metal center drastically changes the energetics of the cationic species, whereas the ligation of neutral iron has much smaller effects and the interaction is even repulsive for some neutral quintet states. As a consequence, the associated adiabatic and vertical transitions between the manifold of the neutral and monocationic species experience substantial changes with differences exceeding 1 eV in the ionization energies. The results are used to explain the results of earlier studies of (OC)Fe(OH2)0/+ and (H2O)Fe(OH2)0/+ by means of neutralization–reionization mass spectrometry.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (141 K)Download as PowerPoint slideHighlights► High level ab initio studies of the small neutral and monocationic species [(OC)mFe(OH2)n]+ (m, n = 0–2, m + n = 1, 2). ► CO as a ligand stabilizes the low-spin configuration in the cationic as well as the neutral forms. ► Carbonyl complexes form bound states for the neutral species. ► Redox chemistry of iron is drastically influenced by ligation.