Equilibrium studies of weakly bound Fe(L)+ complexes with L = Xe, CO2, N2 and CH4

The binding energies of Xe, N2, CO2 and CH4 to the Fe+ cation have been studied by equilibrium measurements using Fourier-transform mass spectrometry. Reacting mass-selected Fe(CO2)+ with the mixtures N2/CH4, CO4, CO2/CH4, CO2/Xe CO2/N2 and Xe/N2 provides an internally consistent set of equilibrium constants and free energies ΔΔG (298 K). Consideration of B3LYP calculated thermal corrections suggests Fe+−Xe⩽Fe+−CO2⩽Fe+−N2⩽Fe+−CH4 for the bond dissociation energies. Using the literature value for D0(Fe+CH4) as an achor point, D0(Fe+Xe) = 11.7 ± 1.5, D0(Fe+CO2) = 13.0 ± 1.3 and D0 (Fe+N2) = 13.4 ± 1.1 kcal/mol are obtained.