Electron-induced ionization and dissociative ionization of iron pentacarbonyl molecules

Abstract

Electron ionization (EI) and dissociative ionization (DI) of Iron pentacarbonyl molecule (Fe(CO)5) was studied using a crossed molecular and electron beam mass spectrometry technique. Positive ions FeO(CO)+, FeC(CO)2+ and CO+ of Fe(CO)5 were detected for the first time. We have determined the experimental appearance energies of positive ions, the thresholds for dissociative reactions, the experimental bond dissociation energies for (CO) n Fe+-CO bond breaks (for n = 4,..., 0) and their average value for Fe-C bond energy 1.25 eV in Fe(CO) 5 + . We have performed extensive density functional theory (DFT) studies of the ground states of neutral molecule and fragments 1A′1 Fe(CO)5, 3B1 Fe(CO)4, 3A1 Fe(CO)3, 3∑g Fe(CO)2, 3 ∑FeCO as well as positive ions 2A1 Fe(CO) 5 + , 4A1 Fe(CO) 4 + , 4A1 Fe(CO) 3 + , 4∑ g Fe(CO) 2 + and 4∑ FeCO+. The structures and energies of the states have beendetermined and the calculated bond dissociation energies (BDEs) were compared with present experiments as well as with previous works.