Fe+ and FeOS with Inorganic Ligands Containing Hydrogen, Nitrogen, and Oxygen

The coordination of the electronic ground states of Fe+ (6D) and FeO+ (6x+) has been investigated in the gas phase with the inorganic molecules H2, HD, D2, H20, CO, NO, N2, 02, C02, N02, and N20. Reaction rate coefficients and product distributions were measured with the Selected-Ion Flow Tube (SIFT) technique operating at 294 f 3 K and a helium buffer-gas pressure of 0.35 f 0.01 Torr. Except with NO2 and N20, Fe+ was found to be unreactive: there was no evidence for the ligation of Fe+ with H2, HD, D2, H20, CO, NO, N2,02, and C02 under the conditions of the experiments, and Fe+ was observed to react in a bimolecular fashion with NO2 and N20 by 0-atom transfer to yield FeO+. FeO+ generally was observed to be much more reactive than Fe+. While no reactions were seen to occur with NO and 0 2 , FeO+ reacted with H2, HD, D2, and CO to produce Fe+ and with NO2 by 0transfer to produce NO+ + FeO2. A very slow sequential addition of two molecules was seen with N2. With N20, C02, and H20, FeO+ was observed to add sequentially three ligand molecules; this corresponds to the availability of three coordination sites around iron in FeO+. Rate coefficients were measured for each addition and structures have been proposed for the ligated FeO+. Further addition, but at a much reduced rate, was observed with H20, but this was attributed to a second coordination shell involving hydrogen-bond formation. Also, experimental evidence is provided for the extension of the catalytic role of FeO+ in the oxidation of CO to C02 to the ligated ions FeO(N20),+ with n = 1-3.