Abstract
We report on the gas phase reactions of small Fe^+^~n~ clusters (n = 2–10) with O~2~, N~2~O and CO~2~ in an FT‐ICR mass spectrometer. Under our experimental conditions, clusters of all sizes reacted readily with O~2~ and all but the dimer reacted with N~2~O. Only the smallest Fe^+^~n~ clusters (n = 2–4) appeared to activate CO~2~. For all X–O molecules (X = O, N~2~, CO), reaction pathways were observed that include the transfer of O atoms. In addition, the reactions with O~2~ and N~2~O were accompanied by the loss of one or two Fe atoms. Thermochemical considerations based upon the well‐known X–O bond energies were used to calculate Fe~n~‐O^+^ bond dissociation energies (BDEs) for sizes n = 2–6; these amount to roughly 550 kJ mol^‐1^ and thus are considerably higher than the BDE of the Fe‐O^+^ ion. All oxidation reactions of the Fe^+^~n~ clusters (n = 2–6) studied in more detail were terminated by products of Fe~x~O~x~^+^ stoichiometry (x = 1–4). These “microoxides of iron” are not able to activate any further X–O bonds. Secondary reactions of Fe~x~O~x~^+^ clusters with C~6~H~6~, C~2~H~4~ and NH~3~ were investigated for two selected sizes (x = 2, 3) and compared with reactions of the naked Fe^+^~n~ clusters.