Investigations of the gas phase reactions of Fe+ with the halocarbons CF3X (X = I, Br) were performed in order to identify decomposition pathways arising from metal-induced C–X bond activation. Experiments were carried out in a selected-ion drift cell apparatus operated at 3.5 torr at room temperature. Under these conditions, the interaction energy between the Fe+ and CF3X can be described as near-thermal, with effective temperatures on the order of 850 K with respect to the neutral reactant. Fe+ reactant ions were formed in a sputtering glow discharge using Ne or Ar as the working gas. The possible presence of Fe+ excited states in the drift cell was ruled out with the use of charge-transfer bracketing reactions. Products in the reactions of interest were identified with mass spectra. Several ionic product species consistent with activation of the C–X bond by Fe+ were observed, including FeCF3+, FeX+, and FeFX+ (CF3I only). Product branching ratios indicate that FeX+ was formed preferentially. Association via a three-body process was also observed as a primary product channel. Reaction sequences determined by manipulating the extent of reaction also indicated secondary production of CF2X+ via FeX+. Secondary association was also observed with several products. Formation of FeX+ and FeCF3+ is consistent with a mechanism proceeding through a bond-insertion intermediate. The bimolecular rate constant measured for the Fe+/CF3I reaction indicates an efficient reaction, suggesting that this bond-insertion mechanism proceeds with little barrier to reaction.

Evidence of Fe+-induced decomposition of two significant greenhouse gases

253rd National Meeting (2017)

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