Vibrational-state distribution of IF from the reaction F+3-iodopropene: an example of radical resonance energy participation

• Published in: The Journal of chemical physics 1986-04, Vol.84 (7), p.3814-3818
• Main Authors: COLLINS, S. T, TRAUTMANN, M, WANNER, J
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; Kinetics and mechanisms; Organic chemistry; Reactivity and mechanisms
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.450092

The role of the double bond and allyl radical resonance energy has been investigated in the reaction F+C3H5I→IF+C3H5. The vibrational state distributions of the IF product from this reaction and from the corresponding saturated iodo-hydrocarbon reaction F+C3H7I→IF+C3H7 have been determined using laser-induced fluorescence. A bimodal distribution for the reaction F+C3H5I has been observed in contrast to the monotonically decreasing distribution for the reaction F+C3H7I. The bimodal distribution consists of a monotonically decreasing branch, identical to the results for the case of F+C3H7I, and an inverted branch which accounts for the majority of vibrational excitation. The statistical part of the distribution is ascribed to an abstraction mechanism with 〈 f′v〉I =0.07, whereas the inverted part can be explained in terms of an addition–elimination mechanism with 〈 fv〉II =0.59. The branching ratio for the two channels is 5.7:1 in favor of the addition–elimination mechanism. The spectra show that the allyl radical product resonance energy is transformed into vibrational excitation of IF for mechanism II. This can be understood in mechanistic terms.