Cations of halogenated methanes: adiabatic ionization energies, potential energy surfaces, and ion fragment appearance energies |
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Authors: | Yi-Liang He Liming Wang |
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Institution: | (1) School of Chemistry and Chemical Engineering, South China University of Technology, 510640 Guangzhou, People’s Republic of China |
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Abstract: | The DFT-B3LYP and G3X model chemistry were used to predict the cation structures and energetics of fluorinated, chlorinated,
and brominated methanes. Ion–complex structures between methylene cations and HX (X = F, Cl, Br) were found for all H-containing
cations, and CHF–FH]+, CF2–FH]+, CCl2–ClH]+, and CCl2–FH]+ structures are more stable than their normal tetravalent structures. Several cations should also be better described as ion–complex
structures between methyl cations and halogen atoms, e.g., CF3–Br]+. Transition states connecting normal and ion–complex structures were also located, and potential energy diagrams were constructed
for decomposition of methane cations and to predict the fragmentation pathways. The G3X energies were used to predict the
adiabatic ionization energies (IEas) and ion fragment appearance energies (AEs) from methanes. Many of the experimental AEs correspond to the energies of transition
states instead of the thermodynamic dissociation limits.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Cation Halogenated methane Ionization energy Transition state Appearance energy Potential energy diagram |
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