The reaction HCl++CF4→HCF4++Cl: Implications for the heat of formation of CF3+

Abstract

For some years there has been a dispute concerning the appearance energy of CF3+ from CF4 [AE(CF3+/CF4)], or alternatively, the ionization energy of CF3[IE(CF3)] or the heat of formation of CF3+[ΔfH(CF3+)]. In an earlier work [M. Tichy, G. Javahery, N. D. Twiddy, and E. E. Ferguson, Int. J. Mass Spectrom. Ion Processes 79, 231 (1987)] the reaction between HCl+ was used to support a low value, AE(CF3+/CF4)=14.2 eV. A remeasurement of this reaction over the temperature range 173–500 K shows that the original study was in error, both in the reported rate constant and the ion product. In the present work, the rate constant was found to be collisional, producing HCF4+. The rate constant for thermal decomposition of HCF4+ into HF+CF3+ was measured in the course of this work. These new measurements bring into harmony AE(CF3+/CF4) obtained from the HCl+ reaction and the value AE(CF3+/CF4)=14.67±0.04 eV reported by R. L. Asher and B. Ruscic [J. Chem. Phys. 106, 210 (1997)].

Chemical ionization using CF3+: Efficient detection of small alkanes and fluorocarbons

“…This ion is also reported to be unreactive with water [21]. According to a recent study, the ionization energy of CF 3 lies in the range 9.0-9.1 eV [22], which is lower than the 12-15 eV ionization energies of O 2 , N 2 , Ar, H 2 O and than the ionization energies of most organic molecules (9-12 eV), confirming that CF 3 + cannot undergo charge transfer with these molecules. However, CF 3 + displays other types of reactivity with most organic molecules: small alkenes react by addition followed by HF elimination and/or react by hydride abstraction [23], aromatic hydrocarbons react by electrophilic addition followed by HF elimination [24], charge transfer being reported under more energetic conditions [25].…”

The dissociative recombination of fluorocarbon ions III: CF+2and CF+3

“…For these two ions, the following dissociation channels are energetically allowed at zero relative energy, assuming that the parents and products are in their ground states. All energies are calculated using data from the NIST Webbook [5], except for the value of the CF•3 heat of formation, which is deduced from the appearance energy of CF•3 from CF 4 [6]:…”

Comprehensive vacuum ultraviolet photoionization study of the CF3• trifluoromethyl radical using synchrotron radiation

“…It is interesting to note in Fig. 6 that, if we only consider the range of n 2 + values experimentally observed (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26), the ν 2 + spacing ( G(n 2 + )) is roughly constant and we could think that the anharmonicity is negligible, which is not the case. Hence, we cannot use a simple harmonic model to directly derive IE ad.…”