Pressure-Dependent Rate Constant Predictions Utilizing the Inverse Laplace Transform: A Victim of Deficient Input Data

<i>k</i>(<i>E</i>) can be calculated either from the Rice–Ramsperger–Kassel–Marcus theory or by inverting macroscopic rate constants <i>k</i>(<i>T</i>). Here, we elaborate the inverse Laplace transform approach for <i>k</i>(<i>E</i>) reconstruction by examining the impact of <i>k</i>(<i>T</i>) data fitting accuracy. For this approach, any inaccuracy in the reconstructed <i>k</i>(<i>E</i>) results from inaccurate/incomplete <i>k</i>(<i>T</i>) description. Therefore, we demonstrate how an improved mathematical description of <i>k</i>(<i>T</i>) data leads to accurate <i>k</i>(<i>E</i>) data. Refitting inaccurate/incomplete <i>k</i>(<i>T</i>), hence, allows for recapturing <i>k</i>(<i>T</i>) information that yields more accurate <i>k</i>(<i>E</i>) reconstructions. The present work suggests that accurate representation of experimental and theoretical <i>k</i>(<i>T</i>) data in a broad temperature range could be used to obtain <i>k</i>(<i>T</i>,<i>p</i>). Thus, purely temperature-dependent kinetic models could be converted into fully temperature- and pressure-dependent kinetic models

Pressure-Dependent Rate Constant Predictions Utilizing the Inverse Laplace Transform: A Victim of Deficient Input Data

<i>k</i>(<i>E</i>) can be calculated either from the Rice–Ramsperger–Kassel–Marcus theory or by inverting macroscopic rate constants <i>k</i>(<i>T</i>). Here, we elaborate the inverse Laplace transform approach for <i>k</i>(<i>E</i>) reconstruction by examining the impact of <i>k</i>(<i>T</i>) data fitting accuracy. For this approach, any inaccuracy in the reconstructed <i>k</i>(<i>E</i>) results from inaccurate/incomplete <i>k</i>(<i>T</i>) description. Therefore, we demonstrate how an improved mathematical description of <i>k</i>(<i>T</i>) data leads to accurate <i>k</i>(<i>E</i>) data. Refitting inaccurate/incomplete <i>k</i>(<i>T</i>), hence, allows for recapturing <i>k</i>(<i>T</i>) information that yields more accurate <i>k</i>(<i>E</i>) reconstructions. The present work suggests that accurate representation of experimental and theoretical <i>k</i>(<i>T</i>) data in a broad temperature range could be used to obtain <i>k</i>(<i>T</i>,<i>p</i>). Thus, purely temperature-dependent kinetic models could be converted into fully temperature- and pressure-dependent kinetic models

Pressure-Dependent Rate Constant Predictions Utilizing the Inverse Laplace Transform: A Victim of Deficient Input Data

<i>k</i>(<i>E</i>) can be calculated either from the Rice–Ramsperger–Kassel–Marcus theory or by inverting macroscopic rate constants <i>k</i>(<i>T</i>). Here, we elaborate the inverse Laplace transform approach for <i>k</i>(<i>E</i>) reconstruction by examining the impact of <i>k</i>(<i>T</i>) data fitting accuracy. For this approach, any inaccuracy in the reconstructed <i>k</i>(<i>E</i>) results from inaccurate/incomplete <i>k</i>(<i>T</i>) description. Therefore, we demonstrate how an improved mathematical description of <i>k</i>(<i>T</i>) data leads to accurate <i>k</i>(<i>E</i>) data. Refitting inaccurate/incomplete <i>k</i>(<i>T</i>), hence, allows for recapturing <i>k</i>(<i>T</i>) information that yields more accurate <i>k</i>(<i>E</i>) reconstructions. The present work suggests that accurate representation of experimental and theoretical <i>k</i>(<i>T</i>) data in a broad temperature range could be used to obtain <i>k</i>(<i>T</i>,<i>p</i>). Thus, purely temperature-dependent kinetic models could be converted into fully temperature- and pressure-dependent kinetic models

Carbene Formation in Ionic Liquids: Spontaneous, Induced, or Prohibited?

We present a theoretical study of carbene formation from the 1-ethyl-3-methylimidazolium acetate ionic liquid in the absence and presence of CO₂ in gas and liquid phase. Although CO₂ physisorption constitutes a precursory step of chemisorption (the CO₂’s reaction with carbenes, which forms from cations via proton abstraction by anions), it also enables a very stable CO₂–anion associate. However, this counteracts the chemical absorption by reducing the basicity of the anion and the electrophilicity of the CO₂, which is reflected by charge transfer. Accordingly, the observable carbene formation in the gas phase is hindered in the presence of CO₂. In the neat liquid, the carbene formation is also suppressed by the charge screening compared to the case of the gas phase; nevertheless, indications for carbene incidents appear. Interestingly, in the CO₂-containing liquid we detect more carbene-like incidents than in the neat one, which is caused by the way CO₂ is solvated. Despite the weakness of the CO₂–cation interaction, the CO₂–anion associate is distorted by cations, which can be seen in longer associate distances and reduced “binding” energies. While the single solvating anion is shifted away from CO₂, many more solvating cations approach it compared to the case of the gas phase. This leads to the conclusion that while the ionic liquid effect stabilizes charged species, introducing neutral species such as CO₂ provides an opposite trend, leading to an inverse ionic liquid effect with the facilitation of carbene formation and thus of chemical absorption