Energetics and dynamics of threshold photoion-pair formation in HF∕DF

ENTHALPY OF FORMATION OF AQUEOUS HYDROFLUORIC ACID: REVISION NEEDED?

Accurate enthalpies of formation of hydrofluoric acid in the gas and liquid states as well as in aqueous solutions are critical for reduction and interpretation of combustion calorimetry data for fluorinated compounds. Analysis of current recommendations reveals inconsistencies with the existing literature that can significantly affect experimental values derived using these recommendations. Through thorough and comprehensive analysis of available experimental data, including the sources not considered before, we provide recommendations that substantially improve consistency with these results. However, the scatter in the existing data also prevents further improvements and uncertainty reduction. New experimental data, particularly for aqueous HF solutions, are needed to advance.

Superhalogen and Superacid

A superhalogen F@C₂₀ (CN)₂₀ and a corresponding Brønsted superacid were designed and investigated on DFT and DLPNO-CCSD(T) levels of theory. Calculated compounds have outstanding electron affinity and deprotonation energy, respectively. We consider superacid H[F@C₂₀ (CN)₂₀ ] to be able to protonate molecular nitrogen. The stability of these structures is discussed, while some of the previous predictions concerning neutral Brønsted superacids of record strength are doubted. © 2019 Wiley Periodicals, Inc.

Critical evaluation of the enthalpies of formation for fluorinated compounds using experimental data and high-level ab initio calculations

The ab initio method for prediction of the enthalpies of formation for CHON-containing organic compounds proposed earlier (J. Chem. Theory Comput. 2018, 14, 5920-5932) has been extended to their fluorinated derivatives. A single experimental Δ_f H ^o _m is typically available for compounds in this scope. Thus, a priori evaluation of the data quality was found to be inefficient despite all available experimental data for C₁─C₃ hydrofluorocarbons and 34 data points for medium-size organofluorine compounds being considered. The training set was derived by analyzing consistency of the experimental and predicted values and removal of outliers. Significant issues in the experimental data, including inconsistency across different laboratories, were identified and potential causes for these problems were discussed. A conservative estimate of uncertainty for the experimental Δ_f H ^o _m of organofluorine compounds was proposed.

The divide-and-conquer second-order proton propagator method based on nuclear orbital plus molecular orbital theory for the efficient computation of proton binding energies

An efficient computational method to evaluate the binding energies of many protons in large systems was developed.