The monochlorine fluorides (ClFn) and their anions (ClFn-) n = 1-7: structures and energetics

Abstract

Predictions of molecular structure and energies have been made for each of the members in the ClF n /ClF n - (n = 1-7) series of molecules using density functional theory (DFT). The three different types of prediction for electron affinities determined in this work are: the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE) of the anion. Also reported are the first Cl-F dissociation energies for both the neutral and the anion (D CIFn ). Self-consistent Kohn-Sham orbitals were obtained using four different functional forms and a double-ζ plus polarization (DZP) basis set. When diffuse s- and p-type functions were added to the basis set, the anions were stabilized significantly with respect to the neutrals, and the electron affinity values were increased significantly. Overall, the best agreement with experimental structures was obtained with the DZP++ BHLYP method based upon Becke's half-and-half exchange functional and the Lee-Yang-Parr correlation functional, while the other three functionals tended to overshoot bond lengths and bond angles. Although a number of experimental energetic results for the ClF n /ClF n series exist, many are ruled out of bounds by this study.The most reliable adiabatic electron affinities predicted are 2⋅74 eV (ClF), 4⋅93 eV (ClF2), 4⋅32 eV (ClF3), 5⋅73 eV (ClF4), 5⋅17 eV (ClF5), 5⋅51 eV (ClF6) and 8⋅65 eV (ClF7). It is hoped that the abundance of theoretical predictions reported in this work will provide a stimulus for future experimental studies in the important area of chlorine fluoride chemistry.