Structures, electron affinities, and vibrational frequencies of the mono-, di-substituted SF6 radicals

Optimized molecular structures, electron affinities, and IR-active vibrational frequencies have been predicted using five different hybrid Hartree-Fock/density functional theory (DFT) methods for a series of mono-, di-substituted SF6 compounds. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. These methods have been carefully calibrated [J.C. Rienstra-Kiracofe, G.S. Tschumper, H.F. Schaefer, S. Nandi, G.B. Ellison, Chem. Rev. 102 (2002) 231]. The equilibrium configurations of the anions CF3SF4CH3- and CF3SF4CF3- are found to be a zigzag geometry with 2A electronic state. Three different types of the neutral-anion energy separation reported in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities of the mono-, di-substituted SF6 compounds obtained at the KMLYP function are 1.48 eV (SF6), 3.20 eV (SF5Cl), 3.49 eV (SF5Br), 1.59 eV (SF5CF3), 3.21 eV (CF3SF4Cl), 3.59 eV (CF3SF4Br), 1.36 eV (CF3SF4CH3), 2.32 eV (CF3SF4CF3), respectively.