The Perfluoroadamantyl Radicals C10F15 and Their Anions

The optimized geometries, electron affinities, and harmonic vibrational frequencies of perfluoroadamantyl radicals (C10F15) have been obtained using four carefully calibrated density functional theory methods in conjunction with diffuse function augmented double-ζ plus polarization (DZP++) basis sets. There are two C10F15 isomers with close energies. With the DZP++ B3LYP method, the C3v isomer (1-C10F15) lies energetically above the Cs isomer (2-C10F15) by 0.086 eV (2.0 kcal/mol), while the anionic 1-C10F15(-) isomer is predicted to lie below 2-C10F15(-) anion by 1.00 eV (23.0 kcal/mol). The DZP++ B3LYP method predicts the ZPVE-corrected adiabatic electron affinity for the C3v isomer (1-C10F15) to be 4.16 eV, and that for the Cs isomer (2-C10F15) is 3.10 eV. These EAad values are significantly larger than that (1.31 eV) of the parent molecule perfluoroadamantane (C10F16). For the 1-C10F15 radical, the C*-C bond length is shortened by 0.043 Å upon removal of F from the C10F16 molecule. The C*-C bond distance for the 1-C10F15(-) anion is 0.068 Å shorter than that for C10F16. Similarly, for 2-C10F15 the C*-C distance is 0.053 Å shorter than for C10F16, while re(C*-C) for the anion is 0.061 Å shorter than for C10F16.