Effects of fluorine on the structures and energetics of the propynyl and propargyl radicals and their anions

reaction: see text] The adiabatic electron affinity (EA(ad)) of the CH(3)-Ctriple bond]C(*) radical experiment = 2.718 +/- 0.008 eV] and the gas-phase basicity of the CH(3)-Ctriple bond]C:(-) anion experiment = 373.4 +/- 2 kcal/mol] have been compared with those of their fluorine derivatives. The latter are studied using theoretical methods. It is found that there are large effects on the electron affinities and gas-phase basicities as the H atoms of the alpha-CH(3) group in the propynyl system are substituted by F atoms. The predicted electron affinities are 3.31 eV (FCH(2)-Ctriple bond]C(*)), 3.86 eV (F(2)CH-Ctriple bond]C(*)), and 4.24 eV (F(3)C-Ctriple bond]C(*)), and the predicted gas-phase basicities of the fluorocarbanion derivatives are 366.4 kcal/mol (FCH(2)-Ctriple bond]C:(-)), 356.6 kcal/mol (F(2)CH-Ctriple bond]C:(-)), and 349.8 kcal/mol (F(3)C-Ctriple bond]C:(-)). It is concluded that the electron affinities of fluoropropynyl radicals increase and the gas-phase basicities decrease as F atoms sequentially replace H atoms of the alpha-CH(3) in the propynyl system. The propargyl radicals, lower in energy than the isomeric propynyl radicals, are also examined and their electron affinities are predicted to be 0.98 eV ((*)CH(2)-Ctriple bond]CH), 1.18 eV ((*)CFH-Ctriple bond]CH), 1.32 eV ((*)CF(2)-Ctriple bond] CH), 1.71 eV ((*)CH(2)-Ctriple bond]CF), 2.05 eV ((*)CFH-Ctriple bond]CF), and 2.23 eV ((*)CF(2)-Ctriple bond]CF).