Free Radicals by Mass Spectrometry. IX. Ionization Potentials of CF3 and CCl3 Radicals and Bond Dissociation Energies in Some Derivatives

The vertical ionization potentials of CF3 and CCl3 radicals, as measured by electron impact, are 10.10±0.05 and 8.78±0.05 v respectively. From the appearance potentials of the CF3+ and CCl3+ ions from derivatives, the heats of formation of CF3 and CCl3 radicals were found to be —117±2 kcal/mole and +13.4±3 kcal/mole respectively, assuming that no excess energy was included in the appearance potentials. From this data and other heats of formation the following bond dissociation energies (in kcal/mole) have been evaluated: D(CCl3−H)=88.9±3D(CCl3−F)=102±7D(CCl3−Cl)=67.9±3D(CCl3−Br)=49.5±3D(CF3−H)=103±4D(CF3−F)=121±4D(CF3−Cl)=83±3