DISSOCIATIONS OF GAS-PHASE CHCLF AND CHCL2 RADICALS AND CATIONS FOLLOWING COLLISIONAL ELECTRON-TRANSFER - A VARIABLE-TIME NEUTRALIZATION-REIONIZATION AND AB-INITIO STUDY

Variable-time neutralization-reionization mass spectrometry is used to generate CHClF . and CHCl2 . radicals and to study their unimolecular dissociations within 0.4-4.1 mu s. Loss of Cl . is a major dissociati on of CHClF . following collisional neutralizations with di-n-butyl et her, chlorobenzene, di-n-butylamine, aniline, and N,N-dimethylaniline, which range from 0.28 eV endoergic to 1.7 eV exoergic in the same ser ies. Loss of H . also occurs, whereas loss of F . and eliminations of HF and HCl are unimportant. Dissociations of CHClF+ cations following collisional reionization of CHClF . show eliminations of HF and HCl an d losses of F . and Cl . whose rate parameters depend on the nature of the neutralization target. Both CHCl2 radicals and ions undergo elimi nation of HCl and loss of Cl . whose rate parameters are distinguished by the variable-time measurements. Ab initio calculations at the G2(M P2) level of theory give the bond dissociation energies for C-H, C-Cl, and C-F in CHClF . as 307, 333, and 465 kJ mol(-1), respectively. Eli minations of HCl and HF have the lowest thermochemical thresholds, 217 and 225 kJ mol(-1), respectively, but overcome activation barriers. F ranck-Condon effects in fast electron transfer are calculated to depos it 34 and 91 kJ mol(-1) in the vertically formed CHClF . and CHClF+, r espectively.