Reactions of photogenerated fluorine atoms with molecules trapped in solidargon - 4. Spectroscopic characteristics Of beta-C2H2F circle radicals generated in reactions of mobile F atoms with C2H2 molecules trapped in solid argon

Reactions of mobile fluorine atoms with C2H2, C2D2, and C2HD molecules in s olid argon were studied by ESR and IR spectroscopic techniques. Highly reso lved ESR spectra of the stabilized radicals CHF= (CH)-C-., CDF= (CD)-C-., C HF= (CD)-C-., and CDF= (CH)-C-. were obtained for the first time. Isotropic hyperfine constants on fluorine and proton nuclei were measured. it was fo und that the radicals formed in the reaction F + C2H2 correspond to the cis -beta -C2H2F. isomer. A comparison of the measured HFC constants with the v alues calculated by modern quantum-chemical methods allows the identificati on of the isomeric form of the radical, whereas vibrational analysis of the IR absorption spectra gives unreliable results. The calculation of the ene rgy of the radical isomers predicts that CiS-beta -C2H2F. is more stable th an trans-beta -C2H2F. by similar to1.0 kJ mol(-1).