Infrared and EPR spectroscopic studies of 2-C2H2F and 1-C2H2F radicals isolated in solid argon

2-fluorovinyl radicals were generated in solid argon by solid-state chemica l reactions of mobile F atoms with acetylene and its deuterated analogues. Highly resolved EPR spectra of the stabilized radicals CHF=(CH)-C-., CDF=(C D)-C-., CHF=(CD)-C-., and CDF=(CH)-C-. were obtained for the first time. Th e observed spectra were assigned to cis-2-fluorovinyl radical based on exce llent agreement between the measured (a(F) = 6.50, a(betaH) = 3.86, a(alpha H) = 0.25 mT) hyperfine constants and those calculated using density functi onal (B3LYP) theory. Analogous experiments carried out using infrared spect roscopy yielded a complete assignment of the vibrational frequencies. An un usual reversible photochemical conversion is observed in which cis-2-fluoro vinyl radicals can be partially converted to 1-fluorovinyl radicals by puls ed laser photolysis at 532 nm. Photolysis at 355 nm converts 1-fluorovinyl back to cis-2-fluorovinyl. High-resolution EPR and infrared spectra of 1-fl uorovinyl were obtained for the first time. The measured hyperfine constant s (a(F) = 13.71, a(H1) = 4.21, a(H2) = 1.16 mT) are in good agreement with calculated values. (C) 2001 Academic Press.