Infrared spectroscopic investigation of propargyl radicals stabilized in low-temperature argon matrix

Abstract

1. The propargyl radical, obtained by vacuum pyrolysis of propargyl iodide and dipropargly oxalate, has been stabilized in an argon matrix at 12 K and characterized by IR spectroscopy on the basis of 12 of its absorption bands. 2. The vibration frequencies of the propargyl radical have been calculated theoretically, the observed bands have been assigned to normal vibrations, and the force field of this radical has been determined. 3. The values obtained for the stretching vibration frequencies νC≡C, νC-C, νCH, and νCH2 indicate strengthening of the ordinary carbon-carbon bond and weakening of the triple bond in the propargyl radical as a result of electron density delocalization in the conjugated system of orbitals.