Infrared Spectroscopic Study of Perfluorobenzyl Peroxyl Radical and Its UV Photolysis Products in An Argon Matrix

The perfluorobenzyl peroxyl radical (C₆F₅CF₂O₂) was prepared by the reaction of the perfluorobenzyl radical, generated in the gas phase by vacuum pyrolysis of the perfluorobenzyl iodide, with molecular oxygen. The IR spectra of the radicals C₆F₅CF₂O₂ and C₆F₅CF₂¹⁸O₂ trapped in argon matrices at 10 K were measured for the first time and assigned to two conformers with the O–O moiety in anti- and gauche orientation with respect to the C–C bond by comparing the results of the matrix isolation IR spectroscopy study with the data of quantum chemical calculations at the B3LYP/aug-cc-pVTZ and CBS-QB3 levels of theory. UV photolysis of this peroxyl radical resulted in the elimination of F₂C═O with the formation of the perfluorophenoxyl radical C₆F₅O, which formed complexes in the matrix. This reaction pathway considerably differs from that observed for the unsubstituted benzyl peroxyl radical, which decomposes to hydroxyl radical and benzaldehyde.