Matrix Isolation and IR Characterization of the Benzoyl and Benzoylperoxy Radicals

The benzoyl radical 1 was synthesized in argon matrices by the thermal reaction of the phenyl radical 2 with CO. The IR spectrum with the C=O str. vibration at 1824.4 cm –1 is in good agreement with DFT calculations. The formation of 1 is reversible and UV irradiation results in the cleavage back to 2 and CO. The benzoyl radical 1 can react with molecular oxygen in the matrix to produce the benzoylperoxy radical 3 . Radical 3 was also characterized by IR spectroscopy in combination with DFT calculations.