Photolysis of pentafluorophenyl azide or pentafluorophenyl isocyanate in low-temperature matrices gives pentafluorophenyl nitrene which, in the presence of CO, may react photochemically but not thermally to give the isocyanate. ... Numerous photolyses of aryl azides in a variety of rigid media at low temperatures have permitted the observation of electronic or esr spectra of the corresponding nitrenes.l On the other hand, ir studies of the photolysis of phenyl azide2 in Ar matrices ...