Direct ir spectral study of phenylchlorocarbene

By virtue of its singlet ground state, the reactive intermediate phenylchlorocarbene (PCC) cannot be identified by ESR spectroscopy [i] and thus its direct IR spectroscopic detection has esPecially great significance. In order to establish the IR spectrum of PCC, we carried out the UV photolysis of phenylchlorodiazirine (I) [2] with filtered light from a highpressure mercury lamp in an argon matrix cooled to 12~ on a CsI base of an optical helium cryostat.