CHEMISTRY AND KINETICS OF SINGLET (PENTAFLUOROPHENYL)NITRENE

The chemistry and kinetics of singlet (pentafluorophenyl)nitrene were studied by chemical trapping and laser flash photolysis techniques. Photolysis of pentafluorophenyl azide in cyclohexane, benzene, diethylamine, pyridine, tetramethylethylene, tetrahydrofuran, dimethyl sulfoxide, and dimethyl sulfide forms adducts in fair to good yields. At ambient temperature singlet (pentafluorophenyl)nitrene is intercepted, and intersystem crossing to the lower energy triplet state is unimportant. Triplet nitrene chemistry can be achieved by benzoylbiphenyl photosensitization, the presence of methanol or ethyl iodide, or by lowering the reaction temperature below 0-degrees-C. The singlet nitrene adduct formed in pyridine is an ylide whose structure has been determined by X-ray crystallography. The ylide has an intense absorption maximum at 390 nm which varies only slightly with solvent. The pyridine ylide is a useful probe for monitoring the absolute kinetics of singlet (pentafluorophenyl)nitrene by laser flash photolysis techniques.