No abstract

No abstract

Triplet 4-methylbenzenesulfonylnitrene 3 was studied by solution phase laser flash photolysis, low-temperature absorption spectroscopy, and low-temperature EPR spectroscopy. Upon laser flash photolysis of 4-methylbenzenesulfonyl azide 1 in ethanol, absorption maxima were observed at 325 and 460 nm while in cyclohexane, a single maximum was observed at 310 nm. The short-wavelength absorptions were assigned to the triplet nitrene. There was no evidence that hydroxylic solvents catalyzed intersystem crossing from the singlet to the triplet state of 3. After irradiation of 1 in an EPA glass at 77 K, a band at 313 nm was observed. The zero-field splitting parameters from the EPR spectrum of the nitrene in an EPA glass at 77 K were |D/hc| = 1.471 cm-1 and |E/hc| = 0 cm-1. Remarkably, 3 was not stable at 77 K in EPA. Irradiation of 1 also produced a second nitrene species, possibly (4-methylphenyl)nitrene, with |D/hc| = 0.9840 cm-1 and |E/hc| = 0 cm-1. The decay of the 325 nm transient was first order in ethanol (τ = 8.96 ± 0.48 μs), methanol (τ = 8.18 ± 0.08 μs), and methanol-d 4 (τ = 8.02 ± 1.76 μs).

No abstract

Triplet (diphenoxyphosphory1)nitrene (3) was studied by solution phase laser flash photolysis, low-temperature absorption spectroscopy, and low-temperature EPR spectroscopy. In ethanol, an absorption maximum at 345 nm was observed upon laser flash photolysis of diphenyl phosphorazidate (1) and assigned to the triplet nitrene (z = 3.8 f 0.6 ps). After irradiation of 1 in an EPA glass at 77 K, an absorption attributed to the triplet nitrene was observed at 336 nm. The zero field splitting parameters from the EPR spectrum of the nitrene in EPA glass at 77 K were IDlhcl = 1.5408 cm-' and IElhcl = 0.007 39 cm-I. Stronger transient absorptions observed in hydroxylic solvents support the proposal that hydrogen bonding catalyzes intersystem crossing in nitrenes. [(a) Schuster, G. B.; Platz, M. S .