Showing papers by "Bruce S. Ault published in 2011"
TL;DR: The calculations show that 3 has significant 1,3-carbon iminyl biradical character, which explains why 3 reacts efficiently with oxygen and decays by intersystem crossing to the singlet surface.
Abstract: The photoreactivity of (3-methyl-2H-azirin-2-yl)-phenylmethanone, 1, is wavelength-dependent (Singh et al. J. Am. Chem. Soc. 1972, 94, 1199−1206). Irradiation at short wavelengths yields 2P, whereas longer wavelengths produce 3P. Laser flash photolysis of 1 in acetonitrile using a 355 nm laser forms its triplet ketone (T1K, broad absorption with λmax ∼ 390–410 nm, τ ∼ 90 ns), which cleaves and yields triplet vinylnitrene 3 (broad absorption with λmax ∼ 380–400 nm, τ = 2 μs). Calculations (B3LYP/6-31+G(d)) reveal that T1K of 1 is located 67 kcal/mol above its ground state (S0) and has a long C–N bond (1.58 A), and the calculated transition state to form 3 is only 1 kcal/mol higher in energy than T1K of 1. The calculations show that 3 has significant 1,3-carbon iminyl biradical character, which explains why 3 reacts efficiently with oxygen and decays by intersystem crossing to the singlet surface. Photolysis of 1 in argon matrixes at 14 K produced ketene imine 7, which presumably is formed from 3 intersyste...
30 citations
TL;DR: Density functional theory (DFT) calculations showed that the transition state barrier for the formation of 5 is approximately 4 kcal/mol, and photolysis of 1 in argon matrices resulted in triplet nitrene 6, which was further characterized with (15)N and D isotope labeling and DFT calculations.
Abstract: Photolysis of 1 in chloroform yielded 2 as the major product and a small quantity of 3. Laser flash photolysis demonstrated that upon irradiation, the first excited triplet state of the ketone (T1K...
12 citations