Electron-Deficient Strong Bases. Generation of the 4-Biphenylyl- and 2-Fluorenylnitrenium Ions by Nitrene Protonation in Water

Inhibitory effect of DNA structure on the efficiency of reaction of guanosine moieties with a nitrenium ion

“…6 The measured values of k az at 20°C for several nitrenium ions, including 2a, with lifetimes (1/k s ) of 0.2-30 ms are in the range 4.0 Â 10 9 -5.0 Â 10 9 M À1 s À1 . 6,7 This is very similar to diffusionlimited second-order rate constants for trapping of carbocations by N 3 À and other small, strong nucleophiles. Competition experiments show that the diffusion-limited rate constant for reaction of purine nucleosides with the nitrenium ions 2b and 2c at 20°C under these conditions is ca 2.0 Â 10 9 M À1 s À1 .…”

“…6,7 Although it is known that 2a-c react efficiently with d-G, and the C-8 adducts generated from reaction with monomeric d-G are equivalent to the major adducts isolated from in vivo and in vitro experiments with DNA, 5,8,9 the effect of DNA structure on the adductforming reaction is unknown. In particular, it is not known if the tertiary structure of the DNA double helix promotes or inhibits the formation of the d-G-nitrenium ion adducts.…”

Singlet and triplet states in the reactions of nitrenium ions

“…They therefore tend to participate in chemical reactions involving shifts of electron pairs. For example, both nitrenes 18 and carbenes 19 can act as bases, abstracting protons via their non-bonding pair. In contrast, triplet states, having two semi-occupied orbitals, tend to behave as radicals.…”

Time-Resolved Resonance Raman Spectroscopy and Density Functional Study of 2-Fluorenylnitrene and Its Dehydroazepine Products

“…The singlet 2-fluorenylnitrene species appears to have a lifetime in the order of approximately 30 ± 50 ns (see Figure 2), while the singlet 2-fluorenylnitrenium ion has a substantially longer lifetime, namely on the microsecond timescale. [31] There appears to be an interesting correlation of the degree of cyclohexadienyl character and charge delocalization into the two phenyl rings with the lifetime of the 2-fluorenylnitrene and 2-fluorenylnitrenium ion species. Our results also indicate that the nitrenium ion moiety enables substantially better charge delocalization into the phenyl rings than the neutral nitrene moiety for similar imine character of the C À N bond.…”