Chemistry Reference
In-Depth Information
FIGURE 1.6.
Transient absorption spectra produced by 308 nm photolysis of 1-chloro-2-
naphthyl azide in methanol at ambient temperature. The transient spectra were recorded
over time windows of (a) 0.4-1.0 ps (b) 1-6 ps, and (c) 7-1000 ps.
Source
: Reprinted with
permission, from Ref. 54.
naphthyl nitrene (
1
Cl-2-NpN) and by extension, we assign the carrier of 420 nm
absorption in Figure 1.4 to singlet 2-naphthyl nitrene. This species (
1
2-NpN) is the
shortest-lived nitrene yet observed (
1.8 ps). The excited state of the azide
1
Cl-2-
NpN
3
likely has some absorbance at 370 and 520 nm which accounts for the fast (fs)
decay component observed at these wavelengths.
Theory predicts that the cyclization of singlet 2-naphthyl nitrene
1
2-NpN to
naphthazirine 2-NpAZ involves a much lower barrier than the corresponding
reaction of singlet 1-naphthyl nitrene (3.02 vs. 5.53 kcal/mol).
52
In fact, nanosecond
LFP of 2-naphthyl azide at 77 K
fails
to provide any evidence for the existence of
t ΒΌ
