Comparative Study of the Photochemistry of the Azidopyridine 1-Oxides

Abstract

The photochemistry of azidopyridine 1-oxides was studied using an array of glass and matrix isolation techniques. As with room temperature, the photochemistry of 4-azidopyridine 1-oxide is dominated by triplet nitrene chemistry. However, in the case of the 3-azide, matrix photolysis indicates the formation of diazabicyclo[4.1.0]hepta-2,4,6-triene N-oxide and diazacycloheptatetraene N-oxide intermediates as well as triplet nitrene.

Singlet stabilization of oxazole- and isoxazolenitrene-n-oxides by radical delocalization

“…Similarly, the singlet-triplet splitting in PNO has been calculated to be ca. 6 kcal/mol lower than that in phenylnitrene [37,38]. For both systems, the stabilization of the singlet state can be attributed to delocalization of the p-electrons, as shown in Fig.…”

A computational study of the chemistry of substituted 3-nitrenopyridine 1-oxides

“…Recently, a study on the low temperature (matrix-isolated) spectroscopy of 3-and 4-nitrenopyridine 1-oxide has been reported [1]. The solution and matrix photochemistry of 4-nitrenopyridine 1-oxide is dominated by triplet nitrene chemistry, due to the selective stabilization of the nitrene S 1 state, which may be described as having iminyl-aminoxyl biradical character [1,2].…”

“…The solution and matrix photochemistry of 4-nitrenopyridine 1-oxide is dominated by triplet nitrene chemistry, due to the selective stabilization of the nitrene S 1 state, which may be described as having iminyl-aminoxyl biradical character [1,2]. This selective stabilization enhances the rate of intersystem crossing to the T 0 state of the nitrene, and also greatly increases the barrier to cyclization.…”

Reactivity of 3- and 4-pyridinylnitrene-n-oxide radical anions

“…The synthesis and characterization of the samples used in this work has been reported previously [40]. Other materials were obtained from commercial suppliers and used as received.…”