Matrix isolation and IR spectroscopic characterization of 3,5‐difluoropyridyl‐2,4,6‐trinitrene

Abstract

The photochemistry of 2,4,6-triazido-3,5-difluoropyridine 21 was investigated by matrix infrared and electron paramagnetic resonance spectroscopies. Ultraviolet irradiation (>260 nm) of 21 results in the formation of 3,5-difluoropyridyl-2,4,6-trinitrene 26 in yields high enough for characterization by infrared spectroscopy. The experimental infrared spectrum is in good agreement with density functional theory calculations. Under similar conditions, a very strong electron paramagnetic resonance spectrum of septet trinitrene 26 was obtained. Shorter irradiation times resulted in more complex product mixtures containing, in addition, mononitrenes and dinitrenes. Surprisingly, azirines and keteneimines, the typical photoproducts of arylnitrenes, were not observed.

15N NMR spectra and reactivity of 2,4,6‐triazidopyridines, 2,4,6‐triazidopyrimidine and 2,4,6‐triazido‐s‐triazine

“…The present 15 N NMR spectroscopic study confirmed that none of triazides 1–7 and 10 displays any signals between δ +50 and −90 ppm that can be assigned to isomeric tetrazoles. These data agree well with the results of previous 13 C NMR spectroscopic studies of triazides 1–7 and 10 …”

“…When aromatic polyazides have two or more nonequivalent azido groups, these groups can selectively react with dipolarophiles, electrophiles, nucleophiles and reductants or undergo selective thermolysis and photolysis . Recently, we have reported the synthesis and some chemical transformations of triazides 1–6 (Scheme ) . It was found that, upon UV irradiation, triazides 2 and 3 undergo selective photolysis of the α ‐azido groups to form the corresponding quintet 2,6‐dinitrenopyridines .…”

“…Recently, we have reported the synthesis and some chemical transformations of triazides 1–6 (Scheme ) . It was found that, upon UV irradiation, triazides 2 and 3 undergo selective photolysis of the α ‐azido groups to form the corresponding quintet 2,6‐dinitrenopyridines . Triazides 3 and 5 added electron‐rich dipolarophiles and phosphines selectively on the γ ‐azido group, while cycloadditions of electron‐poor dipolarophiles occurred selectively on the α ‐azido groups of these triazides .…”

High-spin intermediates of the photolysis of 2,4,6-triazido-3-chloro-5-fluoropyridine

“…Thus, previous EPR studies have shown that irradiation of triazide 1a with light at λ = 313 nm selectively gave quintet dinitrene 4a as the major intermediate product (Scheme 1) [7–8]. Most recently, a similar selectivity was observed during the photolysis of triazide 1b where quintet dinitrene 4b was the major intermediate product (Scheme 1) [9]. By contrast, the photolysis of triazide 7 occurs selectively on the azido group located on the γ-phenyl ring, yielding dinitrene 9 as a single quintet intermediate (Scheme 1) [10].…”

High-spin organic molecules with dominant spin-orbit contribution and unprecedentedly large magnetic anisotropy

“…Previous studies have shown that parent 2,4,6-triazido-3,5-difluoropyridine and 2,4,6-triazido-3,5-dichloropyridine also underwent selective photolysis of the azido groups to form corresponding quintet pyridyl-2,6-dinitrenes as the major intermediate products. 25,26 Based on these analogies, we assigned the product with |D q1 | = 0.289 cm −1 and |E q1 | = 0.0571 cm −1 to quintet dinitrene Q-1 (Scheme 1).…”