Anomeric Effects in Sulfonyl Compounds: An Experimental and Computational Study of Fluorosulfonyl Azide, FSO₂N₃, and Trifluoromethylsulfonyl Azide, CF₃SO₂N₃

Abstract

Fluorosulfonyl azide, FSO(2)N(3), was characterized by IR (gas phase, Ar matrix), and Raman (liquid) spectroscopy. According to the matrix IR spectrum of (18)O-labeled FSO(2)N(3), its two oxygen atoms are nonequivalent. This assumption was confirmed by the X-ray crystal structure of FSO(2)N(3) at -123 degrees C, as only one conformer was observed with one of the S=O bonds in synperiplanar position to the N(3) group (phi(OS-NN) = -14.8(3) degrees) with respect to the S-N bond. The same conformation was found for trifluoromethylsulfonyl azide, CF(3)SO(2)N(3) (phi(OS-NN) = -23.74(15) degrees), in the solid state. The preference of such a synperiplanar configuration between S=O and N(3) was rationalized by a predominant anomeric interaction of n(sigma)(N) --> sigma*(S-O), as supported by the experiment and quantum chemical calculations.

Sulfonyl Nitrene and Amidyl Radical: Structure and Reactivity

“…First, we tested the experimental and theoretical methods by studying the stable precursor Im H+ SO 2 N 3 . The predicted structure of Im H+ SO 2 N 3 has a synperiplanar geometry between the azide function and one of the S=O bonds which agrees with geometries of other sulfonyl azides (see Figure S74) [36,37] . The corresponding theoretical IR spectrum matches very well with the experimental infrared photodissociation spectrum (IRPD) of mass‐selected Im H+ SO 2 N 3 (Figure 4a and b).…”

“…The predicted structure of Im H + SO 2 N 3 has a synperiplanar geometry between the azide function and one of the S=O bonds which agrees with geometries of other sulfonyl azides (see Figure S74). [36,37] The corresponding theoretical IR spectrum matches very well with the experimental infrared photodissociation spectrum (IRPD) of mass-selected Im H + SO 2 N 3 (Figure 4a and b). We confirmed the assignment by comparing the IR spectra of the 32 S and 34 S isotopologs (black and yellow spectra in Figure 4a and b).…”

Elusive Fluoro Sulfinyl Nitrite, FS(O)NO, Produced by Photolysis of Matrix‐isolated FS(O)2N

“…In experiments using a mixture of the three possible 16/18 O‐isotopomers of FS(O) 2 N 3 each vibrational mode in triplet FS(O) 2 N was split into three bands, establishing the structural equivalence of its two S–O bonds ( C s symmetry). On the other hand, for the mono 18 O‐substituted precursor FS(O) 2 N 3 ( C 1 symmetry) ν as (SO 2 ) and ν s (SO 2 ) split into a doublet, proving the non‐equivalence of its two S–O bonds 22…”

“…Gaseous fluoro sulfonyl azide, FS(O) 2 N 3 ,22 exhibits a weak UV absorption band centered at about 250 nm as well as a strong absorption at λ max = 202 nm (Figure S1, Supporting Information), suitable for ArF excimer laser ( λ = 193 nm) excitation. A mixture of gaseous azide highly diluted in argon (1:1000) was deposited onto an oxygen‐free high‐conductivity copper‐rod cooled to about 5 K. EPR spectra of the deposit were recorded prior and after laser irradiation.…”

Methanesulfonyl Azide: Molecular Structure and Photolysis in Solid Noble Gas Matrices

“…5 Despite being known for half a century, methanesulfonyl azide remains barely characterized, as far as we know only its IR and UV absorption spectra in solution have been reported. 7,8 This is in sharp contrast to the closely related perfluorinated sulfonyl azides FSO 2 N 3 9 and CF 3 SO 2 N 3 9,10 and sulfonyl diazide O 2 S(N 3 ) 2 , 11 for which the vibrational spectroscopy (IR and Raman), conformation, and X-ray crystal structures have been already studied from both aspects of experiment and theory.…”