The infra-red spectra of methyl-, ethyl- and phenyl thionylamine

We present a computational study on the concerted hydrolysis of several classes of N-sulfinylamines of generic formula R-N═S═O, such as the -amines themselves (R-NSO), -hydrazines (R-NH-NSO), -hydrazides (R-CO-NH-NSO) and -amides (R-CO-NSO), as these species are known to possess a wide range of hydrolytic reactivity. Two possible mechanisms of hydrolysis, with a water dimer across the S═O and N═S bonds, in the gas phase are investigated. The reactivity is discussed with respect to the electronic structures, established with the use of the quantum theory of Atoms in Molecules, Natural Bond Orbital and Natural Resonance Theory approaches. For the inert N-sulfinylhydrazines and the keto tautomers of N-sulfinylhydrazides, extended π-conjugation adds a sulfide-like resonance structure that is responsible for their insensitivity toward moisture. Activation barriers for hydrolysis, where water acts as a nucleophilic reagent, decrease with increasing positive charge on the NSO sulfur atom, a finding that might prove useful as a predictive tool in the determination of the general reactivity of an N-sulfinyl compound by experimentalists.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

From Inert to Explosive, The Hydrolytic Reactivity of R−NSO Compounds Understood: A Computational Study

Ivanova

Muchall

2011

“…N -Sulfinylamines I − IV have a planar H−N−S−O or C−N−S−O skeleton. For N -sulfinylaniline ( IV ) this leads to conjugation of the NSO group with the aromatic ring, − and the oxygen atom is found to interact with an ortho hydrogen atom on the ring . Figure shows that II and III exhibit different conformations, a C−H bond in III being aligned with the SO bond in a favorable interaction of bond dipoles, whereas such an alignment is avoided for a C−F bond in II .…”

Section: Resultsmentioning

confidence: 99%

Hydrolysis ofN-Sulfinylamines and Isocyanates: A Computational Comparison

Ivanova

Muchall

2007

A comparative study of the concerted hydrolysis of H-, CF3-, CH3-, and Ph-substituted N-sulfinylamines (R-NSO) and isocyanates (R-NCO) was performed using B3LYP/6-31+G(2d,2p). The "two-water-molecule" model was found to be sufficient for a proper description of the hydrolysis reaction for both classes of compounds. Despite their overall similar reactivity, N-sulfinylamines react across both the N=S and the S=O bonds, whereas isocyanates hydrolyze predominantly through the N=C bond, in agreement with the proton affinities of the nitrogen and oxygen atoms. The charges on sulfur (N=S=O) and carbon (N=C=O) were found to correlate well with the activation enthalpy for hydrolysis. While the reactivity of an N-sulfinylamine toward water increases with increasing electron-withdrawing ability of the substituent, the substituent effect on isocyanates becomes notable only in the presence of the strongly electron-withdrawing CF3 group.

“…The strongest IR band at 1258.2 cm −1 locates in the typical ν asym (OSN) stretching vibration region (1200−1300 cm −1 ) for N-sulfinylimines (R−NSO), 62 and it is very close to the frequency of 1252 cm −1 for the most likely candidate species CH 3 NSO in the liquid phase. 63 By analogy, the IR bands at 1468.2, 1447.1, 1258.2, 1131.2, 1116.4, and 828.8 cm −1 in Figure 2A can also be assigned to CH 3 NSO (Table S2), which is formed through the Curtius-type rearrangement of the azide (CH 3 S(O)N 3 → CH 3 NSO + N 2 ) under the irradiation conditions.…”

Section: ■ Results and Discussionmentioning

confidence: 89%

Curtius-Type Rearrangement of Sulfinyl Azides: A Matrix Isolation and Computational Study

Zeng

2022

The highly unstable methyl sulfinyl azide, CH 3 S-(O)N 3 , has been synthesized and characterized for the first time. In the gas phase, CH 3 S(O)N 3 decomposes quickly at room temperature (300 K) with an estimated half-life (t 1/2 ) of 7 min. Upon irradiation at 266 nm in cryogenic Ar (10 K) and Ne (3 K) matrices, the azide extrudes molecular nitrogen by yielding the novel sulfinyl nitrene intermediate CH 3 S(O)N in the closed-shell singlet ground state, which has been characterized with matrixisolation IR and UV−vis spectroscopy. Prolonged irradiation at 266 nm causes Curtius rearrangement of the nitrene to form Nsulfinylamine CH 3 NSO and S-nitrosothiol CH 3 SNO. By highvacuum flash pyrolysis (HVFP) at 800 K, CH 3 S(O)N 3 also decomposes and furnishes CH 3 S(O)N with minor fragmentation products HNSO and CH 2 in the gas phase. A similar photo-induced Curtius-type rearrangement of trifluoromethyl sulfinyl azide CF 3 S(O)N 3 to CF 3 NSO and CF 3 SNO has also been observed in matrices. According to the theoretical calculations at the CCSD(T)/aug-cc-pVTZ//B3LYP/6-311++G (3df,3pd) level of theory, the rearrangement of CH 3 S(O)N 3 prefers a stepwise pathway by initial formation of the nitrene intermediate CH 3 S(O)N. In line with the thermal persistence of CH 3 S(O)N in the gas phase, the barriers for its subsequent rearrangement are higher than 30 kcal mol −1 .