Photolysis of Carbonyl Diisocyanate: Generation of Isocyanatocarbonyl Nitrene and Diazomethanone

Carbenes and nitrenes can exist in both singlet and triplet states, sometimes equally stable and interconverting either thermally or photochemically. Many carbene and nitrene reactions proceed via tunneling at low temperatures. Numerous singlet and triplet states have been characterized spectroscopically, and a detailed understanding of the chemical and physical properties of carbenes and nitrenes is emerging. There has been significant progress in the direct observation of carbenes, nitrenes, and many other reactive intermediates in recent years through the application of matrix photolysis and flash vacuum pyrolysis linked with matrix isolation at cryogenic temperatures. Our understanding of singlet and triplet states has improved through the interplay of spectroscopy and computations. Bistable carbenes and nitrenes as well as many examples of tunneling have been discovered and numerous rearrangements and fragmentations have been documented. The correlation of the zero-field splitting parameter D with calculated spin densities on nitrenes and carbenes is discussed. This Minireview gives an overview of some of these developments.

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“…Eqs. (13) and (14)], [59][60][61] alkoxy-and aryloxycarbonylnitrenes [Eq. (15)], [62] and carbamoylnitrenes R 2 NÀCOÀN [Eq.…”

Section: Triplet and Singlet Acylnitrenes (Oxazirines)mentioning

confidence: 99%

Carbenes and Nitrenes: Recent Developments in Fundamental Chemistry

2018

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“…Given the frequently observed photolytic CO-elimination in covalent isocyanates R-NCO (!RN + CO, R=OCNC(O)À , [30] MeOC (O)À , [31] Me 2 NC(O)À [32] ), the photochemistry of F 2 P(S)NCO in solid Ar-matrix was also studied. Upon an ArF excimer laser (193 nm) irradiation, decomposition of F 2 P(S)NCO occurs as evidenced by the depletion of its IR band (Figure 4, lower trace).…”

Section: Photodecomposition Of F 2 P(s)ncomentioning

confidence: 99%

Spectroscopic Properties, Conformation and Structure of Difluorothiophosphoryl Isocyanate in the Gaseous and Solid Phase

et al. 2020

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Difluorothiophosphoryl isocyanate, F 2 P(S)NCO was characterized with UV/vis, NMR, IR (gas and Ar-matrix), and Raman (liquid) spectroscopy. Its molecular structure was also established by means of gas electron diffraction (GED) and single crystal X-ray diffraction (XRD) in the gas phase and solid state, respectively. The analysis of the spectroscopic data and molecular structures is complemented by extensive quantumchemical calculations. Theoretically, the C s symmetric syn-conformer is predicted to be the most stable conformation. Rotation about the PÀ N bond requires about 9 kJ mol À 1 and the predicted existence of an anti-conformer is dependent on the quantum-chemical method used. This syn-orientation of the isocyanate group is the only one found in the gas phase and contained likewise in the crystal. The overall molecular structure is very similar in gas and solid, despite in the solid state the molecules arrange through intramolecular O•••F contacts into layers, which are further interconnected by S•••N, S•••C and C•••F contacts. Additionally, the photodecomposition of F 2 P(S)NCO to form CO, F 2 P(S)N, and F 2 PNCO is observed in the solid Armatrix.

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“…The compound is surprisingly stable with a halflife of over 1 h in the gas-phase at room temperature, decomposing to N 2 and CO with a calculated activation energy of ~25 kcal/mol. [102,103] It is remarkable that this molecule was successfully generated by FVP after previous exhaustive attempts had failed. [104] FVP of fluorocarbonyl azide F-CON 3 at 700 o C with isolation of the product in Ar matrix allowed the isolation and IR-spectroscopic characterization of triplet fluorocarbonylnitrene, FCON, a rare example of a thermally generated, observable carbonylnitrene.…”

Section: Esr Ir and Uv-visible Spectroscopymentioning

confidence: 99%