Infrared spectra of methyl isocyanate isolated in Ar, Xe and N2 matrices

Reva, Igor; Lapiński, Leszek; Fausto, Rui

doi:10.1016/j.molstruc.2010.03.081

Cited by 18 publications

(29 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Also a clear red shift of about 10 cm −1 of the two features is seen between the sample of 12 CH 4 and 13 CH 4 , moving transitions at 2322 and 2303 cm −1 to 2313 and 2294 cm −1 . These spectroscopic features are therefore the result of a product formed in the reaction between methane and isocyanic acid, and, since they are found close to known CH 3 NCO features (given by Sullivan et al (1994) and Reva et al (2010)), are plausibly identified with methyl isocyanate. Another feature is seen in the wing of the HNCO peak around 2235 cm −1 , which does not clearly shift with methane isotopologues.…”

Section: Set-up and Methodssupporting

confidence: 71%

“…Sullivan et al (1994) lists these at 2320, 2280, 2270, 2240 and 2228 cm −1 , with 2280 cm −1 being the strongest band. Zhou & Durig (2009) positioned all bands around 2300 cm −1 and Reva et al (2010) puts the band for methyl isocyanate in a nitrogen matrix at 2334.7, 2307.9, 2288.9, 2265.2 and 2259.7 cm −1 , finding the strongest transition at 2288.9 cm −1 . The region around these bands is used to monitor CH 3 NCO formation in the ice.…”

Section: Set-up and Methodsmentioning

confidence: 99%

See 1 more Smart Citation

The ALMA-PILS survey: detection of CH3NCO towards the low-mass protostar IRAS 16293−2422 and laboratory constraints on its formation

Ligterink

Coutens

Kofman

et al. 2017

Monthly Notices of the Royal Astronomical Society

130

View full text Add to dashboard Cite

Methyl isocyanate (CH 3 NCO) belongs to a select group of interstellar molecules considered to be relevant precursors in the formation of larger organic compounds, including those with peptide bonds. The molecule has only been detected in a couple of high-mass protostars and potentially on comets. A formation route on icy grains has been postulated for this molecule but experimental evidence is lacking. Here we extend the range of environments where methyl isocyanate is found, and unambiguously identify CH 3 NCO through the detection of 43 unblended transitions in the ALMA Protostellar Interferometric Line Survey (PILS) of the low mass solar-type protostellar binary IRAS 16293-2422. The molecule is detected toward both components of the binary with a ratio HNCO/CH 3 NCO ∼4-12. The isomers CH 3 CNO and CH 3 OCN are not identified, resulting in upper abundance ratios of CH 3 NCO/CH 3 CNO > 100 and CH 3 NCO/CH 3 OCN > 10. The resulting abundance ratios compare well with those found for related N-containing species toward high-mass protostars. To constrain its formation, a set of cryogenic UHV experiments is performed. VUV irradiation of CH 4 :HNCO mixtures at 20 K strongly indicate that methyl isocyanate can be formed in the solid-state through CH 3 and (H)NCO recombinations. Combined with gas-grain models that include this reaction, the solid-state route is found to be a plausible scenario to explain the methyl isocyanate abundances found in IRAS 16293-2422.

show abstract

Section: Set-up and Methodssupporting

confidence: 71%

Section: Set-up and Methodsmentioning

confidence: 99%

The ALMA-PILS survey: detection of CH3NCO towards the low-mass protostar IRAS 16293−2422 and laboratory constraints on its formation

Ligterink

Coutens

Kofman

et al. 2017

Monthly Notices of the Royal Astronomical Society

130

View full text Add to dashboard Cite

show abstract

“…The band broadening in this case is usually associated with vibrations along shallow potential energy profiles that result in large amplitude vibrations. 42,59,60 Analysis of Figure 1 shows that conformer 1ccc has a very shallow potential energy profile for internal rotation along the CCC=O and, especially, NCCC dihedral angles. The carboxylic group in 1ccc is slightly distorted from the tetrazole ring plane (Figure 4), and this conformer may undergo large variations of geometry, keeping a low internal energy (Figure 1, top).…”

Section: Experimental Infrared Spectrum Of Matrix-isolated Taamentioning

confidence: 99%

Tetrazole acetic acid: Tautomers, conformers, and isomerization

Araujo-Andrade

Reva

Fausto

2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric modifications, 1H- and 2H-, depending on the position of the annular hydrogen atom. Two-dimensional potential energy surfaces (PESs) of TAA were theoretically calculated at the MP2/6-311++G(d,p) level, for each tautomer. Four and six symmetry-unique minima were located on these PESs, for 1H- and 2H-TAA, respectively. The energetics of the detected minima was subsequently refined by calculations at the QCISD level. Two 1H- and three 2H-conformers fall within the 0-8 kJ mol(-1) energy range and should be appreciably populated at the sublimation temperature (∼330 K). Observation of only one conformer for each tautomer (1ccc and 2pcc) is explained in terms of calculated barriers to conformational rearrangements. All conformers with the cis O=COH moiety are separated by low barriers (less than 10 kJ mol(-1)) and collapse to the most stable 1ccc (1H-) and 2pcc (2H-) forms during deposition of the matrix. On the trans O=COH surfaces, the relative energies are very high (between 12 and 27 kJ mol(-1)). The trans forms are not thermally populated at the sublimation conditions and were not detected in matrices. One high-energy form in each tautomer, 1cct (1H-) and 2pct (2H-), was found to differ from the most stable form only by rotation of the OH group and separated from other forms by high barriers. This opened a perspective for their stabilization in a matrix. 1cct and 2pct were generated in the matrices selectively by means of narrow-band near-infrared (NIR) irradiations of the samples at 6920 and 6937 cm(-1), where the first OH stretching overtone vibrations of 1ccc and 2pcc occur. The reverse transformations could be induced by irradiations at 7010 and 7030 cm(-1), transforming 1cct and 2pct back to 1ccc and 2pcc, also selectively. Besides the NIR-induced transformations, the photogenerated 1cct and 2pct forms also decay in N2 matrices back to 1ccc and 2pcc spontaneously, with characteristic decay times of hours (1H) and tens of minutes (2H). The decay mechanism is rationalized in terms of the proton tunneling. In crystals, TAA exists exclusively as 1H-tautomer. By contrast, the tautomeric composition of the matrix-isolated monomers was found to consist of both 1H- and 2H-tautomers, in comparable amounts. A mechanistic discussion of the tautomerization process occurring during sublimation, accounting also for the observed minor decomposition of TAA leading to CO2 and 5-methyl-tetrazole, is proposed.

show abstract

“…23 The infrared and Raman spectra of the gas and solid phases were measured by Sullivan et al 24 in the 3200-20 cm −1 and 3200-10 cm −1 regions, respectively. Reva et al 25 recorded the infrared spectra of methyl isocyanate isolated in Ar, Xe, and N 2 matrices.…”

Section: Introductionmentioning

confidence: 99%

Structural and spectroscopic characterization of methyl isocyanate, methyl cyanate, methyl fulminate, and acetonitrile N-oxide using highly correlated ab initio methods

Dalbouha

Senent

Komiha

et al. 2016

The Journal of Chemical Physics

View full text Add to dashboard Cite

Various astrophysical relevant molecules obeying the empirical formula CHNO are characterized using explicitly correlated coupled cluster methods (CCSD(T)-F12). Rotational and rovibrational parameters are provided for four isomers: methyl isocyanate (CHNCO), methyl cyanate (CHOCN), methyl fulminate (CHONC), and acetonitrile N-oxide (CHCNO). A CHCON transition state is inspected. A variational procedure is employed to explore the far infrared region because some species present non-rigidity. Second order perturbation theory is used for the determination of anharmonic frequencies, rovibrational constants, and to predict Fermi resonances. Three species, methyl cyanate, methyl fulminate, and CHCON, show a unique methyl torsion hindered by energy barriers. In methyl isocyanate, the methyl group barrier is so low that the internal top can be considered a free rotor. On the other hand, acetonitrile N-oxide presents a linear skeleton, C symmetry, and free internal rotation. Its equilibrium geometry depends strongly on electron correlation. The remaining isomers present a bend skeleton. Divergences between theoretical rotational constants and previous parameters fitted from observed lines for methyl isocyanate are discussed on the basis of the relevant rovibrational interaction and the quasi-linearity of the molecular skeleton.

show abstract

Infrared spectra of methyl isocyanate isolated in Ar, Xe and N2 matrices

Cited by 18 publications

References 62 publications

The ALMA-PILS survey: detection of CH3NCO towards the low-mass protostar IRAS 16293−2422 and laboratory constraints on its formation

The ALMA-PILS survey: detection of CH3NCO towards the low-mass protostar IRAS 16293−2422 and laboratory constraints on its formation

Tetrazole acetic acid: Tautomers, conformers, and isomerization

Structural and spectroscopic characterization of methyl isocyanate, methyl cyanate, methyl fulminate, and acetonitrile N-oxide using highly correlated ab initio methods

Contact Info

Product

Resources

About