The Microwave and Millimetre Wave Spectrum, Molecular Constants, Dipole Moment, and Structure of Isocyanic Acid, HNCO

Hocking, W. H.; Gerry, Michael C. L.; Winnewisser, G.

doi:10.1139/p75-239

Cited by 112 publications

(55 citation statements)

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“…In summary the ab initio results indicated that cyanate has the excess charge distributed approximately equally well on the nitrogen and oxygen ends of the ion with the nitrogen slightly more negative. The fact that the calculations indicated a stronger hydrogen bond from water to the N atom of cyanate than to the oxygen was consistent with the known stability of isocyanic acid (HNCO) compared to the cyanic acid isomer (NCOH) (19)(20)(21). It has been established from microwave studies (19) of isocyanic acid that the NCO angle was very close to 180" with a maximum error of 10" while the HNC angle was about 128".…”

Section: Hydration Of Cynnntesupporting

confidence: 73%

Raman studies of cyanate: Fermi resonance, hydration and hydrolysis to urea

Brooker¹,

Wen²

1993

Can. J. Chem.

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. Rarnan spectra were measured for potassium cyanate in the solid phase and as aqueous solutions in H20 and D20 for freshly prepared and for aged solutions. The results indicated that the assignment of the Fermi doublet, v, and 2v2, for solid potassium cyanate was reversed from the assignment for the aqueous solution. The Fermi doublet has an associated pair of hot bands at 1191 and 1315 cm-' which originate from the 638 cm-I v, state, 010. Assignment of the hot bands was confirmed by studies of solid potassium cyanate at liquid-N, temperature, room temperature, and at 473 K. Raman spectra of aged aqueous potassium cyanate revealed that the cyanate ion hydrolyzed slowly and spontaneously at room temperature (even without added ammonium) to produce urea and a carbamate, carbonate equilibrium mixture in parallel reactions. Hydrolysis of cyanate in aqueous ammonium chloride solution resulted in almost total conversion of cyanate to urea. The reaction was not reversible under ambient conditions. Differences in peak frequencies and halfwidths were observed for the cyanate dissolved in Hz0 compared to solutions in D,O. The results provide evidence for strong hydrogen bonding of cyanate to water and are consistent with greater structure in the D20 solution. Theoretical ab initio calculations indicated that the water molecules hydrogen bond well at both the oxygen and nitrogen atoms of cyanate although the hydrogen bond to nitrogen was found to be slightly stronger.MURRAY H. BROOKER et NANPING WEN. Can. J. Chem. 71, 1764Chem. 71, (1993. On a mesure les spectres Raman du cyanate de potassium en phase solide et en solutions aqueuses dans le H,O et le D,0 pour des solutions frafchement prkparees ainsi que pour des solutions qui avaient vieillies. Les resultats obtenus indiquent que l'attribution du doublet de Fermi, v, et 2v2, pour le cyanate de potassium a 1'Ctat solide doit &tre inverse par rapport a ce qui est observe en solution aqueuse. La doublet de Fermi est associk a une paire de bandes chaudes 2 1191 et 1315 cm-I qui ont leur origine dans l'etat v2, 010, a 638 cm-I. On a pu confirmer l'attribution des bandes chaudes par des etudes sur le cyanate de potassium solide la temperature de I'azote liquide, a la temperature ambiante et a 473 K. Les spectres Raman des solutions aqueuses du cyanate de potassium qui ont vieillies rkvklent que I'ion cyanate s'hydrolyse lentement et spontanement a la temperature ambiante (mCme sans addition d'ammonium) pour former de l'uree et un melange a l'equilibre de carbamate/carbonate provenant de reactions parallkles. L'hydrolyse du cyanate en solution aqueuse de chlorure d'amrnonium provoque une conversion presque globale du cyanate en uree. La reaction n'est pas reversible dans les conditions ambiantes. On a observe des differences dans les frequences et les demi-largueurs des bandes du cyanate dissous dans le H20 par rapport aux solutions dans le DzO. Les resultats suggkrent qu'il existe de fortes liaisons hydrogenes entre le cyanate et l'eau et ils sont en accord avec la plus gran...

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Section: Hydration Of Cynnntesupporting

confidence: 73%

Raman studies of cyanate: Fermi resonance, hydration and hydrolysis to urea

Brooker¹,

Wen²

1993

Can. J. Chem.

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“…We use the CDMS entries for the vibrational ground state of the 12 C isotopologue (tag 43 511 version 1) by Lapinov et al (2007) with additional measurements in the range of our survey by Hocking et al (1975), the JPL entries for the 13 C and 18 O isotopologues (tags 44 008 and 45 006, both version 1, Hocking et al 1975), and private entries for the vibrationally excited states 5 = 1, 6 = 1, and 4 = 1 of the main isotopologue, prepared by one of us (HSPM) based on a preliminary, unpublished analysis of the ground and the four lowest excited states. The excited states data were summarized in Niedenhoff et al (1996).…”

Section: Isocyanic Acid Hncomentioning

confidence: 99%

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Беллоче

Müller

Menten

et al. 2013

A&A

390

523

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Context. The discovery of amino acids in meteorites fallen to Earth and the detection of glycine, the simplest of them, in samples returned from a comet to Earth strongly suggest that the chemistry of the interstellar medium is capable of producing such complex organic molecules and that they may be widespread in our Galaxy. Aims. Our goal is to investigate the degree of chemical complexity that can be reached in the interstellar medium, in particular in dense star-forming regions. Methods. We performed an unbiased, spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window. Partial surveys at 2 and 1.3 mm were performed in parallel. The spectra were analyzed with a simple radiative transfer model that assumes local thermodynamic equilibrium but takes optical depth effects into account. Results. About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected at 3 mm toward Sgr B2(N) and (M), i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of two over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward Sgr B2(N) and (M) are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. In addition, we report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively, up to a vibration energy of 1400 cm −1 (2000 K). Excitation temperatures and column densities were derived for each species but should be used with caution. The rotation temperatures of the detected complex molecules typically range from ∼50 to 200 K. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were five rare isotopologues of vinyl cyanide, cyanoacetylene, and hydrogen cyanide. We also report the detection of transitions from within twelve new vibrationally or torsionally excited states of known molecules. Absorption features produced by diffuse clouds along the line of sight are detected in transitions with low rotation quantum numbers of many simple molecules and are modeled with ∼30-40 velocity components with typical linewidths of ∼3-5 km s −1 . Conclusions. Although the large number of unidentified lines may still allow future identification of new molecules, we expect most of these lines to belong to vibrationally or torsionally excited states or to rare isotopologues of known molecules for which spectroscopic predictions are currently missing. Significant progress in extending the inventory of complex organic molecules in Sgr B2(N) and deriving tighter constraints on their location, origin, and abundance is expected in the near future thanks to an ongoing spectral line survey at 3 mm with ALMA in its cycles 0 and 1. The present single-dish surve...

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“…We use the CDMS entry for HNCO in its ground state (tag 43 511 version 1) by Lapinov et al (2007) with additional measurements in the range of our survey by Hocking et al (1975), and the JPL entry for the 13 C isotopologue (tag 44 008 version 1, Hocking et al 1975). Private entries for the vibrationally excited states 5 = 1, 6 = 1, and 4 = 1 of the main isotopologue were prepared by one of us (HSPM).…”

Section: Isocyanic Acid (Hnco)mentioning

confidence: 99%

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

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Meshcheryakov

Garrod

et al. 2017

A&A

156

261

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Context. N-methylformamide, CH 3 NHCHO, may be an important molecule for interstellar pre-biotic chemistry because it contains a peptide bond, which in terrestrial chemistry is responsible for linking amino acids in proteins. The rotational spectrum of the most stable trans conformer of N-methylformamide is complicated by strong torsion-rotation interaction due to the low barrier of the methyl torsion. For this reason, the theoretical description of the rotational spectrum of the trans conformer has up to now not been accurate enough to provide a firm basis for its interstellar detection. Aims. In this context, as a prerequisite for a successful interstellar detection, our goal is to improve the characterization of the rotational spectrum of N-methylformamide. Methods. We use two absorption spectrometers in Kharkiv and Lille to measure the rotational spectra over the frequency range 45-630 GHz. The analysis is carried out using the Rho-axis method and the RAM36 code. We search for N-methylformamide toward the hot molecular core Sagittarius (Sgr) B2(N2) using a spectral line survey carried out with the Atacama Large Millimeter/submillimeter Array (ALMA). The astronomical spectra are analyzed under the assumption of local thermodynamic equilibrium. The astronomical results are put into a broader astrochemical context with the help of a gas-grain chemical kinetics model. Results. The new laboratory data set for the trans conformer of N-methylformamide consists of 9469 distinct line frequencies with J ≤ 62, including the first assignment of the rotational spectra of the first and second excited torsional states. All these lines are fitted within experimental accuracy for the first time. Based on the reliable frequency predictions obtained in this study, we report the tentative detection of N-methylformamide towards Sgr B2(N2). We find N-methylformamide to be more than one order of magnitude less abundant than formamide (NH 2 CHO), a factor of two less abundant than the unsaturated molecule methyl isocyanate (CH 3 NCO), but only slightly less abundant than acetamide (CH 3 CONH 2 ). We also report the tentative detection of the 15 N isotopologue of formamide ( 15 NH 2 CHO) toward Sgr B2(N2). The chemical models indicate that the efficient formation of HNCO via NH + CO on grains is a necessary step in the achievement of the observed gas-phase abundance of CH 3 NCO. Production of CH 3 NHCHO may plausibly occur on grains either through the direct addition of functional-group radicals or through the hydrogenation of CH 3 NCO. Conclusions. Provided the detection of N-methylformamide is confirmed, the only slight underabundance of this molecule compared to its more stable structural isomer acetamide and the sensitivity of the model abundances to the chemical kinetics parameters suggest that the formation of these two molecules is controlled by kinetics rather than thermal equilibrium.

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The Microwave and Millimetre Wave Spectrum, Molecular Constants, Dipole Moment, and Structure of Isocyanic Acid, HNCO

Cited by 112 publications

References 1 publication

Raman studies of cyanate: Fermi resonance, hydration and hydrolysis to urea

Raman studies of cyanate: Fermi resonance, hydration and hydrolysis to urea

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

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