Studies in spectroscopy. Part VI. Ultra-violet and infra-red spectra of nitrosamines, nitrites, and related compounds

Haszeldine, R. N.; Jander, Jochen

doi:10.1039/jr9540000691

Cited by 42 publications

(16 citation statements)

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“…For (CH 3 ) 2 NNO, the vertical excitation energy of the first excited state blue shifts from 3.49 eV in gas phase to 3.50 eV in n-hexane, 3.59 eV in ethanol, and 3.60 eV in water. The results are in reasonable agreement with experimental data: 3.53 eV in light petroleum, 28 3.58 eV in ethanol, 28 and B3.70 eV in water. 29 As for CH 3 NHNO and CH 2 NHNOH, the same blue-shift character could be found for the first singlet transition.…”

Section: Pcm Calculationssupporting

confidence: 89%

Do primary nitrosamines form and exist in the gas phase? A computational study of CH3NHNO and (CH3)2NNO

Tang

Hanrath

Nielsen

2012

Phys. Chem. Chem. Phys.

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The reactions of the CH(3)NH and (CH(3))(2)N radicals with NO have been studied using quantum chemistry methods to compare the formation and stability of primary and secondary nitrosamines. The calculations show that the entrance part of potential energy surfaces of CH(3)NHNO and (CH(3))(2)NNO formation are similar, and it is concluded that primary amines form nitrosamines under the atmospheric conditions. CH(3)NHNO can, in contrast to (CH(3))(2)NNO, undergo isomerization via a barrier below the reactants entrance energy to CH(2)NHNOH, which through reaction with O(2) eventually leads to formation of CH(2)=NH on a short timescale. TDDFT, CASPT2 and MR-CI calculations show little difference between the n→π* transitions in CH(3)NHNO and (CH(3))(2)NNO and that the two molecules should have comparable photolysis lifetimes in the atmosphere.

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Section: Pcm Calculationssupporting

confidence: 89%

Do primary nitrosamines form and exist in the gas phase? A computational study of CH3NHNO and (CH3)2NNO

Tang

Hanrath

Nielsen

2012

Phys. Chem. Chem. Phys.

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“…The molecules are shown in Figure , and the four groups are nitroso, AB, NQ, and U (for uracil). We chose medium size molecules that were affordable with EOM-CCSD with all basis sets, and for which experimental data in polar solvents is available. − The effect of nonpolar solvents on electronic energies is either small or due to nonelectrostatic interactions, and in either case using PCM is ineffective. Most of the solvents in this work are protic and can form hydrogen bonds, which are also not well reproduced with PCM.…”

Section: Resultsmentioning

confidence: 99%

An EOM-CCSD-PCM Benchmark for Electronic Excitation Energies of Solvated Molecules

Ren

Harms²,

Caricato

2016

J. Chem. Theory Comput.

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In this work, we benchmark the equation of motion coupled cluster with single and double excitations (EOM-CCSD) method combined with the polarizable continuum model (PCM) for the calculation of electronic excitation energies of solvated molecules. EOM-CCSD is one of the most accurate methods for computing one-electron excitation energies, and accounting for the solvent effect on this property is a key challenge. PCM is one of the most widely employed solvation models due to its adaptability to virtually any solute and its efficient implementation with density functional theory methods (DFT). Our goal in this work is to evaluate the reliability of EOM-CCSD-PCM, especially compared to time-dependent DFT-PCM (TDDFT-PCM). Comparisons between calculated and experimental excitation energies show that EOM-CCSD-PCM consistently overestimates experimental results by 0.4-0.5 eV, which is larger than the expected EOM-CCSD error in vacuo. We attribute this decrease in accuracy to the approximated solvation model. Thus, we investigate a particularly important source of error: the lack of H-bonding interactions in PCM. We show that this issue can be addressed by computing an energy shift, Δ, from bare-PCM to microsolvation + PCM at DFT level. Our results show that such a shift is independent of the functional used, contrary to the absolute value of the excitation energy. Hence, we suggest an efficient protocol where the EOM-CCSD-PCM transition energy is corrected by Δ(DFT), which consistently improves the agreement with the experimental measurements.

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“…7 in the Nujol spectrum of P-benzaldoxime seems t o be displaced t o 1321 cm.-I in the solution spectrum. I n P-p-chlorobenzaldoxime Can There is evidence in the literature for the assignment of the N-0 stretching mode to the 900 cm.-l (7, 9, 12) ancl the 800-850 cm.-l regions (5,11,16).…”

Section: Resultsmentioning

confidence: 99%

Infrared Study of the N—oh Group in Alpha and Beta Oximes

Palm¹,

Werbin²

1954

Can. J. Chem.

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The 0-H bending and N-0 stretching vibrations were studied in four pairs of isomeric oximes. A band a t 1265 cn1.-', characteristic of the solution spectra of the a oximes, is identified with the 0-H bending mode. Tentative assignments for the N-0 stretching vibration both in solid and solution spectra are advanced.The p isomers show a distinct shift of the band associated with the N-0 mode from about 950 cm.-' in the solid to about 930 cm.-l i n solution.The results of a recent investigation (13) of the infrared spectra of five pairs of isomeric oximes demonstrated that the most pronounced difference between the geometric isomers was the position of the band associated with the 0-H stretching vibration which occurred near 3250 cm.-I in the a and near 3115 cm.-I in the P oximes. Although the isomers could not be distinguished from one another on the basis of their frequencies in the 1300 cm.-1 and 900 cm.-I regions, tentatively attributed to the 0-H deformation and N-0 stretching modes, more detailed examination of these absorption bands seemed desirable in order to verify these assignments. This was attempted in the present study by examining the spectra of eight isomeric oximes a s Nujol mulls and in benzene and chloroforn~ solutions. The spectra of several N-and 0-methyl ethers as well as the sodium salts of some of the oximes were also obtained in order t o complenlent this work. E X P E R I M E N T A LThe preparation of the oximes has been described previously (13). T h e method of Goldschmidt and Kjellin (8) The sodium salts of a-benzaldoxime, a-p-nitro-, and a-p-cl~lorobenzaldoximes were prepared in the following manner. Slightly less than one millimole of sodium methoxide in methanol was added t o one nlillimok of the oxime. After standing for one to two minutes, the oxime salt was precipitated with copious amounts of anhydrous ether and filtered. T h e salt was washed several times with ether to remove unreacted oxime and was dried over phosphorous pentoxide. T h e infrared spectra de~nonstrated that the unreacted oximes had been completely removed from the salts. N o attempt was made to obtain analytically pure salts since they were used 'Manzrscript received M a y 17, 1954. Contribution jrom the

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Studies in spectroscopy. Part VI. Ultra-violet and infra-red spectra of nitrosamines, nitrites, and related compounds

Cited by 42 publications

References 0 publications

Do primary nitrosamines form and exist in the gas phase? A computational study of CH3NHNO and (CH3)2NNO

Do primary nitrosamines form and exist in the gas phase? A computational study of CH3NHNO and (CH3)2NNO

An EOM-CCSD-PCM Benchmark for Electronic Excitation Energies of Solvated Molecules

Infrared Study of the N—oh Group in Alpha and Beta Oximes

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