Theoretical Predictions of Structures and Vibrational Infrared Frequencies. I. Mercaptans and Sulfides

Hameka, Hendrik F.; Emery, Silvio L.; Famini, George R.; Jensen, James O.; Leonard, Joseph M.; Reutter, Dennis J.

doi:10.1080/10426509008038047

Cited by 24 publications

(8 citation statements)

References 11 publications

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“…This conclusion has been reached previously based on the electron diffraction data 7 and theoretical calculations at the RHF/3-21G level. 8,9 Our present calculations at a higher level of theory with larger basis sets also support this finding.…”

Section: Conformational Analysissupporting

confidence: 83%

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Raman and infrared spectra, conformational stability, andab initio calculations for chloromethyl methyl sulfide

Durig

Robb

et al. 2000

J. Raman Spectrosc.

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The Raman (3500-20 cm −1 ) and infrared (3500-40 cm −1 ) spectra of gaseous and solid chloromethyl methyl sulfide [chloro(methylthio)methane], CICH 2 SCH 3 , and the corresponding deuterated molecule, CICD 2 SCD 3 , were recorded. Additionally, the Raman spectra of the liquids were recorded from 3500 to 50 cm −1 and qualitative depolarization values were obtained. These data were interpreted on the basis that only the gauche conformer (methyl group gauche to the chlorine atom) is present in all three physical states. A complete vibrational assignment is given for the normal and d 5 -isotopomer. Ab initio calculations were carried out with the RHF/6-31G * basis set, and also with full electron correlation by the perturbation method to second order (MP2) with the 6-31G * and 6-311YG * * basis sets, to obtain the structural parameters, relative conformational stabilities, harmonic force constants, Raman and infrared intensities and fundamental wavenumbers. The fundamental vibrational wavenumbers and barriers to internal rotation which were obtained experimentally are compared with those obtained from the MP2/6-31G * calculation. From the ab initio calculations the gauche conformer is estimated to be more than 10.22 kJ mol −1 more stable than the trans conformer. All of these results are discussed and compared with the corresponding quantities obtained for some similar molecules. Figure 1. Raman spectra of chloromethyl methyl sulfide: (A) gas; (B) liquid; and (C) annealed solid.

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Section: Conformational Analysissupporting

confidence: 83%

“…Theoretical calculations have been carried out to predict the structure, vibrational wavenumbers for the normal modes and barriers to internal rotation about the CH 2 -S bond. 8,9 Full optimizations were performed with a very small basis set, i.e. 3-21G at the restricted Hartree-Fock (RHF) level.…”

Section: Introductionmentioning

confidence: 99%

Raman and infrared spectra, conformational stability, andab initio calculations for chloromethyl methyl sulfide

Durig

Robb

et al. 2000

J. Raman Spectrosc.

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“… Optimized geometries obtained at the a MP2(Full)/6-31G(d), b MP2/6-31G(d′), c B3LYP/6-31G(d), d B3LYP/6-311G(2d,d,p), e B3LYP/6-31G(2df,p), and f B3LYP/cc-pVTZ+d level of theory. g Reference . h Reference . i Reference . j Reference . k Reference . l Reference . m Reference . n Reference . o Reference . p Reference . q Reference . r Reference . s Excluded from the statistical analyses. t Reference . …”

Section: Resultsmentioning

confidence: 99%

Computational Tests of Quantum Chemical Models for Structures, Vibrational Frequencies, and Heats of Formation of Molecules with Phosphorus and Sulfur Atoms

2010

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The Gaussian-n, complete basis set, and Weizmann-1 quantum chemical models for heats of formation are applied to a set of molecules with relevance to the combustion or pyrolysis of chemical warfare materials. Most of these models generate standard deviations from experiment that are less than 2 kcal/mol. The structures and vibrational frequencies that are generated in the course of these calculations are in good agreement with experimental data. Detailed comparisons with respect to structural types indicate that the present computational models are likely to generate useful data for complex models of combustion and pyrolysis of chemical warfare materials.

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“…Attaining the desired degree of accuracy in the calculated spectrum is not always possible because the experimental frequencies depend on effects not included in the theory, such as anharmonicity, Fermi resonance, molecular associations, and solvent effects. To correct this deficiency, sets of scale factors or correction factors were reported in the ab initio 33 and semiempirical methods34 to be used on the computed frequencies. In the molecules of the present work the scale factors determined in 2‐azetidinone, 1‐methyl‐2‐azetidinone, and 3‐methyl‐2‐azetidinone were used for the frequencies of the β‐lactam ring, and the scale factors determined in the benzene molecule and their derivatives were used for the other frequencies.…”

Section: Resultsmentioning

confidence: 99%

FTIR study of five complex β‐lactam molecules

et al. 2001

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Five monocyclic 4-benzoyl-4-phenyl-beta-lactam derivatives in carbon tetrachloride solutions were studied by FTIR spectroscopy. The Fourier self-deconvolution method was applied to enhance the resolution of the FTIR spectra. The calculated spectra of these five compounds, which were obtained by quantum mechanical methods, were compared with FTIR data. A complete assignment of the vibrational frequencies in the 4000-400 cm(-1) range was made. Several vibrations were selected as being useful to characterize the beta-lactam ring. Substituents on N1 (p-methoxyphenyl) and C3 (methyl, phenyl, maleimidyl, and phthalimidyl) on the beta-lactam ring increase the amide resonance and the planarity of the ring. The optimized geometry along with the total electric charges on the four atoms of the ring support an antibiotic action mechanism by a nucleophilic attack of the enzymes on the carbonyl carbon atom of the beta-lactam ring.

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Theoretical Predictions of Structures and Vibrational Infrared Frequencies. I. Mercaptans and Sulfides

Cited by 24 publications

References 11 publications

Raman and infrared spectra, conformational stability, andab initio calculations for chloromethyl methyl sulfide

Raman and infrared spectra, conformational stability, andab initio calculations for chloromethyl methyl sulfide

Computational Tests of Quantum Chemical Models for Structures, Vibrational Frequencies, and Heats of Formation of Molecules with Phosphorus and Sulfur Atoms

FTIR study of five complex β‐lactam molecules

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