Microwave spectrum and conformation of vinyl mercaptan

Tanimoto, Mitsutoshi; Macdonald, John N.

doi:10.1016/0022-2852(79)90038-9

Cited by 29 publications

(23 citation statements)

References 9 publications

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“…Antiperiplanar H 2 CCHSH has a small hump at the exact planar position of 0.23 kJ/mol. The energy difference between the two rotamers is now only 0.60(30) kJ/mol with the synperiplanar form as the more stable, which is quite different from the alcohol case (4.5(6) kJ/mol) …”

Section: Introductionmentioning

confidence: 73%

“…Antiperiplanar H 2 CdCHSH has a small hump at the exact planar position of 0.23 kJ/mol. The energy difference between the two rotamers is now only 0.60(30) kJ/ mol with the synperiplanar form as the more stable, 8 which is quite different from the alcohol case (4.5 (6) kJ/mol). 4 Both a microwave 9 and an infrared study 10 are available for the selenol analogue, H 2 CdCHSeH, demonstrating the existence of two rotameric forms.…”

Section: Introductionmentioning

confidence: 84%

“…The synperiplanar form was found to be preferred by 4.5 (6) kJ/mol over the antiperiplanar rotamer in this case. 4 The conformational properties of H 2 CdCHSH resemble those of its alcohol analogue by having a synperiplanar [5][6][7] as well as an antiperiplanar 8 conformer. However, the antiperiplanar form of the thiol is different from the corresponding conformer of its alcohol congener.…”

Section: Introductionmentioning

confidence: 99%

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High Resolution Millimeter-Wave Spectroscopy of Vinyltellurol

et al. 2010

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The millimeter-wave rotational spectrum of vinyltellurol has been recorded and assigned for the first time. To support the spectrum assignment, high level ab initio calculations have been carried out. Geometries, total electronic energies, and harmonic vibrational frequencies have been determined at the MP2 level. A small-core relativistic pseudopotential basis set (cc-pVTZ-PP) was employed to describe the tellurium atom. Two stable conformers, synperiplanar (sp) and anticlinal (ac), have been identified. The sp conformer is planar with a small negative inertia defect of -0.025 u Å(2). The ac conformer was found to be nonplanar with a C-C-Te-H dihedral angle of about 140° from sp. This conformer exhibits a large amplitude motion associated with the torsion about the C-Te bond. The barrier to internal rotation is about 1 kJ/mol, according to the theoretical calculations. For the ac conformation, a torsional potential function consisting of quartic and quadratic terms of the torsional angle has been partially determined from the observed rotational constants.

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

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High Resolution Millimeter-Wave Spectroscopy of Vinyltellurol

et al. 2010

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“…It has been shown experimentally that H 2 S and acetylene are major and minor products, respectively, of the thermal decomposition of thiirane. , Ultraviolet photolysis of a mixture of H 2 S and acetylene is actually used for the preparation of THI, ,, but it is unlikely that the fragmentation occurs directly without any intermediate. One reasonable hypothesis is that an intermediate biradical, similar to I2′, is formed upon the transfer of a hydrogen atom from one of the CH 2 residues to the sulfur atom.…”

Section: Resultsmentioning

confidence: 99%

“…Being the simplest compound containing a SH group adjacent to a CC double bond, VTH has been used as a model system for theoretical investigations on the π-donating ability of heteroatoms and on the importance of σ conjugative interaction in rotational isomerism . The conformation of this molecule, especially concerning internal rotation around the C–S bond, was studied experimentally and theoretically several times. − Microwave and infrared spectroscopic data suggest that VTH exists in the planar syn (VTHs) and nearly planar anti (VTHa) conformations, with the syn conformer being the predominant species. − Planar trans VTH is actually a transition state separating two equivalent VTHa conformers. VTH can be customarily produced by thermolysis of thiirane (THI) under reduced pressure in a flow system .…”

Section: Introductionmentioning

confidence: 99%

Isomerization and Fragmentation Reactions on the [C₂SH₄] Potential Energy Surface: The Metastable Thione S-Methylide Isomer

et al. 2021

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Thione S-methylide, parent species of the thiocarbonyl ylide family, is a 1,3dipolar species on the [C 2 SH 4 ] potential energy surface, not so much studied as its isomers, thiirane, vinyl thiol, and thioacetaldehyde. The conrotatory ring-closure reaction toward thiirane was studied in the 90s, but no complete analysis of the potential energy surface is available. In this paper, we report a computational study of the reaction scheme linking all species. We employed several computational methods (density functional theory, CCSD(T) composite schemes, and CASSCF/CASPT2 multireference procedures) to find the best description of thione S-methylide, its isomers, and transition states. The barrier from thiirane to thione Smethylide amounts to 52.2 kcal mol −1 (against 17.6 kcal mol −1 for the direct one), explaining why thiocarbonyl ylides cannot be prepared from thiiranes. Conversion of thiirane to vinyl thiol implies a large barrier, supporting why the reaction has been observed only at high temperatures. Fragmentations of thiirane to S( 3 P) or S( 1 D) and ethylene as well as decomposition to hydrogen sulfide plus acetylene were also explored. Triplet and singlet open-shell species were identified as intermediates in the fragmentations, with energies lower than the transition state between thiirane and vinyl thiol, explaining the preference of the latter at low temperatures.

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