Proton transfer processes in selenourea: UV-induced selenone→selenol photoreaction and ground state selenol→selenone proton tunneling

Rostkowska, Hanna; Lapiński, Leszek; Khvorostov, Artem; Nowak, Maciej J.

doi:10.1016/j.chemphys.2003.11.024

Cited by 19 publications

(20 citation statements)

References 39 publications

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“…on thiourea [17, 18] and selenourea [51] . The tunneling half‐lives in Ar at 10 K are 52 h and 16 h with activation barriers of 25.1 kcal mol −1 and 22.7 kcal mol −1 , respectively, determined at the MP2/6–311++G(2d,p) level of theory [51] . At this level the minima are 14.8 kcal mol −1 and 16.0 kcal mol −1 apart from each other with the thioamide (selenoamide) form being more stable [51] .…”

Section: Resultsmentioning

confidence: 99%

“…Such studies were carried out by Nowak et al. on thiourea [17, 18] and selenourea [51] . The tunneling half‐lives in Ar at 10 K are 52 h and 16 h with activation barriers of 25.1 kcal mol −1 and 22.7 kcal mol −1 , respectively, determined at the MP2/6–311++G(2d,p) level of theory [51] .…”

Section: Resultsmentioning

confidence: 99%

“…The tunneling half‐lives in Ar at 10 K are 52 h and 16 h with activation barriers of 25.1 kcal mol −1 and 22.7 kcal mol −1 , respectively, determined at the MP2/6–311++G(2d,p) level of theory [51] . At this level the minima are 14.8 kcal mol −1 and 16.0 kcal mol −1 apart from each other with the thioamide (selenoamide) form being more stable [51] . For matrix isolated urea such a reaction has not been reported, probably indicating a tunneling half‐life too long to be observable.…”

Section: Resultsmentioning

confidence: 99%

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Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide

Bernhardt

Dressler

Eckhardt

et al. 2021

Chemistry A European J

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As sulfur‐containing organic molecules thioamides and their isomers are conceivable intermediates in prebiotic chemistry, for example, in the formation of amino acids and thiazoles and resemble viable candidates for detection in interstellar media. Here, we report the characterization of parent thioformamide in the solid state via single‐crystal X‐ray diffraction and its photochemical interconversion to its hitherto unreported higher energy tautomer thiolimine in inert argon and dinitrogen matrices. Upon photogeneration, four conformers of thiolimine form, whose ratio depends on the employed wavelength. One of these conformers interconverts due to quantum mechanical tunneling with a half‐life of 30–45 min in both matrix materials at 3 and 20 K. A spontaneous reverse reaction from thiolimine to thioformamide is not observed. To support our experimental findings, we explored the potential energy surface of the system at the AE‐CCSD(T)/aug‐cc‐pCVTZ level of theory and computed tunneling half‐lives with the CVT/SCT approach applying DFT methods.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide

Bernhardt

Dressler

Eckhardt

et al. 2021

Chemistry A European J

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“…The experiment has been extended to selenourea. 399 Again the selenone tautomer is seen exclusively on deposition. UV irradiation again gives two conformers of the selenol tautomer.…”

Section: Biological Molecules Generalmentioning

confidence: 99%

Chemistry in low-temperature matrices

Almond

Goldberg

2007

Annu. Rep. Prog. Chem., Sect. C: Phys. Chem.

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the Progress of Chemistry, Section C. The report is divided into sections: weak adducts and conformational isomers; reactions of atoms; high-temperature molecules; photochemistry; biological molecules; astrochemistry. The last two sections reflect the fact that matrix isolation now extends into areas outside the traditional mainstream disciplines of chemistry. There are a number of areas where substantial progress has been made during the period of this report. First, the routine use of laser-ablation to generate atoms and to initiate atomic reactions in matrices has increased the scope of matrix isolation to synthesise many new molecular species in inorganic chemistry. Laser-ablation allows ground state atoms to be more easily studied than is the case when atoms are produced by thermal methods. Moreover, this procedure allows atoms to be generated from materials where thermal production is difficult. Secondly, the manufacture of more efficient closed-cycle helium refrigerators allows hydrogen matrices to be deposited readily. A significant body of work therefore has focussed upon metal hydrides, dihydrogen complexes and other hydrogen species in matrices. Underpinning all of this experimental work are theoretical calculations, without which the correct identification of most matrix isolation molecules would remain dangerously ambiguous. Infrared spectroscopy remains-as it has for the past 50 years-the workhorse of matrix isolation studies. It does seem that this situation will not change-it is impossible to conceive of another spectroscopic method that combines the necessary sensitivity to study molecules at very low dilution with the structural information required to make a reasonably certain identification.

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“…Peak deconvolution identified three species, namely the selenone and selenol tautomers, as well as a small peak corresponding to oxidation of the selenium to selenic acid. There is still some debate in the literature as to the exact nature of the tautomerization of selenourea moieties, however, the general consensus is that due to the large π-delocalization in the N–CSe system, as well as the substantial rotational barrier between the N–C bond, an equilibrium between the selenone and the selenol/zwitterionic moiety exists approximately 1:1. − The entire library of Se-containing polymers P1 – P6 , were additionally analyzed via 1 H NMR (Figures S3–S8), where the expected broad pronounced urea-like N–H proton signals were observed as well as the methyl, ethyl, or polyethylene glycol-like protons, depending on the monomer structure.…”

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confidence: 99%

Polyselenoureas via Multicomponent Polymerizations Using Elemental Selenium as Monomer

et al. 2018

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Multicomponent polymerizations (MCPs) have emerged as a powerful tool in the synthesis of advanced, sequence-regulated polymers based on their mild reaction conditions, ease of use, and high atom economy. Herein, we exploit MCP methodology to introduce elemental selenium into a polymer chain, accessing a unique polymer class,i.e., polyselenoureas. These polyselenoureas can be synthesized from a broad range of commercially available starting materials, in a simple ambient temperature one-step procedure. The incorporation of selenium directly into the polymer backbone provides a unique handle for polymer characterization based on the distinctive isotope profiles exposed by high-resolution mass spectrometry, along with diagnostic signals observed in infrared and X-ray photoelectron spectroscopies. In addition, diffusion ordered spectroscopy provides access to hydrodynamic diameter information on the generated unique polymer class.

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Proton transfer processes in selenourea: UV-induced selenone→selenol photoreaction and ground state selenol→selenone proton tunneling

Cited by 19 publications

References 39 publications

Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide

Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide

Chemistry in low-temperature matrices

Polyselenoureas via Multicomponent Polymerizations Using Elemental Selenium as Monomer

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