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

Bastian Bernhardt, Friedemann Dressler, André K Eckhardt, Jonathan Becker, Peter R Schreiner

Chemistry (Weinheim an der Bergstrasse, Germany) 2021 Apr 16

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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. © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.

Citation

Bastian Bernhardt, Friedemann Dressler, André K Eckhardt, Jonathan Becker, Peter R Schreiner. Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide. Chemistry (Weinheim an der Bergstrasse, Germany). 2021 Apr 16;27(22):6732-6739