Ability of Lewis Acids with Shallow σ-Holes to Engage in Chalcogen Bonds in Different Environments

Rafał Wysokiński; Wiktor Zierkiewicz; Mariusz Michalczyk; Steve Scheiner

doi:10.3390/molecules26216394

Ability of Lewis Acids with Shallow σ-Holes to Engage in Chalcogen Bonds in Different Environments

Molecules. 2021 Oct 22;26(21):6394. doi: 10.3390/molecules26216394.

Authors

Rafał Wysokiński¹, Wiktor Zierkiewicz¹, Mariusz Michalczyk¹, Steve Scheiner²

Affiliations

¹ Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
² Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA.

Abstract

Molecules of the type XYT = Ch (T = C, Si, Ge; Ch = S, Se; X,Y = H, CH₃, Cl, Br, I) contain a σ-hole along the T = Ch bond extension. This hole can engage with the N lone pair of NCH and NCCH₃ so as to form a chalcogen bond. In the case of T = C, these bonds are rather weak, less than 3 kcal/mol, and are slightly weakened in acetone or water. They owe their stability to attractive electrostatic energy, supplemented by dispersion, and a much smaller polarization term. Immersion in solvent reverses the electrostatic interaction to repulsive, while amplifying the polarization energy. The σ-holes are smaller for T = Si and Ge, even negative in many cases. These Lewis acids can nonetheless engage in a weak chalcogen bond. This bond owes its stability to dispersion in the gas phase, but it is polarization that dominates in solution.

Keywords: AIM; LMOEDA; molecular electrostatic potential; solvent effects.

Abstract

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