Ability of Lewis Acids with Shallow σ-Holes to Engage in Chalcogen Bonds in Different Environments
Molecules of the type XYT = Ch (T = C, Si, Ge; Ch = S, Se; X,Y = H, CH<sub>3</sub>, 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 NCCH<sub>3</sub> so as to form a chalcogen bond. In the case of T = C, these b...
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| Main Authors: | , , , |
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| Format: | article |
| Language: | EN |
| Published: |
MDPI AG
2021
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| Subjects: | |
| Online Access: | https://doaj.org/article/2383cf7e9f3444df9bb5f3060cb1cf34 |
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| Summary: | Molecules of the type XYT = Ch (T = C, Si, Ge; Ch = S, Se; X,Y = H, CH<sub>3</sub>, 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 NCCH<sub>3</sub> 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. |
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