Blue‐Shift Hydrogen Bonds in Silyltriptycene Derivatives: Antibonding σ* Orbitals of the Si−C Bond as Effective Acceptors of Electron Density
| Autor: | Tomasz Ratajczyk, Adam Mames, Krzysztof Kazimierczuk, Sławomir Szymański, Dariusz Gołowicz, Mariusz Pietrzak |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
chemistry.chemical_classification
Hydrogen bond Chemistry 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Antibonding molecular orbital 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Crystallography chemistry.chemical_compound Atomic orbital Triptycene Electronic effect Non-covalent interactions Physical and Theoretical Chemistry 0210 nano-technology Conformational isomerism Natural bond orbital |
| Zdroj: | ChemPhysChem. 21:540-545 |
| ISSN: | 1439-7641 1439-4235 |
| Popis: | Triptycene derivatives are widely utilized in different fields of chemistry and materials sciences. Their physicochemical properties, often of pivotal importance for the rational design of triptycene-based functional materials, are influenced by noncovalent interactions between substituents mounted on the triptycene skeleton. Herein, a unique interaction between electron-rich substituents in the peri position and the silyl group located on the bridgehead sp3 -carbon is discussed on the example of 1,4-dichloro-9-(p-methoxyphenyl)-silyltriptycene (TRPCl) which exists in solution in the form of two rotamers differing by dispositions, syn or anti, of the Si-CPh (the CPh atom is from the p-methoxyphenyl group) bond against the peri-Cl atom. For the first time, substantial differences between the Si-CPh bonds in these two dispositions are identified, based on indirect experimental and direct theoretical evidence. For these two orientations, the experimental 1 J(Si,CPh ) values differ by as much as 10 percent. The differences are explained in terms of effective electron density transfer from the peri-Cl atom to the antibonding σ* orbitals of the Si-X bonds (X=H, CPh ) oriented anti to that atom. The electronic effects are revealed by an NBO analysis. Connections of these observations with the notion of blue-shifting hydrogen bonds are discussed. |
| Databáze: | OpenAIRE |
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