The hierarchy of ab initio and DFT methods for describing an intramolecular non-covalent Si⋯N contact in the silicon compounds using electron diffraction geometries
| Autor: | Sergey A. Shlykov, Evgeniya P. Doronina, Alexey V. Eroshin, Valery F. Sidorkin, Elena F. Belogolova |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
Geminal Series (mathematics) Silicon 010405 organic chemistry Gas electron diffraction Ab initio General Physics and Astronomy chemistry.chemical_element 010402 general chemistry 01 natural sciences 0104 chemical sciences Crystallography Electron diffraction chemistry Intramolecular force Molecule Physical and Theoretical Chemistry |
| Zdroj: | Physical Chemistry Chemical Physics. 23:2762-2774 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/d0cp05872f |
| Popis: | In the series of silatranes XSi(OCH2CH2)3N, 1 (X = Me, 1a; H, 1b; F, 1c) with the known gas electron diffraction (GED) structures, the problematic geometry of 1-methylsilatrane 1a has been revised. In particular, the new value of the SiN distance (dSiN) in 1a turned out to be ∼0.06 A longer than the generally accepted one. This dSiN resolves the long-standing contradiction between the data of the structural and spectral experiments regarding the sensitivity of 1 to the medium effect. We also performed the ab initio and DFT study of the combined series of silatranes 1a-c, silylalkylamines H3Si(CH2)3NMe2 (2a) and F3SiCH2NMe2 (2b), silylhydrazines F3SiN(Me)NMe2 (2c) and F3SiN(SiMe3)NMe2 (2d), and silyloxyamines ClH2SiONMe2 (2e,f), (F3C)F2SiONMe2 (2g,h) and F3SiONMe2 (2i), in which the GED dSiN values are in a wide range of 2-3 A. None of the involved quantum chemical methods has succeeded in reproducing all the experimental gas-phase dSiN values in 1a-c, 2a-i with an acceptable accuracy (0.01-0.03 A). The problems of the used methods, primarily CCSD with the Pople basis sets, are caused by four molecules with the geminal SiNN and SiON fragments (2d,f-i) and dSiN 2.3 A: MP2 < PBE0 ∼ B3PW91 ∼ SCS-MP2 < CCSD < CCSD(T). |
| Databáze: | OpenAIRE |
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