| Autor: |
Dunning TH Jr; Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States., Xu LT; Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States., Thompson JVK; Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
The journal of physical chemistry. A [J Phys Chem A] 2021 Sep 02; Vol. 125 (34), pp. 7414-7424. Date of Electronic Publication: 2021 Aug 23. |
| DOI: |
10.1021/acs.jpca.1c05357 |
| Abstrakt: |
It has long been known that there is a fundamental difference in the electronic structures of CH 5 - and SiH 5 - , two isoelectronic molecules. The former is a saddle point for the S N 2 exchange reaction H - + CH 4 → [CH 5 - ] ‡ → CH 4 + H - , while the latter is a stable molecule that is bound relative to SiH 4 + H - . SCGVB calculations indicate that this difference is the result of a dramatic difference in the nature of the axial electron pairs in these anions. In SiH 5 - , the axial pairs represent two stable bonds-a weak recoupled pair bond dyad. In CH 5 - , the axial electron pairs represent an intermediate transition between the electron pairs in the reactants and those in the products. Furthermore, the axial orbitals at the saddle point in CH 5 - are highly overlapping, giving rise to strong Pauli repulsion and a high barrier for the S N 2 exchange reaction. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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