Altered torquoselectivity of fluorine in the iron-tricarbonyl-mediated thermal ring opening of 3-fluorocyclobutene: a density-functional exploration
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- 作者：Chandresakaran Prathipa ; Lakshminarayanan Akilandeswari
- 关键词：Torquoselectivity ; Fe(CO)3 ; DFT ; Electrocyclic ring opening
- 刊名：Journal of Molecular Modeling
- 出版年：2016
- 出版时间：November 2016
- 年：2016
- 卷：22
- 期：11
- 全文大小：1,376 KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry
Computer Applications in Chemistry
Biomedicine
Molecular Medicine
Health Informatics and Administration
Life Sciences
Computer Application in Life Sciences - 出版者：Springer Berlin / Heidelberg
- ISSN：0948-5023
- 卷排序：22
文摘
There are eight possible pathways for the iron-tricarbonyl-assisted thermal electrocyclic ring opening of fluorocyclobutene due to variations in the orientation of the binding of Fe(CO)3 relative to the fluorine substituent (R1 or R2), stereoselectivity (conrotatory or disrotatory, i.e., C or D), and the torquoselectivity of fluorine (inward-facing or outward-facing, i.e., in or out). A density functional study revealed that the energetically favored pathway is R1Din. Not only is the D mode favored energetically, but the in configuration was observed to be the lowest-lying mode of R1, despite the general tendency of fluorine substituents to prefer an out configuration. Data on the activation hardness and aromaticity indices such as BAC and HOMA lead to the same conclusion. However, the R2 mode surprisingly shows no particular preference for either the Cout or the Dout pathway (i.e., the R2 mode shows less stereoselectivity than R1). This behavior occurs due to the influences of both the fluorine substituent and metal coordination. Also, the geminal bond orbitals σ(C–F) and σ*(C–F) appear to participate in ring opening, given the excellent correlation of ∆BE with the activation barrier of the transition state.