Twisting and planarization in push-pull ethylenes

Bernhardt, Paul V., Koch, Rainer, Moloney, Daniel W. J., Shtaiwi, Majed H. and Wentrup, Curt (2002) Twisting and planarization in push-pull ethylenes. Journal of the Chemical Society- Perkin Transactions 2, 3 3: 515-523. doi:10.1039/b109624a


Author Bernhardt, Paul V.
Koch, Rainer
Moloney, Daniel W. J.
Shtaiwi, Majed H.
Wentrup, Curt
Title Twisting and planarization in push-pull ethylenes
Journal name Journal of the Chemical Society- Perkin Transactions 2   Check publisher's open access policy
ISSN 1472-779X
Publication date 2002-01-01
Sub-type Article (original research)
DOI 10.1039/b109624a
Volume 3
Issue 3
Start page 515
End page 523
Total pages 9
Place of publication Cambridge, UK
Publisher The Royal Society of Chemistry
Language eng
Subject C1
250303 Physical Organic Chemistry
780103 Chemical sciences
Abstract As determined by X-ray crystallography, Meldrum's acid derivatives 8–19 feature dihedral angles around the central CC double bonds between 3 and 83°. Hydrogen bonds between substituents RHN and the carbonyl groups favour near-planarity. Sterically demanding substituents favour large dihedral angles and zwitterionic structures as in formula 20. AM1 calculations of the structures are in excellent agreement with the experimental X-ray data, provided a dielectric field is incorporated (?= 40). This can be ascribed to the highly polar (zwitterionic) nature of the molecules. It is further predicted that all these molecules, including those that are stabilised in a planar form by intramolecular hydrogen bonds, undergo rapid rotation about the central CC bonds at room temperature. DFT calculations incorporating a dielectric field model (PCM) are in excellent agreement with the near-perpendicular arrangement of the alkene moiety in 19.
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Chemistry and Molecular Biosciences
 
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Created: Wed, 15 Aug 2007, 03:25:00 EST