Twisted Push–Pull Ethylenes

Rakesh Naduvile Veedu; Paul V. Bernhardt; Rainer Koch; Curt Wentrup

doi:10.1071/CH08277

RESEARCH ARTICLE

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Twisted Push–Pull Ethylenes

Rakesh Naduvile Veedu ^A , Paul V. Bernhardt ^A , Rainer Koch ^B and Curt Wentrup ^A ^C

+ Author Affiliations

- Author Affiliations

^A Chemistry Building, School of Molecular and Microbial Sciences, University of Queensland, Brisbane, QLD 4072, Australia.

^B Institut für Reine und Angewandte Chemie, Carl von Ossietzky Universität Oldenburg, 26111 Oldenburg, Germany.

^C Corresponding author. Email: wentrup@uq.edu.au

Australian Journal of Chemistry 61(10) 805-812 https://doi.org/10.1071/CH08277
Submitted: 1 July 2008 Accepted: 8 August 2008 Published: 6 October 2008

Abstract

As determined by X-ray crystallography, Meldrum’s acid derivatives 5, 6, and 8 feature dihedral angles around the central C5=C7 double bond of 14–35°, whereas for the anion 9 this angle is 90°. Density functional theory and MP2 calculations are in agreement with the experimental X-ray data for compounds 5–8, but for anion 9 an angle of only ~65° is predicted. It is concluded that a part of the torsion is due to packing forces in the crystal. It is further concluded that these molecules undergo rapid rotation about the central CC bonds at room temperature (calculated activation barriers 5–14 kcal mol^–1).

Acknowledgement

This research was supported by the Australian Research Council. R.K. gratefully acknowledges generous allocation of computer time at the CSC Oldenburg. We are indebted to Dr David Kvaskoff (University of Queensland) for resynthesizing compound 8.

References

Twisted Push–Pull Ethylenes

Abstract

Acknowledgement

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