Is It Conjugated or Not? The Theoretical and Experimental Electron Density Map of Bonding in p-CH3CH2COC6H4-C≡C-C≡C- p-C6H4COCH3CH2

Przemysław Starynowicz; Sławomir Berski; Nurbey Gulia; Karolina Osowska; Tadeusz Lis; Sławomir Szafert

doi:10.3390/molecules25194388

Is It Conjugated or Not? The Theoretical and Experimental Electron Density Map of Bonding in p-CH₃CH₂COC₆H₄-C≡C-C≡C- p-C₆H₄COCH₃CH₂

Molecules. 2020 Sep 24;25(19):4388. doi: 10.3390/molecules25194388.

Authors

Przemysław Starynowicz¹, Sławomir Berski¹, Nurbey Gulia¹, Karolina Osowska¹, Tadeusz Lis¹, Sławomir Szafert¹

Affiliation

¹ Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland.

Abstract

The electron density of p-CH₃CH₂COC₆H₄-C≡CC≡C-p-C₆H₄COCH₃CH₂ has been investigated on the basis of single-crystal X-ray diffraction data collected to high resolution at 100 K and from theoretical calculations. An analysis of the X-ray data of the diyne showed interesting "liquidity" of electron distribution along the carbon chain compared to 1,2-diphenylacetylene. These findings are compatible with the results of topological analysis of Electron Localization Function (ELF), which has also revealed a larger (than expected) concentration of the electron density at the single bonds. Both methods indicate a clear π-type or "banana" character of a single bond and a significant distortion from the typical conjugated structure of the bonding in the diyne with a small contribution of cumulenic structures.

Keywords: density map; electron localization function; polyynes; single-crystal X-ray diffraction; theoretical calculations.

MeSH terms

Alkynes / chemistry*
Crystallography, X-Ray
Hydrogen Bonding
Models, Molecular*
X-Ray Diffraction

Substances

Alkynes