The tetracyanoquinodimethane motif in overcrowded bistricyclic aromatic enes: Avoiding thermochromism

Sergey Pogodin, Michal Rachel Suissa, Amalia Levy, Shmuel Cohen, Israel Agranat

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The overcrowded bistricyclicaromatic enes(BAEs)[10-[10-(dicyanomethylene)- 9(10H)-anthracenylidene]-9(10H)-anthracenylidene] propanedinitrile (7) and [10-[10-oxo-9(10H)-anthracenylidene]-9(10H)-anthracenylidene)]propanedinitrile (8) were synthesized by a condensation of bianthrone (2) with malononitrile in the presence of TiCl4 and pyridine. The crystal and molecular structure of 7 were determined. It crystallizes in two polymorphic forms, belonging to the space groups P21/c and P21/n. DFT calculations of 7 and 8 show that the overcrowding due to introducing dicyanomethylene substituents to 10 and 10′ positions is more pronounced in the twisted conformations, decreasing their stabilities. The enthalpy differences between the anti-folded and the lowest lying twisted conformations in BAEs 7 and 8 are 61.3 and 42.3 kJ/mol, respectively. In accordance with theory, BAEs 7 and 8 do not exhibit thermochromic behavior.

Original languageEnglish
Pages (from-to)2887-2894
Number of pages8
JournalEuropean Journal of Organic Chemistry
Issue number17
StatePublished - 1 Jun 2008
Externally publishedYes


  • Conformation analysis
  • Density functional calculations
  • Strained molecules
  • Thermochromism
  • X-ray crystal structure

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry


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