Search for singlet-triplet bistabilities in conjugated hydrocarbons

New Journal of Chemistry

Volumn 22, Issue 3, 1998, Pages 281-286

  Guihery, Nathalie ^a   Maynau, Daniel ^a   Malrieu, Jean Paul ^a  

^a UNIVERSITÉ PAUL SABATIER   (France)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0004790142     PISSN: 11440546     EISSN: None     Source Type: Journal    
DOI: 10.1039/a708330k     Document Type: Article

References (31)

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31. We call attention to an interesting characteristic of the potential energy surface. The symmetry of the singlet state is broken. Hence, a mirror-image broken-symmetry structure of singlet nature must exist, corresponding to a third minimum on the potential energy surface (PES). Resonance between these two singlet states is weak and therefore does not induce a sufficient mixing to result in an intermediate symmetrical conformation. The optimized symmetrical conformation is 0.1 eV above the symmetry-broken minima. We note that this symmetrical geometry strongly differs from the geometry of the triplet state (which is also symmetric) by the length of the bond common to the two odd rings and by a deviation from aromaticity in the six-membered rings in the singlet state. In fact, this compound is tristable, presenting three quasi-degenerate wells corresponding to two broken symmetry singlet states and to a symmetrical triplet one.