A Thermally Populated, Perpendicularly Twisted Alkene Triplet Diradical

DOI Web Site Web Site 2 Citations
  • Curt Wentrup
    School of Chemistry and Molecular Biosciences The University of Queensland Brisbane Queensland 4072 Australia
  • Michèle J. Regimbald‐Krnel
    School of Chemistry and Molecular Biosciences The University of Queensland Brisbane Queensland 4072 Australia
  • Dennis Müller
    Anorganisch-Chemisches Institut and IWR Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
  • Peter Comba
    Anorganisch-Chemisches Institut and IWR Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany

Search this article

Description

<jats:title>Abstract</jats:title><jats:p>Variable‐temperature NMR and ESR spectroscopic studies reveal that bis(dibenzo[a,i]fluorenylidene) <jats:bold>1</jats:bold> possesses a singlet ground state, <jats:bold>1</jats:bold>(S<jats:sub>0</jats:sub>), while the 90° twisted triplet <jats:bold>1</jats:bold>(T<jats:sub>1</jats:sub>) is populated to a small extent already at room temperature. Analysis of the increasing amount of paramagnetic <jats:bold>1</jats:bold>(T<jats:sub>1</jats:sub>) at temperatures between 300 and 500 K yields the exchange interaction <jats:italic>J</jats:italic><jats:sub>ex</jats:sub>/<jats:italic>h</jats:italic> <jats:italic>c</jats:italic>=3351 cm<jats:sup>−1</jats:sup> and a singlet–triplet energy splitting of 9.6 kcal mol<jats:sup>−1</jats:sup>, which is in excellent agreement with calculations (9.3 kcal mol<jats:sup>−1</jats:sup> at the UKS BP86/B3LYP/revPBE level of theory). In contrast, the zero‐field splitting parameter <jats:italic>D</jats:italic> is very small (calculated value −0.018 cm<jats:sup>−1</jats:sup>) and unmeasurable.</jats:p>

Journal

Citations (2)*help

See more

Report a problem

Back to top