cAAC‐Stabilized 9,10‐diboraanthracenes—Acenes with Open‐Shell Singlet Biradical Ground States
| Autor: | Rüdiger Bertermann, Ivo Krummenacher, Holger Braunschweig, Raphael Wirthensohn, Maik Finze, Kai Hammond, Bernd Engels, Volker Engel, Benedikt Ritschel, Felipe Fantuzzi, Thomas Kupfer, Christian Saalfrank, Paul Schmid |
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| Rok vydání: | 2020 |
| Předmět: |
acenes
Materials science Heptacene chemistry.chemical_element Conjugated system 010402 general chemistry Photochemistry 01 natural sciences Catalysis chemistry.chemical_compound bond Activation Molecule Singlet state Boron Heterocycles | Very Important Paper Open shell Research Articles Alkyl chemistry.chemical_classification heterocycles Anthracene 010405 organic chemistry General Chemistry biradicals 0104 chemical sciences chemistry ddc:540 boron Research Article |
| Zdroj: | Angewandte Chemie (International Ed. in English) |
| ISSN: | 1521-3773 1433-7851 |
| Popis: | Narrow HOMO–LUMO gaps and high charge‐carrier mobilities make larger acenes potentially high‐efficient materials for organic electronic applications. The performance of such molecules was shown to significantly increase with increasing number of fused benzene rings. Bulk quantities, however, can only be obtained reliably for acenes up to heptacene. Theoretically, (oligo)acenes and (poly)acenes are predicted to have open‐shell singlet biradical and polyradical ground states, respectively, for which experimental evidence is still scarce. We have now been able to dramatically lower the HOMO–LUMO gap of acenes without the necessity of unfavorable elongation of their conjugated π system, by incorporating two boron atoms into the anthracene skeleton. Stabilizing the boron centers with cyclic (alkyl)(amino)carbenes gives neutral 9,10‐diboraanthracenes, which are shown to feature disjointed, open‐shell singlet biradical ground states. 9,10‐diboraanthracenes (DBAs) stabilized by cyclic (alkyl)(amino)carbenes (cAACs) are prepared. EPR spectroscopy and quantum chemistry established disjointed singlet biradical ground states for these molecules, which provides experimental evidence for the predicted open‐shell configurations of larger acenes. The incorporation of two boron atoms is a suitable way to lower the HOMO–LUMO band gaps of acene‐type species. |
| Databáze: | OpenAIRE |
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