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cAAC‐Stabilized 9,10‐diboraanthracenes—Acenes with Open‐Shell Singlet Biradical Ground States
Author(s) -
Saalfrank Christian,
Fantuzzi Felipe,
Kupfer Thomas,
Ritschel Benedikt,
Hammond Kai,
Krummenacher Ivo,
Bertermann Rüdiger,
Wirthensohn Raphael,
Finze Maik,
Schmid Paul,
Engel Volker,
Engels Bernd,
Braunschweig Holger
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202008206
Subject(s) - pentacene , singlet state , anthracene , acene , conjugated system , open shell , homo/lumo , boron , alkyl , chemistry , materials science , computational chemistry , chemical physics , molecule , photochemistry , nanotechnology , atomic physics , excited state , organic chemistry , physics , polymer , layer (electronics) , thin film transistor
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.