N-Heterocyclic Olefins as Electron Donors in Combination with Triarylborane Acceptors: Synthesis, Optical and Electronic Properties of D-π-A Compounds
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- N‐heterocyclic olefins (NHOs), relatives of N‐heterocyclic carbenes (NHCs), exhibit high nucleophilicity and soft Lewis basic character. To investigate their π‐electron donating ability, NHOs were attached to triarylborane π‐acceptors (A) giving donor (D)–π–A compounds 1–3. In addition, an enamine π‐donor analogue (4) was synthesized for comparison. UV–visible absorption studies show a larger red shift for the NHO‐containing boranes than for the enamine analogue, a relative of cyclic (alkyl)(amino) carbenes (CAACs). Solvent‐dependent emissionN‐heterocyclic olefins (NHOs), relatives of N‐heterocyclic carbenes (NHCs), exhibit high nucleophilicity and soft Lewis basic character. To investigate their π‐electron donating ability, NHOs were attached to triarylborane π‐acceptors (A) giving donor (D)–π–A compounds 1–3. In addition, an enamine π‐donor analogue (4) was synthesized for comparison. UV–visible absorption studies show a larger red shift for the NHO‐containing boranes than for the enamine analogue, a relative of cyclic (alkyl)(amino) carbenes (CAACs). Solvent‐dependent emission studies indicate that 1–4 have moderate intramolecular charge‐transfer (ICT) behavior. Electrochemical investigations reveal that the NHO‐containing boranes have extremely low reversible oxidation potentials (e.g., for 3, \(E^{ox}_{1/2}\) =−0.40 V vs. ferrocene/ferrocenium, Fc/Fc\(^+\), in THF). Time‐dependent (TD) DFT calculations show that the HOMOs of 1–3 are much more destabilized than that of the enamine‐containing 4, which confirms the stronger donating ability of NHOs.…
Autor(en): | Jiang He, Florian Rauch, Alexandra Friedrich, Daniel Sieh, Tatjana Ribbeck, Ivo Krummenacher, Holger BraunschweigORCiD, Maik Finze, Todd B. Marder |
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URN: | urn:nbn:de:bvb:20-opus-204690 |
Dokumentart: | Artikel / Aufsatz in einer Zeitschrift |
Institute der Universität: | Fakultät für Chemie und Pharmazie / Institut für Anorganische Chemie |
Sprache der Veröffentlichung: | Englisch |
Titel des übergeordneten Werkes / der Zeitschrift (Englisch): | Chemistry - A European Journal |
Erscheinungsjahr: | 2019 |
Band / Jahrgang: | 25 |
Seitenangabe: | 13777-13784 |
Originalveröffentlichung / Quelle: | Chemistry - A European Journal (2019) 25, 13777-13784. doi:10.1002/chem.201903118 |
DOI: | https://doi.org/10.1002/chem.201903118 |
Allgemeine fachliche Zuordnung (DDC-Klassifikation): | 5 Naturwissenschaften und Mathematik / 54 Chemie / 546 Anorganische Chemie |
Freie Schlagwort(e): | N-heterocyclic olefins; donor-acceptor systems; electrochemistry; photophysical prosperties; triarylboranes |
Datum der Freischaltung: | 26.06.2020 |
Lizenz (Deutsch): | CC BY-NC: Creative-Commons-Lizenz: Namensnennung, Nicht kommerziell 4.0 International |