Twisting versus delocalization in CAAC- and NHC-stabilized boron-based biradicals: the roles of sterics and electronics

Please always quote using this URN: urn:nbn:de:bvb:20-opus-256636
  • Twisted boron-based biradicals featuring unsaturated C\(_2\)R\(_2\) (R=Et, Me) bridges and stabilization by cyclic (alkyl)(amino)carbenes (CAACs) were recently prepared. These species show remarkable geometrical and electronic differences with respect to their unbridged counterparts. Herein, a thorough computational investigation on the origin of their distinct electrostructural properties is performed. It is shown that steric effects are mostly responsible for the preference for twisted over planar structures. The ground-state multiplicity ofTwisted boron-based biradicals featuring unsaturated C\(_2\)R\(_2\) (R=Et, Me) bridges and stabilization by cyclic (alkyl)(amino)carbenes (CAACs) were recently prepared. These species show remarkable geometrical and electronic differences with respect to their unbridged counterparts. Herein, a thorough computational investigation on the origin of their distinct electrostructural properties is performed. It is shown that steric effects are mostly responsible for the preference for twisted over planar structures. The ground-state multiplicity of the twisted structure is modulated by the σ framework of the bridge, and different R groups lead to distinct multiplicities. In line with the experimental data, a planar structure driven by delocalization effects is observed as global minimum for R=H. The synthetic elusiveness of C\(_2\)R\(_2\)-bridged systems featuring N-heterocyclic carbenes (NHCs) was also investigated. These results could contribute to the engineering of novel main group biradicals.show moreshow less

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Metadaten
Author: Paul Schmidt, Felipe FantuzziORCiD, Jonas Klopf, Niklas B. Schröder, Rian D. DewhurstORCiD, Holger BraunschweigORCiD, Volker EngelORCiD, Bernd EngelsORCiD
URN:urn:nbn:de:bvb:20-opus-256636
Document Type:Journal article
Faculties:Fakultät für Chemie und Pharmazie / Institut für Anorganische Chemie
Fakultät für Chemie und Pharmazie / Institut für Physikalische und Theoretische Chemie
Language:English
Parent Title (English):Chemistry - A European Journal
Year of Completion:2021
Volume:27
Issue:16
Pagenumber:5160–5170
Source:Chemistry - A European Journal (2021) 27:16, 5160–5170. DOI: 10.1002/chem.202004619
DOI:https://doi.org/10.1002/chem.202004619
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Tag:ab initio calculations; boron; carbene ligands; chemistry; density functional calculations; radicals
Release Date:2022/02/25
Licence (German):License LogoCC BY-NC: Creative-Commons-Lizenz: Namensnennung, Nicht kommerziell 4.0 International