TY  - JOUR
A1  - Schmidt, Paul
A1  - Fantuzzi, Felipe
A1  - Klopf, Jonas
A1  - Schröder, Niklas B.
A1  - Dewhurst, Rian D.
A1  - Braunschweig, Holger
A1  - Engel, Volker
A1  - Engels, Bernd
T1  - Twisting versus delocalization in CAAC- and NHC-stabilized boron-based biradicals: the roles of sterics and electronics
JF  - Chemistry - A European Journal
N2  - 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 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.
KW  - chemistry
KW  - radicals
KW  - ab initio calculations
KW  - boron
KW  - carbene ligands
KW  - density functional calculations
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256636
VL  - 27
IS  - 16
ER  -