Threat to the throne: can two cooperating boron atoms rival transition metals in chemical bond activation and catalysis?

  • Certain electron-rich 1,4-diborabenzene derivatives efficiently activate single, double, and triple bonds and thereby increasingly compete with transition metals in homogeneous catalysis. This review compares the activation of three model substrates (H2, H2C=CH2, CO2) by (i) 9,10-dihydro-9,10-diboraanthracene dianions, (ii) their neutral carbene-stabilized congeners, (iii) 1,3,2,5-diazadiborinines, and (iv) 1,4,2,5-diazadiborinines. Distinct structure-properties relationships become apparent, the most influential factors being (i) the steric demands of the B-bonded substituents, (ii) the charges on the B-doped (hetero)arenes, (iii) charge polarization as a result of additional N-doping, and (iv) the energies and nodal structures of the frontier orbitals. The observed reactions are explained by a transition metal-like activation mechanism. If the two boron atoms are chemically inequivalent, contributions of a B(+I)/B(+III) mixed-valence state determine the observed regioselectivities when polar substrates are added. The lessons learned from the conversions of the model substrates are subsequently used to rationalize the behavior of the B2 heterocycles also toward more sophisticated substrate molecules. Finally, catalytic cycles based on H2- and H−-transfers, hydroboration reactions, and CO2 reductions will be covered.
Author:Sven E. Prey, Matthias Wagner
Parent Title (English):Advanced synthesis & catalysis
Place of publication:Weinheim
Document Type:Article
Date of Publication (online):2020/11/29
Date of first Publication:2020/11/29
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/03/15
Tag:boron heterocycles; homogeneous catalysis; main group elements; nucleophilic boron; subvalent compounds
Page Number:20
First Page:2290
Last Page:2309
Open access funding enabled and organized by Projekt DEAL.
Institutes:Biochemie, Chemie und Pharmazie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Licence (German):License LogoCreative Commons - Namensnennung-Nicht kommerziell - Keine Bearbeitung 4.0