A03 • Boron-Functionalized Anionic N-Heterocyclic Carbenes for Small Molecule Activation

N-Heterocyclic carbenes (NHCs) are ubiquitous and indispensable in many research areas that include main-group element and transition metal (TM) chemistry, homogeneous catalysis and organocatalysis, as well as medicinal chemistry. The well-established NHCs are typically neutral molecules.
Recently, we have developed unprecedentedly stable anionic NHCs and cAACs (cyclic (alkyl)(amino)carbenes) that have tricyanoborane or pentafluoroethyldifluoroborane substituents bonded via boron to the nitrogen atoms of the heterocyclic ring (N-boron substituted anionic N-heterocyclic carbenes, NBA-NHCs, and anionic cyclic (alkyl)(amino)carbenes, Ani-cAACs). Due to the borane substituents at nitrogen and their negative charge, NBA-NHCs and Ani-cAACs have distinctly different properties than their neutral counterparts that have substituents bonded via carbon to the nitrogen atoms of the N-heterocycle. The differences between neutral NHCs and cAACs and negatively charged NBA-NHCs and Ani-cAACs are not only limited to stereroelectronic properties but include solubility and coordination ability as a consequence of their different charges.
The aim of this project is (i) the targeted modification of properties of NBA-NHCs and Ani-cAACs by variationof the N-heterocyclic ring and the type as well as the number of boron-based group(s) attached to the heterocyclic ring, (ii) the introduction of NBA-NHCs and Ani-cAACs into diboron(IV) compounds for TM-free borylations, and (iii) the development of the main-group and coordination chemistry of NBA-NHCs and Ani-cAACs, in general.