Steric and Electronic Properties of Indole‐Derived CAAC Ligands

The electronic properties of two indole‐derived CAAC ligands, featuring N−Et ( II ) or N−H ( IV ) substituents, have been investigated by DFT calculations. The calculations revealed frontier orbitals (HOMO and LUMO) with energies closely related to those of the conventional N‐DIPP substituted CAAC I . The selenium adduct of the N−H substituted CAAC 1 has been prepared and characterized by X‐ray diffraction methods and 77 Se NMR spectroscopy revealing π‐acceptor properties of the CAAC similar to classical CAACs of type I . While the electronic properties of the indole‐derived CAACs II and IV are similar to those of classical CAACs, their % V bur is significantly smaller due to the smaller N‐substituents falling in the range of % V bur for sterically less demanding N‐heterocyclic carbenes.