Triazine Annelated NHC Featuring Unprecedented Coordination Versatility

The new N-heterocyclic carbene ligand 3 is presented, which features both a weak σ-donor and a pronounced π-acceptor character. This electronic feature is realized by a side-on annelation of a bis­(imidazo)­triazine fragment. The coordination chemistry shows the ability of the species to act as a monodentate as well as a chelating and a bridging ligand. The last coordination mode is realized in the solid state of the complex [Rh­(cod)­(3)]­BF4, in which three fragments are assembled around a BF4– fragment via anion−π interactions with the triazine moieties.