Triazine Annelated NHC Featuring Unprecedented Coordination Versatility

The new N-heterocyclic carbene ligand 3 is presented, which features both a weak sigma-donor and a pronounced pi-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-pi interactions with the triazine moieties.