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.