A Pyrene-Based N‑Heterocyclic Carbene: Study of Its Coordination Chemistry and Stereoelectronic Properties

A new pyrene-N-heterocyclic carbene ligand has been obtained and coordinated to rhodium and iridium, affording the corresponding [MCl­(NHC)­(COD)] and [MCl­(NHC)­(CO)2] complexes (M = Ir, Rh). The presence of the pyrene backbone allows the introduction of a η6-bonded [RuCp]+ fragment and facilitates the formation of the corresponding heterometallic complexes of Rh/Ru and Ir/Ru. The stereoelectronic properties of the new ligand have been studied by means of IR spectroscopy and cyclic voltammetry and demonstrate that the introduction of the [RuCp]+ fragment results in the reduction of the electron-donating power of the ligand.