Ruthenium(II) Bipyridyl Complexes with C∧C* Cyclometalated Mesoionic Carbene Ligands

The synthesis of four 2,2′-bipyridyl ruthenium­(II) complexes with cyclometalating mesoionic 1,2,3-triazolylidene ligands via their respective p-cymene ruthenium­(II) precursors is presented. Solid-state structures confirm the formation of the proposed complexes, which were characterized by UV/vis and electrochemical experiments as well as time-dependent DFT calculations including NTO analysis. The title motif shows improved photophysical properties compared to structurally related ruthenium­(II) complexes with C∧C* cyclometalating imidazole-based N-heterocyclic carbene ligands. Due to their electronic properties, the presented dyes are promising candidates for an application in dye-sensitized solar cells.