N-Heterocyclic Carbene Complexes of Iron as Photosensitizers for Light-Induced Water Reduction

For the first time, the potential of noble-metal-free iron-based photosensitizers for photocatalytic water reduction by using homo- and heteroleptic carbene complexes was proven. The development of a facile synthesis route for such carbene complexes was delineated. The complexes were investigated by UV/Vis and fluorescence spectroscopy, DFT calculations, cyclic voltammetry, and X-ray absorption spectroscopy. Their catalytic performance was compared to that of established noble-metal-containing photosensitizers such as [Ir(ppy)(2)(bpy)][PF6] (Hppy = 2-phenylpyridine, bpy = 2,2'-bipyridine).